rfc9810v1.txt   rfc9810.txt 
Internet Engineering Task Force (IETF) H. Brockhaus Internet Engineering Task Force (IETF) H. Brockhaus
Request for Comments: 9810 D. von Oheimb Request for Comments: 9810 D. von Oheimb
Obsoletes: 4210, 9480 Siemens Obsoletes: 4210, 9480 Siemens
Updates: 5912 M. Ounsworth Updates: 5912 M. Ounsworth
Category: Standards Track J. Gray Category: Standards Track J. Gray
ISSN: 2070-1721 Entrust ISSN: 2070-1721 Entrust
June 2025 July 2025
Internet X.509 Public Key Infrastructure -- Certificate Management Internet X.509 Public Key Infrastructure -- Certificate Management
Protocol (CMP) Protocol (CMP)
Abstract Abstract
This document describes the Internet X.509 Public Key Infrastructure This document describes the Internet X.509 Public Key Infrastructure
(PKI) Certificate Management Protocol (CMP). Protocol messages are (PKI) Certificate Management Protocol (CMP). Protocol messages are
defined for X.509v3 certificate creation and management. CMP defined for X.509v3 certificate creation and management. CMP
provides interactions between client systems and PKI components such provides interactions between client systems and PKI components such
as a Registration Authority (RA) and a Certification Authority (CA). as a Registration Authority (RA) and a Certification Authority (CA).
This document adds support for management of certificates containing This document adds support for management of certificates containing
a Key Encapsulation Mechanism (KEM) public key and uses EnvelopedData a Key Encapsulation Mechanism (KEM) public key and uses EnvelopedData
instead of EncryptedValue. This document also includes the updates instead of EncryptedValue. This document also includes the updates
specified in Section 2 and Appendix A.2 of RFC 9480. specified in Section 2 and Appendix A.2 of RFC 9480.
The updates maintain backward compatibility with CMP version 2
wherever possible. Updates to CMP version 2 are improving crypto
agility, extending the polling mechanism, adding new general message
types, and adding extended key usages (EKUs) to identify special CMP
server authorizations. CMP version 3 is introduced for changes to
the ASN.1 syntax, which support EnvelopedData, certConf with hashAlg,
POPOPrivKey with agreeMAC, and RootCaKeyUpdateContent in ckuann
messages.
This document obsoletes RFC 4210, and together with RFC 9811, it also This document obsoletes RFC 4210, and together with RFC 9811, it also
obsoletes RFC 9480. Appendix F of this document updates Section 9 of obsoletes RFC 9480. Appendix F of this document updates Section 9 of
RFC 5912. RFC 5912.
Status of This Memo Status of This Memo
This is an Internet Standards Track document. This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has (IETF). It represents the consensus of the IETF community. It has
skipping to change at line 95 skipping to change at line 86
4.1. End Entity Initialization 4.1. End Entity Initialization
4.2. Initial Registration/Certification 4.2. Initial Registration/Certification
4.2.1. Criteria Used 4.2.1. Criteria Used
4.2.1.1. Initiation of Registration/Certification 4.2.1.1. Initiation of Registration/Certification
4.2.1.2. End Entity Message Origin Authentication 4.2.1.2. End Entity Message Origin Authentication
4.2.1.3. Location of Key Generation 4.2.1.3. Location of Key Generation
4.2.1.4. Confirmation of Successful Certification 4.2.1.4. Confirmation of Successful Certification
4.2.2. Initial Registration/Certification Schemes 4.2.2. Initial Registration/Certification Schemes
4.2.2.1. Centralized Scheme 4.2.2.1. Centralized Scheme
4.2.2.2. Basic Authenticated Scheme 4.2.2.2. Basic Authenticated Scheme
4.3. Proof-of-Possession (POP) of Private Key 4.3. POP of Private Key
4.3.1. Signature Keys 4.3.1. Signature Keys
4.3.2. Encryption Keys 4.3.2. Encryption Keys
4.3.3. Key Agreement Keys 4.3.3. Key Agreement Keys
4.3.4. Key Encapsulation Mechanism Keys 4.3.4. KEM Keys
4.4. Root CA Key Update 4.4. Root CA Key Update
4.4.1. CA Operator Actions 4.4.1. CA Operator Actions
4.4.2. Verifying Certificates 4.4.2. Verifying Certificates
4.4.2.1. Verification in Cases 1 and 4 4.4.2.1. Verification in Cases 1 and 4
4.4.2.2. Verification in Case 2 4.4.2.2. Verification in Case 2
4.4.2.3. Verification in Case 3 4.4.2.3. Verification in Case 3
4.4.3. Revocation - Change of the CA Key 4.4.3. Revocation - Change of the CA Key
4.5. Extended Key Usage for PKI Entities 4.5. EKU for PKI Entities
5. Data Structures 5. Data Structures
5.1. Overall PKI Message 5.1. Overall PKI Message
5.1.1. PKI Message Header 5.1.1. PKI Message Header
5.1.1.1. ImplicitConfirm 5.1.1.1. ImplicitConfirm
5.1.1.2. ConfirmWaitTime 5.1.1.2. ConfirmWaitTime
5.1.1.3. OrigPKIMessage 5.1.1.3. OrigPKIMessage
5.1.1.4. CertProfile 5.1.1.4. CertProfile
5.1.1.5. KemCiphertextInfo 5.1.1.5. KemCiphertextInfo
5.1.2. PKI Message Body 5.1.2. PKI Message Body
5.1.3. PKI Message Protection 5.1.3. PKI Message Protection
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5.1.3.4. Key Encapsulation 5.1.3.4. Key Encapsulation
5.1.3.5. Multiple Protection 5.1.3.5. Multiple Protection
5.2. Common Data Structures 5.2. Common Data Structures
5.2.1. Requested Certificate Contents 5.2.1. Requested Certificate Contents
5.2.2. Encrypted Values 5.2.2. Encrypted Values
5.2.3. Status Codes and Failure Information for PKI Messages 5.2.3. Status Codes and Failure Information for PKI Messages
5.2.4. Certificate Identification 5.2.4. Certificate Identification
5.2.5. Out-of-Band Root CA Public Key 5.2.5. Out-of-Band Root CA Public Key
5.2.6. Archive Options 5.2.6. Archive Options
5.2.7. Publication Information 5.2.7. Publication Information
5.2.8. Proof-of-Possession Structures 5.2.8. POP Structures
5.2.8.1. raVerified 5.2.8.1. raVerified
5.2.8.2. POPOSigningKey Structure 5.2.8.2. POPOSigningKey Structure
5.2.8.3. POPOPrivKey Structure 5.2.8.3. POPOPrivKey Structure
5.2.8.4. Summary of POP Options 5.2.8.4. Summary of POP Options
5.2.9. GeneralizedTime 5.2.9. GeneralizedTime
5.3. Operation-Specific Data Structures 5.3. Operation-Specific Data Structures
5.3.1. Initialization Request 5.3.1. Initialization Request
5.3.2. Initialization Response 5.3.2. Initialization Response
5.3.3. Certification Request 5.3.3. Certification Request
5.3.4. Certification Response 5.3.4. Certification Response
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5.3.19.18. KEM Ciphertext 5.3.19.18. KEM Ciphertext
5.3.20. PKI General Response Content 5.3.20. PKI General Response Content
5.3.21. Error Message Content 5.3.21. Error Message Content
5.3.22. Polling Request and Response 5.3.22. Polling Request and Response
6. Mandatory PKI Management Functions 6. Mandatory PKI Management Functions
6.1. Root CA Initialization 6.1. Root CA Initialization
6.2. Root CA Key Update 6.2. Root CA Key Update
6.3. Subordinate CA Initialization 6.3. Subordinate CA Initialization
6.4. CRL Production 6.4. CRL Production
6.5. PKI Information Request 6.5. PKI Information Request
6.6. Cross Certification 6.6. Cross-Certification
6.6.1. One-Way Request-Response Scheme 6.6.1. One-Way Request-Response Scheme
6.7. End Entity Initialization 6.7. End Entity Initialization
6.7.1. Acquisition of PKI Information 6.7.1. Acquisition of PKI Information
6.7.2. Out-of-Band Verification of the Root CA Key 6.7.2. Out-of-Band Verification of the Root CA Key
6.8. Certificate Request 6.8. Certificate Request
6.9. Key Update 6.9. Key Update
7. Version Negotiation 7. Version Negotiation
7.1. Supporting RFC 2510 Implementations 7.1. Supporting RFC 2510 Implementations
7.1.1. Clients Talking to RFC 2510 Servers 7.1.1. Clients Talking to RFC 2510 Servers
7.1.2. Servers Receiving Version cmp1999 PKIMessages 7.1.2. Servers Receiving Version cmp1999 PKIMessages
8. Security Considerations 8. Security Considerations
8.1. On the Necessity of Proof-of-Possession 8.1. On the Necessity of POP
8.2. Proof-of-Possession with a Decryption Key 8.2. POP with a Decryption Key
8.3. Proof-of-Possession by Exposing the Private Key 8.3. POP by Exposing the Private Key
8.4. Attack Against Diffie-Hellman Key Exchange 8.4. Attack Against DH Key Exchange
8.5. Perfect Forward Secrecy 8.5. Perfect Forward Secrecy
8.6. Private Keys for Certificate Signing and CMP Message 8.6. Private Keys for Certificate Signing and CMP Message
Protection Protection
8.7. Entropy of Random Numbers, Key Pairs, and Shared Secret 8.7. Entropy of Random Numbers, Key Pairs, and Shared Secret
Information Information
8.8. Recurring Usage of KEM Keys for Message Protection 8.8. Recurring Usage of KEM Keys for Message Protection
8.9. Trust Anchor Provisioning Using CMP Messages 8.9. Trust Anchor Provisioning Using CMP Messages
8.10. Authorizing Requests for Certificates with Specific EKUs 8.10. Authorizing Requests for Certificates with Specific EKUs
8.11. Usage of Certificate Transparency Logs 8.11. Usage of CT Logs
9. IANA Considerations 9. IANA Considerations
10. References 10. References
10.1. Normative References 10.1. Normative References
10.2. Informative References 10.2. Informative References
Appendix A. Reasons for the Presence of RAs Appendix A. Reasons for the Presence of RAs
Appendix B. The Use of Revocation Passphrase Appendix B. The Use of Revocation Passphrase
Appendix C. PKI Management Message Profiles (REQUIRED) Appendix C. PKI Management Message Profiles (REQUIRED)
C.1. General Rules for Interpretation of These Profiles C.1. General Rules for Interpretation of These Profiles
C.2. Algorithm Use Profile C.2. Algorithm Use Profile
C.3. Proof-of-Possession Profile C.3. POP Profile
C.4. Initial Registration/Certification (Basic Authenticated C.4. Initial Registration/Certification (Basic Authenticated
Scheme) Scheme)
C.5. Certificate Request C.5. Certificate Request
C.6. Key Update Request C.6. Key Update Request
Appendix D. PKI Management Message Profiles (OPTIONAL) Appendix D. PKI Management Message Profiles (OPTIONAL)
D.1. General Rules for Interpretation of These Profiles D.1. General Rules for Interpretation of These Profiles
D.2. Algorithm Use Profile D.2. Algorithm Use Profile
D.3. Self-Signed Certificates D.3. Self-Signed Certificates
D.4. Root CA Key Update D.4. Root CA Key Update
D.5. PKI Information Request/Response D.5. PKI Information Request/Response
D.6. Cross-Certification Request/Response (1-way) D.6. Cross-Certification Request/Response (1-way)
D.7. In-Band Initialization Using External Identity Certificate D.7. In-Band Initialization Using External Identity Certificate
Appendix E. Variants of Using KEM Keys for PKI Message Protection Appendix E. Variants of Using KEM Keys for PKI Message Protection
Appendix F. Compilable ASN.1 Definitions Appendix F. Compilable ASN.1 Definitions
Acknowledgements Acknowledgements
Authors' Addresses Authors' Addresses
1. Introduction 1. Introduction
This document describes the Internet X.509 Public Key Infrastructure This document describes the Internet X.509 PKI CMP. Protocol
(PKI) Certificate Management Protocol (CMP). Protocol messages are messages are defined for certificate creation and management. The
defined for certificate creation and management. The term term "certificate" in this document refers to an X.509v3 certificate
"certificate" in this document refers to an X.509v3 Certificate as as defined in [RFC5280].
defined in [RFC5280].
1.1. Changes Made by RFC 4210 1.1. Changes Made by RFC 4210
[RFC4210] differs from [RFC2510] in the following areas: [RFC4210] differs from [RFC2510] in the following areas:
* The PKI management message profile section is split to two * The PKI management message profile section is split to two
appendices: the required profile and the optional profile. Some appendices: the required profile and the optional profile. Some
of the formerly mandatory functionality is moved to the optional of the formerly mandatory functionality is moved to the optional
profile. profile.
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* The new specification contains some less prominent protocol * The new specification contains some less prominent protocol
enhancements and improved explanatory text on several issues. enhancements and improved explanatory text on several issues.
1.2. Updates Made by RFC 9480 1.2. Updates Made by RFC 9480
CMP Updates [RFC9480] and CMP Algorithms [RFC9481] updated [RFC4210], CMP Updates [RFC9480] and CMP Algorithms [RFC9481] updated [RFC4210],
supporting the PKI management operations specified in the Lightweight supporting the PKI management operations specified in the Lightweight
CMP Profile [RFC9483], in the following areas: CMP Profile [RFC9483], in the following areas:
* Added new extended key usages for various CMP server types, e.g., * Added new extended key usages (EKUs) for various CMP server types,
registration authority and certification authority, to express the e.g., RA and CA, to express the authorization of the certificate
authorization of the certificate holder that acts as the indicated holder that acts as the indicated type of PKI management entity.
type of PKI management entity.
* Extended the description of multiple protection to cover * Extended the description of multiple protection to cover
additional use cases, e.g., batch processing of messages. additional use cases, e.g., batch processing of messages.
* Used the Cryptographic Message Syntax (CMS) [RFC5652] type * Used the Cryptographic Message Syntax (CMS) [RFC5652] type
EnvelopedData as the preferred choice instead of EncryptedValue to EnvelopedData as the preferred choice instead of EncryptedValue to
better support crypto agility in CMP. better support crypto agility in CMP.
For reasons of completeness and consistency, the type For reasons of completeness and consistency, the type
EncryptedValue has been exchanged in all occurrences. This EncryptedValue has been exchanged in all occurrences. This
includes the protection of centrally generated private keys, includes the protection of centrally generated private keys,
encryption of certificates, proof-of-possession methods, and encryption of certificates, Proof-of-Possession (POP) methods, and
protection of revocation passphrases. To properly differentiate protection of revocation passphrases. To properly differentiate
the support of EnvelopedData instead of EncryptedValue, CMP the support of EnvelopedData instead of EncryptedValue, CMP
version 3 is introduced in case a transaction is supposed to use version 3 is introduced in case a transaction is supposed to use
EnvelopedData. EnvelopedData.
Note: According to point 9 in Section 2.1 of [RFC4211], the use of Note: According to point 9 in Section 2.1 of [RFC4211], the use of
the EncryptedValue structure has been deprecated in favor of the the EncryptedValue structure has been deprecated in favor of the
EnvelopedData structure. [RFC4211] offers the EncryptedKey EnvelopedData structure. [RFC4211] offers the EncryptedKey
structure a choice of EncryptedValue and EnvelopedData for structure a choice of EncryptedValue and EnvelopedData for
migration to EnvelopedData. migration to EnvelopedData.
* Offered an optional hashAlg field in CertStatus supporting cases * Offered an optional hashAlg field in CertStatus supporting cases
that a certificate needs to be confirmed that has a signature when a certificate needs to be confirmed, but the certificate was
algorithm that does not indicate a specific hash algorithm to use signed using a signature algorithm that does not indicate a
for computing the certHash. This is also in preparation for specific hash algorithm to use for computing the certHash. This
upcoming post-quantum algorithms. is also in preparation for upcoming post-quantum algorithms.
* Added new general message types to request CA certificates, a root * Added new general message types to request CA certificates, a root
CA update, a certificate request template, or Certificate CA update, a certificate request template, or Certificate
Revocation List (CRL) updates. Revocation List (CRL) updates.
* Extended the use of polling to p10cr, certConf, rr, genm, and * Extended the use of polling to p10cr, certConf, rr, genm, and
error messages. error messages.
* Deleted the mandatory algorithm profile in Appendix C.2 and * Deleted the mandatory algorithm profile in Appendix C.2 and
instead referred to Section 7 of [RFC9481]. instead referred to Section 7 of [RFC9481].
* Added Sections 8.6, 8.7, 8.9, and 8.10 to the security * Added Sections 8.6, 8.7, 8.9, and 8.10 to the security
considerations. considerations.
1.3. Changes Made by This Document 1.3. Changes Made by This Document
This document obsoletes [RFC4210] and [RFC9480]. It includes the This document obsoletes [RFC4210] and [RFC9480].
changes specified by Section 2 and Appendix A.2 of [RFC9480] as
described in Section 1.2. Additionally, this document updates the
content of [RFC4210] in the following areas:
* Added Section 3.1.1.4 introducing the Key Generation Authority. Backward compatibility with CMP version 2 is maintained wherever
possible. Updates to CMP version 2 improve crypto agility, extend
the polling mechanism, add new general message types, and add EKUs to
identify special CMP server authorizations. CMP version 3 is
introduced for changes to the ASN.1 syntax, which support
EnvelopedData, certConf with hashAlg, POPOPrivKey with agreeMAC, and
RootCaKeyUpdateContent in ckuann messages.
The updates made in this document include the changes specified by
Section 2 and Appendix A.2 of [RFC9480] as described in Section 1.2.
Additionally, this document updates the content of [RFC4210] in the
following areas:
* Added Section 3.1.1.4 introducing the Key Generation Authority
(KGA).
* Extended Section 3.1.2 regarding use of Certificate Transparency * Extended Section 3.1.2 regarding use of Certificate Transparency
logs. (CT) logs.
* Updated Section 4.4 introducing RootCaKeyUpdateContent as an * Updated Section 4.4 introducing RootCaKeyUpdateContent as an
alternative to using a repository to acquire new root CA alternative to using a repository to acquire new root CA
certificates. certificates.
* Added Section 5.1.1.3 containing a description of origPKIMessage * Added Section 5.1.1.3 containing a description of origPKIMessage
content, moved here from Section 5.1.3.4. content, moved here from Section 5.1.3.4.
* Added support for KEM keys for proof-of-possession to Sections 4.3 * Added support for KEM keys for POP to Sections 4.3 and 5.2.8, for
and 5.2.8, for message protection to Sections 5.1.1 and 5.1.3.4 message protection to Sections 5.1.1 and 5.1.3.4 and Appendix E,
and Appendix E, and for usage with CMS EnvelopedData to and for usage with CMS EnvelopedData to Section 5.2.2.
Section 5.2.2.
* Deprecated CAKeyUpdAnnContent in favor of RootCaKeyUpdateContent. * Deprecated CAKeyUpdAnnContent in favor of RootCaKeyUpdateContent.
* Incorporated the request message behavioral clarifications from * Incorporated the request message behavioral clarifications from
Appendix C of [RFC4210] to Section 5. The definition of Appendix C of [RFC4210] to Section 5. The definition of
altCertTemplate was incorporated into Section 5.2.1, and the altCertTemplate was incorporated into Section 5.2.1, and the
clarification on POPOSigningKey and on POPOPrivKey was clarification on POPOSigningKey and on POPOPrivKey was
incorporated into Section 5.2.8. incorporated into Section 5.2.8.
* Added support for CMS EnvelopedData to different proof-of- * Added support for CMS EnvelopedData to different POP methods for
possession methods for transferring encrypted private keys, transferring encrypted private keys, certificates, and challenges
certificates, and challenges to Section 5.2.8. to Section 5.2.8.
* Added Sections 8.1, 8.5, 8.8, and 8.11 to the security * Added Sections 8.1, 8.5, 8.8, and 8.11 to the security
considerations. considerations.
2. Terminology and Abbreviations 2. Terminology and Abbreviations
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
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3. PKI Management Overview 3. PKI Management Overview
The PKI must be structured to be consistent with the types of The PKI must be structured to be consistent with the types of
individuals who must administer it. Providing such administrators individuals who must administer it. Providing such administrators
with unbounded choices not only complicates the software required but with unbounded choices not only complicates the software required but
also increases the chances that a subtle mistake by an administrator also increases the chances that a subtle mistake by an administrator
or software developer will result in broader compromise. Similarly, or software developer will result in broader compromise. Similarly,
restricting administrators with cumbersome mechanisms will cause them restricting administrators with cumbersome mechanisms will cause them
not to use the PKI. not to use the PKI.
Management protocols are REQUIRED to support on-line interactions Management protocols are REQUIRED to support online interactions
between Public Key Infrastructure (PKI) components. For example, a between PKI components. For example, a management protocol might be
management protocol might be used between a Certification Authority used between a CA and a client system with which a key pair is
(CA) and a client system with which a key pair is associated or associated or between two CAs that issue cross-certificates for each
between two CAs that issue cross-certificates for each other. other.
3.1. PKI Management Model 3.1. PKI Management Model
Before specifying particular message formats and procedures, we first Before specifying particular message formats and procedures, we first
define the entities involved in PKI management and their interactions define the entities involved in PKI management and their interactions
(in terms of the PKI management functions required). We then group (in terms of the PKI management functions required). We then group
these functions in order to accommodate different identifiable types these functions in order to accommodate different identifiable types
of end entities. of EEs.
3.1.1. Definitions of PKI Entities 3.1.1. Definitions of PKI Entities
The entities involved in PKI management include the end entity (i.e., The entities involved in PKI management include the EE (i.e., the
the entity to whom the certificate is issued) and the certification entity to whom the certificate is issued) and the CA (i.e., the
authority (i.e., the entity that issues the certificate). A entity that issues the certificate). An RA might also be involved in
registration authority might also be involved in PKI management. PKI management.
3.1.1.1. Subjects and End Entities 3.1.1.1. Subjects and End Entities
The term "subject" is used here to refer to the entity to whom the The term "subject" is used here to refer to the entity to whom the
certificate is issued, typically named in the subject or certificate is issued, typically named in the subject or
subjectAltName field of a certificate. When we wish to distinguish subjectAltName field of a certificate. When we wish to distinguish
the tools and/or software used by the subject (e.g., a local the tools and/or software used by the subject (e.g., a local
certificate management module), we will use the term "subject certificate management module), we will use the term "subject
equipment". In general, the term "end entity" (EE), rather than equipment". In general, the term "end entity" (EE), rather than
"subject", is preferred in order to avoid confusion with the field "subject", is preferred in order to avoid confusion with the field
name. It is important to note that the end entities here will name. It is important to note that the EEs here will include not
include not only human users of applications but also applications only human users of applications but also applications themselves
themselves (e.g., for Internet Key Exchange Protocol (IKE) / IPsec) (e.g., for Internet Key Exchange Protocol (IKE) / IPsec) or devices
or devices (e.g., routers or industrial control systems). This (e.g., routers or industrial control systems). This factor
factor influences the protocols that the PKI management operations influences the protocols that the PKI management operations use; for
use; for example, application software is far more likely to know example, application software is far more likely to know exactly
exactly which certificate extensions are required than are human which certificate extensions are required than are human users. PKI
users. PKI management entities are also end entities in the sense management entities are also EEs in the sense that they are sometimes
that they are sometimes named in the subject or subjectAltName field named in the subject or subjectAltName field of a certificate or
of a certificate or cross-certificate. Where appropriate, the term cross-certificate. Where appropriate, the term "end entity" will be
"end entity" will be used to refer to end entities who are not PKI used to refer to EEs who are not PKI management entities.
management entities.
All end entities require secure local access to some information -- All EEs require secure local access to some information -- at a
at a minimum, their own name and private key, the name of a CA that minimum, their own name and private key, the name of a CA that is
is directly trusted by this entity, and that CA's public key (or a directly trusted by this entity, and that CA's public key (or a
fingerprint of the public key where a self-certified version is fingerprint of the public key where a self-certified version is
available elsewhere). Implementations MAY use secure local storage available elsewhere). Implementations MAY use secure local storage
for more than this minimum (e.g., the end entity's own certificates for more than this minimum (e.g., the EE's own certificates or
or application-specific information). The form of storage will also application-specific information). The form of storage will also
vary -- from files to tamper-resistant cryptographic tokens. The vary -- from files to tamper-resistant cryptographic tokens. The
information stored in such local, trusted storage is referred to here information stored in such local, trusted storage is referred to here
as the end entity's Trusted Execution Environment (TEE), also known as the EE's TEE, also known as Personal Security Environment (PSE).
as Personal Security Environment (PSE).
Though TEE formats are beyond the scope of this document (they are Though TEE formats are beyond the scope of this document (they are
very dependent on equipment, et cetera), a generic interchange format very dependent on equipment, et cetera), a generic interchange format
for TEEs is defined here: a certification response message (see for TEEs is defined here: a certification response message (see
Section 5.3.4) MAY be used. Section 5.3.4) MAY be used.
3.1.1.2. Certification Authority 3.1.1.2. Certification Authority
The certification authority (CA) may or may not actually be a real The CA may or may not actually be a real "third party" from the EE's
"third party" from the end entity's point of view. Quite often, the point of view. Quite often, the CA will actually belong to the same
CA will actually belong to the same organization as the end entities organization as the EEs it supports.
it supports.
Again, we use the term "CA" to refer to the entity named in the Again, we use the term "CA" to refer to the entity named in the
issuer field of a certificate. When it is necessary to distinguish issuer field of a certificate. When it is necessary to distinguish
the software or hardware tools used by the CA, we use the term "CA the software or hardware tools used by the CA, we use the term "CA
equipment". equipment".
The CA equipment will often include both an "off-line" component and The CA equipment will often include both an "offline" component and
an "on-line" component, with the CA private key only available to the an "online" component, with the CA private key only available to the
"off-line" component. This is, however, a matter for implementers "offline" component. This is, however, a matter for implementers
(though it is also relevant as a policy issue). (though it is also relevant as a policy issue).
We use the term "root CA" to indicate a CA that is directly trusted We use the term "root CA" to indicate a CA that is directly trusted
by an end entity; that is, securely acquiring the value of a root CA by an EE; that is, securely acquiring the value of a root CA public
public key requires some out-of-band step(s). This term is not meant key requires some out-of-band step(s). This term is not meant to
to imply that a root CA is necessarily at the top of any hierarchy, imply that a root CA is necessarily at the top of any hierarchy,
simply that the CA in question is trusted directly. The "root CA" simply that the CA in question is trusted directly. The "root CA"
may provide its trust anchor information with or without using a may provide its trust anchor information with or without using a
certificate. In some circumstances, such a certificate may be self- certificate. In some circumstances, such a certificate may be self-
signed, but in other circumstances, it may be cross-signed, signed by signed, but in other circumstances, it may be cross-signed, signed by
a peer, signed by a superior CA, or unsigned. a peer, signed by a superior CA, or unsigned.
Note that other documents like [X509.2019] and [RFC5280] use the term Note that other documents like [X509.2019] and [RFC5280] use the term
"trusted CA" or "trust anchor" instead of "root CA". This document "trusted CA" or "trust anchor" instead of "root CA". This document
continues using "root CA" based on the above definition because it is continues using "root CA" based on the above definition because it is
also present in the ASN.1 syntax that cannot be changed easily. also present in the ASN.1 syntax that cannot be changed easily.
A "subordinate CA" is one that is not a root CA for the end entity in A "subordinate CA" is one that is not a root CA for the EE in
question. Often, a subordinate CA will not be a root CA for any question. Often, a subordinate CA will not be a root CA for any
entity, but this is not mandatory. entity, but this is not mandatory.
3.1.1.3. Registration Authority 3.1.1.3. Registration Authority
In addition to end entities and CAs, many environments call for the In addition to EEs and CAs, many environments call for the existence
existence of a Registration Authority (RA) separate from the of an RA separate from the CA. The functions that the RA may carry
Certification Authority. The functions that the registration out will vary from case to case but MAY include identity checking,
authority may carry out will vary from case to case but MAY include token distribution, checking certificate requests and authentication
identity checking, token distribution, checking certificate requests of their origin, revocation reporting, name assignment, archival of
and authentication of their origin, revocation reporting, name key pairs, et cetera.
assignment, archival of key pairs, et cetera.
This document views the RA as an OPTIONAL component: When it is not This document views the RA as an OPTIONAL component: When it is not
present, the CA is assumed to be able to carry out the RA's functions present, the CA is assumed to be able to carry out the RA's functions
so that the PKI management protocols are the same from the end so that the PKI management protocols are the same from the EE's point
entity's point of view. of view.
Again, we distinguish, where necessary, between the RA and the tools Again, we distinguish, where necessary, between the RA and the tools
used (the "RA equipment"). used (the "RA equipment").
Note that an RA is itself an end entity. We further assume that all Note that an RA is itself an EE. We further assume that all RAs are
RAs are in fact certified end entities and that RAs have private keys in fact certified EEs and that RAs have private keys that are usable
that are usable for signing. How a particular CA equipment for signing. How a particular CA equipment identifies some EEs as
identifies some end entities as RAs is an implementation issue (i.e., RAs is an implementation issue (i.e., this document specifies no
this document specifies no special RA certification operation). We special RA certification operation). We do not mandate that the RA
do not mandate that the RA is certified by the CA with which it is is certified by the CA with which it is interacting at the moment (so
interacting at the moment (so one RA may work with more than one CA one RA may work with more than one CA whilst only being certified
whilst only being certified once). once).
In some circumstances, end entities will communicate directly with a In some circumstances, EEs will communicate directly with a CA even
CA even where an RA is present. For example, for initial where an RA is present. For example, for initial registration and/or
registration and/or certification, the end entity may use its RA but certification, the EE may use its RA but communicate directly with
communicate directly with the CA in order to refresh its certificate. the CA in order to refresh its certificate.
3.1.1.4. Key Generation Authority 3.1.1.4. Key Generation Authority
A Key Generation Authority (KGA) is a PKI management entity A KGA is a PKI management entity generating key pairs on behalf of an
generating key pairs on behalf of an end entity. As the KGA EE. As the KGA generates the key pair, it knows the public and the
generates the key pair, it knows the public and the private part. private part.
This document views the KGA as an OPTIONAL component. When it is not This document views the KGA as an OPTIONAL component. When it is not
present and central key generation is needed, the CA is assumed to be present and central key generation is needed, the CA is assumed to be
able to carry out the KGA's functions so that the PKI management able to carry out the KGA's functions so that the PKI management
protocol messages are the same from the end entity's point of view. protocol messages are the same from the EE's point of view. If
If certain tasks of a CA are delegated to other components, this certain tasks of a CA are delegated to other components, this
delegation needs authorization, which can be indicated by extended delegation needs authorization, which can be indicated by EKUs (see
key usages (see Section 4.5). Section 4.5).
Note: When doing central generation of key pairs, implementers should Note: When doing central generation of key pairs, implementers should
consider the implications of server-side retention on the overall consider the implications of server-side retention on the overall
security of the system; in some cases, retention is good, for security of the system; in some cases, retention is good, for
example, for escrow reasons, but in other cases, the server should example, for escrow reasons, but in other cases, the server should
clear its copy after delivery to the end entity. clear its copy after delivery to the EE.
Note: If the CA delegates key generation to a KGA, the KGA can be Note: If the CA delegates key generation to a KGA, the KGA can be
collocated with the RA. collocated with the RA.
3.1.2. PKI Management Requirements 3.1.2. PKI Management Requirements
The protocols given here meet the following requirements on PKI The protocols given here meet the following requirements on PKI
management management
1. PKI management must conform to the ISO/IEC 9594-8/ITU-T X.509 1. PKI management must conform to the ISO/IEC 9594-8/ITU-T X.509
standards. standards, in particular [X509.2019].
2. It must be possible to regularly update any key pair without 2. It must be possible to regularly update any key pair without
affecting any other key pair. affecting any other key pair.
3. The use of confidentiality in PKI management protocols must be 3. The use of confidentiality in PKI management protocols must be
kept to a minimum in order to ease acceptance in environments kept to a minimum in order to ease acceptance in environments
where strong confidentiality might cause regulatory problems. where strong confidentiality might cause regulatory problems.
4. PKI management protocols must allow the use of different 4. PKI management protocols must allow the use of different
industry-standard cryptographic algorithms (see CMP Algorithms industry-standard cryptographic algorithms (see CMP Algorithms
[RFC9481]). This means that any given CA, RA, or end entity [RFC9481]). This means that any given CA, RA, or EE may, in
may, in principle, use whichever algorithms suit it for its own principle, use whichever algorithms suit it for its own key
key pair(s). pair(s).
5. PKI management protocols must not preclude the generation of key 5. PKI management protocols must not preclude the generation of key
pairs by the end entity concerned, by a KGA, or by a CA. Key pairs by the EE concerned, by a KGA, or by a CA. Key generation
generation may also occur elsewhere, but for the purposes of PKI may also occur elsewhere, but for the purposes of PKI
management, we can regard key generation as occurring wherever management, we can regard key generation as occurring wherever
the key is first present at an end entity, KGA, or CA. the key is first present at an EE, KGA, or CA.
6. PKI management protocols must support the publication of 6. PKI management protocols must support the publication of
certificates by the end entity concerned, by an RA, or by a CA. certificates by the EE concerned, by an RA, or by a CA.
Different implementations and different environments may choose Different implementations and different environments may choose
any of the above approaches. any of the above approaches.
7. PKI management protocols must support the production of 7. PKI management protocols must support the production of
Certificate Revocation Lists (CRLs) by allowing certified end Certificate Revocation Lists (CRLs) by allowing certified EEs to
entities to make requests for the revocation of certificates. make requests for the revocation of certificates. This must be
This must be done in such a way that the denial-of-service done in such a way that the denial-of-service attacks, which are
attacks, which are possible, are not made simpler. possible, are not made simpler.
8. PKI management protocols must be usable over a variety of 8. PKI management protocols must be usable over a variety of
"transport" mechanisms, specifically including mail, Hypertext "transport" mechanisms, specifically including email, Hypertext
Transfer Protocol (HTTP), Message Queuing Telemetry Transport Transfer Protocol (HTTP), Message Queuing Telemetry Transport
(MQTT), Constrained Application Protocol (CoAP), and off-line (MQTT), Constrained Application Protocol (CoAP), and various
file-based. offline and non-networked file transfer methods.
9. Final authority for certification creation rests with the CA. 9. Final authority for certification creation rests with the CA.
No RA or end entity equipment can assume that any certificate No RA or EE equipment can assume that any certificate issued by
issued by a CA will contain what was requested; a CA may alter a CA will contain what was requested; a CA may alter certificate
certificate field values or may add, delete, or alter extensions field values or may add, delete, or alter extensions according
according to its operating policy. In other words, all PKI to its operating policy. In other words, all PKI entities (EEs,
entities (end entities, RAs, KGAs, and CAs) must be capable of RAs, KGAs, and CAs) must be capable of handling responses to
handling responses to requests for certificates in which the requests for certificates in which the actual certificate issued
actual certificate issued is different from that requested (for is different from that requested (for example, a CA may shorten
example, a CA may shorten the validity period requested). Note the validity period requested). Note that policy may dictate
that policy may dictate that the CA must not publish or that the CA must not publish or otherwise distribute the
otherwise distribute the certificate until the requesting entity certificate until the requesting entity has reviewed and
has reviewed and accepted the newly created certificate or the accepted the newly created certificate or the POP is completed.
POP is completed. In case of publication of the certificate In case of publication of the certificate (when using indirect
(when using indirect POP, see Section 8.11) or a precertificate POP, see Section 8.11) or a precertificate in a CT log
in a Certificate Transparency log [RFC9162], the certificate [RFC9162], the certificate must be revoked if it was not
must be revoked if it was not accepted by the EE or the POP accepted by the EE or the POP could not be completed.
could not be completed.
10. A graceful, scheduled changeover from one non-compromised CA key 10. A graceful, scheduled changeover from one non-compromised CA key
pair to the next (CA key update) must be supported (note that if pair to the next (CA key update) must be supported (note that if
the CA key is compromised, re-initialization must be performed the CA key is compromised, re-initialization must be performed
for all entities in the domain of that CA). An end entity whose for all entities in the domain of that CA). An EE whose TEE
TEE contains the new CA public key (following a CA key update) contains the new CA public key (following a CA key update) may
may also need to be able to verify certificates verifiable using also need to be able to verify certificates verifiable using the
the old public key. End entities who directly trust the old CA old public key. EEs who directly trust the old CA key pair may
key pair may also need to be able to verify certificates signed also need to be able to verify certificates signed using the new
using the new CA private key (required for situations where the CA private key (required for situations where the old CA public
old CA public key is "hardwired" into the end entity's key is "hardwired" into the EE's cryptographic equipment).
cryptographic equipment).
11. The functions of an RA may, in some implementations or 11. The functions of an RA may, in some implementations or
environments, be carried out by the CA itself. The protocols environments, be carried out by the CA itself. The protocols
must be designed so that end entities will use the same protocol must be designed so that EEs will use the same protocol
regardless of whether the communication is with an RA or CA. regardless of whether the communication is with an RA or CA.
Naturally, the end entity must use the correct RA or CA public Naturally, the EE must use the correct RA or CA public key to
key to verify the protection of the communication. verify the protection of the communication.
12. Where an end entity requests a certificate containing a given 12. Where an EE requests a certificate containing a given public key
public key value, the end entity must be ready to demonstrate value, the EE must be ready to demonstrate possession of the
possession of the corresponding private key value. This may be corresponding private key value. This may be accomplished in
accomplished in various ways, depending on the type of various ways, depending on the type of certification request.
certification request. See Section 4.3 for details of the in- See Section 4.3 for details of the in-band methods defined for
band methods defined for the PKIX-CMP (i.e., Certificate the PKIX-CMP (i.e., CMP) messages.
Management Protocol) messages.
3.1.3. PKI Management Operations 3.1.3. PKI Management Operations
The following diagram shows the relationship between the entities The following diagram shows the relationship between the entities
defined above in terms of the PKI management operations. The letters defined above in terms of the PKI management operations. The letters
in the diagram indicate "protocols" in the sense that a defined set in the diagram indicate "protocols" in the sense that a defined set
of PKI management messages can be sent along each of the lettered of PKI management messages can be sent along each of the lettered
lines. lines.
+---+ cert. publish +------------+ j +---+ cert. publish +------------+ j
skipping to change at line 707 skipping to change at line 699
public key). public key).
2. End entity initialization: This includes importing a root CA 2. End entity initialization: This includes importing a root CA
public key and requesting information about the options supported public key and requesting information about the options supported
by a PKI management entity. by a PKI management entity.
3. Certification: Various operations result in the creation of new 3. Certification: Various operations result in the creation of new
certificates: certificates:
a. initial registration/certification: This is the process a. initial registration/certification: This is the process
whereby an end entity first makes itself known to a CA or RA, whereby an EE first makes itself known to a CA or RA, prior
prior to the CA issuing a certificate or certificates for to the CA issuing a certificate or certificates for that EE.
that end entity. The end result of this process (when it is The end result of this process (when it is successful) is
successful) is that a CA issues a certificate for an end that a CA issues a certificate for an EE's public key and
entity's public key and returns that certificate to the end returns that certificate to the EE and/or posts that
entity and/or posts that certificate in a repository. This certificate in a repository. This process may, and typically
process may, and typically will, involve multiple "steps", will, involve multiple "steps", possibly including an
possibly including an initialization of the end entity's initialization of the EE's equipment. For example, the EE's
equipment. For example, the end entity's equipment must be equipment must be securely initialized with the public key of
securely initialized with the public key of a CA, e.g., using a CA, e.g., using zero-touch methods like Bootstrapping
zero-touch methods like Bootstrapping Remote Secure Key Remote Secure Key Infrastructure (BRSKI) [RFC8995] or Secure
Infrastructure (BRSKI) [RFC8995] or Secure Zero Touch Zero Touch Provisioning (SZTP) [RFC8572], to be used in
Provisioning (SZTP) [RFC8572], to be used in validating validating certificate paths. Furthermore, an EE typically
certificate paths. Furthermore, an end entity typically
needs to be initialized with its own key pair(s). needs to be initialized with its own key pair(s).
b. key pair update: Every key pair needs to be updated regularly b. key pair update: Every key pair needs to be updated regularly
(i.e., replaced with a new key pair), and a new certificate (i.e., replaced with a new key pair), and a new certificate
needs to be issued. needs to be issued.
c. certificate update: As certificates expire, they may be c. certificate update: As certificates expire, they may be
"refreshed" if nothing relevant in the environment has "refreshed" if nothing relevant in the environment has
changed. changed.
d. CA key pair update: As with end entities, CA key pairs need d. CA key pair update: As with EEs, CA key pairs need to be
to be updated regularly; however, different mechanisms are updated regularly; however, different mechanisms are
required. required.
e. cross-certification request: One CA requests issuance of a e. cross-certification request: One CA requests issuance of a
cross-certificate from another CA. For the purposes of this cross-certificate from another CA. For the purposes of this
standard, the following terms are defined. A "cross- standard, the following terms are defined. A "cross-
certificate" is a certificate in which the subject CA and the certificate" is a certificate in which the subject CA and the
issuer CA are distinct and SubjectPublicKeyInfo contains a issuer CA are distinct and SubjectPublicKeyInfo contains a
verification key (i.e., the certificate has been issued for verification key (i.e., the certificate has been issued for
the subject CA's signing key pair). When it is necessary to the subject CA's signing key pair). When it is necessary to
distinguish more finely, the following terms may be used: A distinguish more finely, the following terms may be used: A
skipping to change at line 781 skipping to change at line 772
needed. The "means" defined in PKIX MAY involve the messages needed. The "means" defined in PKIX MAY involve the messages
specified in Sections 5.3.13 to 5.3.16 or MAY involve other specified in Sections 5.3.13 to 5.3.16 or MAY involve other
methods (for example, Lightweight Directory Access Protocol methods (for example, Lightweight Directory Access Protocol
(LDAP)) as described in [RFC4511] or [RFC2585] (the (LDAP)) as described in [RFC4511] or [RFC2585] (the
"Operational Protocols" documents of the PKIX series of "Operational Protocols" documents of the PKIX series of
specifications). specifications).
b. CRL publication: As for certificate publication. b. CRL publication: As for certificate publication.
5. Recovery operations: Some PKI management operations are used when 5. Recovery operations: Some PKI management operations are used when
an end entity has "lost" its TEE: an EE has "lost" its TEE:
a. key pair recovery: As an option, user client key materials a. key pair recovery: As an option, user client key materials
(e.g., a user's private key used for decryption purposes) MAY (e.g., a user's private key used for decryption purposes) MAY
be backed up by a CA, an RA, or a key backup system be backed up by a CA, an RA, or a key backup system
associated with a CA or RA. If an entity needs to recover associated with a CA or RA. If an entity needs to recover
these backed up key materials (e.g., as a result of a these backed up key materials (e.g., as a result of a
forgotten password or a lost key chain file), a protocol forgotten password or a lost key chain file), a protocol
exchange may be needed to support such recovery. exchange may be needed to support such recovery.
6. Revocation operations: Some PKI management operations result in 6. Revocation operations: Some PKI management operations result in
the creation of new CRL entries and/or new CRLs: the creation of new CRL entries and/or new CRLs:
a. revocation request: An authorized person advises a CA of an a. revocation request: An authorized person advises a CA of an
abnormal situation requiring certificate revocation. abnormal situation requiring certificate revocation.
7. TEE operations: Whilst the definition of TEE operations (e.g., 7. TEE operations: Whilst the definition of TEE operations (e.g.,
moving a TEE, changing a PIN, etc.) are beyond the scope of this moving a TEE, changing a PIN, etc.) are beyond the scope of this
specification, we do define a PKIMessage (CertRepMessage) that specification, we do define a PKIMessage (CertRepMessage) that
can form the basis of such operations. can form the basis of such operations.
Note that on-line protocols are not the only way of implementing the Note that online protocols are not the only way of implementing the
above operations. For all operations, there are off-line methods of above operations. For all operations, there are offline methods of
achieving the same result, and this specification does not mandate achieving the same result, and this specification does not mandate
use of on-line protocols. For example, when hardware tokens are use of online protocols. For example, when hardware tokens are used,
used, many of the operations MAY be achieved as part of the physical many of the operations MAY be achieved as part of the physical token
token delivery. delivery.
Later sections define a set of standard messages supporting the above Later sections define a set of standard messages supporting the above
operations. Transfer protocols for conveying these exchanges in operations. Transfer protocols for conveying these exchanges in
various environments (e.g., off-line: file-based; on-line: mail, HTTP various environments (e.g., offline: file-based; online: mail, HTTP
[RFC9811], MQTT, and CoAP [RFC9482]) are beyond the scope of this [RFC9811], MQTT, and CoAP [RFC9482]) are beyond the scope of this
document and must be specified separately. Appropriate transfer document and must be specified separately. Appropriate transfer
protocols MUST be capable of delivering the CMP messages reliably. protocols MUST be capable of delivering the CMP messages reliably.
CMP provides inbuilt integrity protection and authentication. The CMP provides inbuilt integrity protection and authentication. The
information communicated unencrypted in CMP messages does not contain information communicated unencrypted in CMP messages does not contain
sensitive information endangering the security of the PKI when sensitive information endangering the security of the PKI when
intercepted. However, it might be possible for an eavesdropper to intercepted. However, it might be possible for an eavesdropper to
utilize the available information to gather confidential technical or utilize the available information to gather confidential technical or
business-critical information. Therefore, users should consider business-critical information. Therefore, users should consider
protection of confidentiality on lower levels of the protocol stack, protection of confidentiality on lower levels of the protocol stack,
e.g., by using TLS [RFC8446], DTLS [RFC9147], or IPsec e.g., by using TLS [RFC8446], DTLS [RFC9147], or IPsec
[RFC7296][RFC4303]. [RFC7296][RFC4303].
4. Assumptions and Restrictions 4. Assumptions and Restrictions
4.1. End Entity Initialization 4.1. End Entity Initialization
The first step for an end entity in dealing with PKI management The first step for an EE in dealing with PKI management entities is
entities is to request information about the PKI functions supported to request information about the PKI functions supported and to
and to securely acquire a copy of the relevant root CA public key(s). securely acquire a copy of the relevant root CA public key(s).
4.2. Initial Registration/Certification 4.2. Initial Registration/Certification
There are many schemes that can be used to achieve initial There are many schemes that can be used to achieve initial
registration and certification of end entities. No one method is registration and certification of EEs. No one method is suitable for
suitable for all situations due to the range of policies that a CA all situations due to the range of policies that a CA may implement
may implement and the variation in the types of end entity that can and the variation in the types of EE that can occur.
occur.
However, we can classify the initial registration/certification However, we can classify the initial registration/certification
schemes that are supported by this specification. Note that the word schemes that are supported by this specification. Note that the word
"initial", above, is crucial: We are dealing with the situation where "initial", above, is crucial: We are dealing with the situation where
the end entity in question has had no previous contact with the PKI, the EE in question has had no previous contact with the PKI, except
except having received the root CA certificate of that PKI by some having received the root CA certificate of that PKI by some zero-
zero-touch method like BRSKI [RFC8995] [RFC9733] or SZTP [RFC8572]. touch method like BRSKI [RFC8995] [RFC9733] or SZTP [RFC8572]. In
In case the end entity already possesses certified keys, then some case the EE already possesses certified keys, then some
simplifications/alternatives are possible. simplifications/alternatives are possible.
Having classified the schemes that are supported by this Having classified the schemes that are supported by this
specification, we can then specify some as mandatory and some as specification, we can then specify some as mandatory and some as
optional. The goal is that the mandatory schemes cover a sufficient optional. The goal is that the mandatory schemes cover a sufficient
number of the cases that will arise in real use, whilst the optional number of the cases that will arise in real use, whilst the optional
schemes are available for special cases that arise less frequently. schemes are available for special cases that arise less frequently.
In this way, we achieve a balance between flexibility and ease of In this way, we achieve a balance between flexibility and ease of
implementation. implementation.
Further classification of mandatory and optional schemes addressing Further classification of mandatory and optional schemes addressing
different environments is available, e.g., in Appendices C and D of different environments is available, e.g., in Appendices C and D of
this specification on managing human user certificates as well as in this specification on managing human user certificates as well as in
the Lightweight CMP Profile [RFC9483] on fully automating certificate the Lightweight CMP Profile [RFC9483] on fully automating certificate
management in a machine-to-machine and Internet of Things (IoT) management in a machine-to-machine and Internet of Things (IoT)
environment. Also, industry standards like [ETSI-3GPP.33.310] for environment. Industry standards such as [ETSI-3GPP.33.310] for
mobile networks and [UNISIG.Subset-137] for Rail Automation adopted mobile networks and [UNISIG.Subset-137] for railroad automation have
CMP and have specified a set of mandatory schemes for their use case. adopted CMP and defined a series of mandatory schemes for their use
cases.
We will now describe the classification of initial registration/ We will now describe the classification of initial registration/
certification schemes. certification schemes.
4.2.1. Criteria Used 4.2.1. Criteria Used
4.2.1.1. Initiation of Registration/Certification 4.2.1.1. Initiation of Registration/Certification
In terms of the PKI messages that are produced, we can regard the In terms of the PKI messages that are produced, we can regard the
initiation of the initial registration/certification exchanges as initiation of the initial registration/certification exchanges as
occurring wherever the first PKI message relating to the end entity occurring wherever the first PKI message relating to the EE is
is produced. Note that the real-world initiation of the produced. Note that the real-world initiation of the registration/
registration/certification procedure may occur elsewhere (e.g., a certification procedure may occur elsewhere (e.g., a personnel
personnel department may telephone an RA operator or use zero touch department may telephone an RA operator or use zero-touch methods
methods like BRSKI [RFC8995] or SZTP [RFC8572]). like BRSKI [RFC8995] or SZTP [RFC8572]).
The possible locations are at the end entity, an RA, or a CA. The possible locations are at the EE, an RA, or a CA.
4.2.1.2. End Entity Message Origin Authentication 4.2.1.2. End Entity Message Origin Authentication
The on-line messages produced by the end entity that requires a The online messages produced by the EE that requires a certificate
certificate may be authenticated or not. The requirement here is to may be authenticated or not. The requirement here is to authenticate
authenticate the origin of any messages from the end entity to the the origin of any messages from the EE to the PKI (CA/RA).
PKI (CA/RA).
In this specification, such authentication is achieved by two In this specification, such authentication is achieved by two
different means: different means:
* symmetric: The PKI (CA/RA) issuing the end entity with a secret * symmetric: The PKI (CA/RA) issuing the EE with a secret value
value (initial authentication key) and reference value (used to (initial authentication key) and reference value (used to identify
identify the secret value) via some out-of-band means. The the secret value) via some out-of-band means. The initial
initial authentication key can then be used to protect relevant authentication key can then be used to protect relevant PKI
PKI messages. messages.
* asymmetric: Using a private key and certificate issued by another * asymmetric: Using a private key and certificate issued by another
PKI trusted for initial authentication, e.g., an Initial Device PKI trusted for initial authentication, e.g., an Initial Device
Identifier (IDevID) IEEE 802.1AR [IEEE.802.1AR-2018]. The trust Identifier (IDevID) IEEE 802.1AR [IEEE.802.1AR-2018]. The trust
establishment in this external PKI is out of scope of this establishment in this external PKI is out of scope of this
document. document.
Thus, we can classify the initial registration/certification scheme Thus, we can classify the initial registration/certification scheme
according to whether or not the on-line 'end entity -> PKI management according to whether or not the online 'end entity -> PKI management
entity' messages are authenticated or not. entity' messages are authenticated or not.
Note 1: We do not discuss the authentication of the 'PKI management Note 1: We do not discuss the authentication of the 'PKI management
entity -> end entity' messages here, as this is always entity -> end entity' messages here, as this is always
REQUIRED. In any case, it can be achieved simply once the REQUIRED. In any case, it can be achieved simply once the
root-CA public key has been installed at the end entity's root-CA public key has been installed at the EE's equipment
equipment or it can be based on the initial authentication or it can be based on the initial authentication key.
key.
Note 2: An initial registration/certification procedure can be Note 2: An initial registration/certification procedure can be
secure where the messages from the end entity are secure where the messages from the EE are authenticated via
authenticated via some out-of-band means (e.g., a subsequent some out-of-band means (e.g., a subsequent visit).
visit).
4.2.1.3. Location of Key Generation 4.2.1.3. Location of Key Generation
In this specification, "key generation" is regarded as occurring In this specification, "key generation" is regarded as occurring
wherever either the public or private component of a key pair first wherever either the public or private component of a key pair first
occurs in a PKIMessage. Note that this does not preclude a occurs in a PKIMessage. Note that this does not preclude a
centralized key generation service by a KGA; the actual key pair MAY centralized key generation service by a KGA; the actual key pair MAY
have been generated elsewhere and transported to the end entity, RA, have been generated elsewhere and transported to the EE, RA, or CA
or CA using a (proprietary or standardized) key generation request/ using a (proprietary or standardized) key generation request/response
response protocol (outside the scope of this specification). protocol (outside the scope of this specification).
Thus, there are three possibilities for the location of "key Thus, there are three possibilities for the location of "key
generation": the end entity, a KGA, or a CA. generation": the EE, a KGA, or a CA.
4.2.1.4. Confirmation of Successful Certification 4.2.1.4. Confirmation of Successful Certification
Following the creation of a certificate for an end entity, additional Following the creation of a certificate for an EE, additional
assurance can be gained by having the end entity explicitly confirm assurance can be gained by having the EE explicitly confirm
successful receipt of the message containing (or indicating the successful receipt of the message containing (or indicating the
creation of) the certificate. Naturally, this confirmation message creation of) the certificate. Naturally, this confirmation message
must be protected (based on the initial symmetric or asymmetric must be protected (based on the initial symmetric or asymmetric
authentication key or other means). authentication key or other means).
This gives two further possibilities: confirmed or not. This gives two further possibilities: confirmed or not.
4.2.2. Initial Registration/Certification Schemes 4.2.2. Initial Registration/Certification Schemes
The criteria above allow for a large number of initial registration/ The criteria above allow for a large number of initial registration/
skipping to change at line 962 skipping to change at line 950
entity may support other schemes specified in profiles of PKIX-CMP, entity may support other schemes specified in profiles of PKIX-CMP,
such as Appendices C and D or [RFC9483]. such as Appendices C and D or [RFC9483].
4.2.2.1. Centralized Scheme 4.2.2.1. Centralized Scheme
In terms of the classification above, this scheme is, in some ways, In terms of the classification above, this scheme is, in some ways,
the simplest possible, where: the simplest possible, where:
* initiation occurs at the certifying CA; * initiation occurs at the certifying CA;
* no on-line message authentication is required; * no online message authentication is required;
* "key generation" occurs at the certifying CA (see * "key generation" occurs at the certifying CA (see
Section 4.2.1.3); and Section 4.2.1.3); and
* no confirmation message is required. * no confirmation message is required.
In terms of message flow, this scheme means that the only message In terms of message flow, this scheme means that the only message
required is sent from the CA to the end entity. The message must required is sent from the CA to the EE. The message must contain the
contain the entire TEE for the end entity. Some out-of-band means entire TEE for the EE. Some out-of-band means must be provided to
must be provided to allow the end entity to authenticate the message allow the EE to authenticate the message received and to decrypt any
received and to decrypt any encrypted values. encrypted values.
4.2.2.2. Basic Authenticated Scheme 4.2.2.2. Basic Authenticated Scheme
In terms of the classification above, this scheme is where: In terms of the classification above, this scheme is where:
* initiation occurs at the end entity; * initiation occurs at the EE;
* message authentication is required; * message authentication is required;
* "key generation" occurs at the end entity (see Section 4.2.1.3); * "key generation" occurs at the EE (see Section 4.2.1.3); and
and
* a confirmation message is recommended. * a confirmation message is recommended.
Note: An Initial Authentication Key (IAK) can be either a symmetric Note: An Initial Authentication Key (IAK) can be either a symmetric
key or an asymmetric private key with a certificate issued by another key or an asymmetric private key with a certificate issued by another
PKI trusted for this purpose. The establishment of such trust is out PKI trusted for this purpose. The establishment of such trust is out
of scope of this document. of scope of this document.
In terms of message flow, the basic authenticated scheme is as In terms of message flow, the basic authenticated scheme is as
follows: follows:
skipping to change at line 1020 skipping to change at line 1007
-----> cert conf message -----> -----> cert conf message ----->
verify confirmation verify confirmation
create response create response
<----- conf ack (optional) <----- <----- conf ack (optional) <-----
handle response handle response
Note: Where verification of the cert confirmation message fails, the Note: Where verification of the cert confirmation message fails, the
RA/CA MUST revoke the newly issued certificate if it has been RA/CA MUST revoke the newly issued certificate if it has been
published or otherwise made available. published or otherwise made available.
4.3. Proof-of-Possession (POP) of Private Key 4.3. POP of Private Key
Proof-of-possession (POP) is where a PKI management entity (CA/RA) POP is where a PKI management entity (CA/RA) verifies if an EE has
verifies if an end entity has access to the private key corresponding access to the private key corresponding to a given public key. The
to a given public key. The question of whether, and in what question of whether, and in what circumstances, POPs add value to a
circumstances, POPs add value to a PKI is a debate as old as PKI PKI is a debate as old as PKI itself! See Section 8.1 for a further
itself! See Section 8.1 for a further discussion on the necessity of discussion on the necessity of POP in PKI.
proof-of-possession in PKI.
The PKI management operations specified here make it possible for an The PKI management operations specified here make it possible for an
end entity to prove to a CA/RA that it has possession of (i.e., is EE to prove to a CA/RA that it has possession of (i.e., is able to
able to use) the private key corresponding to the public key for use) the private key corresponding to the public key for which a
which a certificate is requested (see Section 5.2.8 for different POP certificate is requested (see Section 5.2.8 for different POP
methods). A given CA/RA is free to choose how to enforce POP (e.g., methods). A given CA/RA is free to choose how to enforce POP (e.g.,
out-of-band procedural means versus PKIX-CMP in-band messages) in its out-of-band procedural means versus PKIX-CMP in-band messages) in its
certification exchanges (i.e., this may be a policy issue). However, certification exchanges (i.e., this may be a policy issue). However,
it is REQUIRED that CAs/RAs MUST enforce POP by some means because it is REQUIRED that CAs/RAs MUST enforce POP by some means because
there are currently many non-PKIX operational protocols in use there are currently many non-PKIX operational protocols in use
(various electronic mail protocols are one example) that do not (various electronic mail protocols are one example) that do not
explicitly check the binding between the end entity and the private explicitly check the binding between the EE and the private key.
key. Until operational protocols that do verify the binding (for Until operational protocols that do verify the binding (for
signature, encryption, key agreement, and KEM key pairs) exist, and signature, encryption, key agreement, and KEM key pairs) exist, and
are ubiquitous, this binding can only be assumed to have been are ubiquitous, this binding can only be assumed to have been
verified by the CA/RA. Therefore, if the binding is not verified by verified by the CA/RA. Therefore, if the binding is not verified by
the CA/RA, certificates in the Internet Public Key Infrastructure end the CA/RA, certificates in the Internet PKI end up being somewhat
up being somewhat less meaningful. less meaningful.
POP is accomplished in different ways depending upon the type of key POP is accomplished in different ways depending upon the type of key
for which a certificate is requested. If a key can be used for for which a certificate is requested. If a key can be used for
multiple purposes (e.g., an RSA key), then any appropriate method MAY multiple purposes (e.g., an RSA key), then any appropriate method MAY
be used (e.g., a key that may be used for signing, as well as other be used (e.g., a key that may be used for signing, as well as other
purposes, MUST NOT be sent to the CA/RA in order to prove possession purposes, MUST NOT be sent to the CA/RA in order to prove possession
unless archival of the private key is explicitly desired). unless archival of the private key is explicitly desired).
This specification explicitly allows for cases where an end entity This specification explicitly allows for cases where an EE supplies
supplies the relevant proof to an RA and the RA subsequently attests the relevant proof to an RA and the RA subsequently attests to the CA
to the CA that the required proof has been received (and validated!). that the required proof has been received (and validated!). For
For example, an end entity wishing to have a signing key certified example, an EE wishing to have a signing key certified could send the
could send the appropriate signature to the RA, which then simply appropriate signature to the RA, which then simply notifies the
notifies the relevant CA that the end entity has supplied the relevant CA that the EE has supplied the required proof. Of course,
required proof. Of course, such a situation may be disallowed by such a situation may be disallowed by some policies (e.g., CAs may be
some policies (e.g., CAs may be the only entities permitted to verify the only entities permitted to verify POP during certification).
POP during certification).
4.3.1. Signature Keys 4.3.1. Signature Keys
For signature keys, the end entity can sign a value to prove For signature keys, the EE can sign a value to prove possession of
possession of the private key; see Section 5.2.8.2. the private key; see Section 5.2.8.2.
4.3.2. Encryption Keys 4.3.2. Encryption Keys
For encryption keys, the end entity can provide the private key to For encryption keys, the EE can provide the private key to the CA/RA
the CA/RA (e.g., for archiving), see Section 5.2.8.3.1, or can be (e.g., for archiving), see Section 5.2.8.3.1, or can be required to
required to decrypt a value in order to prove possession of the decrypt a value in order to prove possession of the private key.
private key. Decrypting a value can be achieved either directly (see Decrypting a value can be achieved either directly (see
Section 5.2.8.3.3) or indirectly (see Section 5.2.8.3.2). Section 5.2.8.3.3) or indirectly (see Section 5.2.8.3.2).
The direct method is for the RA/CA to issue a random challenge to The direct method is for the RA/CA to issue a random challenge to
which an immediate response by the EE is required. which an immediate response by the EE is required.
The indirect method is to issue a certificate that is encrypted for The indirect method is to issue a certificate that is encrypted for
the end entity (and have the end entity demonstrate its ability to the EE (and have the EE demonstrate its ability to decrypt this
decrypt this certificate in the confirmation message). This allows a certificate in the confirmation message). This allows a CA to issue
CA to issue a certificate in a form that can only be used by the a certificate in a form that can only be used by the intended EE.
intended end entity.
This specification encourages use of the indirect method because it This specification encourages use of the indirect method because it
requires no extra messages to be sent (i.e., the proof can be requires no extra messages to be sent (i.e., the proof can be
demonstrated using the {request, response, confirmation} triple of demonstrated using the {request, response, confirmation} triple of
messages). messages).
4.3.3. Key Agreement Keys 4.3.3. Key Agreement Keys
For key agreement keys, the end entity and the PKI management entity For key agreement keys, the EE and the PKI management entity (i.e.,
(i.e., CA or RA) must establish a shared secret key in order to prove CA or RA) must establish a shared secret key in order to prove that
that the end entity has possession of the private key. the EE has possession of the private key.
Note that this need not impose any restrictions on the keys that can Note that this need not impose any restrictions on the keys that can
be certified by a given CA. In particular, for Diffie-Hellman keys, be certified by a given CA. In particular, for Diffie-Hellman (DH)
the end entity may freely choose its algorithm parameters provided keys, the EE may freely choose its algorithm parameters provided that
that the CA can generate a short-term (or one-time) key pair with the the CA can generate a short-term (or one-time) key pair with the
appropriate parameters when necessary. appropriate parameters when necessary.
4.3.4. Key Encapsulation Mechanism Keys 4.3.4. KEM Keys
For key encapsulation mechanism (KEM) keys, the end entity can For KEM keys, the EE can provide the private key to the CA/RA (e.g.,
provide the private key to the CA/RA (e.g., for archiving), see for archiving), see Section 5.2.8.3.1, or can be required to decrypt
Section 5.2.8.3.1, or can be required to decrypt a value in order to a value in order to prove possession of the private key. Decrypting
prove possession of the private key. Decrypting a value can be a value can be achieved either directly (see Section 5.2.8.3.3) or
achieved either directly (see Section 5.2.8.3.3) or indirectly (see indirectly (see Section 5.2.8.3.2).
Section 5.2.8.3.2).
Note: A definition of key encapsulation mechanisms can be found in Note: A definition of KEMs can be found in Section 1 of [RFC9629].
Section 1 of [RFC9629].
The direct method is for the RA/CA to issue a random challenge to The direct method is for the RA/CA to issue a random challenge to
which an immediate response by the EE is required. which an immediate response by the EE is required.
The indirect method is to issue a certificate that is encrypted for The indirect method is to issue a certificate that is encrypted for
the end entity using a shared secret key derived from a key the EE using a shared secret key derived from a key encapsulated
encapsulated using the public key (and have the end entity using the public key (and have the EE demonstrate its ability to use
demonstrate its ability to use its private key for decapsulation of its private key for decapsulation of the KEM ciphertext, derive the
the KEM ciphertext, derive the shared secret key, decrypt this shared secret key, decrypt this certificate, and provide a hash of
certificate, and provide a hash of the certificate in the the certificate in the confirmation message). This allows a CA to
confirmation message). This allows a CA to issue a certificate in a issue a certificate in a form that can only be used by the intended
form that can only be used by the intended end entity. EE.
This specification encourages use of the indirect method because it This specification encourages use of the indirect method because it
requires no extra messages to be sent (i.e., the proof can be requires no extra messages to be sent (i.e., the proof can be
demonstrated using the {request, response, confirmation} triple of demonstrated using the {request, response, confirmation} triple of
messages). messages).
A certification request message for a KEM certificate SHALL use A certification request message for a KEM certificate SHALL use
POPOPrivKey by using the keyEncipherment choice of ProofOfPossession POPOPrivKey by using the keyEncipherment choice of ProofOfPossession
(see Section 5.2.8) in the popo field of CertReqMsg as long as no (see Section 5.2.8) in the popo field of CertReqMsg as long as no
KEM-specific choice is available. KEM-specific choice is available.
4.4. Root CA Key Update 4.4. Root CA Key Update
This discussion only applies to CAs that are directly trusted by some This discussion only applies to CAs that are directly trusted by some
end entities. Recognizing whether a self-signed or non-self-signed EEs. Recognizing whether a self-signed or non-self-signed CA is
CA is supposed to be directly trusted for some end entities is a supposed to be directly trusted for some EEs is a matter of CA policy
matter of CA policy and end entity configuration. Thus, this is and EE configuration. Thus, this is beyond the scope of this
beyond the scope of this document. document.
The basis of the procedure described here is that the CA protects its The basis of the procedure described here is that the CA protects its
new public key using its previous private key and vice versa. Thus, new public key using its previous private key and vice versa. Thus,
when a CA updates its key pair, it may generate two link when a CA updates its key pair, it may generate two link
certificates: "old with new" and "new with old". certificates: "old with new" and "new with old".
Note: The usage of link certificates has been shown to be very Note: The usage of link certificates has been shown to be very
specific for each use case, and no assumptions are done on this specific for each use case, and no assumptions are done on this
aspect. RootCaKeyUpdateContent is updated to specify these link aspect. RootCaKeyUpdateContent is updated to specify these link
certificates as optional. certificates as optional.
Note: When an LDAP directory is used to publish root CA updates, the Note: When an LDAP directory is used to publish root CA updates, the
old and new root CA certificates together with the two link old and new root CA certificates together with the two link
certificates are stored as cACertificate attribute values. certificates are stored as cACertificate attribute values.
When a CA changes its key pair, those entities who have acquired the When a CA changes its key pair, those entities who have acquired the
old CA public key via "out-of-band" means are most affected. These old CA public key via "out-of-band" means are most affected. These
end entities need to acquire the new CA public key in a trusted way. EEs need to acquire the new CA public key in a trusted way. This may
This may be achieved "out-of-band" by using a repository or by using be achieved "out-of-band" by using a repository or by using online
online messages also containing the link certificates "new with old". messages also containing the link certificates "new with old". Once
Once the end entity acquired and properly verified the new CA public the EE acquired and properly verified the new CA public key, it must
key, it must load the new trust anchor information into its trusted load the new trust anchor information into its trusted store.
store.
The data structure used to protect the new and old CA public keys is The data structure used to protect the new and old CA public keys is
typically a standard X.509 v3 certificate (which may also contain typically a standard X.509v3 certificate (which may also contain
extensions). There are no new data structures required. extensions). There are no new data structures required.
Note: Sometimes self-signed root CA certificates do not make use of Note: Sometimes self-signed root CA certificates do not make use of
X.509 v3 extensions and may be X.509 v1 certificates. Therefore, a X.509v3 extensions and may be X.509v1 certificates. Therefore, a
root CA key update must be able to work for version 1 certificates. root CA key update must be able to work for version 1 certificates.
The use of the X.509 v3 KeyIdentifier extension is recommended for The use of the X.509v3 KeyIdentifier extension is recommended for
easier path building. easier path building.
Note: While the scheme could be generalized to cover cases where the Note: While the scheme could be generalized to cover cases where the
CA updates its key pair more than once during the validity period of CA updates its key pair more than once during the validity period of
one of its end entities' certificates, this generalization seems of one of its EEs' certificates, this generalization seems of dubious
dubious value. Not having this generalization simply means that the value. Not having this generalization simply means that the validity
validity periods of certificates issued with the old CA key pair periods of certificates issued with the old CA key pair cannot exceed
cannot exceed the end of the "old with new" certificate validity the end of the "old with new" certificate validity period.
period.
Note: This scheme offers a mechanism to ensures that end entities Note: This scheme offers a mechanism to ensures that EEs will acquire
will acquire the new CA public key, at the latest by the expiry of the new CA public key, at the latest by the expiry of the last
the last certificate they owned that was signed with the old CA certificate they owned that was signed with the old CA private key.
private key. Certificate and/or key update operations occurring at Certificate and/or key update operations occurring at other times do
other times do not necessarily require this (depending on the end not necessarily require this (depending on the EE's equipment).
entity's equipment).
Note: In practice, a new root CA may have a slightly different Note: In practice, a new root CA may have a slightly different
subject Distinguished Name (DN), e.g., indicating a generation subject Distinguished Name (DN), e.g., indicating a generation
identifier like the year of issuance or a version number, for identifier like the year of issuance or a version number, for
instance, in an Organizational Unit (OU) element. How to bridge instance, in an Organizational Unit (OU) element. How to bridge
trust to the new root CA certificate in a CA DN change or a cross- trust to the new root CA certificate in a CA DN change or a cross-
certificate scenario is out of scope for this document. certificate scenario is out of scope for this document.
4.4.1. CA Operator Actions 4.4.1. CA Operator Actions
skipping to change at line 1218 skipping to change at line 1197
"new with new" certificate). "new with new" certificate).
3. Optionally: Create a link certificate containing the new CA 3. Optionally: Create a link certificate containing the new CA
public key signed with the old private key (the "new with old" public key signed with the old private key (the "new with old"
certificate). certificate).
4. Optionally: Create a link certificate containing the old CA 4. Optionally: Create a link certificate containing the old CA
public key signed with the new private key (the "old with new" public key signed with the new private key (the "old with new"
certificate). certificate).
5. Publish these new certificates so that end entities may acquire 5. Publish these new certificates so that EEs may acquire it, e.g.,
it, e.g., using a repository or RootCaKeyUpdateContent. using a repository or RootCaKeyUpdateContent.
The old CA private key is then no longer required when the validity The old CA private key is then no longer required when the validity
of the "old with old" certificate ended. However, the old CA public of the "old with old" certificate ended. However, the old CA public
key will remain in use for validating the "new with old" link key will remain in use for validating the "new with old" link
certificate until the new CA public key is loaded into the trusted certificate until the new CA public key is loaded into the trusted
store. The old CA public key is no longer required (other than for store. The old CA public key is no longer required (other than for
non-repudiation) when all end entities of this CA have securely non-repudiation) when all EEs of this CA have securely acquired and
acquired and stored the new CA public key. stored the new CA public key.
The "new with new" certificate must have a validity period with a The "new with new" certificate must have a validity period with a
notBefore time that is before the notAfter time of the "old with old" notBefore time that is before the notAfter time of the "old with old"
certificate and a notAfter time that is after the notBefore time of certificate and a notAfter time that is after the notBefore time of
the next update of this certificate. the next update of this certificate.
The "new with old" certificate must have a validity period with the The "new with old" certificate must have a validity period with the
same notBefore time as the "new with new" certificate and a notAfter same notBefore time as the "new with new" certificate and a notAfter
time by which all end entities of this CA will securely possess the time by which all EEs of this CA will securely possess the new CA
new CA public key (at the latest, at the notAfter time of the "old public key (at the latest, at the notAfter time of the "old with old"
with old" certificate). certificate).
The "old with new" certificate must have a validity period with the The "old with new" certificate must have a validity period with the
same notBefore and notAfter time as the "old with old" certificate. same notBefore and notAfter time as the "old with old" certificate.
Note: Further operational considerations on transition from one root Note: Further operational considerations on transition from one root
CA self-signed certificate to the next is available in Section 5 of CA self-signed certificate to the next is available in Section 5 of
[RFC8649]. [RFC8649].
4.4.2. Verifying Certificates 4.4.2. Verifying Certificates
skipping to change at line 1360 skipping to change at line 1339
4.4.3. Revocation - Change of the CA Key 4.4.3. Revocation - Change of the CA Key
As we saw above, the verification of a certificate becomes more As we saw above, the verification of a certificate becomes more
complex once the CA is allowed to change its key. This is also true complex once the CA is allowed to change its key. This is also true
for revocation checks, as the CA may have signed the CRL using a for revocation checks, as the CA may have signed the CRL using a
newer private key than the one within the user's TEE. newer private key than the one within the user's TEE.
The analysis of the alternatives is the same as for certificate The analysis of the alternatives is the same as for certificate
verification. verification.
4.5. Extended Key Usage for PKI Entities 4.5. EKU for PKI Entities
The extended key usage (EKU) extension indicates the purposes for The EKU extension indicates the purposes for which the certified key
which the certified key pair may be used. Therefore, it restricts pair may be used. Therefore, it restricts the use of a certificate
the use of a certificate to specific applications. to specific applications.
A CA may want to delegate parts of its duties to other PKI management A CA may want to delegate parts of its duties to other PKI management
entities. This section provides a mechanism to both prove this entities. This section provides a mechanism to both prove this
delegation and enable automated means for checking the authorization delegation and enable automated means for checking the authorization
of this delegation. Such delegation may also be expressed by other of this delegation. Such delegation may also be expressed by other
means, e.g., explicit configuration. means, e.g., explicit configuration.
To offer automatic validation for the delegation of a role by a CA to To offer automatic validation for the delegation of a role by a CA to
another entity, the certificates used for CMP message protection or another entity, the certificates used for CMP message protection or
signed data for central key generation MUST be issued by the signed data for central key generation MUST be issued by the
skipping to change at line 1395 skipping to change at line 1374
id-kp-cmcRA OBJECT IDENTIFIER ::= { id-kp-cmcRA OBJECT IDENTIFIER ::= {
iso(1) identified-organization(3) dod(6) internet(1) iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) kp(3) 28 } security(5) mechanisms(5) pkix(7) kp(3) 28 }
id-kp-cmKGA OBJECT IDENTIFIER ::= { id-kp-cmKGA OBJECT IDENTIFIER ::= {
iso(1) identified-organization(3) dod(6) internet(1) iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) kp(3) 32 } security(5) mechanisms(5) pkix(7) kp(3) 32 }
Note: Section 2.10 of [RFC6402] specifies OIDs for a Certificate Note: Section 2.10 of [RFC6402] specifies OIDs for a Certificate
Management over CMS (CMC) CA and a CMC RA. As the functionality of a Management over CMS (CMC) CA and a CMC RA. As the functionality of a
CA and RA is not specific to any certificate management protocol CA and RA is not specific to any protocol used for managing
(such as CMC or CMP), these EKUs are reused by CMP. certificates (such as CMC or CMP), these EKUs are reused by CMP.
The meaning of the id-kp-cmKGA EKU is as follows: The meaning of the id-kp-cmKGA EKU is as follows:
CMP KGA: CMP key generation authorities are CAs or are identified by CMP KGA: CMP KGAs are CAs or are identified by the id-kp-cmKGA EKU.
the id-kp-cmKGA extended key usage. The CMP KGA knows the private The CMP KGA knows the private key it generated on behalf of the
key it generated on behalf of the end entity. This is a very EE. This is a very sensitive service and needs specific
sensitive service and needs specific authorization, which by authorization, which by default is with the CA certificate itself.
default is with the CA certificate itself. The CA may delegate The CA may delegate its authorization by placing the id-kp-cmKGA
its authorization by placing the id-kp-cmKGA extended key usage in EKU in the certificate used to authenticate the origin of the
the certificate used to authenticate the origin of the generated generated private key. The authorization may also be determined
private key. The authorization may also be determined through through local configuration of the EE.
local configuration of the end entity.
5. Data Structures 5. Data Structures
This section contains descriptions of the data structures required This section contains descriptions of the data structures required
for PKI management messages. Section 6 describes constraints on for PKI management messages. Section 6 describes constraints on
their values and the sequence of events for each of the various PKI their values and the sequence of events for each of the various PKI
management operations. management operations.
5.1. Overall PKI Message 5.1. Overall PKI Message
skipping to change at line 1442 skipping to change at line 1420
The PKIHeader contains information that is common to many PKI The PKIHeader contains information that is common to many PKI
messages. messages.
The PKIBody contains message-specific information. The PKIBody contains message-specific information.
The PKIProtection, when used, contains bits that protect the PKI The PKIProtection, when used, contains bits that protect the PKI
message. message.
The extraCerts field can contain certificates that may be useful to The extraCerts field can contain certificates that may be useful to
the recipient. For example, this can be used by a CA or RA to the recipient. For example, this can be used by a CA or RA to
present an end entity with certificates that it needs to verify its present an EE with certificates that it needs to verify its own new
own new certificate (for example, if the CA that issued the end certificate (for example, if the CA that issued the EE's certificate
entity's certificate is not a root CA for the end entity). Note that is not a root CA for the EE). Note that this field does not
this field does not necessarily contain a certification path; the necessarily contain a certification path; the recipient may have to
recipient may have to sort, select from, or otherwise process the sort, select from, or otherwise process the extra certificates in
extra certificates in order to use them. order to use them.
5.1.1. PKI Message Header 5.1.1. PKI Message Header
All PKI messages require some header information for addressing and All PKI messages require some header information for addressing and
transaction identification. Some of this information will also be transaction identification. Some of this information will also be
present in a transport-specific envelope. However, if the PKI present in a transport-specific envelope. However, if the PKI
message is protected, then this information is also protected (i.e., message is protected, then this information is also protected (i.e.,
we make no assumption about secure transport). we make no assumption about secure transport).
The following data structure is used to contain this information: The following data structure is used to contain this information:
skipping to change at line 1486 skipping to change at line 1464
PKIFreeText ::= SEQUENCE SIZE (1..MAX) OF UTF8String PKIFreeText ::= SEQUENCE SIZE (1..MAX) OF UTF8String
The usage of the protocol version number (pvno) is described in The usage of the protocol version number (pvno) is described in
Section 7. Section 7.
The sender field contains the name of the sender of the PKIMessage. The sender field contains the name of the sender of the PKIMessage.
This name (in conjunction with senderKID, if supplied) should be This name (in conjunction with senderKID, if supplied) should be
sufficient to indicate the key to use to verify the protection on the sufficient to indicate the key to use to verify the protection on the
message. If nothing about the sender is known to the sending entity message. If nothing about the sender is known to the sending entity
(e.g., in the initial request message, where the end entity may not (e.g., in the initial request message, where the EE may not know its
know its own Distinguished Name (DN), email name, IP address, etc.), own DN, email name, IP address, etc.), then the "sender" field MUST
then the "sender" field MUST contain a "NULL-DN" value in the contain a "NULL-DN" value in the directoryName choice. A "NULL-DN"
directoryName choice. A "NULL-DN" is a SEQUENCE OF relative is a SEQUENCE OF relative DNs of zero length and is encoded as
distinguished names of zero length and is encoded as 0x3000. In such 0x3000. In such a case, the senderKID field MUST hold an identifier
a case, the senderKID field MUST hold an identifier (i.e., a (i.e., a reference number) that indicates to the receiver the
reference number) that indicates to the receiver the appropriate appropriate shared secret information to use to verify the message.
shared secret information to use to verify the message.
The recipient field contains the name of the recipient of the The recipient field contains the name of the recipient of the
PKIMessage. This name (in conjunction with recipKID, if supplied) PKIMessage. This name (in conjunction with recipKID, if supplied)
should be usable to verify the protection on the message. should be usable to verify the protection on the message.
The protectionAlg field specifies the algorithm used to protect the The protectionAlg field specifies the algorithm used to protect the
message. If no protection bits are supplied (note that PKIProtection message. If no protection bits are supplied (note that PKIProtection
is OPTIONAL), then this field MUST be omitted; if protection bits are is OPTIONAL), then this field MUST be omitted; if protection bits are
supplied, then this field MUST be supplied. supplied, then this field MUST be supplied.
senderKID and recipKID are usable to indicate which keys have been senderKID and recipKID are usable to indicate which keys have been
used to protect the message (recipKID will normally only be required used to protect the message (recipKID will normally only be required
where protection of the message uses Diffie-Hellman (DH) or Elliptic where protection of the message uses DH or Elliptic Curve Diffie-
Curve Diffie-Hellman (ECDH) keys). These fields MUST be used if Hellman (ECDH) keys). These fields MUST be used if required to
required to uniquely identify a key (e.g., if more than one key is uniquely identify a key (e.g., if more than one key is associated
associated with a given sender name). The senderKID SHOULD be used with a given sender name). The senderKID SHOULD be used in any case.
in any case.
Note: The recommendation of using senderKID has changed since Note: The recommendation of using senderKID has changed since
[RFC4210], where it was recommended to be omitted if not needed to [RFC4210], where it was recommended to be omitted if not needed to
identify the protection key. identify the protection key.
The transactionID field within the message header is to be used to The transactionID field within the message header is to be used to
allow the recipient of a message to correlate this with an ongoing allow the recipient of a message to correlate this with an ongoing
transaction. This is needed for all transactions that consist of transaction. This is needed for all transactions that consist of
more than just a single request/response pair. For transactions that more than just a single request/response pair. For transactions that
consist of a single request/response pair, the rules are as follows. consist of a single request/response pair, the rules are as follows.
skipping to change at line 1568 skipping to change at line 1544
reduce the probability of having the transactionID in use at the reduce the probability of having the transactionID in use at the
server. server.
The senderNonce and recipNonce fields protect the PKIMessage against The senderNonce and recipNonce fields protect the PKIMessage against
replay attacks. The senderNonce will typically be 128 bits of replay attacks. The senderNonce will typically be 128 bits of
(pseudo-)random data generated by the sender, whereas the recipNonce (pseudo-)random data generated by the sender, whereas the recipNonce
is copied from the senderNonce field of the previous message in the is copied from the senderNonce field of the previous message in the
transaction. transaction.
The messageTime field contains the time at which the sender created The messageTime field contains the time at which the sender created
the message. This may be useful to allow end entities to correct/ the message. This may be useful to allow EEs to correct/check their
check their local time for consistency with the time on a central local time for consistency with the time on a central system.
system.
The freeText field may be used to send a human-readable message to The freeText field may be used to send a human-readable message to
the recipient (in any number of languages). Each UTF8String MAY the recipient (in any number of languages). Each UTF8String MAY
include a language tag [RFC5646] to indicate the language of the include a language tag [RFC5646] to indicate the language of the
contained text. The first language used in this sequence indicates contained text. The first language used in this sequence indicates
the desired language for replies. the desired language for replies.
The generalInfo field may be used to send machine-processable The generalInfo field may be used to send machine-processable
additional data to the recipient. The following generalInfo additional data to the recipient. The following generalInfo
extensions are defined and MAY be supported. extensions are defined and MAY be supported.
skipping to change at line 1733 skipping to change at line 1708
There MAY be cases in which the PKIProtection BIT STRING is There MAY be cases in which the PKIProtection BIT STRING is
deliberately not used to protect a message (i.e., this OPTIONAL field deliberately not used to protect a message (i.e., this OPTIONAL field
is omitted) because other protection, external to PKIX, will be is omitted) because other protection, external to PKIX, will be
applied instead. Such a choice is explicitly allowed in this applied instead. Such a choice is explicitly allowed in this
specification. Examples of such external protection include CMS specification. Examples of such external protection include CMS
[RFC5652] and Security Multiparts [RFC1847] encapsulation of the [RFC5652] and Security Multiparts [RFC1847] encapsulation of the
PKIMessage (or simply the PKIBody (omitting the CHOICE tag), if the PKIMessage (or simply the PKIBody (omitting the CHOICE tag), if the
relevant PKIHeader information is securely carried in the external relevant PKIHeader information is securely carried in the external
mechanism). It is noted, however, that many such external mechanisms mechanism). It is noted, however, that many such external mechanisms
require that the end entity already possesses a public-key require that the EE already possesses a public-key certificate, a
certificate, a unique Distinguished Name, and/or other such unique DN, and/or other such infrastructure-related information.
infrastructure-related information. Thus, they may not be Thus, they may not be appropriate for initial registration, key-
appropriate for initial registration, key-recovery, or any other recovery, or any other process with "bootstrapping" characteristics.
process with "boot-strapping" characteristics. For those cases, it For those cases, it may be necessary that the PKIProtection parameter
may be necessary that the PKIProtection parameter be used. In the be used. In the future, if/when external mechanisms are modified to
future, if/when external mechanisms are modified to accommodate boot- accommodate bootstrapping scenarios, the use of PKIProtection may
strapping scenarios, the use of PKIProtection may become rare or non- become rare or non-existent.
existent.
Depending on the circumstances, the PKIProtection bits may contain a Depending on the circumstances, the PKIProtection bits may contain a
Message Authentication Code (MAC) or signature. Only the following MAC or signature. Only the following cases can occur:
cases can occur:
5.1.3.1. Shared Secret Information 5.1.3.1. Shared Secret Information
In this case, the sender and recipient share secret information with In this case, the sender and recipient share secret information with
sufficient entropy (established via out-of-band means). sufficient entropy (established via out-of-band means).
PKIProtection will contain a MAC value, and the protectionAlg MAY be PKIProtection will contain a MAC value, and the protectionAlg MAY be
one of the options described in Section 6.1 of CMP Algorithms one of the options described in Section 6.1 of CMP Algorithms
[RFC9481]. [RFC9481].
The algorithm identifier id-PasswordBasedMac is defined in The algorithm identifier id-PasswordBasedMac is defined in
skipping to change at line 1770 skipping to change at line 1743
id-PasswordBasedMac OBJECT IDENTIFIER ::= {1 2 840 113533 7 66 13} id-PasswordBasedMac OBJECT IDENTIFIER ::= {1 2 840 113533 7 66 13}
PBMParameter ::= SEQUENCE { PBMParameter ::= SEQUENCE {
salt OCTET STRING, salt OCTET STRING,
owf AlgorithmIdentifier, owf AlgorithmIdentifier,
iterationCount INTEGER, iterationCount INTEGER,
mac AlgorithmIdentifier mac AlgorithmIdentifier
} }
The following text gives a method of key expansion to be used when The following text gives a method of key expansion to be used when
the MAC algorithm requires an input length that is larger than the the MAC algorithm requires an input length that is larger than the
size of the one-way function. size of the one-way function (OWF).
Note: Section 4.4 of [RFC4211] and [RFC9045] do not mention this key Note: Section 4.4 of [RFC4211] and [RFC9045] do not mention this key
expansion method or give an example using HMAC algorithms where key expansion method or give an example using HMAC algorithms where key
expansion is not needed. It is recognized that this omission in expansion is not needed. It is recognized that this omission in
[RFC4211] can lead to confusion and possible incompatibility if key [RFC4211] can lead to confusion and possible incompatibility if key
expansion [RFC4210] is not used when needed. Therefore, when key expansion [RFC4210] is not used when needed. Therefore, when key
expansion is required (when K > H), the key expansion defined in the expansion is required (when K > H), the key expansion defined in the
following text MUST be used. following text MUST be used.
In the above protectionAlg, the salt value is appended to the shared In the above protectionAlg, the salt value is appended to the shared
secret input. The one-way function (OWF) is then applied secret input. The OWF is then applied iterationCount times, where
iterationCount times, where the salted secret is the input to the the salted secret is the input to the first iteration and, for each
first iteration and, for each successive iteration, the input is set successive iteration, the input is set to be the output of the
to be the output of the previous iteration. The output of the final previous iteration. The output of the final iteration (called
iteration (called "BASEKEY" for ease of reference, with a size of "BASEKEY" for ease of reference, with a size of "H") is what is used
"H") is what is used to form the symmetric key. If the MAC algorithm to form the symmetric key. If the MAC algorithm requires a K-bit key
requires a K-bit key and K <= H, then the most significant K bits of and K <= H, then the most significant K bits of BASEKEY are used. If
BASEKEY are used. If K > H, then all of BASEKEY is used for the most K > H, then all of BASEKEY is used for the most significant H bits of
significant H bits of the key, OWF("1" || BASEKEY) is used for the the key, OWF("1" || BASEKEY) is used for the next most significant H
next most significant H bits of the key, OWF("2" || BASEKEY) is used bits of the key, OWF("2" || BASEKEY) is used for the next most
for the next most significant H bits of the key, and so on, until all significant H bits of the key, and so on, until all K bits have been
K bits have been derived. [Here "N" is the ASCII byte encoding the derived. [Here "N" is the ASCII byte encoding the number N and "||"
number N and "||" represents concatenation.] represents concatenation.]
Note: It is RECOMMENDED that the fields of PBMParameter remain Note: It is RECOMMENDED that the fields of PBMParameter remain
constant throughout the messages of a single transaction (e.g., constant throughout the messages of a single transaction (e.g.,
ir/ip/certConf/pkiConf) to reduce the overhead associated with ir/ip/certConf/pkiConf) to reduce the overhead associated with
PasswordBasedMac computation. PasswordBasedMac computation.
5.1.3.2. DH Key Pairs 5.1.3.2. DH Key Pairs
Where the sender and receiver possess finite-field or elliptic-curve- Where the sender and receiver possess finite-field or elliptic-curve-
based Diffie-Hellman certificates with compatible DH parameters in based DH certificates with compatible DH parameters in order to
order to protect the message, the end entity must generate a protect the message, the EE must generate a symmetric key based on
symmetric key based on its private DH key value and the DH public key its private DH key value and the DH public key of the recipient of
of the recipient of the PKI message. PKIProtection will contain a the PKI message. PKIProtection will contain a MAC value keyed with
MAC value keyed with this derived symmetric key, and the this derived symmetric key, and the protectionAlg will be the
protectionAlg will be the following: following:
id-DHBasedMac OBJECT IDENTIFIER ::= {1 2 840 113533 7 66 30} id-DHBasedMac OBJECT IDENTIFIER ::= {1 2 840 113533 7 66 30}
DHBMParameter ::= SEQUENCE { DHBMParameter ::= SEQUENCE {
owf AlgorithmIdentifier, owf AlgorithmIdentifier,
-- AlgId for a One-Way Function -- AlgId for an OWF
mac AlgorithmIdentifier mac AlgorithmIdentifier
-- the MAC AlgId -- the MAC AlgId
} }
In the above protectionAlg, OWF is applied to the result of the In the above protectionAlg, OWF is applied to the result of the DH
Diffie-Hellman computation. The OWF output (called "BASEKEY" for computation. The OWF output (called "BASEKEY" for ease of reference,
ease of reference, with a size of "H") is what is used to form the with a size of "H") is what is used to form the symmetric key. If
symmetric key. If the MAC algorithm requires a K-bit key and K <= H, the MAC algorithm requires a K-bit key and K <= H, then the most
then the most significant K bits of BASEKEY are used. If K > H, then significant K bits of BASEKEY are used. If K > H, then all of
all of BASEKEY is used for the most significant H bits of the key, BASEKEY is used for the most significant H bits of the key,
OWF("1" || BASEKEY) is used for the next most significant H bits of OWF("1" || BASEKEY) is used for the next most significant H bits of
the key, OWF("2" || BASEKEY) is used for the next most significant H the key, OWF("2" || BASEKEY) is used for the next most significant H
bits of the key, and so on, until all K bits have been derived. bits of the key, and so on, until all K bits have been derived.
[Here "N" is the ASCII byte encoding the number N and "||" represents [Here "N" is the ASCII byte encoding the number N and "||" represents
concatenation.] concatenation.]
Note: Hash algorithms that can be used as one-way functions are Note: Hash algorithms that can be used as OWFs are listed in
listed in Section 2 of CMP Algorithms [RFC9481]. Section 2 of CMP Algorithms [RFC9481].
5.1.3.3. Signature 5.1.3.3. Signature
In this case, the sender possesses a signature key pair and simply In this case, the sender possesses a signature key pair and simply
signs the PKI message. PKIProtection will contain the signature signs the PKI message. PKIProtection will contain the signature
value and the protectionAlg will be an AlgorithmIdentifier for a value and the protectionAlg will be an AlgorithmIdentifier for a
digital signature, which MAY be one of the options described in digital signature, which MAY be one of the options described in
Section 3 of CMP Algorithms [RFC9481]. Section 3 of CMP Algorithms [RFC9481].
5.1.3.4. Key Encapsulation 5.1.3.4. Key Encapsulation
In case the sender of a message has a Key Encapsulation Mechanism In case the sender of a message has a KEM key pair, it can be used to
(KEM) key pair, it can be used to establish a shared secret key for establish a shared secret key for MAC-based message protection. This
MAC-based message protection. This can be used for message can be used for message authentication.
authentication.
This approach uses the definition of Key Encapsulation Mechanism This approach uses the definition of KEM algorithm functions in
(KEM) algorithm functions in Section 1 of [RFC9629] as follows: Section 1 of [RFC9629] as follows:
A KEM algorithm provides three functions: A KEM algorithm provides three functions:
1. KeyGen() -> (pk, sk): Generate a public key (pk) and a private 1. KeyGen() -> (pk, sk): Generate a public key (pk) and a private
(secret) key (sk). (secret) key (sk).
2. Encapsulate(pk) -> (ct, ss): Given the public key (pk), produce a 2. Encapsulate(pk) -> (ct, ss): Given the public key (pk), produce a
ciphertext (ct) and a shared secret (ss). ciphertext (ct) and a shared secret (ss).
3. Decapsulate(sk, ct) -> (ss): Given the private key (sk) and the 3. Decapsulate(sk, ct) -> (ss): Given the private key (sk) and the
skipping to change at line 1962 skipping to change at line 1934
successfully validated by Bob beforehand. successfully validated by Bob beforehand.
Bob generates a shared secret (ss) and the associated ciphertext Bob generates a shared secret (ss) and the associated ciphertext
(ct) using the KEM Encapsulate function with Alice's public KEM (ct) using the KEM Encapsulate function with Alice's public KEM
key (pk). Bob MUST NOT reuse the ss and ct for other PKI key (pk). Bob MUST NOT reuse the ss and ct for other PKI
management operations. From this data, Bob produces a management operations. From this data, Bob produces a
KemCiphertextInfo structure, including the KEM algorithm KemCiphertextInfo structure, including the KEM algorithm
identifier and the ciphertext (ct) and sends it to Alice in an identifier and the ciphertext (ct) and sends it to Alice in an
InfoTypeAndValue structure, as defined in Section 5.3.19.18. InfoTypeAndValue structure, as defined in Section 5.3.19.18.
Encapsulate(pk) -> (ct, ss) Encapsulate(pk) -> (ct, ss)
2. Alice decapsulates the shared secret (ss) from the ciphertext 2. Alice decapsulates the shared secret (ss) from the ciphertext
(ct) using the KEM Decapsulate function and its private KEM key (ct) using the KEM Decapsulate function and its private KEM key
(sk). (sk).
Decapsulate(ct, sk) -> (ss) Decapsulate(ct, sk) -> (ss)
If the decapsulation operation outputs an error, any failInfo If the decapsulation operation outputs an error, any failInfo
field in an error response message SHALL contain the value field in an error response message SHALL contain the value
badMessageCheck and the PKI management operation SHALL be badMessageCheck and the PKI management operation SHALL be
terminated. terminated.
Alice derives the shared secret key (ssk) using a KDF. The Alice derives the shared secret key (ssk) using a KDF. The
shared secret (ss) is used as input key material for the KDF, and shared secret (ss) is used as input key material for the KDF, and
the value len is the desired output length of the KDF as required the value len is the desired output length of the KDF as required
by the MAC algorithm to be used for message protection. KDF, by the MAC algorithm to be used for message protection. KDF,
len, and MAC will be transferred to Bob in the protectionAlg len, and MAC will be transferred to Bob in the protectionAlg
KemBMParameter. The DER-encoded KemOtherInfo structure, as KemBMParameter. The DER-encoded KemOtherInfo structure, as
defined below, is used as context for the KDF. defined below, is used as context for the KDF.
KDF(ss, len, context)->(ssk) KDF(ss, len, context)->(ssk)
The shared secret key (ssk) is used for MAC-based protection by The shared secret key (ssk) is used for MAC-based protection by
Alice. Alice.
3. Bob derives the same shared secret key (ssk) using the KDF. Also 3. Bob derives the same shared secret key (ssk) using the KDF. Also
here, the shared secret (ss) is used as input key material for here, the shared secret (ss) is used as input key material for
the KDF, the value len is the desired output length for the KDF, the KDF, the value len is the desired output length for the KDF,
and the DER-encoded KemOtherInfo structure constructed in the and the DER-encoded KemOtherInfo structure constructed in the
same way as on Alice's side is used as context for the KDF. same way as on Alice's side is used as context for the KDF.
KDF(ss, len, context)->(ssk) KDF(ss, len, context)->(ssk)
Bob uses the shared secret key (ssk) for verifying the MAC-based Bob uses the shared secret key (ssk) for verifying the MAC-based
protection of the message received and in this way authenticates protection of the message received and in this way authenticates
Alice. Alice.
This shared secret key (ssk) can be reused by Alice for MAC-based This shared secret key (ssk) can be reused by Alice for MAC-based
protection of further messages sent to Bob within the current PKI protection of further messages sent to Bob within the current PKI
management operation. management operation.
This approach employs the notation of KDF(IKM, L, info) as described This approach employs the notation of KDF(IKM, L, info) as described
in Section 5 of [RFC9629] with the following changes: in Section 5 of [RFC9629] with the following changes:
* IKM is the input key material. It is the symmetric secret called * IKM is the input key material. It is the symmetric secret called
"ss" resulting from the key encapsulation mechanism. "ss" resulting from the KEM.
* L is dependent of the MAC algorithm that is used with the shared * L is dependent of the MAC algorithm that is used with the shared
secret key for CMP message protection and is called "len" in this secret key for CMP message protection and is called "len" in this
document. document.
* info is an additional input to the KDF, is called "context" in * info is an additional input to the KDF, is called "context" in
this document, and contains the DER-encoded KemOtherInfo structure this document, and contains the DER-encoded KemOtherInfo structure
defined as: defined as:
KemOtherInfo ::= SEQUENCE { KemOtherInfo ::= SEQUENCE {
skipping to change at line 2074 skipping to change at line 2046
several use cases for such messages. several use cases for such messages.
* The RA confirms having validated and authorized a message and * The RA confirms having validated and authorized a message and
forwards the original message unchanged. forwards the original message unchanged.
* A PKI management entity collects several messages that are to be * A PKI management entity collects several messages that are to be
forwarded in the same direction and forwards them in a batch. forwarded in the same direction and forwards them in a batch.
Request messages can be transferred as a batch upstream (towards Request messages can be transferred as a batch upstream (towards
the CA); response or announce messages can be transferred as a the CA); response or announce messages can be transferred as a
batch downstream (towards an RA but not to the EE). For instance, batch downstream (towards an RA but not to the EE). For instance,
this can be used when bridging an off-line connection between two this can be used when bridging an offline connection between two
PKI management entities. PKI management entities.
These use cases are accomplished by nesting the messages within a new These use cases are accomplished by nesting the messages within a new
PKI message. The structure used is as follows: PKI message. The structure used is as follows:
NestedMessageContent ::= PKIMessages NestedMessageContent ::= PKIMessages
In case an RA needs to modify a request message, it MAY include the In case an RA needs to modify a request message, it MAY include the
original PKIMessage in the generalInfo field of the modified message, original PKIMessage in the generalInfo field of the modified message,
as described in Section 5.1.1.3. as described in Section 5.1.1.3.
5.2. Common Data Structures 5.2. Common Data Structures
Before specifying the specific types that may be placed in a PKIBody, Before specifying the specific types that may be placed in a PKIBody,
we define some data structures that are used in more than one case. we define some data structures that are used in more than one case.
5.2.1. Requested Certificate Contents 5.2.1. Requested Certificate Contents
Various PKI management messages require that the originator of the Various PKI management messages require that the originator of the
message indicate some of the fields that are required to be present message indicate some of the fields that are required to be present
in a certificate. The CertTemplate structure allows an end entity or in a certificate. The CertTemplate structure allows an EE or RA to
RA to specify as much as it wishes about the certificate it requires. specify as many data fields as the structure wishes for the requested
CertTemplate is identical to a Certificate but with all fields certificate. The structure also allows an EE or RA to include any
optional. other necessary data, such as the publicKey field, when it is
required for the certificate. A CertTemplate structure is identical
to a TBSCertificate structure (see [RFC5280]) but with all fields
optional/situational.
Note: Even if the originator completely specifies the contents of a Note: Even if the originator completely specifies the contents of a
certificate it requires, a CA is free to modify fields within the certificate it requires, a CA is free to modify fields within the
certificate actually issued. If the modified certificate is certificate actually issued. If the modified certificate is
unacceptable to the requester, the requester MUST send back a unacceptable to the requester, the requester MUST send back a
certConf message that either does not include this certificate (via a certConf message that either does not include this certificate (via a
CertHash) or does include this certificate (via a CertHash) along CertHash) or does include this certificate (via a CertHash) along
with a status of "rejected". See Section 5.3.18 for the definition with a status of "rejected". See Section 5.3.18 for the definition
and use of CertHash and the certConf message. and use of CertHash and the certConf message.
Note: Before requesting a new certificate, an end entity can request Note: Before requesting a new certificate, an EE can request a
a certTemplate structure as a kind of certificate request blueprint certTemplate structure as a kind of certificate request blueprint in
in order to learn which data the CA expects to be present in the order to learn which data the CA expects to be present in the
certificate request (see Section 5.3.19.16). certificate request (see Section 5.3.19.16).
See CRMF [RFC4211] for CertTemplate syntax. See CRMF [RFC4211] for CertTemplate syntax.
If certTemplate is an empty SEQUENCE (i.e., all fields omitted), then If certTemplate is an empty SEQUENCE (i.e., all fields omitted), then
the controls field in the CertRequest structure MAY contain the id- the controls field in the CertRequest structure MAY contain the id-
regCtrl-altCertTemplate control, specifying a template for a regCtrl-altCertTemplate control, specifying a template for a
certificate other than an X.509v3 public-key certificate. certificate other than an X.509v3 public-key certificate.
Conversely, if certTemplate is not empty (i.e., at least one field is Conversely, if certTemplate is not empty (i.e., at least one field is
present), then controls MUST NOT contain id-regCtrl-altCertTemplate. present), then controls MUST NOT contain id-regCtrl-altCertTemplate.
skipping to change at line 2160 skipping to change at line 2135
The use of the EncryptedValue structure has been deprecated in favor The use of the EncryptedValue structure has been deprecated in favor
of the EnvelopedData structure. Therefore, it is RECOMMENDED to use of the EnvelopedData structure. Therefore, it is RECOMMENDED to use
EnvelopedData. EnvelopedData.
Note: The EncryptedKey structure defined in CRMF [RFC4211] is used Note: The EncryptedKey structure defined in CRMF [RFC4211] is used
here, which makes the update backward compatible. Using the new here, which makes the update backward compatible. Using the new
syntax with the untagged default choice EncryptedValue is bits-on- syntax with the untagged default choice EncryptedValue is bits-on-
the-wire compatible with the old syntax. the-wire compatible with the old syntax.
To indicate support for EnvelopedData, the pvno cmp2021 has been To indicate support for EnvelopedData, the pvno cmp2021 has been
introduced. Details on the usage of the protocol version number introduced. Details on the usage of the pvno are described in
(pvno) are described in Section 7. Section 7.
The EnvelopedData structure is RECOMMENDED to be used in CMP to The EnvelopedData structure is RECOMMENDED to be used in CMP to
transport a private key, certificate, POP challenge, or revocation transport a private key, certificate, POP challenge, or revocation
passphrase in encrypted form as follows: passphrase in encrypted form as follows:
* It contains only one RecipientInfo structure because the content * It contains only one RecipientInfo structure because the content
is encrypted only for one recipient. is encrypted only for one recipient.
* It may contain a private key in the AsymmetricKeyPackage structure * It may contain a private key in the AsymmetricKeyPackage structure
(which is placed in the encryptedContentInfo field), as defined in (which is placed in the encryptedContentInfo field), as defined in
[RFC5958], that is wrapped in a SignedData structure, as specified [RFC5958], that is wrapped in a SignedData structure, as specified
in Section 5 of [RFC5652] and [RFC8933], signed by the Key in Section 5 of [RFC5652] and [RFC8933], signed by the KGA or CA.
Generation Authority or CA.
* It may contain a certificate, POP challenge, or revocation * It may contain a certificate, POP challenge, or revocation
passphrase directly in the encryptedContent field. passphrase directly in the encryptedContent field.
The content of the EnvelopedData structure, as specified in Section 6 The content of the EnvelopedData structure, as specified in Section 6
of [RFC5652], MUST be encrypted using a newly generated symmetric of [RFC5652], MUST be encrypted using a newly generated symmetric
content-encryption key. This content-encryption key MUST be securely content-encryption key. This content-encryption key MUST be securely
provided to the recipient using one of four key management provided to the recipient using one of four key management
techniques. techniques.
skipping to change at line 2205 skipping to change at line 2179
key that supports key agreement and where any given key usage key that supports key agreement and where any given key usage
extension allows keyAgreement: The content-encryption key will be extension allows keyAgreement: The content-encryption key will be
protected using the key agreement key management technique, as protected using the key agreement key management technique, as
specified in Section 6.2.2 of [RFC5652]. specified in Section 6.2.2 of [RFC5652].
* a password or shared secret: The content-encryption key will be * a password or shared secret: The content-encryption key will be
protected using the password-based key management technique, as protected using the password-based key management technique, as
specified in Section 6.2.4 of [RFC5652]. specified in Section 6.2.4 of [RFC5652].
* recipient's certificate with an algorithm identifier and a public * recipient's certificate with an algorithm identifier and a public
key that supports key encapsulation mechanism and where any given key that supports KEM and where any given key usage extension
key usage extension allows keyEncipherment: The content-encryption allows keyEncipherment: The content-encryption key will be
key will be protected using the key management technique for KEM protected using the key management technique for KEM keys, as
keys, as specified in [RFC9629]. specified in [RFC9629].
Note: There are cases where the algorithm identifier, the type of the Note: There are cases where the algorithm identifier, the type of the
public key, and the key usage extension will not be sufficient to public key, and the key usage extension will not be sufficient to
decide on the key management technique to use, e.g., when decide on the key management technique to use, e.g., when
rsaEncryption is the algorithm identifier. In such cases, it is a rsaEncryption is the algorithm identifier. In such cases, it is a
matter of local policy to decide. matter of local policy to decide.
5.2.3. Status Codes and Failure Information for PKI Messages 5.2.3. Status Codes and Failure Information for PKI Messages
All response messages will include some status information. The All response messages will include some status information. The
skipping to change at line 2336 skipping to change at line 2310
See [RFC4211] for PKIArchiveOptions syntax. See [RFC4211] for PKIArchiveOptions syntax.
5.2.7. Publication Information 5.2.7. Publication Information
Requesters may indicate that they wish the PKI to publish a Requesters may indicate that they wish the PKI to publish a
certificate using the PKIPublicationInfo structure. certificate using the PKIPublicationInfo structure.
See [RFC4211] for PKIPublicationInfo syntax. See [RFC4211] for PKIPublicationInfo syntax.
5.2.8. Proof-of-Possession Structures 5.2.8. POP Structures
The proof-of-possession structure used is indicated in the popo field The POP structure used is indicated in the popo field of type
of type ProofOfPossession in the CertReqMsg sequence (see Section 4 ProofOfPossession in the CertReqMsg sequence (see Section 4 of
of [RFC4211]). [RFC4211]).
ProofOfPossession ::= CHOICE { ProofOfPossession ::= CHOICE {
raVerified [0] NULL, raVerified [0] NULL,
signature [1] POPOSigningKey, signature [1] POPOSigningKey,
keyEncipherment [2] POPOPrivKey, keyEncipherment [2] POPOPrivKey,
keyAgreement [3] POPOPrivKey keyAgreement [3] POPOPrivKey
} }
5.2.8.1. raVerified 5.2.8.1. raVerified
An EE MUST NOT use raVerified. If an RA performs changes to a An EE MUST NOT use raVerified. If an RA performs changes to a
certification request breaking the provided proof-of-possession certification request breaking the provided POP, or if the RA
(POP), or if the RA requests a certificate on behalf of an EE and requests a certificate on behalf of an EE and cannot provide the POP
cannot provide the POP itself, the RA MUST use raVerified. itself, the RA MUST use raVerified. Otherwise, it SHOULD NOT use
Otherwise, it SHOULD NOT use raVerified. raVerified.
When introducing raVerified, the RA MUST check the existing POP, or When introducing raVerified, the RA MUST check the existing POP, or
it MUST ensure by other means that the EE is the holder of the it MUST ensure by other means that the EE is the holder of the
private key. The RA MAY provide the original message containing the private key. The RA MAY provide the original message containing the
POP in the generalInfo field using the id-it-origPKIMessage (see POP in the generalInfo field using the id-it-origPKIMessage (see
Section 5.1.1.3) enabling the CA to verify it. Section 5.1.1.3) enabling the CA to verify it.
5.2.8.2. POPOSigningKey Structure 5.2.8.2. POPOSigningKey Structure
If the certification request is for a key pair that supports signing If the certification request is for a key pair that supports signing
(i.e., a request for a verification certificate), then the proof-of- (i.e., a request for a verification certificate), then the POP of the
possession of the private key is demonstrated through use of the private key is demonstrated through use of the POPOSigningKey
POPOSigningKey structure; for details, see Section 4.1 of [RFC4211]. structure; for details, see Section 4.1 of [RFC4211].
POPOSigningKey ::= SEQUENCE { POPOSigningKey ::= SEQUENCE {
poposkInput [0] POPOSigningKeyInput OPTIONAL, poposkInput [0] POPOSigningKeyInput OPTIONAL,
algorithmIdentifier AlgorithmIdentifier, algorithmIdentifier AlgorithmIdentifier,
signature BIT STRING signature BIT STRING
} }
POPOSigningKeyInput ::= SEQUENCE { POPOSigningKeyInput ::= SEQUENCE {
authInfo CHOICE { authInfo CHOICE {
sender [0] GeneralName, sender [0] GeneralName,
skipping to change at line 2413 skipping to change at line 2387
In the special case that the CA/RA has a DH certificate that is known In the special case that the CA/RA has a DH certificate that is known
to the EE and the certification request is for a key agreement key to the EE and the certification request is for a key agreement key
pair, the EE can also use the POPOSigningKey structure (where the pair, the EE can also use the POPOSigningKey structure (where the
algorithmIdentifier field is DHBasedMAC and the signature field is algorithmIdentifier field is DHBasedMAC and the signature field is
the MAC) for demonstrating POP. the MAC) for demonstrating POP.
5.2.8.3. POPOPrivKey Structure 5.2.8.3. POPOPrivKey Structure
If the certification request is for a key pair that does not support If the certification request is for a key pair that does not support
signing (i.e., a request for an encryption or key agreement signing (i.e., a request for an encryption or key agreement
certificate), then the proof-of-possession of the private key is certificate), then the POP of the private key is demonstrated through
demonstrated through use of the POPOPrivKey structure in one of the use of the POPOPrivKey structure in one of the following three ways;
following three ways; for details see Sections 4.2 and 4.3 in for details see Sections 4.2 and 4.3 in [RFC4211].
[RFC4211].
POPOPrivKey ::= CHOICE { POPOPrivKey ::= CHOICE {
thisMessage [0] BIT STRING, -- deprecated thisMessage [0] BIT STRING, -- deprecated
subsequentMessage [1] SubsequentMessage, subsequentMessage [1] SubsequentMessage,
dhMAC [2] BIT STRING, -- deprecated dhMAC [2] BIT STRING, -- deprecated
agreeMAC [3] PKMACValue, agreeMAC [3] PKMACValue,
encryptedKey [4] EnvelopedData encryptedKey [4] EnvelopedData
} }
SubsequentMessage ::= INTEGER { SubsequentMessage ::= INTEGER {
encrCert (0), encrCert (0),
challengeResp (1) challengeResp (1)
} }
When using agreeMAC or encryptedKey choices, the pvno cmp2021(3) MUST When using agreeMAC or encryptedKey choices, the pvno cmp2021(3) MUST
be used. Details on the usage of the protocol version number (pvno) be used. Details on the usage of the pvno are described in
are described in Section 7. Section 7.
5.2.8.3.1. Inclusion of the Private Key 5.2.8.3.1. Inclusion of the Private Key
This method mentioned previously in Section 4.3 demonstrates proof- This method mentioned previously in Section 4.3 demonstrates POP of
of-possession of the private key by including the encrypted private the private key by including the encrypted private key in the
key in the CertRequest in the POPOPrivKey structure or in the CertRequest in the POPOPrivKey structure or in the PKIArchiveOptions
PKIArchiveOptions control structure. This method SHALL only be used control structure. This method SHALL only be used if archival of the
if archival of the private key is desired. private key is desired.
For a certification request message indicating cmp2021(3) in the pvno For a certification request message indicating cmp2021(3) in the pvno
field of the PKIHeader, the encrypted private key MUST be transferred field of the PKIHeader, the encrypted private key MUST be transferred
in the encryptedKey choice of POPOPrivKey (or within the in the encryptedKey choice of POPOPrivKey (or within the
PKIArchiveOptions control) in a CMS EnvelopedData structure, as PKIArchiveOptions control) in a CMS EnvelopedData structure, as
defined in Section 5.2.2. defined in Section 5.2.2.
Note: The thisMessage choice has been deprecated in favor of Note: The thisMessage choice has been deprecated in favor of
encryptedKey. When using cmp2000(2) in the certification request encryptedKey. When using cmp2000(2) in the certification request
message header for backward compatibility, the thisMessage choice of message header for backward compatibility, the thisMessage choice of
POPOPrivKey is used containing the encrypted private key in an POPOPrivKey is used containing the encrypted private key in an
EncryptedValue structure wrapped in a BIT STRING. This allows the EncryptedValue structure wrapped in a BIT STRING. This allows the
necessary conveyance and protection of the private key while necessary conveyance and protection of the private key while
maintaining bits-on-the-wire compatibility with [RFC4211]. maintaining bits-on-the-wire compatibility with [RFC4211].
5.2.8.3.2. Indirect Method - Encrypted Certificate 5.2.8.3.2. Indirect Method - Encrypted Certificate
The indirect method mentioned previously in Section 4.3 demonstrates The indirect method mentioned previously in Section 4.3 demonstrates
proof-of-possession of the private key by having the CA return the POP of the private key by having the CA return the requested
requested certificate in encrypted form (see Section 5.2.2). This certificate in encrypted form (see Section 5.2.2). This method is
method is indicated in the CertRequest by requesting the encrCert indicated in the CertRequest by requesting the encrCert option in the
option in the subsequentMessage choice of POPOPrivKey. subsequentMessage choice of POPOPrivKey.
EE RA/CA EE RA/CA
---- req ----> ---- req ---->
<--- rep (enc cert) ----- <--- rep (enc cert) -----
---- conf (cert hash) ----> ---- conf (cert hash) ---->
<--- ack ----- <--- ack -----
The end entity proves knowledge of the private key to the CA by The EE proves knowledge of the private key to the CA by providing the
providing the correct CertHash for this certificate in the certConf correct CertHash for this certificate in the certConf message. This
message. This demonstrates POP because the EE can only compute the demonstrates POP because the EE can only compute the correct CertHash
correct CertHash if it is able to recover the encrypted certificate, if it is able to recover the encrypted certificate, and it can only
and it can only recover the certificate if it is able to obtain the recover the certificate if it is able to obtain the symmetric key
symmetric key using the required private key. Clearly, for this to using the required private key. Clearly, for this to work, the CA
work, the CA MUST NOT publish the certificate until the certConf MUST NOT publish the certificate until the certConf message arrives
message arrives (when certHash is to be used to demonstrate POP). (when certHash is to be used to demonstrate POP). See Section 5.3.18
See Section 5.3.18 for further details, and see Section 8.11 for for further details, and see Section 8.11 for security considerations
security considerations regarding use of Certificate Transparency regarding use of CT logs.
logs.
The recipient SHOULD maintain a context of the PKI management The recipient SHOULD maintain a context of the PKI management
operation, e.g., using transactionID and certReqId, to identify the operation, e.g., using transactionID and certReqId, to identify the
private key to use when decrypting the EnvelopedData containing the private key to use when decrypting the EnvelopedData containing the
newly issued certificate. The recipient may be unable to use the newly issued certificate. The recipient may be unable to use the
RecipientInfo structure as it refers to the certificate that is still RecipientInfo structure as it refers to the certificate that is still
encrypted. The sender MUST populate the rid field as specified by encrypted. The sender MUST populate the rid field as specified by
CMS, and the client MAY ignore it. CMS, and the client MAY ignore it.
5.2.8.3.3. Direct Method - Challenge-Response Protocol 5.2.8.3.3. Direct Method - Challenge-Response Protocol
The direct method mentioned previously in Section 4.3 demonstrates The direct method mentioned previously in Section 4.3 demonstrates
proof-of-possession of the private key by having the end entity POP of the private key by having the EE engage in a challenge-
engage in a challenge-response protocol (using the messages popdecc response protocol (using the messages popdecc of type POPODecKeyChall
of type POPODecKeyChall and popdecr of type POPODecKeyResp; see and popdecr of type POPODecKeyResp; see below) between
below) between CertReqMessages and CertRepMessage. This method is CertReqMessages and CertRepMessage. This method is indicated in the
indicated in the CertRequest by requesting the challengeResp option CertRequest by requesting the challengeResp option in the
in the subsequentMessage choice of POPOPrivKey. subsequentMessage choice of POPOPrivKey.
Note: This method would typically be used in an environment in which Note: This method would typically be used in an environment in which
an RA verifies POP and then makes a certification request to the CA an RA verifies POP and then makes a certification request to the CA
on behalf of the end entity. In such a scenario, the CA trusts the on behalf of the EE. In such a scenario, the CA trusts the RA to
RA to have done POP correctly before the RA requests a certificate have done POP correctly before the RA requests a certificate for the
for the end entity. EE.
The complete protocol then looks as follows (note that req' does not The complete protocol then looks as follows (note that req' does not
necessarily encapsulate req as a nested message): necessarily encapsulate req as a nested message):
EE RA CA EE RA CA
---- req ----> ---- req ---->
<--- chall --- <--- chall ---
---- resp ---> ---- resp --->
---- req' ---> ---- req' --->
<--- rep ----- <--- rep -----
---- conf ---> ---- conf --->
<--- ack ----- <--- ack -----
<--- rep ----- <--- rep -----
---- conf ---> ---- conf --->
<--- ack ----- <--- ack -----
This protocol is obviously much longer than the exchange given in This protocol is obviously much longer than the exchange given in
Section 5.2.8.3.2 above but allows a local Registration Authority to Section 5.2.8.3.2 above but allows a Local Registration Authority
be involved and has the property that the certificate itself is not (LRA) to be involved and has the property that the certificate itself
actually created until the proof-of-possession is complete. In some is not actually created until the POP is complete. In some
environments, a different order of the above messages may be environments, a different order of the above messages may be
required, such as the following (this may be determined by policy): required, such as the following (this may be determined by policy):
EE RA CA EE RA CA
---- req ----> ---- req ---->
<--- chall --- <--- chall ---
---- resp ---> ---- resp --->
---- req' ---> ---- req' --->
<--- rep ----- <--- rep -----
<--- rep ----- <--- rep -----
---- conf ---> ---- conf --->
---- conf ---> ---- conf --->
<--- ack ----- <--- ack -----
<--- ack ----- <--- ack -----
The challenge-response messages for proof-of-possession of a private The challenge-response messages for POP of a private key are
key are specified as follows (for decryption keys, see [MvOV97], specified as follows (for decryption keys, see [MvOV97], p.404 for
p.404 for details). This challenge-response exchange is associated details). This challenge-response exchange is associated with the
with the preceding certification request message (and subsequent preceding certification request message (and subsequent certification
certification response and confirmation messages) by the response and confirmation messages) by the transactionID used in the
transactionID used in the PKIHeader and by the protection applied to PKIHeader and by the protection applied to the PKIMessage.
the PKIMessage.
POPODecKeyChallContent ::= SEQUENCE OF Challenge POPODecKeyChallContent ::= SEQUENCE OF Challenge
Challenge ::= SEQUENCE { Challenge ::= SEQUENCE {
owf AlgorithmIdentifier OPTIONAL, owf AlgorithmIdentifier OPTIONAL,
witness OCTET STRING, witness OCTET STRING,
challenge OCTET STRING, -- deprecated challenge OCTET STRING, -- deprecated
encryptedRand [0] EnvelopedData OPTIONAL encryptedRand [0] EnvelopedData OPTIONAL
} }
skipping to change at line 2595 skipping to change at line 2566
compatible with [RFC4210]. Note that the size of Rand, when used compatible with [RFC4210]. Note that the size of Rand, when used
with challenge, needs to be appropriate for encryption, involving the with challenge, needs to be appropriate for encryption, involving the
public key of the requester. If, in some environment, names are so public key of the requester. If, in some environment, names are so
long that they cannot fit (e.g., very long DNs), then whatever long that they cannot fit (e.g., very long DNs), then whatever
portion will fit should be used (as long as it includes at least the portion will fit should be used (as long as it includes at least the
common name, and as long as the receiver is able to deal meaningfully common name, and as long as the receiver is able to deal meaningfully
with the abbreviation). with the abbreviation).
POPODecKeyRespContent ::= SEQUENCE OF INTEGER POPODecKeyRespContent ::= SEQUENCE OF INTEGER
On receiving the popdecc message, the end entity decrypts all On receiving the popdecc message, the EE decrypts all included
included challenges and responds with a popdecr message containing challenges and responds with a popdecr message containing the
the decrypted integer values in the same order. decrypted integer values in the same order.
5.2.8.4. Summary of POP Options 5.2.8.4. Summary of POP Options
The text in this section provides several options with respect to POP The text in this section provides several options with respect to POP
techniques. Using "SK" for "signing key", "EK" for "encryption key", techniques. Using "SK" for "signing key", "EK" for "encryption key",
"KAK" for "key agreement key", and "KEMK" for "key encapsulation "KAK" for "key agreement key", and "KEMK" for "key encapsulation
mechanism key", the techniques may be summarized as follows: mechanism key", the techniques may be summarized as follows:
RAVerified; RAVerified;
SKPOP; SKPOP;
skipping to change at line 2621 skipping to change at line 2592
KAKPOPEncryptedKey; KAKPOPEncryptedKey;
KEMKPOPEncryptedKey; KEMKPOPEncryptedKey;
KAKPOPThisMessageDHMAC; KAKPOPThisMessageDHMAC;
EKPOPEncryptedCert; EKPOPEncryptedCert;
KAKPOPEncryptedCert; KAKPOPEncryptedCert;
KEMKPOPEncryptedCert; KEMKPOPEncryptedCert;
EKPOPChallengeResp; EKPOPChallengeResp;
KAKPOPChallengeResp; and KAKPOPChallengeResp; and
KEMKPOPChallengeResp. KEMKPOPChallengeResp.
Given this array of options, it is natural to ask how an end entity Given this array of options, it is natural to ask how an EE can know
can know what is supported by the CA/RA (i.e., which options it may what is supported by the CA/RA (i.e., which options it may use when
use when requesting certificates). The following guidelines should requesting certificates). The following guidelines should clarify
clarify this situation for EE implementers. this situation for EE implementers.
* RAVerified: This is not an EE decision; the RA uses this if and * RAVerified: This is not an EE decision; the RA uses this if and
only if it has verified POP before forwarding the request on to only if it has verified POP before forwarding the request on to
the CA, so it is not possible for the EE to choose this technique. the CA, so it is not possible for the EE to choose this technique.
* SKPOP: If the EE has a signing key pair, this is the only POP * SKPOP: If the EE has a signing key pair, this is the only POP
method specified for use in the request for a corresponding method specified for use in the request for a corresponding
certificate. certificate.
* EKPOPThisMessage (deprecated), KAKPOPThisMessage (deprecated), * EKPOPThisMessage (deprecated), KAKPOPThisMessage (deprecated),
skipping to change at line 2766 skipping to change at line 2737
Only one of the failInfo (in PKIStatusInfo) and certificate (in Only one of the failInfo (in PKIStatusInfo) and certificate (in
CertifiedKeyPair) fields can be present in each CertResponse CertifiedKeyPair) fields can be present in each CertResponse
(depending on the status). For some status values (e.g., waiting), (depending on the status). For some status values (e.g., waiting),
neither of the optional fields will be present. neither of the optional fields will be present.
Given an EncryptedCert and the relevant decryption key, the Given an EncryptedCert and the relevant decryption key, the
certificate may be obtained. The purpose of this is to allow a CA to certificate may be obtained. The purpose of this is to allow a CA to
return the value of a certificate but with the constraint that only return the value of a certificate but with the constraint that only
the intended recipient can obtain the actual certificate. The the intended recipient can obtain the actual certificate. The
benefit of this approach is that a CA may reply with a certificate benefit of this approach is that a CA may reply with a certificate
even in the absence of proof that the requester is the end entity even in the absence of proof that the requester is the EE that can
that can use the relevant private key (note that the proof is not use the relevant private key (note that the proof is not obtained
obtained until the certConf message is received by the CA). Thus, until the certConf message is received by the CA). Thus, the CA will
the CA will not have to revoke that certificate in the event that not have to revoke that certificate in the event that something goes
something goes wrong with the proof-of-possession (but MAY do so wrong with the POP (but MAY do so anyway, depending upon policy).
anyway, depending upon policy).
The use of EncryptedKey is described in Section 5.2.2. The use of EncryptedKey is described in Section 5.2.2.
Note: To indicate support for EnvelopedData, the pvno cmp2021 has Note: To indicate support for EnvelopedData, the pvno cmp2021 has
been introduced. Details on the usage of different protocol version been introduced. Details on the usage of different protocol version
numbers (pvnos) are described in Section 7. numbers are described in Section 7.
5.3.5. Key Update Request Content 5.3.5. Key Update Request Content
For key update requests, the CertReqMessages syntax is used. For key update requests, the CertReqMessages syntax is used.
Typically, SubjectPublicKeyInfo, KeyId, and Validity are the template Typically, SubjectPublicKeyInfo, KeyId, and Validity are the template
fields that may be supplied for each key to be updated (see the fields that may be supplied for each key to be updated (see the
profiles defined in Section 4.1.3 of [RFC9483] and Appendix C.6 for profiles defined in Section 4.1.3 of [RFC9483] and Appendix C.6 for
further information). This message is intended to be used to request further information). This message is intended to be used to request
updates to existing (non-revoked and non-expired) certificates updates to existing (non-revoked and non-expired) certificates
(therefore, it is sometimes referred to as a "Certificate Update" (therefore, it is sometimes referred to as a "Certificate Update"
skipping to change at line 2811 skipping to change at line 2781
5.3.7. Key Recovery Request Content 5.3.7. Key Recovery Request Content
For key recovery requests, the syntax used is identical to the For key recovery requests, the syntax used is identical to the
initialization request CertReqMessages. Typically, initialization request CertReqMessages. Typically,
SubjectPublicKeyInfo and KeyId are the template fields that may be SubjectPublicKeyInfo and KeyId are the template fields that may be
used to supply a signature public key for which a certificate is used to supply a signature public key for which a certificate is
required. required.
See Section 5.2.1 and [RFC4211] for CertReqMessages syntax. Note See Section 5.2.1 and [RFC4211] for CertReqMessages syntax. Note
that if a key history is required, the requester must supply a that if a key history is required, the requester must supply a
Protocol Encryption Key control in the request message. protocol encryption key control in the request message.
5.3.8. Key Recovery Response Content 5.3.8. Key Recovery Response Content
For key recovery responses, the following syntax is used. For some For key recovery responses, the following syntax is used. For some
status values (e.g., waiting), none of the optional fields will be status values (e.g., waiting), none of the optional fields will be
present. present.
KeyRecRepContent ::= SEQUENCE { KeyRecRepContent ::= SEQUENCE {
status PKIStatusInfo, status PKIStatusInfo,
newSigCert [0] Certificate OPTIONAL, newSigCert [0] Certificate OPTIONAL,
skipping to change at line 2892 skipping to change at line 2862
newWithOld [0] CMPCertificate OPTIONAL, newWithOld [0] CMPCertificate OPTIONAL,
oldWithNew [1] CMPCertificate OPTIONAL oldWithNew [1] CMPCertificate OPTIONAL
} }
CAKeyUpdContent ::= CHOICE { CAKeyUpdContent ::= CHOICE {
cAKeyUpdAnnV2 CAKeyUpdAnnContent, -- deprecated cAKeyUpdAnnV2 CAKeyUpdAnnContent, -- deprecated
cAKeyUpdAnnV3 [0] RootCaKeyUpdateContent cAKeyUpdAnnV3 [0] RootCaKeyUpdateContent
} }
When using RootCaKeyUpdateContent in the ckuann message, the pvno When using RootCaKeyUpdateContent in the ckuann message, the pvno
cmp2021 MUST be used. Details on the usage of the protocol version cmp2021 MUST be used. Details on the usage of the pvno are described
number (pvno) are described in Section 7. in Section 7.
In contrast to CAKeyUpdAnnContent as supported with cmp2000, In contrast to CAKeyUpdAnnContent as supported with cmp2000,
RootCaKeyUpdateContent offers omitting newWithOld and oldWithNew, RootCaKeyUpdateContent offers omitting newWithOld and oldWithNew,
depending on the needs of the EE. depending on the needs of the EE.
5.3.14. Certificate Announcement 5.3.14. Certificate Announcement
This structure MAY be used to announce the existence of certificates. This structure MAY be used to announce the existence of certificates.
Note that this message is intended to be used for those cases (if Note that this message is intended to be used for those cases (if
skipping to change at line 2949 skipping to change at line 2919
5.3.17. PKI Confirmation Content 5.3.17. PKI Confirmation Content
This data structure is used in the protocol exchange as the final This data structure is used in the protocol exchange as the final
PKIMessage. Its content is the same in all cases -- actually, there PKIMessage. Its content is the same in all cases -- actually, there
is no content since the PKIHeader carries all the required is no content since the PKIHeader carries all the required
information. information.
PKIConfirmContent ::= NULL PKIConfirmContent ::= NULL
Use of this message for certificate confirmation is NOT RECOMMENDED; Use of this message for certificate confirmation is NOT RECOMMENDED;
certConf SHOULD be used instead. Upon receiving a PKIConfirm for a certConf SHOULD be used instead. Upon receiving a pkiconf for a
certificate response, the recipient MAY treat it as a certConf with certificate response, the recipient MAY treat it as a certConf with
all certificates being accepted. all certificates being accepted.
5.3.18. Certificate Confirmation Content 5.3.18. Certificate Confirmation Content
This data structure is used by the client to send a confirmation to This data structure is used by the client to send a confirmation to
the CA/RA to accept or reject certificates. the CA/RA to accept or reject certificates.
CertConfirmContent ::= SEQUENCE OF CertStatus CertConfirmContent ::= SEQUENCE OF CertStatus
skipping to change at line 2991 skipping to change at line 2961
indicates acceptance of the specified certificate. Alternatively, indicates acceptance of the specified certificate. Alternatively,
explicit status details (with respect to acceptance or rejection) MAY explicit status details (with respect to acceptance or rejection) MAY
be provided in the statusInfo field, perhaps for auditing purposes at be provided in the statusInfo field, perhaps for auditing purposes at
the CA/RA. the CA/RA.
Within CertConfirmContent, omission of a CertStatus structure Within CertConfirmContent, omission of a CertStatus structure
corresponding to a certificate supplied in the previous response corresponding to a certificate supplied in the previous response
message indicates rejection of the certificate. Thus, an empty message indicates rejection of the certificate. Thus, an empty
CertConfirmContent (a zero-length SEQUENCE) MAY be used to indicate CertConfirmContent (a zero-length SEQUENCE) MAY be used to indicate
rejection of all supplied certificates. See Section 5.2.8.3.2 for a rejection of all supplied certificates. See Section 5.2.8.3.2 for a
discussion of the certHash field with respect to proof-of-possession. discussion of the certHash field with respect to POP.
5.3.19. PKI General Message Content 5.3.19. PKI General Message Content
InfoTypeAndValue ::= SEQUENCE { InfoTypeAndValue ::= SEQUENCE {
infoType OBJECT IDENTIFIER, infoType OBJECT IDENTIFIER,
infoValue ANY DEFINED BY infoType OPTIONAL infoValue ANY DEFINED BY infoType OPTIONAL
} }
-- where {id-it} = {id-pkix 4} = {1 3 6 1 5 5 7 4} -- where {id-it} = {id-pkix 4} = {1 3 6 1 5 5 7 4}
GenMsgContent ::= SEQUENCE OF InfoTypeAndValue GenMsgContent ::= SEQUENCE OF InfoTypeAndValue
skipping to change at line 3297 skipping to change at line 3267
delivery of responses. delivery of responses.
ErrorMsgContent ::= SEQUENCE { ErrorMsgContent ::= SEQUENCE {
pKIStatusInfo PKIStatusInfo, pKIStatusInfo PKIStatusInfo,
errorCode INTEGER OPTIONAL, errorCode INTEGER OPTIONAL,
errorDetails PKIFreeText OPTIONAL errorDetails PKIFreeText OPTIONAL
} }
This message MAY be generated at any time during a PKI transaction. This message MAY be generated at any time during a PKI transaction.
If the client sends this request, the server MUST respond with a If the client sends this request, the server MUST respond with a
PKIConfirm response or another ErrorMsg if any part of the header is pkiconf response or another error message if any part of the header
not valid. is not valid.
In case a PKI management entity sends an error message to the EE with In case a PKI management entity sends an error message to the EE with
the pKIStatusInfo field containing the status "waiting", the EE the pKIStatusInfo field containing the status "waiting", the EE
SHOULD initiate polling as described in Section 5.3.22. If the EE SHOULD initiate polling as described in Section 5.3.22. If the EE
does not initiate polling, both sides MUST treat this message as the does not initiate polling, both sides MUST treat this message as the
end of the transaction (if a transaction is in progress). end of the transaction (if a transaction is in progress).
If protection is desired on the message, the client MUST protect it If protection is desired on the message, the client MUST protect it
using the same technique (i.e., signature or MAC) as the starting using the same technique (i.e., signature or MAC) as the starting
message of the transaction. The CA MUST always sign it with a message of the transaction. The CA MUST always sign it with a
skipping to change at line 3338 skipping to change at line 3308
polling is initiated with an ip, cp, kup, krp, or ccp response polling is initiated with an ip, cp, kup, krp, or ccp response
message containing status "waiting". For any type of request message containing status "waiting". For any type of request
message, polling can be initiated with an error response message with message, polling can be initiated with an error response message with
status "waiting". The following clauses describe how polling status "waiting". The following clauses describe how polling
messages are used. It is assumed that multiple certConf messages can messages are used. It is assumed that multiple certConf messages can
be sent during transactions. There will be one sent in response to be sent during transactions. There will be one sent in response to
each ip, cp, kup, krp, or ccp that contains a CertStatus for an each ip, cp, kup, krp, or ccp that contains a CertStatus for an
issued certificate. issued certificate.
1. In response to an ip, cp, kup, krp, or ccp message, an EE will 1. In response to an ip, cp, kup, krp, or ccp message, an EE will
send a certConf for all issued certificates and expect a PKIconf send a certConf for all issued certificates and expect a pkiconf
for each certConf. An EE will send a pollReq message in response for each certConf. An EE will send a pollReq message in response
to each CertResponse element of an ip, cp, or kup message with to each CertResponse element of an ip, cp, or kup message with
status "waiting" and in response to an error message with status status "waiting" and in response to an error message with status
"waiting". Its certReqId MUST be either the index of a "waiting". Its certReqId MUST be either the index of a
CertResponse data structure with status "waiting" or -1 referring CertResponse data structure with status "waiting" or -1 referring
to the complete response. to the complete response.
2. In response to a pollReq, a CA/RA will return an ip, cp, kup, 2. In response to a pollReq, a CA/RA will return an ip, cp, kup,
krp, or ccp if one or more of the still pending requested krp, or ccp if one or more of the still pending requested
certificates are ready or the final response to some other type certificates are ready or the final response to some other type
skipping to change at line 3399 skipping to change at line 3369
(conf list) / \ | (conf list) / \ |
/ \ ip | / \ ip |
/ \ +-----------------+ / \ +-----------------+
(empty pending list) V V | pollRep (empty pending list) V V | pollRep
END <---- Send certConf Send pollReq---------->Wait END <---- Send certConf Send pollReq---------->Wait
| ^ ^ | | ^ ^ |
| | | | | | | |
+-----------------+ +---------------+ +-----------------+ +---------------+
(pending list) (pending list)
In the following exchange, the end entity is enrolling for two In the following exchange, the EE is enrolling for two certificates
certificates in one request. in one request.
Step# End Entity PKI Step# End Entity PKI
--------------------------------------------------------------------- ---------------------------------------------------------------------
1 format ir 1 format ir
2 --> ir --> 2 --> ir -->
3 handle ir 3 handle ir
4 manual intervention is 4 manual intervention is
required for both certs required for both certs
5 <-- ip <-- 5 <-- ip <--
6 process ip 6 process ip
skipping to change at line 3429 skipping to change at line 3399
14 --> pollReq --> 14 --> pollReq -->
15 check status of cert requests, 15 check status of cert requests,
one certificate is ready one certificate is ready
16 format ip 16 format ip
17 <-- ip <-- 17 <-- ip <--
18 handle ip 18 handle ip
19 format certConf 19 format certConf
20 --> certConf --> 20 --> certConf -->
21 handle certConf 21 handle certConf
22 format ack 22 format ack
23 <-- pkiConf <-- 23 <-- pkiconf <--
24 format pollReq 24 format pollReq
25 --> pollReq --> 25 --> pollReq -->
26 check status of certificate, 26 check status of certificate,
certificate is ready certificate is ready
27 format ip 27 format ip
28 <-- ip <-- 28 <-- ip <--
29 handle ip 29 handle ip
30 format certConf 30 format certConf
31 --> certConf --> 31 --> certConf -->
32 handle certConf 32 handle certConf
33 format ack 33 format ack
34 <-- pkiConf <-- 34 <-- pkiconf <--
The following client-side state machine describes polling for a The following client-side state machine describes polling for a
complete response message. complete response message.
Start Start
| |
| Send request | Send request
v v
+----------- Receive response ------------+ +----------- Receive response ------------+
| | | |
skipping to change at line 3470 skipping to change at line 3440
| | | | | |
| v | | v |
+-----------+------------------->+<-------------------+ +-----------+------------------->+<-------------------+
pollRep other response | pollRep other response |
v v
Handle response Handle response
| |
v v
End End
In the following exchange, the end entity is sending a general In the following exchange, the EE is sending a general message
message request, and the response is delayed by the server. request, and the response is delayed by the server.
Step# End Entity PKI Step# End Entity PKI
--------------------------------------------------------------------- ---------------------------------------------------------------------
1 format genm 1 format genm
2 --> genm --> 2 --> genm -->
3 handle genm 3 handle genm
4 delay in response is necessary 4 delay in response is necessary
5 format error message "waiting" 5 format error message "waiting"
with certReqId set to -1 with certReqId set to -1
6 <-- error <-- 6 <-- error <--
skipping to change at line 3506 skipping to change at line 3476
17 format genp 17 format genp
18 <-- genp <-- 18 <-- genp <--
19 handle genp 19 handle genp
6. Mandatory PKI Management Functions 6. Mandatory PKI Management Functions
Some of the PKI management functions outlined in Section 3.1 are Some of the PKI management functions outlined in Section 3.1 are
described in this section. described in this section.
This section deals with functions that are "mandatory" in the sense This section deals with functions that are "mandatory" in the sense
that all end entity and CA/RA implementations MUST be able to provide that all EE and CA/RA implementations MUST be able to provide the
the functionality described. This part is effectively the profile of functionality described. This part is effectively the profile of the
the PKI management functionality that MUST be supported. Note, PKI management functionality that MUST be supported. Note, however,
however, that the management functions described in this section do that the management functions described in this section do not need
not need to be accomplished using the PKI messages defined in to be accomplished using the PKI messages defined in Section 5 if
Section 5 if alternate means are suitable for a given environment. alternate means are suitable for a given environment. See Section 7
See Section 7 of [RFC9483] and Appendix C for profiles of the of [RFC9483] and Appendix C for profiles of the PKIMessage structures
PKIMessage structures that MUST be supported for specific use cases. that MUST be supported for specific use cases.
6.1. Root CA Initialization 6.1. Root CA Initialization
[See Section 3.1.1.2 for this document's definition of "root CA".] [See Section 3.1.1.2 for this document's definition of "root CA".]
If a newly created root CA is at the top of a PKI hierarchy, it If a newly created root CA is at the top of a PKI hierarchy, it
usually produces a "self-certificate", which is a certificate usually produces a "self-certificate", which is a certificate
structure with the profile defined for the "newWithNew" certificate structure with the profile defined for the "newWithNew" certificate
issued following a root CA key update. issued following a root CA key update.
In order to make the CA's self-certificate useful to end entities In order to make the CA's self-certificate useful to EEs that do not
that do not acquire the self-certificate via "out-of-band" means, the acquire the self-certificate via "out-of-band" means, the CA must
CA must also produce a fingerprint for its certificate. End entities also produce a fingerprint for its certificate. EEs that acquire
that acquire this fingerprint securely via some "out-of-band" means this fingerprint securely via some "out-of-band" means can then
can then verify the CA's self-certificate and, hence, the other verify the CA's self-certificate and, hence, the other attributes
attributes contained therein. contained therein.
The data structure used to carry the fingerprint may be the The data structure used to carry the fingerprint may be the
OOBCertHash (see Section 5.2.5). OOBCertHash (see Section 5.2.5).
6.2. Root CA Key Update 6.2. Root CA Key Update
CA keys (as all other keys) have a finite lifetime and will have to CA keys (as all other keys) have a finite lifetime and will have to
be updated on a periodic basis. The certificates NewWithNew, be updated on a periodic basis. The certificates NewWithNew,
NewWithOld, and OldWithNew (see Section 4.4.1) MAY be issued by the NewWithOld, and OldWithNew (see Section 4.4.1) MAY be issued by the
CA to aid existing end entities who hold the current root CA CA to aid existing EEs who hold the current root CA certificate
certificate (OldWithOld) to transition securely to the new root CA (OldWithOld) to transition securely to the new root CA certificate
certificate (NewWithNew) and to aid new end entities who will hold (NewWithNew) and to aid new EEs who will hold NewWithNew to acquire
NewWithNew to acquire OldWithOld securely for verification of OldWithOld securely for verification of existing data.
existing data.
6.3. Subordinate CA Initialization 6.3. Subordinate CA Initialization
[See Section 3.1.1.2 for this document's definition of "subordinate [See Section 3.1.1.2 for this document's definition of "subordinate
CA".] CA".]
From the perspective of PKI management protocols, the initialization From the perspective of PKI management protocols, the initialization
of a subordinate CA is the same as the initialization of an end of a subordinate CA is the same as the initialization of an EE. The
entity. The only difference is that the subordinate CA must also only difference is that the subordinate CA must also produce an
produce an initial revocation list. initial revocation list.
6.4. CRL Production 6.4. CRL Production
Before issuing any certificates, a newly established CA (which issues Before issuing any certificates, a newly established CA (which issues
CRLs) must produce "empty" versions of each CRL, which are to be CRLs) must produce "empty" versions of each CRL, which are to be
periodically produced. periodically produced.
6.5. PKI Information Request 6.5. PKI Information Request
When a PKI entity (CA, RA, or EE) wishes to acquire information about When a PKI entity (CA, RA, or EE) wishes to acquire information about
skipping to change at line 3577 skipping to change at line 3546
The CA MUST respond to the request by providing (at least) all of the The CA MUST respond to the request by providing (at least) all of the
information requested by the requester. If some of the information information requested by the requester. If some of the information
cannot be provided, then an error must be conveyed to the requester. cannot be provided, then an error must be conveyed to the requester.
If PKIMessages are used to request and supply this PKI information, If PKIMessages are used to request and supply this PKI information,
then the request MUST be the GenMsg message, the response MUST be the then the request MUST be the GenMsg message, the response MUST be the
GenRep message, and the error MUST be the Error message. These GenRep message, and the error MUST be the Error message. These
messages are protected using a MAC based on shared secret information messages are protected using a MAC based on shared secret information
(e.g., password-based MAC; see Section 6.1 of "CMP Algorithms" (e.g., password-based MAC; see Section 6.1 of "CMP Algorithms"
[RFC9481]) or using any asymmetric authentication means such as a [RFC9481]) or using any asymmetric authentication means such as a
signature (if the end entity has an existing certificate). signature (if the EE has an existing certificate).
6.6. Cross Certification 6.6. Cross-Certification
The requester CA is the CA that will become the subject of the cross- The requester CA is the CA that will become the subject of the cross-
certificate; the responder CA will become the issuer of the cross- certificate; the responder CA will become the issuer of the cross-
certificate. certificate.
The requester CA must be "up and running" before initiating the The requester CA must be "up and running" before initiating the
cross-certification operation. cross-certification operation.
6.6.1. One-Way Request-Response Scheme 6.6.1. One-Way Request-Response Scheme
skipping to change at line 3604 skipping to change at line 3573
must initiate a cross-certification operation (or use another must initiate a cross-certification operation (or use another
scheme). scheme).
This scheme is suitable where the two CAs in question can already This scheme is suitable where the two CAs in question can already
verify each other's signatures (they have some common points of verify each other's signatures (they have some common points of
trust) or where there is an out-of-band verification of the origin of trust) or where there is an out-of-band verification of the origin of
the certification request. the certification request.
Detailed Description: Detailed Description:
Cross certification is initiated at one CA known as the responder. Cross-certification is initiated at one CA known as the responder.
The CA administrator for the responder identifies the CA it wants The CA administrator for the responder identifies the CA it wants
to cross certify and the responder CA equipment generates an to cross-certify and the responder CA equipment generates an
authorization code. The responder CA administrator passes this authorization code. The responder CA administrator passes this
authorization code by out-of-band means to the requester CA authorization code by out-of-band means to the requester CA
administrator. The requester CA administrator enters the administrator. The requester CA administrator enters the
authorization code at the requester CA in order to initiate the authorization code at the requester CA in order to initiate the
on-line exchange. online exchange.
The authorization code is used for authentication and integrity The authorization code is used for authentication and integrity
purposes. This is done by generating a symmetric key based on the purposes. This is done by generating a symmetric key based on the
authorization code and using the symmetric key for generating authorization code and using the symmetric key for generating
Message Authentication Codes (MACs) on all messages exchanged. MACs) on all messages exchanged. (Authentication may
(Authentication may alternatively be done using signatures instead alternatively be done using signatures instead of MACs, if the CAs
of MACs, if the CAs are able to retrieve and validate the required are able to retrieve and validate the required public keys by some
public keys by some means, such as an out-of-band hash means, such as an out-of-band hash comparison.)
comparison.)
The requester CA initiates the exchange by generating a cross- The requester CA initiates the exchange by generating a cross-
certification request (ccr) with a fresh random number (requester certification request (ccr) with a fresh random number (requester
random number). The requester CA then sends the ccr message to random number). The requester CA then sends the ccr message to
the responder CA. The fields in this message are protected from the responder CA. The fields in this message are protected from
modification with a MAC based on the authorization code. modification with a MAC based on the authorization code.
Upon receipt of the ccr message, the responder CA validates the Upon receipt of the ccr message, the responder CA validates the
message and the MAC, saves the requester random number, and message and the MAC, saves the requester random number, and
generates its own random number (responder random number). It generates its own random number (responder random number). It
skipping to change at line 3648 skipping to change at line 3616
Upon receipt of the ccp message, the requester CA validates the Upon receipt of the ccp message, the requester CA validates the
message (including the received random numbers) and the MAC. The message (including the received random numbers) and the MAC. The
requester CA responds with the certConf message. The fields in requester CA responds with the certConf message. The fields in
this message are protected from modification with a MAC based on this message are protected from modification with a MAC based on
the authorization code. The requester CA MAY write the requester the authorization code. The requester CA MAY write the requester
certificate to the Repository as an aid to later certificate path certificate to the Repository as an aid to later certificate path
construction. construction.
Upon receipt of the certConf message, the responder CA validates Upon receipt of the certConf message, the responder CA validates
the message and the MAC and sends back an acknowledgement using the message and the MAC and sends back an acknowledgement using
the PKIConfirm message. It MAY also publish the requester the pkiconf message. It MAY also publish the requester
certificate as an aid to later path construction. certificate as an aid to later path construction.
Notes: Notes:
1. The ccr message must contain a "complete" certification request; 1. The ccr message must contain a "complete" certification request;
that is, all fields except the serial number (including, e.g., a that is, all fields except the serial number (including, e.g., a
BasicConstraints extension) must be specified by the requester BasicConstraints extension) must be specified by the requester
CA. CA.
2. The ccp message SHOULD contain the verification certificate of 2. The ccp message SHOULD contain the verification certificate of
skipping to change at line 3673 skipping to change at line 3641
envisioned, in which the issuing CA acquires the subject CA's public envisioned, in which the issuing CA acquires the subject CA's public
key from some repository, verifies it via some out-of-band mechanism, key from some repository, verifies it via some out-of-band mechanism,
and creates and publishes the cross-certificate without the subject and creates and publishes the cross-certificate without the subject
CA's explicit involvement. This model may be perfectly legitimate CA's explicit involvement. This model may be perfectly legitimate
for many environments, but since it does not require any protocol for many environments, but since it does not require any protocol
message exchanges, its detailed description is outside the scope of message exchanges, its detailed description is outside the scope of
this specification.) this specification.)
6.7. End Entity Initialization 6.7. End Entity Initialization
As with CAs, end entities must be initialized. Initialization of end As with CAs, EEs must be initialized. Initialization of EEs requires
entities requires at least two steps: at least two steps:
* acquisition of PKI information * acquisition of PKI information
* out-of-band verification of one root-CA public key * out-of-band verification of one root-CA public key
(Other possible steps include the retrieval of trust condition (Other possible steps include the retrieval of trust condition
information and/or out-of-band verification of other CA public keys.) information and/or out-of-band verification of other CA public keys.)
6.7.1. Acquisition of PKI Information 6.7.1. Acquisition of PKI Information
skipping to change at line 3699 skipping to change at line 3667
* (if the certifying CA is not a root-CA) the certification path * (if the certifying CA is not a root-CA) the certification path
from the root CA to the certifying CA together with appropriate from the root CA to the certifying CA together with appropriate
revocation lists revocation lists
* the algorithms and algorithm parameters that the certifying CA * the algorithms and algorithm parameters that the certifying CA
supports for each relevant usage supports for each relevant usage
Additional information could be required (e.g., supported extensions Additional information could be required (e.g., supported extensions
or CA policy information) in order to produce a certification request or CA policy information) in order to produce a certification request
that will be successful. However, for simplicity, we do not mandate that will be successful. However, for simplicity, we do not mandate
that the end entity acquires this information via the PKI messages. that the EE acquires this information via the PKI messages. The end
The end result is simply that some certification requests may fail result is simply that some certification requests may fail (e.g., if
(e.g., if the end entity wants to generate its own encryption key, the EE wants to generate its own encryption key, but the CA doesn't
but the CA doesn't allow that). allow that).
The required information MAY be acquired as described in Section 6.5. The required information MAY be acquired as described in Section 6.5.
6.7.2. Out-of-Band Verification of the Root CA Key 6.7.2. Out-of-Band Verification of the Root CA Key
An end entity must securely possess the public key of its root CA. An EE must securely possess the public key of its root CA. One
One method to achieve this is to provide the end entity with the CA's method to achieve this is to provide the EE with the CA's self-
self-certificate fingerprint via some secure "out-of-band" means. certificate fingerprint via some secure "out-of-band" means. The EE
The end entity can then securely use the CA's self-certificate. can then securely use the CA's self-certificate.
See Section 6.1 for further details. See Section 6.1 for further details.
6.8. Certificate Request 6.8. Certificate Request
An initialized end entity MAY request an additional certificate at An initialized EE MAY request an additional certificate at any time
any time (for any purpose). This request will be made using the (for any purpose). This request will be made using the certification
certification request (cr) message. If the end entity already request (cr) message. If the EE already possesses a signing key pair
possesses a signing key pair (with a corresponding verification (with a corresponding verification certificate), then this cr message
certificate), then this cr message will typically be protected by the will typically be protected by the entity's digital signature. The
entity's digital signature. The CA returns the new certificate (if CA returns the new certificate (if the request is successful) in a
the request is successful) in a CertRepMessage. CertRepMessage.
6.9. Key Update 6.9. Key Update
When a key pair is due to expire, the relevant end entity MAY request When a key pair is due to expire, the relevant EE MAY request a key
a key update; that is, it MAY request that the CA issue a new update; that is, it MAY request that the CA issue a new certificate
certificate for a new key pair (or, in certain circumstances, a new for a new key pair (or, in certain circumstances, a new certificate
certificate for the same key pair). The request is made using a key for the same key pair). The request is made using a key update
update request (kur) message (referred to, in some environments, as a request (kur) message (referred to, in some environments, as a
"Certificate Update" operation). If the end entity already possesses "Certificate Update" operation). If the EE already possesses a
a signing key pair (with a corresponding verification certificate), signing key pair (with a corresponding verification certificate),
then this message will typically be protected by the entity's digital then this message will typically be protected by the entity's digital
signature. The CA returns the new certificate (if the request is signature. The CA returns the new certificate (if the request is
successful) in a key update response (kup) message, which is successful) in a key update response (kup) message, which is
syntactically identical to a CertRepMessage. syntactically identical to a CertRepMessage.
7. Version Negotiation 7. Version Negotiation
This section defines the version negotiation used to support older This section defines the version negotiation used to support older
protocols between clients and servers. protocols between clients and servers.
skipping to change at line 3783 skipping to change at line 3751
7.1. Supporting RFC 2510 Implementations 7.1. Supporting RFC 2510 Implementations
[RFC2510] did not specify the behavior of implementations receiving [RFC2510] did not specify the behavior of implementations receiving
versions they did not understand since there was only one version in versions they did not understand since there was only one version in
existence. With the introduction of the revision in [RFC4210], the existence. With the introduction of the revision in [RFC4210], the
following versioning behavior is recommended. following versioning behavior is recommended.
7.1.1. Clients Talking to RFC 2510 Servers 7.1.1. Clients Talking to RFC 2510 Servers
If, after sending a message with a protocol version number higher If, after sending a message with a pvno higher than cmp1999, a client
than cmp1999, a client receives an ErrorMsgContent with a version of receives an ErrorMsgContent with a version of cmp1999, then it MUST
cmp1999, then it MUST abort the current transaction. abort the current transaction.
If a client receives a non-error PKIMessage with a version of If a client receives a non-error PKIMessage with a version of
cmp1999, then it MAY decide to continue the transaction (if the cmp1999, then it MAY decide to continue the transaction (if the
transaction hasn't finished) using the semantics described in transaction hasn't finished) using the semantics described in
[RFC2510]. If it does not choose to do so and the transaction is not [RFC2510]. If it does not choose to do so and the transaction is not
finished, then it MUST abort the transaction and send an finished, then it MUST abort the transaction and send an
ErrorMsgContent with a version of cmp1999. ErrorMsgContent with a version of cmp1999.
7.1.2. Servers Receiving Version cmp1999 PKIMessages 7.1.2. Servers Receiving Version cmp1999 PKIMessages
If a server receives a version cmp1999 message, it MAY revert to the If a server receives a version cmp1999 message, it MAY revert to the
behavior described in [RFC2510] and respond with version cmp1999 behavior described in [RFC2510] and respond with version cmp1999
messages. If it does not choose to do so, then it MUST send back an messages. If it does not choose to do so, then it MUST send back an
ErrorMsgContent as described above in Section 7. ErrorMsgContent as described above in Section 7.
8. Security Considerations 8. Security Considerations
8.1. On the Necessity of Proof-of-Possession 8.1. On the Necessity of POP
It is well established that the role of a Certification Authority is It is well established that the role of a CA is to verify that the
to verify that the name and public key belong to the end entity prior name and public key belong to the EE prior to issuing a certificate.
to issuing a certificate. If an entity holding a private key obtains If an entity holding a private key obtains a certificate containing
a certificate containing the corresponding public key issued for a the corresponding public key issued for a different entity, it can
different entity, it can authenticate as the entity named in the authenticate as the entity named in the certificate. This
certificate. This facilitates masquerading. It is not entirely facilitates masquerading. It is not entirely clear what security
clear what security guarantees are lost if an end entity is able to guarantees are lost if an EE is able to obtain a certificate
obtain a certificate containing a public key that they do not possess containing a public key that they do not possess the corresponding
the corresponding private key for. There are some scenarios, private key for. There are some scenarios, described as "forwarding
described as "forwarding attacks" in Appendix A of [Gueneysu], in attacks" in Appendix A of [Gueneysu], in which this can lead to
which this can lead to protocol attacks against a naively implemented protocol attacks against a naively implemented sign-then-encrypt
sign-then-encrypt protocol, but in general, it merely results in the protocol, but in general, it merely results in the EE obtaining a
end entity obtaining a certificate that they cannot use. certificate that they cannot use.
8.2. Proof-of-Possession with a Decryption Key 8.2. POP with a Decryption Key
Some cryptographic considerations are worth explicitly spelling out. Some cryptographic considerations are worth explicitly spelling out.
In the protocols specified above, when an end entity is required to In the protocols specified above, when an EE is required to prove
prove possession of a decryption key, it is effectively challenged to possession of a decryption key, it is effectively challenged to
decrypt something (its own certificate). This scheme (and many decrypt something (its own certificate). This scheme (and many
others!) could be vulnerable to an attack if the possessor of the others!) could be vulnerable to an attack if the possessor of the
decryption key in question could be fooled into decrypting an decryption key in question could be fooled into decrypting an
arbitrary challenge and returning the cleartext to an attacker. arbitrary challenge and returning the cleartext to an attacker.
Although in this specification a number of other failures in security Although in this specification a number of other failures in security
are required in order for this attack to succeed, it is conceivable are required in order for this attack to succeed, it is conceivable
that some future services (e.g., notary, trusted time) could that some future services (e.g., notary, trusted time) could
potentially be vulnerable to such attacks. For this reason, we potentially be vulnerable to such attacks. For this reason, we
reiterate the general rule that implementations should be very reiterate the general rule that implementations should be very
careful about decrypting arbitrary "ciphertext" and revealing careful about decrypting arbitrary "ciphertext" and revealing
recovered "plaintext" since such a practice can lead to serious recovered "plaintext" since such a practice can lead to serious
security vulnerabilities. security vulnerabilities.
The client MUST return the decrypted values only if they match the The client MUST return the decrypted values only if they match the
expected content type. In an indirect method, the decrypted value expected content type. In an indirect method, the decrypted value
MUST be a valid certificate, and in a direct method, the decrypted MUST be a valid certificate, and in a direct method, the decrypted
value MUST be a Rand as defined in Section 5.2.8.3.3. value MUST be a Rand as defined in Section 5.2.8.3.3.
8.3. Proof-of-Possession by Exposing the Private Key 8.3. POP by Exposing the Private Key
Note also that exposing a private key to the CA/RA as a proof-of- Note also that exposing a private key to the CA/RA as a POP technique
possession technique can carry some security risks (depending upon can carry some security risks (depending upon whether or not the CA/
whether or not the CA/RA can be trusted to handle such material RA can be trusted to handle such material appropriately).
appropriately). Implementers are advised to: Implementers are advised to:
* Exercise caution in selecting and using this particular POP * Exercise caution in selecting and using this particular POP
mechanism. mechanism.
* Only use this POP mechanism if archival of the private key is * Only use this POP mechanism if archival of the private key is
desired. desired.
* When appropriate, have the user of the application explicitly * When appropriate, have the user of the application explicitly
state that they are willing to trust the CA/RA to have a copy of state that they are willing to trust the CA/RA to have a copy of
their private key before proceeding to reveal the private key. their private key before proceeding to reveal the private key.
8.4. Attack Against Diffie-Hellman Key Exchange 8.4. Attack Against DH Key Exchange
A small subgroup attack during a Diffie-Hellman key exchange may be A small subgroup attack during a DH key exchange may be carried out
carried out as follows. A malicious end entity may deliberately as follows. A malicious EE may deliberately choose DH parameters
choose DH parameters that enable it to derive (a significant number that enable it to derive (a significant number of bits of) the DH
of bits of) the DH private key of the CA during a key archival or key private key of the CA during a key archival or key recovery
recovery operation. Armed with this knowledge, the EE would then be operation. Armed with this knowledge, the EE would then be able to
able to retrieve the decryption private key of another unsuspecting retrieve the decryption private key of another unsuspecting EE, EE2,
end entity, EE2, during EE2's legitimate key archival or key recovery during EE2's legitimate key archival or key recovery operation with
operation with that CA. In order to avoid the possibility of such an that CA. In order to avoid the possibility of such an attack, two
attack, two courses of action are available. (1) The CA may generate courses of action are available. (1) The CA may generate a fresh DH
a fresh DH key pair to be used as a protocol encryption key pair for key pair to be used as a protocol encryption key pair for each EE
each EE with which it interacts. (2) The CA may enter into a key with which it interacts. (2) The CA may enter into a key validation
validation protocol (not specified in this document) with each protocol (not specified in this document) with each requesting EE to
requesting end entity to ensure that the EE's protocol encryption key ensure that the EE's protocol encryption key pair will not facilitate
pair will not facilitate this attack. Option (1) is clearly simpler this attack. Option (1) is clearly simpler (requiring no extra
(requiring no extra protocol exchanges from either party) and is protocol exchanges from either party) and is therefore RECOMMENDED.
therefore RECOMMENDED.
8.5. Perfect Forward Secrecy 8.5. Perfect Forward Secrecy
Long-term security typically requires perfect forward secrecy (pfs). Long-term security typically requires perfect forward secrecy (pfs).
When transferring encrypted long-term confidential values such as When transferring encrypted long-term confidential values such as
centrally generated private keys or revocation passphrases, pfs is centrally generated private keys or revocation passphrases, pfs is
likely important. Yet, it is not needed for CMP message protection likely important. Yet, it is not needed for CMP message protection
providing integrity and authenticity because transfer of PKI messages providing integrity and authenticity because transfer of PKI messages
is usually completed in very limited time. For the same reason, it is usually completed in very limited time. For the same reason, it
is not typically required for the indirect method to provide a POP is not typically required for the indirect method to provide a POP
skipping to change at line 3925 skipping to change at line 3892
numbers is difficult. ISO/IEC 20543:2019 [ISO.20543-2019], NIST SP numbers is difficult. ISO/IEC 20543:2019 [ISO.20543-2019], NIST SP
800-90A Rev.1 [NIST.SP.800_90Ar1], BSI AIS 31 V2.0 [AIS31], and other 800-90A Rev.1 [NIST.SP.800_90Ar1], BSI AIS 31 V2.0 [AIS31], and other
specifications offer valuable guidance in this area. specifications offer valuable guidance in this area.
If shared secret information is generated by a cryptographically If shared secret information is generated by a cryptographically
secure random number generator (CSRNG), it is safe to assume that the secure random number generator (CSRNG), it is safe to assume that the
entropy of the shared secret information equals its bit length. If entropy of the shared secret information equals its bit length. If
no CSRNG is used, the entropy of shared secret information depends on no CSRNG is used, the entropy of shared secret information depends on
the details of the generation process and cannot be measured securely the details of the generation process and cannot be measured securely
after it has been generated. If user-generated passwords are used as after it has been generated. If user-generated passwords are used as
shared secret information, their entropy cannot be measured and are shared secret information, their entropy cannot be measured.
typically insufficient for protected delivery of centrally generated Passwords generated from user generated entropy are typically
keys or trust anchors. insufficient for protected delivery of centrally generated keys or
trust anchors.
If the entropy of shared secret information protecting the delivery If the entropy of shared secret information protecting the delivery
of a centrally generated key pair is known, it should not be less of a centrally generated key pair is known, it should not be less
than the security strength of that key pair; if the shared secret than the security strength of that key pair; if the shared secret
information is reused for different key pairs, the security of the information is reused for different key pairs, the security of the
shared secret information should exceed the security strength of each shared secret information should exceed the security strength of each
individual key pair. individual key pair.
For the case of a PKI management operation that delivers a new trust For the case of a PKI management operation that delivers a new trust
anchor (e.g., a root CA certificate), using caPubs or genp that is anchor (e.g., a root CA certificate), using caPubs or genp that is
skipping to change at line 4002 skipping to change at line 3970
trust anchor information included in the message. trust anchor information included in the message.
Additionally, the EE MUST verify that the sender is an authorized Additionally, the EE MUST verify that the sender is an authorized
source of trust anchors. This authorization is governed by local source of trust anchors. This authorization is governed by local
policy and typically indicated using shared secret information or policy and typically indicated using shared secret information or
with a signature-based message protection using a certificate issued with a signature-based message protection using a certificate issued
by a PKI that is explicitly authorized for this purpose. by a PKI that is explicitly authorized for this purpose.
8.10. Authorizing Requests for Certificates with Specific EKUs 8.10. Authorizing Requests for Certificates with Specific EKUs
When a CA issues a certificate containing extended key usage When a CA issues a certificate containing EKU extensions as defined
extensions as defined in Section 4.5, this expresses delegation of an in Section 4.5, this expresses delegation of an authorization that
authorization that originally is only with the CA certificate itself. originally is only with the CA certificate itself. Such delegation
Such delegation is a very sensitive action in a PKI, and therefore, is a very sensitive action in a PKI, and therefore, special care must
special care must be taken when approving such certificate requests be taken when approving such certificate requests to ensure that only
to ensure that only legitimate entities receive a certificate legitimate entities receive a certificate containing such an EKU.
containing such an EKU.
8.11. Usage of Certificate Transparency Logs 8.11. Usage of CT Logs
CAs that support indirect POP MUST NOT also publish final CAs that support indirect POP MUST NOT also publish final
certificates to Certificate Transparency (CT) logs [RFC9162] before certificates to CT logs [RFC9162] before having received the certConf
having received the certConf message containing the certHash of that message containing the certHash of that certificate to complete the
certificate to complete the POP. The risk is that a malicious actor POP. The risk is that a malicious actor could fetch the final
could fetch the final certificate from the CT log and use that to certificate from the CT log and use that to spoof a response to the
spoof a response to the implicit POP challenge via a certConf implicit POP challenge via a certConf response. This risk does not
response. This risk does not apply to CT precertificates, so those apply to CT precertificates, so those are OK to publish.
are OK to publish.
If a certificate or its precertificate was published in a CT log, it If a certificate or its precertificate was published in a CT log, it
must be revoked if a required certConf message could not be verified, must be revoked if a required certConf message could not be verified,
especially when the implicit POP was used. especially when the implicit POP was used.
9. IANA Considerations 9. IANA Considerations
This document updates the ASN.1 modules in Appendix A.2 of CMP This document updates the ASN.1 modules in Appendix A.2 of CMP
Updates [RFC9480]. The OID 116 (id-mod-cmp2023-02) was registered in Updates [RFC9480]. The OID 116 (id-mod-cmp2023-02) was registered in
the "SMI Security for PKIX Module Identifier" registry to identify the "SMI Security for PKIX Module Identifier" registry to identify
the updated ASN.1 module. the updated ASN.1 module.
IANA has added the following entry in the "SMI Security for PKIX CMP IANA has added the following entry in the "SMI Security for PKIX CMP
Information Types" registry within the SMI Numbers registry group Information Types" registry within the SMI Numbers registry group
(see <https://www.iana.org/assignments/smi-numbers>) [RFC7299]: (see <https://www.iana.org/assignments/smi-numbers>) [RFC7299]:
Decimal: 24 Decimal: 24
Description: id-it-KemCiphertextInfo Description: id-it-KemCiphertextInfo
Reference: RFC 9810 Reference: RFC 9810
The new OID 1.2.840.113533.7.66.16 was registered by Entrust for id- Note that the new OID 1.2.840.113533.7.66.16 was registered by
KemBasedMac in the arc 1.2.840.113533.7.66. Entrust also registered Entrust, and not by IANA, for id-KemBasedMac in the arch
the OIDs for id-PasswordBasedMac and id-DHBasedMac there. 1.2.840.113533.7.66. This was done to match the previous
registrations for id-PasswordBasedMac and id-DHBasedMac, which are
also on the Entrust private arc.
All existing references to [RFC2510], [RFC4210], and [RFC9480] at All existing references to [RFC2510], [RFC4210], and [RFC9480] at
<https://www.iana.org/assignments/smi-numbers> except those in the <https://www.iana.org/assignments/smi-numbers> except those in the
"SMI Security for PKIX Module Identifier" registry have been replaced "SMI Security for PKIX Module Identifier" registry have been replaced
with references to this document. with references to this document.
10. References 10. References
10.1. Normative References 10.1. Normative References
[MvOV97] Menezes, A., van Oorschot, P., and S. Vanstone, "Handbook
of Applied Cryptography", CRC Press ISBN 0-8493-8523-7,
1996, <https://cacr.uwaterloo.ca/hac/>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2985] Nystrom, M. and B. Kaliski, "PKCS #9: Selected Object [RFC2985] Nystrom, M. and B. Kaliski, "PKCS #9: Selected Object
Classes and Attribute Types Version 2.0", RFC 2985, Classes and Attribute Types Version 2.0", RFC 2985,
DOI 10.17487/RFC2985, November 2000, DOI 10.17487/RFC2985, November 2000,
<https://www.rfc-editor.org/info/rfc2985>. <https://www.rfc-editor.org/info/rfc2985>.
[RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification [RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification
Request Syntax Specification Version 1.7", RFC 2986, Request Syntax Specification Version 1.7", RFC 2986,
DOI 10.17487/RFC2986, November 2000, DOI 10.17487/RFC2986, November 2000,
<https://www.rfc-editor.org/info/rfc2986>. <https://www.rfc-editor.org/info/rfc2986>.
skipping to change at line 4099 skipping to change at line 4076
<https://www.rfc-editor.org/info/rfc5652>. <https://www.rfc-editor.org/info/rfc5652>.
[RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958, [RFC5958] Turner, S., "Asymmetric Key Packages", RFC 5958,
DOI 10.17487/RFC5958, August 2010, DOI 10.17487/RFC5958, August 2010,
<https://www.rfc-editor.org/info/rfc5958>. <https://www.rfc-editor.org/info/rfc5958>.
[RFC6402] Schaad, J., "Certificate Management over CMS (CMC) [RFC6402] Schaad, J., "Certificate Management over CMS (CMC)
Updates", RFC 6402, DOI 10.17487/RFC6402, November 2011, Updates", RFC 6402, DOI 10.17487/RFC6402, November 2011,
<https://www.rfc-editor.org/info/rfc6402>. <https://www.rfc-editor.org/info/rfc6402>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8933] Housley, R., "Update to the Cryptographic Message Syntax [RFC8933] Housley, R., "Update to the Cryptographic Message Syntax
(CMS) for Algorithm Identifier Protection", RFC 8933, (CMS) for Algorithm Identifier Protection", RFC 8933,
DOI 10.17487/RFC8933, October 2020, DOI 10.17487/RFC8933, October 2020,
<https://www.rfc-editor.org/info/rfc8933>. <https://www.rfc-editor.org/info/rfc8933>.
[RFC9045] Housley, R., "Algorithm Requirements Update to the [RFC9045] Housley, R., "Algorithm Requirements Update to the
Internet X.509 Public Key Infrastructure Certificate Internet X.509 Public Key Infrastructure Certificate
Request Message Format (CRMF)", RFC 9045, Request Message Format (CRMF)", RFC 9045,
DOI 10.17487/RFC9045, June 2021, DOI 10.17487/RFC9045, June 2021,
<https://www.rfc-editor.org/info/rfc9045>. <https://www.rfc-editor.org/info/rfc9045>.
skipping to change at line 4121 skipping to change at line 4102
"Certificate Management Protocol (CMP) Algorithms", "Certificate Management Protocol (CMP) Algorithms",
RFC 9481, DOI 10.17487/RFC9481, November 2023, RFC 9481, DOI 10.17487/RFC9481, November 2023,
<https://www.rfc-editor.org/info/rfc9481>. <https://www.rfc-editor.org/info/rfc9481>.
[RFC9629] Housley, R., Gray, J., and T. Okubo, "Using Key [RFC9629] Housley, R., Gray, J., and T. Okubo, "Using Key
Encapsulation Mechanism (KEM) Algorithms in the Encapsulation Mechanism (KEM) Algorithms in the
Cryptographic Message Syntax (CMS)", RFC 9629, Cryptographic Message Syntax (CMS)", RFC 9629,
DOI 10.17487/RFC9629, August 2024, DOI 10.17487/RFC9629, August 2024,
<https://www.rfc-editor.org/info/rfc9629>. <https://www.rfc-editor.org/info/rfc9629>.
[MvOV97] Menezes, A., van Oorschot, P., and S. Vanstone, "Handbook 10.2. Informative References
of Applied Cryptography", CRC Press ISBN 0-8493-8523-7,
1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [AIS31] Killmann, W. and W. Schindler, "A proposal for:
Requirement Levels", BCP 14, RFC 2119, Functionality classes for random number generators -
DOI 10.17487/RFC2119, March 1997, Version 2.0", Federal Office for Information Security
<https://www.rfc-editor.org/info/rfc2119>. (BSI), September 2011,
<https://www.bsi.bund.de/SharedDocs/Downloads/DE/BSI/
Zertifizierung/Interpretationen/AIS_31_Functionality_class
es_for_random_number_generators_e.pdf>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [CVE-2008-0166]
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, National Institute of Science and Technology (NIST),
May 2017, <https://www.rfc-editor.org/info/rfc8174>. "National Vulnerability Database - CVE-2008-0166", May
2008, <https://nvd.nist.gov/vuln/detail/CVE-2008-0166>.
10.2. Informative References [ETSI-3GPP.33.310]
3GPP, "Network Domain Security (NDS); Authentication
Framework (AF)", 3GPP TS 33.310 16.6.0, December 2020,
<http://www.3gpp.org/ftp/Specs/html-info/33310.htm>.
[RFC9480] Brockhaus, H., von Oheimb, D., and J. Gray, "Certificate [Fujisaki] Fujisaki, E. and T. Okamoto, "Secure Integration of
Management Protocol (CMP) Updates", RFC 9480, Asymmetric and Symmetric Encryption Schemes", Journal of
DOI 10.17487/RFC9480, November 2023, Cryptology, vol. 26, no. 1, pp. 80-101,
<https://www.rfc-editor.org/info/rfc9480>. DOI 10.1007/s00145-011-9114-1, December 2011,
<https://doi.org/10.1007/s00145-011-9114-1>.
[RFC9482] Sahni, M., Ed. and S. Tripathi, Ed., "Constrained [Gueneysu] Gueneysu, T., Hodges, P., Land, G., Ounsworth, M.,
Application Protocol (CoAP) Transfer for the Certificate Stebila, D., and G. Zaverucha, "Proof-of-possession for
Management Protocol", RFC 9482, DOI 10.17487/RFC9482, KEM certificates using verifiable generation", Cryptology
November 2023, <https://www.rfc-editor.org/info/rfc9482>. ePrint Archive, Paper 2022/703, 2022,
<https://eprint.iacr.org/2022/703>.
[RFC9483] Brockhaus, H., von Oheimb, D., and S. Fries, "Lightweight [Hofheinz] Hofheinz, D., Hövelmanns, K., and E. Kiltz, "A Modular
Certificate Management Protocol (CMP) Profile", RFC 9483, Analysis of the Fujisaki-Okamoto Transformation", Theory
DOI 10.17487/RFC9483, November 2023, of Cryptography (TCC 2017), Lecture Notes in Computer
<https://www.rfc-editor.org/info/rfc9483>. Science, vol. 10677, pp. 341-371,
DOI 10.1007/978-3-319-70500-2_12, November 2017,
<https://doi.org/10.1007/978-3-319-70500-2_12>.
[RFC9811] Brockhaus, H., von Oheimb, D., Ounsworth, M., and J. Gray, [IEEE.802.1AR-2018]
"Internet X.509 Public Key Infrastructure -- HTTP Transfer IEEE, "IEEE Standard for Local and Metropolitan Area
for the Certificate Management Protocol (CMP)", RFC 9811, Networks - Secure Device Identity", IEEE Std 802.1AR-2018,
June 2025, <https://www.rfc-editor.org/info/rfc9811>. DOI 10.1109/ieeestd.2018.8423794, August 2018,
<https://doi.org/10.1109/ieeestd.2018.8423794>.
[ISO.20543-2019]
ISO/IEC, "Information technology -- Security techniques --
Test and analysis methods for random bit generators within
ISO/IEC 19790 and ISO/IEC 15408", ISO/IEC 20543:2019,
October 2019, <https://www.iso.org/standard/68296.html>.
[MiningPsQs]
Heninger, N., Durumeric, Z., Wustrow, E., and J. A.
Halderman, "Mining Your Ps and Qs: Detection of Widespread
Weak Keys in Network Devices", 21st USENIX Security
Symposium (USENIX Security 12), August 2012,
<https://www.usenix.org/conference/usenixsecurity12/
technical-sessions/presentation/heninger>.
[ML-KEM] Turner, S., Kampanakis, P., Massimo, J., and B.
Westerbaan, "Internet X.509 Public Key Infrastructure -
Algorithm Identifiers for the Module-Lattice-Based Key-
Encapsulation Mechanism (ML-KEM)", Work in Progress,
Internet-Draft, draft-ietf-lamps-kyber-certificates-10, 16
April 2025, <https://datatracker.ietf.org/doc/html/draft-
ietf-lamps-kyber-certificates-10>.
[NIST.SP.800_90Ar1]
Barker, E. B. and J. M. Kelsey, "Recommendation for Random
Number Generation Using Deterministic Random Bit
Generators", NIST SP 800-90Ar1,
DOI 10.6028/NIST.SP.800-90Ar1, June 2015,
<https://nvlpubs.nist.gov/nistpubs/SpecialPublications/
NIST.SP.800-90Ar1.pdf>.
[RFC1847] Galvin, J., Murphy, S., Crocker, S., and N. Freed, [RFC1847] Galvin, J., Murphy, S., Crocker, S., and N. Freed,
"Security Multiparts for MIME: Multipart/Signed and "Security Multiparts for MIME: Multipart/Signed and
Multipart/Encrypted", RFC 1847, DOI 10.17487/RFC1847, Multipart/Encrypted", RFC 1847, DOI 10.17487/RFC1847,
October 1995, <https://www.rfc-editor.org/info/rfc1847>. October 1995, <https://www.rfc-editor.org/info/rfc1847>.
[RFC2510] Adams, C. and S. Farrell, "Internet X.509 Public Key [RFC2510] Adams, C. and S. Farrell, "Internet X.509 Public Key
Infrastructure Certificate Management Protocols", Infrastructure Certificate Management Protocols",
RFC 2510, DOI 10.17487/RFC2510, March 1999, RFC 2510, DOI 10.17487/RFC2510, March 1999,
<https://www.rfc-editor.org/info/rfc2510>. <https://www.rfc-editor.org/info/rfc2510>.
skipping to change at line 4245 skipping to change at line 4266
[RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The [RFC9147] Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version Datagram Transport Layer Security (DTLS) Protocol Version
1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022, 1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,
<https://www.rfc-editor.org/info/rfc9147>. <https://www.rfc-editor.org/info/rfc9147>.
[RFC9162] Laurie, B., Messeri, E., and R. Stradling, "Certificate [RFC9162] Laurie, B., Messeri, E., and R. Stradling, "Certificate
Transparency Version 2.0", RFC 9162, DOI 10.17487/RFC9162, Transparency Version 2.0", RFC 9162, DOI 10.17487/RFC9162,
December 2021, <https://www.rfc-editor.org/info/rfc9162>. December 2021, <https://www.rfc-editor.org/info/rfc9162>.
[RFC9480] Brockhaus, H., von Oheimb, D., and J. Gray, "Certificate
Management Protocol (CMP) Updates", RFC 9480,
DOI 10.17487/RFC9480, November 2023,
<https://www.rfc-editor.org/info/rfc9480>.
[RFC9482] Sahni, M., Ed. and S. Tripathi, Ed., "Constrained
Application Protocol (CoAP) Transfer for the Certificate
Management Protocol", RFC 9482, DOI 10.17487/RFC9482,
November 2023, <https://www.rfc-editor.org/info/rfc9482>.
[RFC9483] Brockhaus, H., von Oheimb, D., and S. Fries, "Lightweight
Certificate Management Protocol (CMP) Profile", RFC 9483,
DOI 10.17487/RFC9483, November 2023,
<https://www.rfc-editor.org/info/rfc9483>.
[RFC9733] von Oheimb, D., Ed., Fries, S., and H. Brockhaus, "BRSKI [RFC9733] von Oheimb, D., Ed., Fries, S., and H. Brockhaus, "BRSKI
with Alternative Enrollment (BRSKI-AE)", RFC 9733, with Alternative Enrollment (BRSKI-AE)", RFC 9733,
DOI 10.17487/RFC9733, March 2025, DOI 10.17487/RFC9733, March 2025,
<https://www.rfc-editor.org/info/rfc9733>. <https://www.rfc-editor.org/info/rfc9733>.
[ML-KEM] Turner, S., Kampanakis, P., Massimo, J., and B. [RFC9811] Brockhaus, H., von Oheimb, D., Ounsworth, M., and J. Gray,
Westerbaan, "Internet X.509 Public Key Infrastructure - "Internet X.509 Public Key Infrastructure -- HTTP Transfer
Algorithm Identifiers for the Module-Lattice-Based Key- for the Certificate Management Protocol (CMP)", RFC 9811,
Encapsulation Mechanism (ML-KEM)", Work in Progress, July 2025, <https://www.rfc-editor.org/info/rfc9811>.
Internet-Draft, draft-ietf-lamps-kyber-certificates-10, 16
April 2025, <https://datatracker.ietf.org/doc/html/draft-
ietf-lamps-kyber-certificates-10>.
[NIST.SP.800_90Ar1]
Barker, E. B. and J. M. Kelsey, "Recommendation for Random
Number Generation Using Deterministic Random Bit
Generators", NIST SP 800-90Ar1,
DOI 10.6028/NIST.SP.800-90Ar1, June 2015,
<https://nvlpubs.nist.gov/nistpubs/SpecialPublications/
NIST.SP.800-90Ar1.pdf>.
[IEEE.802.1AR-2018]
IEEE, "IEEE Standard for Local and Metropolitan Area
Networks - Secure Device Identity", IEEE Std 802.1AR-2018,
DOI 10.1109/ieeestd.2018.8423794, August 2018,
<https://doi.org/10.1109/ieeestd.2018.8423794>.
[CVE-2008-0166]
National Institute of Science and Technology (NIST),
"National Vulnerability Database - CVE-2008-0166", May
2008, <https://nvd.nist.gov/vuln/detail/CVE-2008-0166>.
[MiningPsQs] [UNISIG.Subset-137]
Heninger, N., Durumeric, Z., Wustrow, E., and J. A. UNISIG, "ERTMS/ETCS On-line Key Management FFFIS", Subset-
Halderman, "Mining Your Ps and Qs: Detection of Widespread 137, V1.0.0, December 2015,
Weak Keys in Network Devices", 21st USENIX Security <https://www.era.europa.eu/system/files/2023-01/
Symposium (USENIX Security 12), August 2012, sos3_index083_-_subset-137_v100.pdf>.
<https://www.usenix.org/conference/usenixsecurity12/
technical-sessions/presentation/heninger>.
[X509.2019] [X509.2019]
ITU-T, "Information technology - Open Systems ITU-T, "Information technology - Open Systems
Interconnection - The Directory: Public-key and attribute Interconnection - The Directory: Public-key and attribute
certificate frameworks", ITU-T Recommendation X.509 certificate frameworks", ITU-T Recommendation X.509
(10/2019), October 2019, (10/2019), October 2019,
<https://handle.itu.int/11.1002/1000/14033>. <https://handle.itu.int/11.1002/1000/14033>.
[ISO.20543-2019]
ISO/IEC, "Information technology -- Security techniques --
Test and analysis methods for random bit generators within
ISO/IEC 19790 and ISO/IEC 15408", ISO/IEC 20543:2019,
October 2019, <https://www.iso.org/standard/68296.html>.
[AIS31] Killmann, W. and W. Schindler, "A proposal for:
Functionality classes for random number generators -
Version 2.0", Federal Office for Information Security
(BSI), September 2011,
<https://www.bsi.bund.de/SharedDocs/Downloads/DE/BSI/
Zertifizierung/Interpretationen/AIS_31_Functionality_class
es_for_random_number_generators_e.pdf>.
[Gueneysu] Gueneysu, T., Hodges, P., Land, G., Ounsworth, M.,
Stebila, D., and G. Zaverucha, "Proof-of-possession for
KEM certificates using verifiable generation", Cryptology
ePrint Archive, Paper 2022/703, 2022,
<https://eprint.iacr.org/2022/703>.
[Fujisaki] Fujisaki, E. and T. Okamoto, "Secure Integration of
Asymmetric and Symmetric Encryption Schemes", Journal of
Cryptology, vol. 26, no. 1, pp. 80-101,
DOI 10.1007/s00145-011-9114-1, December 2011,
<https://doi.org/10.1007/s00145-011-9114-1>.
[Hofheinz] Hofheinz, D., Hövelmanns, K., and E. Kiltz, "A Modular
Analysis of the Fujisaki-Okamoto Transformation", Theory
of Cryptography (TCC 2017), Lecture Notes in Computer
Science, vol. 10677, pp. 341-371,
DOI 10.1007/978-3-319-70500-2_12, November 2017,
<https://doi.org/10.1007/978-3-319-70500-2_12>.
[ETSI-3GPP.33.310]
3GPP, "Network Domain Security (NDS); Authentication
Framework (AF)", 3GPP TS 33.310 16.6.0, December 2020,
<http://www.3gpp.org/ftp/Specs/html-info/33310.htm>.
[UNISIG.Subset-137]
UNISIG, "ERTMS/ETCS On-line Key Management FFFIS", Subset-
137, V1.0.0, December 2015,
<https://www.era.europa.eu/system/files/2023-01/
sos3_index083_-_subset-137_v100.pdf>.
Appendix A. Reasons for the Presence of RAs Appendix A. Reasons for the Presence of RAs
The reasons that justify the presence of an RA can be split into The reasons that justify the presence of an RA can be split into
those that are due to technical factors and those that are those that are due to technical factors and those that are
organizational in nature. Technical reasons include the following. organizational in nature. Technical reasons include the following.
* If hardware tokens are in use, then not all end entities will have * If hardware tokens are in use, then not all EEs will have the
the equipment needed to initialize these; the RA equipment can equipment needed to initialize these; the RA equipment can include
include the necessary functionality (this may also be a matter of the necessary functionality (this may also be a matter of policy).
policy).
* Some end entities may not have the capability to publish * Some EEs may not have the capability to publish certificates;
certificates; again, the RA may be suitably placed for this. again, the RA may be suitably placed for this.
* The RA will be able to issue signed revocation requests on behalf * The RA will be able to issue signed revocation requests on behalf
of end entities associated with it, whereas the end entity may not of EEs associated with it, whereas the EE may not be able to do
be able to do this (if the key pair is completely lost). this (if the key pair is completely lost).
Some of the organizational reasons that argue for the presence of an Some of the organizational reasons that argue for the presence of an
RA are the following. RA are the following.
* It may be more cost effective to concentrate functionality in the * It may be more cost effective to concentrate functionality in the
RA equipment than to supply functionality to all end entities RA equipment than to supply functionality to all EEs (especially
(especially if special token initialization equipment is to be if special token initialization equipment is to be used).
used).
* Establishing RAs within an organization can reduce the number of * Establishing RAs within an organization can reduce the number of
CAs required, which is sometimes desirable. CAs required, which is sometimes desirable.
* RAs may be better placed to identify people with their * RAs may be better placed to identify people with their
"electronic" names, especially if the CA is physically remote from "electronic" names, especially if the CA is physically remote from
the end entity. the EE.
* For many applications, there will already be some administrative * For many applications, there will already be some administrative
structure in place so that candidates for the role of RA are easy structure in place so that candidates for the role of RA are easy
to find (which may not be true of the CA). to find (which may not be true of the CA).
Further reasons relevant for automated machine-to-machine certificate Further reasons relevant for automated machine-to-machine certificate
lifecycle management are available in the Lightweight CMP Profile lifecycle management are available in the Lightweight CMP Profile
[RFC9483]. [RFC9483].
Appendix B. The Use of Revocation Passphrase Appendix B. The Use of Revocation Passphrase
skipping to change at line 4437 skipping to change at line 4403
generalInfo field of the PKIHeader of the corresponding response generalInfo field of the PKIHeader of the corresponding response
PKIMessage. If the CA/RA is unable to return the appropriate PKIMessage. If the CA/RA is unable to return the appropriate
response message for any reason, it MUST send an error message response message for any reason, it MUST send an error message
with a status of "rejection" and, optionally, a failInfo reason with a status of "rejection" and, optionally, a failInfo reason
set. set.
* Either the localKeyId attribute of EnvelopedData as specified in * Either the localKeyId attribute of EnvelopedData as specified in
[RFC2985] or the valueHint field of EncryptedValue MAY contain a [RFC2985] or the valueHint field of EncryptedValue MAY contain a
key identifier (chosen by the entity, along with the passphrase key identifier (chosen by the entity, along with the passphrase
itself) to assist in later retrieval of the correct passphrase itself) to assist in later retrieval of the correct passphrase
(e.g., when the revocation request is constructed by the end (e.g., when the revocation request is constructed by the EE and
entity and received by the CA/RA). received by the CA/RA).
* The revocation request message is protected by a password-based * The revocation request message is protected by a password-based
MAC (see Section 6.1 of "CMP Algorithms" [RFC9481]) with the MAC (see Section 6.1 of "CMP Algorithms" [RFC9481]) with the
revocation passphrase as the key. If appropriate, the senderKID revocation passphrase as the key. If appropriate, the senderKID
field in the PKIHeader MAY contain the value previously field in the PKIHeader MAY contain the value previously
transmitted in localKeyId or valueHint. transmitted in localKeyId or valueHint.
Note: For a message transferring a revocation passphrase indicating Note: For a message transferring a revocation passphrase indicating
cmp2021(3) in the pvno field of the PKIHeader, the encrypted cmp2021(3) in the pvno field of the PKIHeader, the encrypted
passphrase MUST be transferred in the envelopedData choice of passphrase MUST be transferred in the envelopedData choice of
skipping to change at line 4489 skipping to change at line 4455
the request message (so that a request for revocation of one the request message (so that a request for revocation of one
certificate may be modified by an unauthorized third party to a certificate may be modified by an unauthorized third party to a
request for revocation of another certificate for that entity). request for revocation of another certificate for that entity).
Appendix C. PKI Management Message Profiles (REQUIRED) Appendix C. PKI Management Message Profiles (REQUIRED)
This appendix contains detailed profiles for those PKIMessages that This appendix contains detailed profiles for those PKIMessages that
MUST be supported by conforming implementations (see Section 6). MUST be supported by conforming implementations (see Section 6).
Note: Appendices C and D focus on PKI management operations managing Note: Appendices C and D focus on PKI management operations managing
certificates for human end entities. In contrast, the Lightweight certificates for human EEs. In contrast, the Lightweight CMP Profile
CMP Profile [RFC9483] focuses on typical use cases of industrial and [RFC9483] focuses on typical use cases of industrial and IoT
IoT scenarios supporting highly automated certificate lifecycle scenarios supporting highly automated certificate lifecycle
management scenarios. management scenarios.
Profiles for the PKIMessages used in the following PKI management Profiles for the PKIMessages used in the following PKI management
operations are provided: operations are provided:
* initial registration/certification * initial registration/certification
* basic authenticated scheme * basic authenticated scheme
* certificate request * certificate request
skipping to change at line 4525 skipping to change at line 4491
separately profiled as appropriate. separately profiled as appropriate.
3. The algorithmIdentifiers from PKIMessage structures are profiled 3. The algorithmIdentifiers from PKIMessage structures are profiled
separately. separately.
4. A "special" X.500 DN is called the "NULL-DN"; this means a DN 4. A "special" X.500 DN is called the "NULL-DN"; this means a DN
containing a zero-length SEQUENCE OF RelativeDistinguishedNames containing a zero-length SEQUENCE OF RelativeDistinguishedNames
(its DER encoding is then '3000'H). (its DER encoding is then '3000'H).
5. Where a GeneralName is required for a field, but no suitable 5. Where a GeneralName is required for a field, but no suitable
value is available (e.g., an end entity produces a request before value is available (e.g., an EE produces a request before knowing
knowing its name), then the GeneralName is to be an X.500 NULL-DN its name), then the GeneralName is to be an X.500 NULL-DN (i.e.,
(i.e., the Name field of the CHOICE is to contain a NULL-DN). the Name field of the CHOICE is to contain a NULL-DN).
6. Where a profile omits to specify the value for a GeneralName, 6. Where a profile omits to specify the value for a GeneralName,
then the NULL-DN value is to be present in the relevant then the NULL-DN value is to be present in the relevant
PKIMessage field. This occurs with the sender field of the PKIMessage field. This occurs with the sender field of the
PKIHeader for some messages. PKIHeader for some messages.
7. Where any ambiguity arises due to naming of fields, the profile 7. Where any ambiguity arises due to naming of fields, the profile
names these using a "dot" notation (e.g., "certTemplate.subject" names these using a "dot" notation (e.g., "certTemplate.subject"
means the subject field within a field called certTemplate). means the subject field within a field called certTemplate).
8. Where a "SEQUENCE OF types" is part of a message, a zero-based 8. Where a "SEQUENCE OF types" is part of a message, a zero-based
array notation is used to describe fields within the SEQUENCE OF array notation is used to describe fields within the SEQUENCE OF
(e.g., crm[0].certReq.certTemplate.subject refers to a subfield (e.g., crm[0].certReq.certTemplate.subject refers to a subfield
of the first CertReqMsg contained in a request message). of the first CertReqMsg contained in a request message).
9. All PKI message exchanges in Appendices C.4 to C.6 require a 9. All PKI message exchanges in Appendices C.4 to C.6 require a
certConf message to be sent by the initiating entity and a certConf message to be sent by the initiating entity and a
PKIConfirm to be sent by the responding entity. The PKIConfirm pkiconf message to be sent by the responding entity. The pkiconf
is not included in some of the profiles given since its body is is not included in some of the profiles given since its body is
NULL and its header contents are clear from the context. Any NULL and its header contents are clear from the context. Any
authenticated means can be used for the protectionAlg (e.g., authenticated means can be used for the protectionAlg (e.g.,
password-based MAC, if shared secret information is known, or password-based MAC, if shared secret information is known, or
signature). signature).
C.2. Algorithm Use Profile C.2. Algorithm Use Profile
For specifications of algorithm identifiers and respective For specifications of algorithm identifiers and respective
conventions for conforming implementations, please refer to conventions for conforming implementations, please refer to
Section 7.1 of CMP Algorithms [RFC9481]. Section 7.1 of CMP Algorithms [RFC9481].
C.3. Proof-of-Possession Profile C.3. POP Profile
POP fields for use (in signature field of pop field of The table below describes the POP fields for use (in signature field
ProofOfPossession structure) when proving possession of a private of pop field of ProofOfPossession structure) when proving possession
signing key that corresponds to a public verification key for which a of a private signing key that corresponds to a public verification
certificate has been requested. key for which a certificate has been requested.
+=====================+=============+===========================+ +=====================+=============+===========================+
| Field | Value | Comment | | Field | Value | Comment |
+=====================+=============+===========================+ +=====================+=============+===========================+
| algorithmIdentifier | MSG_SIG_ALG | only signature protection | | algorithmIdentifier | MSG_SIG_ALG | only signature protection |
| | | is allowed for this proof | | | | is allowed for this proof |
+---------------------+-------------+---------------------------+ +---------------------+-------------+---------------------------+
| signature | present | bits calculated using | | signature | present | bits calculated using |
| | | MSG_SIG_ALG | | | | MSG_SIG_ALG |
+---------------------+-------------+---------------------------+ +---------------------+-------------+---------------------------+
Table 2 Table 2
Note: For examples of MSG_SIG_ALG OIDs, see Section 3 of CMP Note: For examples of MSG_SIG_ALG OIDs, see Section 3 of CMP
Algorithms [RFC9481]. Algorithms [RFC9481].
Proof-of-possession of a private decryption key that corresponds to a POP of a private decryption key that corresponds to a public
public encryption key for which a certificate has been requested does encryption key for which a certificate has been requested does not
not use this profile; the CertHash field of the certConf message is use this profile; the CertHash field of the certConf message is used
used instead. instead.
Not every CA/RA will do Proof-of-Possession (of signing key, Not every CA/RA will do POP (of signing key, decryption key, or key
decryption key, or key agreement key) in the PKIX-CMP in-band agreement key) in the PKIX-CMP in-band certification request protocol
certification request protocol (how POP is done MAY ultimately be a (how POP is done MAY ultimately be a policy issue that is made
policy issue that is made explicit for any given CA in its publicized explicit for any given CA in its publicized Policy OID and
Policy OID and Certification Practice Statement). However, this Certification Practice Statement). However, this specification
specification mandates that CA/RA entities MUST do POP (by some mandates that CA/RA entities MUST do POP (by some means) as part of
means) as part of the certification process. All end entities MUST the certification process. All EEs MUST be prepared to provide POP
be prepared to provide POP (i.e., these components of the PKIX-CMP (i.e., these components of the PKIX-CMP protocol MUST be supported).
protocol MUST be supported).
C.4. Initial Registration/Certification (Basic Authenticated Scheme) C.4. Initial Registration/Certification (Basic Authenticated Scheme)
An (uninitialized) end entity requests a (first) certificate from a An (uninitialized) EE requests a (first) certificate from a CA. When
CA. When the CA responds with a message containing a certificate, the CA responds with a message containing a certificate, the EE
the end entity replies with a certificate confirmation. The CA sends replies with a certificate confirmation. The CA sends a pkiconf
a PKIConfirm back, closing the transaction. All messages are message back, closing the transaction. All messages are
authenticated. authenticated.
This scheme allows the end entity to request certification of a This scheme allows the EE to request certification of a locally
locally generated public key (typically a signature key). The end generated public key (typically a signature key). The EE MAY also
entity MAY also choose to request the centralized generation and choose to request the centralized generation and certification of
certification of another key pair (typically an encryption key pair). another key pair (typically an encryption key pair).
Certification may only be requested for one locally generated public Certification may only be requested for one locally generated public
key (for more, use separate PKIMessages). key (for more, use separate PKIMessages).
The end entity MUST support proof-of-possession of the private key The EE MUST support POP of the private key associated with the
associated with the locally generated public key. locally generated public key.
Preconditions: Preconditions:
1. The end entity can authenticate the CA's signature based on out- 1. The EE can authenticate the CA's signature based on out-of-band
of-band means. means.
2. The end entity and the CA share a symmetric MACing key. 2. The EE and the CA share a symmetric MACing key.
Message Flow: Message Flow:
Step# End entity PKI Step# End entity PKI
--------------------------------------------------------------------- ---------------------------------------------------------------------
1 format ir 1 format ir
2 --> ir --> 2 --> ir -->
3 handle ir 3 handle ir
4 format ip 4 format ip
5 <-- ip <-- 5 <-- ip <--
6 handle ip 6 handle ip
7 format certConf 7 format certConf
8 --> certConf --> 8 --> certConf -->
9 handle certConf 9 handle certConf
10 format PKIConf 10 format pkiconf
11 <-- PKIConf <-- 11 <-- pkiconf <--
12 handle PKIConf 12 handle pkiconf
For this profile, we mandate that the end entity MUST include all For this profile, we mandate that the EE MUST include all (i.e., one
(i.e., one or two) CertReqMsg in a single PKIMessage and that the PKI or two) CertReqMsg in a single PKIMessage and that the PKI (CA) MUST
(CA) MUST produce a single response PKIMessage that contains the produce a single response PKIMessage that contains the complete
complete response (i.e., including the OPTIONAL second key pair, if response (i.e., including the OPTIONAL second key pair, if it was
it was requested and if centralized key generation is supported). requested and if centralized key generation is supported). For
For simplicity, we also mandate that this message MUST be the final simplicity, we also mandate that this message MUST be the final one
one (i.e., no use of "waiting" status value). (i.e., no use of "waiting" status value).
The end entity has an out-of-band interaction with the CA/RA. This The EE has an out-of-band interaction with the CA/RA. This
transaction established the shared secret, the referenceNumber and transaction established the shared secret, the referenceNumber, and
OPTIONALLY the distinguished name used for both the sender and optionally the DN used for both the sender and subject name in the
subject name in the certificate template. See Section 8.7 for certificate template. See Section 8.7 for security considerations on
security considerations on quality of shared secret information. quality of shared secret information.
Initialization Request -- ir Initialization Request -- ir
Field Value Field Value
recipient CA name recipient CA name
-- the name of the CA who is being asked to produce a certificate -- the name of the CA who is being asked to produce a certificate
protectionAlg MSG_MAC_ALG protectionAlg MSG_MAC_ALG
-- only MAC protection is allowed for this request, based -- only MAC protection is allowed for this request, based
-- on initial authentication key -- on initial authentication key
senderKID referenceNum senderKID referenceNum
-- the reference number that the CA has previously issued -- the reference number that the CA has previously issued
-- to the end entity (together with the MACing key) -- to the EE (together with the MACing key)
transactionID present transactionID present
-- implementation-specific value, meaningful to end -- implementation-specific value, meaningful to end
-- entity. -- entity.
-- [If already in use at the CA, then a rejection message MUST -- [If already in use at the CA, then a rejection message MUST
-- be produced by the CA] -- be produced by the CA]
senderNonce present senderNonce present
-- 128 (pseudo-)random bits -- 128 (pseudo-)random bits
freeText any valid value freeText any valid value
body ir (CertReqMessages) body ir (CertReqMessages)
skipping to change at line 4693 skipping to change at line 4658
crm[0].certReq. fixed value of zero crm[0].certReq. fixed value of zero
certReqId certReqId
-- this is the index of the template within the message -- this is the index of the template within the message
crm[0].certReq present crm[0].certReq present
certTemplate certTemplate
-- MUST include subject public key value, otherwise unconstrained -- MUST include subject public key value, otherwise unconstrained
crm[0].pop... optionally present if public key crm[0].pop... optionally present if public key
POPOSigningKey from crm[0].certReq.certTemplate is POPOSigningKey from crm[0].certReq.certTemplate is
a signing key a signing key
-- proof-of-possession MAY be required in this exchange -- POP MAY be required in this exchange
-- (see Appendix D.3 for details) -- (see Appendix D.3 for details)
crm[0].certReq. optionally present crm[0].certReq. optionally present
controls.archiveOptions controls.archiveOptions
-- the end entity MAY request that the locally generated -- the EE MAY request that the locally generated
-- private key be archived -- private key be archived
crm[0].certReq. optionally present crm[0].certReq. optionally present
controls.publicationInfo controls.publicationInfo
-- the end entity MAY ask for publication of resulting cert. -- the EE MAY ask for publication of resulting cert.
crm[1].certReq fixed value of one crm[1].certReq fixed value of one
certReqId certReqId
-- the index of the template within the message -- the index of the template within the message
crm[1].certReq present crm[1].certReq present
certTemplate certTemplate
-- MUST NOT include actual public key bits, otherwise -- MUST NOT include actual public key bits, otherwise
-- unconstrained (e.g., the names need not be the same as in -- unconstrained (e.g., the names need not be the same as in
-- crm[0]). Note that subjectPublicKeyInfo MAY be present -- crm[0]). Note that subjectPublicKeyInfo MAY be present
-- and contain an AlgorithmIdentifier followed by a -- and contain an AlgorithmIdentifier followed by a
-- zero-length BIT STRING for the subjectPublicKey if it is -- zero-length BIT STRING for the subjectPublicKey if it is
-- desired to inform the CA/RA of algorithm and parameter -- desired to inform the CA/RA of algorithm and parameter
-- preferences regarding the to-be-generated key pair. -- preferences regarding the to-be-generated key pair.
crm[1].certReq. present [object identifier MUST be crm[1].certReq. present [object identifier MUST be
PROT_ENC_ALG] PROT_ENC_ALG]
controls.protocolEncrKey controls.protocolEncrKey
-- if centralized key generation is supported by this CA, -- if centralized key generation is supported by this CA,
-- this short-term asymmetric encryption key (generated by -- this short-term asymmetric encryption key (generated by
-- the end entity) will be used by the CA to encrypt (a -- the EE) will be used by the CA to encrypt (a
-- symmetric key used to encrypt) a private key generated by -- symmetric key used to encrypt) a private key generated by
-- the CA on behalf of the end entity -- the CA on behalf of the EE
crm[1].certReq. optionally present crm[1].certReq. optionally present
controls.archiveOptions controls.archiveOptions
crm[1].certReq. optionally present crm[1].certReq. optionally present
controls.publicationInfo controls.publicationInfo
protection present protection present
-- bits calculated using MSG_MAC_ALG -- bits calculated using MSG_MAC_ALG
Initialization Response -- ip Initialization Response -- ip
Field Value Field Value
sender CA name sender CA name
-- the name of the CA who produced the message -- the name of the CA who produced the message
messageTime present messageTime present
-- time at which CA produced message -- time at which CA produced message
protectionAlg MSG_MAC_ALG protectionAlg MSG_MAC_ALG
-- only MAC protection is allowed for this response -- only MAC protection is allowed for this response
senderKID referenceNum senderKID referenceNum
-- the reference number that the CA has previously issued to the -- the reference number that the CA has previously issued to the
-- end entity (together with the MACing key) -- EE (together with the MACing key)
transactionID present transactionID present
-- value from corresponding ir message -- value from corresponding ir message
senderNonce present senderNonce present
-- 128 (pseudo-)random bits -- 128 (pseudo-)random bits
recipNonce present recipNonce present
-- value from senderNonce in corresponding ir message -- value from senderNonce in corresponding ir message
freeText any valid value freeText any valid value
body ip (CertRepMessage) body ip (CertRepMessage)
contains exactly one response contains exactly one response
for each request for each request
skipping to change at line 4834 skipping to change at line 4799
-- 128 (pseudo-)random bits -- 128 (pseudo-)random bits
recipNonce present recipNonce present
-- value from senderNonce in corresponding ip message -- value from senderNonce in corresponding ip message
protectionAlg MSG_MAC_ALG protectionAlg MSG_MAC_ALG
-- only MAC protection is allowed for this message. The -- only MAC protection is allowed for this message. The
-- MAC is based on the initial authentication key shared -- MAC is based on the initial authentication key shared
-- between the EE and the CA. -- between the EE and the CA.
senderKID referenceNum senderKID referenceNum
-- the reference number that the CA has previously issued -- the reference number that the CA has previously issued
-- to the end entity (together with the MACing key) -- to the EE (together with the MACing key)
body certConf body certConf
-- see Section 5.3.18, "PKI Confirmation Content", for the -- see Section 5.3.18, "PKI Confirmation Content", for the
-- contents of the certConf fields. -- contents of the certConf fields.
-- Note: two CertStatus structures are required if both an -- Note: two CertStatus structures are required if both an
-- encryption and a signing certificate were sent. -- encryption and a signing certificate were sent.
protection present protection present
-- bits calculated using MSG_MAC_ALG -- bits calculated using MSG_MAC_ALG
Confirmation -- PKIConf Confirmation -- pkiconf
Field Value Field Value
sender present sender present
-- same as in ip -- same as in ip
recipient present recipient present
-- sender name from certConf -- sender name from certConf
transactionID present transactionID present
-- value from certConf message -- value from certConf message
senderNonce present senderNonce present
-- 128 (pseudo-)random bits -- 128 (pseudo-)random bits
recipNonce present recipNonce present
-- value from senderNonce from certConf message -- value from senderNonce from certConf message
protectionAlg MSG_MAC_ALG protectionAlg MSG_MAC_ALG
-- only MAC protection is allowed for this message. -- only MAC protection is allowed for this message.
senderKID referenceNum senderKID referenceNum
body PKIConf body pkiconf
protection present protection present
-- bits calculated using MSG_MAC_ALG -- bits calculated using MSG_MAC_ALG
C.5. Certificate Request C.5. Certificate Request
An (initialized) end entity requests a certificate from a CA (for any An (initialized) EE requests a certificate from a CA (for any
reason). When the CA responds with a message containing a reason). When the CA responds with a message containing a
certificate, the end entity replies with a certificate confirmation. certificate, the EE replies with a certificate confirmation. The CA
The CA replies with a PKIConfirm to close the transaction. All replies with a pkiconf message to close the transaction. All
messages are authenticated. messages are authenticated.
The profile for this exchange is identical to that given in The profile for this exchange is identical to that given in
Appendix C.4, with the following exceptions: Appendix C.4, with the following exceptions:
* sender name SHOULD be present; * sender name SHOULD be present;
* protectionAlg of MSG_SIG_ALG MUST be supported (MSG_MAC_ALG MAY * protectionAlg of MSG_SIG_ALG MUST be supported (MSG_MAC_ALG MAY
also be supported) in request, response, certConfirm, and also be supported) in request, response, certConf, and pkiconf
PKIConfirm messages; messages;
* senderKID and recipKID are only present if required for message * senderKID and recipKID are only present if required for message
verification; verification;
* body is cr or cp; * body is cr or cp;
* body may contain one or two CertReqMsg structures, but either * body may contain one or two CertReqMsg structures, but either
CertReqMsg may be used to request certification of a locally CertReqMsg may be used to request certification of a locally
generated public key or a centrally generated public key (i.e., generated public key or a centrally generated public key (i.e.,
the position-dependence requirement of Appendix C.4 is removed); the position-dependence requirement of Appendix C.4 is removed);
and and
* protection bits are calculated according to the protectionAlg * protection bits are calculated according to the protectionAlg
field. field.
C.6. Key Update Request C.6. Key Update Request
An (initialized) end entity requests a certificate from a CA (to An (initialized) EE requests a certificate from a CA (to update the
update the key pair and/or corresponding certificate that it already key pair and/or corresponding certificate that it already possesses).
possesses). When the CA responds with a message containing a When the CA responds with a message containing a certificate, the EE
certificate, the end entity replies with a certificate confirmation. replies with a certificate confirmation. The CA replies with a
The CA replies with a PKIConfirm to close the transaction. All PKIConfirm to close the transaction. All messages are authenticated.
messages are authenticated.
The profile for this exchange is identical to that given in The profile for this exchange is identical to that given in
Appendix C.4, with the following exceptions: Appendix C.4, with the following exceptions:
1. sender name SHOULD be present; * sender name SHOULD be present;
2. protectionAlg of MSG_SIG_ALG MUST be supported (MSG_MAC_ALG MAY * protectionAlg of MSG_SIG_ALG MUST be supported (MSG_MAC_ALG MAY
also be supported) in request, response, certConfirm, and also be supported) in request, response, certConfirm, and
PKIConfirm messages; PKIConfirm messages;
3. senderKID and recipKID are only present if required for message * senderKID and recipKID are only present if required for message
verification; verification;
4. body is kur or kup; * body is kur or kup;
5. body may contain one or two CertReqMsg structures, but either * body may contain one or two CertReqMsg structures, but either
CertReqMsg may be used to request certification of a locally CertReqMsg may be used to request certification of a locally
generated public key or a centrally generated public key generated public key or a centrally generated public key (i.e.,the
(i.e.,the position-dependence requirement of Appendix C.4 is position-dependence requirement of Appendix C.4 is removed);
removed);
6. protection bits are calculated according to the protectionAlg * protection bits are calculated according to the protectionAlg
field; and field; and
7. regCtrl OldCertId SHOULD be used (unless it is clear to both the * regCtrl OldCertId SHOULD be used (unless it is clear to both the
sender and receiver -- by means not specified in this document -- sender and receiver -- by means not specified in this document --
that it is not needed). that it is not needed).
Appendix D. PKI Management Message Profiles (OPTIONAL) Appendix D. PKI Management Message Profiles (OPTIONAL)
This appendix contains detailed profiles for those PKIMessages that This appendix contains detailed profiles for those PKIMessages that
MAY be supported by implementations. MAY be supported by implementations.
Profiles for the PKIMessages used in the following PKI management Profiles for the PKIMessages used in the following PKI management
operations are provided: operations are provided:
* root CA key update * root CA key update
skipping to change at line 4969 skipping to change at line 4932
D.1. General Rules for Interpretation of These Profiles D.1. General Rules for Interpretation of These Profiles
Identical to Appendix C.1. Identical to Appendix C.1.
D.2. Algorithm Use Profile D.2. Algorithm Use Profile
Identical to Appendix C.2. Identical to Appendix C.2.
D.3. Self-Signed Certificates D.3. Self-Signed Certificates
Profile of how a certificate structure may be "self-signed". These The table below is a profile of how a certificate structure may be
structures are used for distribution of new root CA public keys. "self-signed". These structures are used for distribution of new
This can occur in one of three ways (see Section 4.4 above for a root CA public keys. This can occur in one of three ways (see
description of the use of these structures): Section 4.4 above for a description of the use of these structures):
+============+=============================================+ +============+=============================================+
| Type | Function | | Type | Function |
+============+=============================================+ +============+=============================================+
| newWithNew | a "self-signed" certificate; the contained | | newWithNew | a "self-signed" certificate; the contained |
| | public key MUST be usable to verify the | | | public key MUST be usable to verify the |
| | signature (though this provides only | | | signature (though this provides only |
| | integrity and no authentication whatsoever) | | | integrity and no authentication whatsoever) |
+------------+---------------------------------------------+ +------------+---------------------------------------------+
| oldWithNew | previous root CA public key signed with new | | oldWithNew | previous root CA public key signed with new |
skipping to change at line 5000 skipping to change at line 4963
A newWithNew certificate (including relevant extensions) must contain A newWithNew certificate (including relevant extensions) must contain
"sensible" values for all fields. For example, when present, "sensible" values for all fields. For example, when present,
subjectAltName MUST be identical to issuerAltName, and, when present, subjectAltName MUST be identical to issuerAltName, and, when present,
keyIdentifiers must contain appropriate values, et cetera. keyIdentifiers must contain appropriate values, et cetera.
D.4. Root CA Key Update D.4. Root CA Key Update
A root CA updates its key pair. It then produces a CA key update A root CA updates its key pair. It then produces a CA key update
announcement message that can be made available (via some transport announcement message that can be made available (via some transport
mechanism) to the relevant end entities. A confirmation message is mechanism) to the relevant EEs. A confirmation message is not
not required from the end entities. required from the EEs.
ckuann message: ckuann message:
+============+================================+=====================+ +============+================================+=====================+
| Field | Value | Comment | | Field | Value | Comment |
+============+================================+=====================+ +============+================================+=====================+
| sender | CA name CA name | | | sender | CA name CA name | |
+------------+--------------------------------+---------------------+ +------------+--------------------------------+---------------------+
| body | ckuann(RootCaKeyUpdateContent) | | | body | ckuann(RootCaKeyUpdateContent) | |
+------------+--------------------------------+---------------------+ +------------+--------------------------------+---------------------+
skipping to change at line 5034 skipping to change at line 4997
| | | (e.g., | | | | (e.g., |
| | | certificates | | | | certificates |
| | | signed using the | | | | signed using the |
| | | new private key) | | | | new private key) |
+------------+--------------------------------+---------------------+ +------------+--------------------------------+---------------------+
Table 4 Table 4
D.5. PKI Information Request/Response D.5. PKI Information Request/Response
The end entity sends a general message to the PKI requesting details The EE sends a general message to the PKI requesting details that
that will be required for later PKI management operations. The RA/CA will be required for later PKI management operations. The RA/CA
responds with a general response. If an RA generates the response, responds with a general response. If an RA generates the response,
then it will simply forward the equivalent message that it previously then it will simply forward the equivalent message that it previously
received from the CA, with the possible addition of certificates to received from the CA, with the possible addition of certificates to
the extraCerts fields of the PKIMessage. A confirmation message is the extraCerts fields of the PKIMessage. A confirmation message is
not required from the end entity. not required from the EE.
Message Flows: Message Flows:
Step# End entity PKI Step# End entity PKI
--------------------------------------------------------------------- ---------------------------------------------------------------------
1 format genm 1 format genm
2 --> genm --> 2 --> genm -->
3 handle genm 3 handle genm
4 produce genp 4 produce genp
5 <-- genp <-- 5 <-- genp <--
skipping to change at line 5087 skipping to change at line 5050
-- name of the CA that produced the message -- name of the CA that produced the message
protectionAlg MSG_MAC_ALG or MSG_SIG_ALG protectionAlg MSG_MAC_ALG or MSG_SIG_ALG
-- any authenticated protection alg. -- any authenticated protection alg.
senderKID present if required senderKID present if required
-- must be present if required for verification of message -- must be present if required for verification of message
-- protection -- protection
body genp (GenRepContent) body genp (GenRepContent)
CAProtEncCert present (object identifier one CAProtEncCert present (object identifier one
of PROT_ENC_ALG), with relevant of PROT_ENC_ALG), with relevant
value value
-- to be used if end entity needs to encrypt information for -- to be used if EE needs to encrypt information for
-- the CA (e.g., private key for recovery purposes) -- the CA (e.g., private key for recovery purposes)
SignKeyPairTypes present, with relevant value SignKeyPairTypes present, with relevant value
-- the set of signature algorithm identifiers that this CA will -- the set of signature algorithm identifiers that this CA will
-- certify for subject public keys -- certify for subject public keys
EncKeyPairTypes present, with relevant value EncKeyPairTypes present, with relevant value
-- the set of encryption / key agreement algorithm identifiers that -- the set of encryption / key agreement algorithm identifiers that
-- this CA will certify for subject public keys -- this CA will certify for subject public keys
PreferredSymmAlg present (object identifier one PreferredSymmAlg present (object identifier one
of PROT_SYM_ALG) , with relevant of PROT_SYM_ALG) , with relevant
skipping to change at line 5119 skipping to change at line 5082
-- the CA MAY provide a copy of a complete CRL (i.e., -- the CA MAY provide a copy of a complete CRL (i.e.,
-- fullest possible one) -- fullest possible one)
protection present protection present
-- bits calculated using MSG_MAC_ALG or MSG_SIG_ALG -- bits calculated using MSG_MAC_ALG or MSG_SIG_ALG
extraCerts optionally present extraCerts optionally present
-- can be used to send some certificates to the end -- can be used to send some certificates to the end
-- entity. An RA MAY add its certificate here. -- entity. An RA MAY add its certificate here.
D.6. Cross-Certification Request/Response (1-way) D.6. Cross-Certification Request/Response (1-way)
Creation of a single cross-certificate (i.e., not two at once). The This section describes the creation of a single cross-certificate
requesting CA MAY choose who is responsible for publication of the (i.e., not two at once). The requesting CA MAY choose who is
cross-certificate created by the responding CA through use of the responsible for publication of the cross-certificate created by the
PKIPublicationInfo control. responding CA through use of the PKIPublicationInfo control.
Preconditions: Preconditions:
1. Responding CA can verify the origin of the request (possibly 1. Responding CA can verify the origin of the request (possibly
requiring out-of-band means) before processing the request. requiring out-of-band means) before processing the request.
2. Requesting CA can authenticate the authenticity of the origin of 2. Requesting CA can authenticate the authenticity of the origin of
the response (possibly requiring out-of-band means) before the response (possibly requiring out-of-band means) before
processing the response. processing the response.
skipping to change at line 5199 skipping to change at line 5162
validity present validity present
-- MUST be completely specified (i.e., both fields present) -- MUST be completely specified (i.e., both fields present)
issuer present issuer present
-- may be NULL-DN only if issuerAltNames extension value proposed -- may be NULL-DN only if issuerAltNames extension value proposed
publicKey present publicKey present
-- the key to be certified (which must be for a signing algorithm) -- the key to be certified (which must be for a signing algorithm)
extensions optionally present extensions optionally present
-- a requesting CA must propose values for all extensions -- a requesting CA must propose values for all extensions
-- that it requires to be in the cross-certificate -- that it requires to be in the cross-certificate
POPOSigningKey present POPOSigningKey present
-- see Appendix C.3: Proof-of-Possession Profile -- see Appendix C.3: POP Profile
protection present protection present
-- bits calculated using MSG_SIG_ALG -- bits calculated using MSG_SIG_ALG
extraCerts optionally present extraCerts optionally present
-- MAY contain any additional certificates that requester wishes -- MAY contain any additional certificates that requester wishes
-- to include -- to include
ccp: ccp:
Field Value Field Value
skipping to change at line 5264 skipping to change at line 5227
-- content of actual certificate must be examined by requesting CA -- content of actual certificate must be examined by requesting CA
-- before publication -- before publication
protection present protection present
-- bits calculated using MSG_SIG_ALG -- bits calculated using MSG_SIG_ALG
extraCerts optionally present extraCerts optionally present
-- MAY contain any additional certificates that responder wishes -- MAY contain any additional certificates that responder wishes
-- to include -- to include
D.7. In-Band Initialization Using External Identity Certificate D.7. In-Band Initialization Using External Identity Certificate
An (uninitialized) end entity wishes to initialize into the PKI with An (uninitialized) EE wishes to initialize into the PKI with a CA,
a CA, CA-1. It uses, for authentication purposes, a pre-existing CA-1. It uses, for authentication purposes, a pre-existing identity
identity certificate issued by another (external) CA, CA-X. A trust certificate issued by another (external) CA, CA-X. A trust
relationship must already have been established between CA-1 and CA-X relationship must already have been established between CA-1 and CA-X
so that CA-1 can validate the EE identity certificate signed by CA-X. so that CA-1 can validate the EE identity certificate signed by CA-X.
Furthermore, some mechanism must already have been established within Furthermore, some mechanism must already have been established within
the Trusted Execution Environment (TEE), also known as Personal the TEE, also known as PSE, of the EE that would allow it to
Security Environment (PSE), of the EE that would allow it to
authenticate and verify PKIMessages signed by CA-1 (as one example, authenticate and verify PKIMessages signed by CA-1 (as one example,
the TEE may contain a certificate issued for the public key of CA-1, the TEE may contain a certificate issued for the public key of CA-1,
signed by another CA that the EE trusts on the basis of out-of-band signed by another CA that the EE trusts on the basis of out-of-band
authentication techniques). authentication techniques).
The EE sends an initialization request to start the transaction. The EE sends an initialization request to start the transaction.
When CA-1 responds with a message containing the new certificate, the When CA-1 responds with a message containing the new certificate, the
end entity replies with a certificate confirmation. CA-1 replies EE replies with a certificate confirmation. CA-1 replies with a
with a PKIConfirm to close the transaction. All messages are signed pkiconf message to close the transaction. All messages are signed
(the EE messages are signed using the private key that corresponds to (the EE messages are signed using the private key that corresponds to
the public key in its external identity certificate; the CA-1 the public key in its external identity certificate; the CA-1
messages are signed using the private key that corresponds to the messages are signed using the private key that corresponds to the
public key in a certificate that can be chained to a trust anchor in public key in a certificate that can be chained to a trust anchor in
the EE's TEE). the EE's TEE).
The profile for this exchange is identical to that given in The profile for this exchange is identical to that given in
Appendix C.4, with the following exceptions: Appendix C.4, with the following exceptions:
* the EE and CA-1 do not share a symmetric MACing key (i.e., there * the EE and CA-1 do not share a symmetric MACing key (i.e., there
skipping to change at line 5327 skipping to change at line 5289
of a KEM key. There are two cases to distinguish, namely whether the of a KEM key. There are two cases to distinguish, namely whether the
PKI entity or the PKI management entity owns a KEM key pair. If both PKI entity or the PKI management entity owns a KEM key pair. If both
sides own KEM key pairs, the flows need to be combined such that for sides own KEM key pairs, the flows need to be combined such that for
each direction a shared secret key is established. each direction a shared secret key is established.
In the following message flows, Alice indicates the PKI entity that In the following message flows, Alice indicates the PKI entity that
uses a KEM key pair for message authentication and Bob provides the uses a KEM key pair for message authentication and Bob provides the
KEM ciphertext using Alice's public KEM key, as described in KEM ciphertext using Alice's public KEM key, as described in
Section 5.1.3.4. Section 5.1.3.4.
Message Flow when the PKI entity has a KEM key pair and certificate:
Step# PKI entity PKI management entity Step# PKI entity PKI management entity
(Alice) (Bob) (Alice) (Bob)
--------------------------------------------------------------------- ---------------------------------------------------------------------
1 format unprotected genm 1 format unprotected genm
of type of type
KemCiphertextInfo KemCiphertextInfo
without value, and without value, and
KEM certificate in KEM certificate in
extraCerts extraCerts
2 --> genm --> 2 --> genm -->
skipping to change at line 5371 skipping to change at line 5331
available key material available key material
14 <-- response <-- 14 <-- response <--
15 verify protection 15 verify protection
provided by the provided by the
PKI management entity PKI management entity
16 Further messages of this PKI management operation 16 Further messages of this PKI management operation
can be exchanged with MAC-based protection by the PKI can be exchanged with MAC-based protection by the PKI
entity using the established shared secret key (ssk) entity using the established shared secret key (ssk)
Figure 3: Message Flow When the PKI Entity Has a KEM Key Pair Figure 3: Message Flow When the PKI Entity Has a KEM Key Pair and
Certificate
Message Flow when the PKI entity knows that the PKI management entity
uses a KEM key pair and has the authentic public key:
Step# PKI entity PKI management entity Step# PKI entity PKI management entity
(Bob) (Alice) (Bob) (Alice)
--------------------------------------------------------------------- ---------------------------------------------------------------------
1 perform KEM Encapsulate 1 perform KEM Encapsulate
2 format request providing 2 format request providing
KEM ciphertext in KEM ciphertext in
generalInfo of type generalInfo of type
KemCiphertextInfo, KemCiphertextInfo,
and with protection and with protection
skipping to change at line 5415 skipping to change at line 5373
Figure 4: Message Flow When the PKI Entity Knows That the PKI Figure 4: Message Flow When the PKI Entity Knows That the PKI
Management Entity Uses a KEM Key Pair and Has the Authentic Management Entity Uses a KEM Key Pair and Has the Authentic
Public Key Public Key
Note: Figure 4 describes the situation where KEM-based message Note: Figure 4 describes the situation where KEM-based message
protection may not require more than one message exchange. In this protection may not require more than one message exchange. In this
case, the transactionID MUST also be used by the PKI entity (Bob) to case, the transactionID MUST also be used by the PKI entity (Bob) to
ensure domain separation between different PKI management operations. ensure domain separation between different PKI management operations.
Message Flow when the PKI entity does not know that the PKI
management entity uses a KEM key pair:
Step# PKI entity PKI management entity Step# PKI entity PKI management entity
(Bob) (Alice) (Bob) (Alice)
--------------------------------------------------------------------- ---------------------------------------------------------------------
1 format request with 1 format request with
protection depending protection depending
on available key on available key
material material
2 --> request --> 2 --> request -->
3 format unprotected error 3 format unprotected error
with status "rejection" with status "rejection"
skipping to change at line 5447 skipping to change at line 5402
Figure 5: Message Flow When the PKI Entity Does Not Know That the PKI Figure 5: Message Flow When the PKI Entity Does Not Know That the PKI
Management Entity Uses a KEM Key Pair Management Entity Uses a KEM Key Pair
Appendix F. Compilable ASN.1 Definitions Appendix F. Compilable ASN.1 Definitions
This section contains the updated 2002 ASN.1 module from [RFC5912], This section contains the updated 2002 ASN.1 module from [RFC5912],
which was updated in [RFC9480]. This module replaces the module in which was updated in [RFC9480]. This module replaces the module in
Section 9 of [RFC5912]. The module contains those changes to the Section 9 of [RFC5912]. The module contains those changes to the
normative ASN.1 module from Appendix F of [RFC4210] that were normative ASN.1 module from Appendix F of [RFC4210] that were
specified in [RFC9480], as well as changes made in this document. specified in [RFC9480], as well as changes made in this document.
This module makes reference to ASN.1 structures defined in [RFC6268],
as well as the UTF-8 encoding defined in [RFC3629].
PKIXCMP-2023 PKIXCMP-2023
{ iso(1) identified-organization(3) dod(6) internet(1) { iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-cmp2023-02(116) } id-mod-cmp2023-02(116) }
DEFINITIONS EXPLICIT TAGS ::= DEFINITIONS EXPLICIT TAGS ::=
BEGIN BEGIN
IMPORTS IMPORTS
AttributeSet{}, SingleAttribute{}, Extensions{}, EXTENSION, ATTRIBUTE AttributeSet{}, SingleAttribute{}, Extensions{}, EXTENSION, ATTRIBUTE
skipping to change at line 5590 skipping to change at line 5547
-- believes that the transport will be "suitable", i.e., -- believes that the transport will be "suitable", i.e.,
-- that the time will still be meaningful upon receipt) -- that the time will still be meaningful upon receipt)
protectionAlg [1] AlgorithmIdentifier{ALGORITHM, {...}} protectionAlg [1] AlgorithmIdentifier{ALGORITHM, {...}}
OPTIONAL, OPTIONAL,
-- algorithm used for calculation of protection bits -- algorithm used for calculation of protection bits
senderKID [2] KeyIdentifier OPTIONAL, senderKID [2] KeyIdentifier OPTIONAL,
recipKID [3] KeyIdentifier OPTIONAL, recipKID [3] KeyIdentifier OPTIONAL,
-- to identify specific keys used for protection -- to identify specific keys used for protection
transactionID [4] OCTET STRING OPTIONAL, transactionID [4] OCTET STRING OPTIONAL,
-- identifies the transaction, i.e., this will be the same in -- identifies the transaction, i.e., this will be the same in
-- corresponding request, response, certConf, and PKIConf -- corresponding request, response, certConf, and pkiconf
-- messages -- messages
senderNonce [5] OCTET STRING OPTIONAL, senderNonce [5] OCTET STRING OPTIONAL,
recipNonce [6] OCTET STRING OPTIONAL, recipNonce [6] OCTET STRING OPTIONAL,
-- nonces used to provide replay protection, senderNonce -- nonces used to provide replay protection, senderNonce
-- is inserted by the creator of this message; recipNonce -- is inserted by the creator of this message; recipNonce
-- is a nonce previously inserted in a related message by -- is a nonce previously inserted in a related message by
-- the intended recipient of this message. -- the intended recipient of this message.
freeText [7] PKIFreeText OPTIONAL, freeText [7] PKIFreeText OPTIONAL,
-- this may be used to indicate context-specific instructions -- this may be used to indicate context-specific instructions
-- (this field is intended for human consumption) -- (this field is intended for human consumption)
skipping to change at line 5654 skipping to change at line 5611
body PKIBody } body PKIBody }
id-PasswordBasedMac OBJECT IDENTIFIER ::= { iso(1) member-body(2) id-PasswordBasedMac OBJECT IDENTIFIER ::= { iso(1) member-body(2)
usa(840) nt(113533) nsn(7) algorithms(66) 13 } usa(840) nt(113533) nsn(7) algorithms(66) 13 }
PBMParameter ::= SEQUENCE { PBMParameter ::= SEQUENCE {
salt OCTET STRING, salt OCTET STRING,
-- Note: Implementations MAY wish to limit acceptable sizes -- Note: Implementations MAY wish to limit acceptable sizes
-- of this string to values appropriate for their environment -- of this string to values appropriate for their environment
-- in order to reduce the risk of denial-of-service attacks. -- in order to reduce the risk of denial-of-service attacks.
owf AlgorithmIdentifier{DIGEST-ALGORITHM, {...}}, owf AlgorithmIdentifier{DIGEST-ALGORITHM, {...}},
-- AlgId for the One-Way Function -- AlgId for the OWF
iterationCount INTEGER, iterationCount INTEGER,
-- number of times the OWF is applied -- number of times the OWF is applied
-- Note: Implementations MAY wish to limit acceptable sizes -- Note: Implementations MAY wish to limit acceptable sizes
-- of this integer to values appropriate for their environment -- of this integer to values appropriate for their environment
-- in order to reduce the risk of denial-of-service attacks. -- in order to reduce the risk of denial-of-service attacks.
mac AlgorithmIdentifier{MAC-ALGORITHM, {...}} mac AlgorithmIdentifier{MAC-ALGORITHM, {...}}
-- AlgId of the Message Authentication Code algorithm -- AlgId of the MAC algorithm
} }
id-DHBasedMac OBJECT IDENTIFIER ::= { iso(1) member-body(2) id-DHBasedMac OBJECT IDENTIFIER ::= { iso(1) member-body(2)
usa(840) nt(113533) nsn(7) algorithms(66) 30 } usa(840) nt(113533) nsn(7) algorithms(66) 30 }
DHBMParameter ::= SEQUENCE { DHBMParameter ::= SEQUENCE {
owf AlgorithmIdentifier{DIGEST-ALGORITHM, {...}}, owf AlgorithmIdentifier{DIGEST-ALGORITHM, {...}},
-- AlgId for a One-Way Function -- AlgId for an OWF
mac AlgorithmIdentifier{MAC-ALGORITHM, {...}} mac AlgorithmIdentifier{MAC-ALGORITHM, {...}}
-- AlgId of the Message Authentication Code algorithm -- AlgId of the MAC algorithm
} }
-- id-KemBasedMac and KemBMParameter were added in [RFC9810] -- id-KemBasedMac and KemBMParameter were added in [RFC9810]
id-KemBasedMac OBJECT IDENTIFIER ::= { iso(1) member-body(2) id-KemBasedMac OBJECT IDENTIFIER ::= { iso(1) member-body(2)
usa(840) nt(113533) nsn(7) algorithms(66) 16 } usa(840) nt(113533) nsn(7) algorithms(66) 16 }
KemBMParameter ::= SEQUENCE { KemBMParameter ::= SEQUENCE {
kdf AlgorithmIdentifier{KEY-DERIVATION, {...}}, kdf AlgorithmIdentifier{KEY-DERIVATION, {...}},
-- AlgId of the Key Derivation Function algorithm -- AlgId of the Key Derivation Function algorithm
kemContext [0] OCTET STRING OPTIONAL, kemContext [0] OCTET STRING OPTIONAL,
-- MAY contain additional algorithm-specific context information -- MAY contain additional algorithm-specific context information
len INTEGER (1..MAX), len INTEGER (1..MAX),
-- Defines the length of the keying material output of the KDF -- Defines the length of the keying material output of the KDF
-- SHOULD be the maximum key length of the MAC function -- SHOULD be the maximum key length of the MAC function
mac AlgorithmIdentifier{MAC-ALGORITHM, {...}} mac AlgorithmIdentifier{MAC-ALGORITHM, {...}}
-- AlgId of the Message Authentication Code algorithm -- AlgId of the MAC algorithm
} }
PKIStatus ::= INTEGER { PKIStatus ::= INTEGER {
accepted (0), accepted (0),
-- you got exactly what you asked for -- you got exactly what you asked for
grantedWithMods (1), grantedWithMods (1),
-- you got something like what you asked for; the -- you got something like what you asked for; the
-- requester is responsible for ascertaining the differences -- requester is responsible for ascertaining the differences
rejection (2), rejection (2),
-- you don't get it, more information elsewhere in the message -- you don't get it, more information elsewhere in the message
skipping to change at line 5738 skipping to change at line 5695
-- the data submitted has the wrong format -- the data submitted has the wrong format
wrongAuthority (6), wrongAuthority (6),
-- the authority indicated in the request is different from the -- the authority indicated in the request is different from the
-- one creating the response token -- one creating the response token
incorrectData (7), incorrectData (7),
-- the requester's data is incorrect (for notary services) -- the requester's data is incorrect (for notary services)
missingTimeStamp (8), missingTimeStamp (8),
-- when the timestamp is missing but should be there -- when the timestamp is missing but should be there
-- (by policy) -- (by policy)
badPOP (9), badPOP (9),
-- the proof-of-possession failed -- the POP failed
certRevoked (10), certRevoked (10),
-- the certificate has already been revoked -- the certificate has already been revoked
certConfirmed (11), certConfirmed (11),
-- the certificate has already been confirmed -- the certificate has already been confirmed
wrongIntegrity (12), wrongIntegrity (12),
-- KEM ciphertext missing for MAC-based protection of response, -- KEM ciphertext missing for MAC-based protection of response,
-- or not valid integrity of message received (password based -- or not valid integrity of message received (password based
-- instead of signature or vice versa) -- instead of signature or vice versa)
badRecipientNonce (13), badRecipientNonce (13),
-- not valid recipient nonce, either missing or wrong value -- not valid recipient nonce, either missing or wrong value
skipping to change at line 5811 skipping to change at line 5768
-- encryptedRand was added in [RFC9810] -- encryptedRand was added in [RFC9810]
Challenge ::= SEQUENCE { Challenge ::= SEQUENCE {
owf AlgorithmIdentifier{DIGEST-ALGORITHM, {...}} owf AlgorithmIdentifier{DIGEST-ALGORITHM, {...}}
OPTIONAL, OPTIONAL,
-- MUST be present in the first Challenge; MAY be omitted in -- MUST be present in the first Challenge; MAY be omitted in
-- any subsequent Challenge in POPODecKeyChallContent (if -- any subsequent Challenge in POPODecKeyChallContent (if
-- omitted, then the owf used in the immediately preceding -- omitted, then the owf used in the immediately preceding
-- Challenge is to be used). -- Challenge is to be used).
witness OCTET STRING, witness OCTET STRING,
-- the result of applying the one-way function (owf) to a -- the result of applying the OWF to a
-- randomly generated INTEGER, A. (Note that a different -- randomly generated INTEGER, A. (Note that a different
-- INTEGER MUST be used for each Challenge.) -- INTEGER MUST be used for each Challenge.)
challenge OCTET STRING, challenge OCTET STRING,
-- MUST be used for cmp2000(2) popdecc messages and MUST be -- MUST be used for cmp2000(2) popdecc messages and MUST be
-- the encryption of Rand (using a mechanism depending on the -- the encryption of Rand (using a mechanism depending on the
-- private key type). -- private key type).
-- MUST be an empty OCTET STRING for cmp2021(3) popdecc messages. -- MUST be an empty OCTET STRING for cmp2021(3) popdecc messages.
-- Note: Using challenge omitting the optional encryptedRand is -- Note: Using challenge omitting the optional encryptedRand is
-- bit-compatible to the syntax without adding this optional -- bit-compatible to the syntax without adding this optional
-- field. -- field.
skipping to change at line 6018 skipping to change at line 5975
issuer [1] GeneralNames } issuer [1] GeneralNames }
CRLStatus ::= SEQUENCE { CRLStatus ::= SEQUENCE {
source CRLSource, source CRLSource,
thisUpdate Time OPTIONAL } thisUpdate Time OPTIONAL }
-- KemCiphertextInfo and KemOtherInfo were added in [RFC9810] -- KemCiphertextInfo and KemOtherInfo were added in [RFC9810]
KemCiphertextInfo ::= SEQUENCE { KemCiphertextInfo ::= SEQUENCE {
kem AlgorithmIdentifier{KEM-ALGORITHM, {...}}, kem AlgorithmIdentifier{KEM-ALGORITHM, {...}},
-- AlgId of the Key Encapsulation Mechanism algorithm -- AlgId of the KEM algorithm
ct OCTET STRING ct OCTET STRING
-- Ciphertext output from the Encapsulate function -- Ciphertext output from the Encapsulate function
} }
KemOtherInfo ::= SEQUENCE { KemOtherInfo ::= SEQUENCE {
staticString PKIFreeText, staticString PKIFreeText,
-- MUST be "CMP-KEM" -- MUST be "CMP-KEM"
transactionID OCTET STRING, transactionID OCTET STRING,
-- MUST contain the values from the message previously received -- MUST contain the values from the message previously received
-- containing the ciphertext (ct) in KemCiphertextInfo -- containing the ciphertext (ct) in KemCiphertextInfo
skipping to change at line 6173 skipping to change at line 6130
PollReqContent ::= SEQUENCE OF SEQUENCE { PollReqContent ::= SEQUENCE OF SEQUENCE {
certReqId INTEGER } certReqId INTEGER }
PollRepContent ::= SEQUENCE OF SEQUENCE { PollRepContent ::= SEQUENCE OF SEQUENCE {
certReqId INTEGER, certReqId INTEGER,
checkAfter INTEGER, -- time in seconds checkAfter INTEGER, -- time in seconds
reason PKIFreeText OPTIONAL } reason PKIFreeText OPTIONAL }
-- --
-- Extended key usage extension for PKI entities used in CMP -- EKU extension for PKI entities used in CMP
-- operations, added due to the changes made in [RFC9480] -- operations, added due to the changes made in [RFC9480]
-- The EKUs for the CA and RA are reused from CMC, as defined in -- The EKUs for the CA and RA are reused from CMC, as defined in
-- [RFC6402] -- [RFC6402]
-- --
-- id-kp-cmcCA OBJECT IDENTIFIER ::= { id-kp 27 } -- id-kp-cmcCA OBJECT IDENTIFIER ::= { id-kp 27 }
-- id-kp-cmcRA OBJECT IDENTIFIER ::= { id-kp 28 } -- id-kp-cmcRA OBJECT IDENTIFIER ::= { id-kp 28 }
id-kp-cmKGA OBJECT IDENTIFIER ::= { id-kp 32 } id-kp-cmKGA OBJECT IDENTIFIER ::= { id-kp 32 }
END END
 End of changes. 265 change blocks. 
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