rfc9942.original   rfc9942.txt 
COSE O. Steele Internet Engineering Task Force (IETF) O. Steele
Internet-Draft Tradeverifyd Request for Comments: 9942 Tradeverifyd
Intended status: Standards Track H. Birkholz Category: Standards Track H. Birkholz
Expires: 5 June 2026 Fraunhofer SIT ISSN: 2070-1721 Fraunhofer SIT
A. Delignat-Lavaud A. Delignat-Lavaud
C. Fournet C. Fournet
Microsoft Microsoft
2 December 2025 March 2026
COSE (CBOR Object Signing and Encryption) Receipts CBOR Object Signing and Encryption (COSE) Receipts
draft-ietf-cose-merkle-tree-proofs-18
Abstract Abstract
COSE (CBOR Object Signing and Encryption) Receipts prove properties CBOR Object Signing and Encryption (COSE) Receipts prove properties
of a verifiable data structure to a verifier. Verifiable data of a Verifiable Data Structure (VDS) to a verifier. Verifiable Data
structures and associated proof types enable security properties, Structures and associated proof types enable security properties,
such as minimal disclosure, transparency and non-equivocation. such as minimal disclosure, transparency, and non-equivocation.
Transparency helps maintain trust over time, and has been applied to Transparency helps maintain trust over time and has been applied to
certificates, end to end encrypted messaging systems, and supply certificates, end-to-end encrypted messaging systems, and supply
chain security. This specification enables concise transparency chain security. This specification enables concise transparency-
oriented systems, by building on CBOR (Concise Binary Object oriented systems by building on Concise Binary Object Representation
Representation) and COSE. The extensibility of the approach is (CBOR) and COSE. The extensibility of the approach is demonstrated
demonstrated by providing CBOR encodings for Merkle inclusion and by providing CBOR encodings for Merkle inclusion and consistency
consistency proofs. proofs.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the CBOR Object Signing
and Encryption Working Group mailing list (cose@ietf.org), which is
archived at https://mailarchive.ietf.org/arch/browse/cose/.
Source for this draft and an issue tracker can be found at
https://github.com/cose-wg/draft-ietf-cose-merkle-tree-proofs.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on 5 June 2026. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9942.
Copyright Notice Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the Copyright (c) 2026 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
1.1. Requirements Notation . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Notation
2. New COSE Header Parameters . . . . . . . . . . . . . . . . . 3 2. New COSE Header Parameters
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology
4. Verifiable Data Structures in CBOR . . . . . . . . . . . . . 5 4. Verifiable Data Structures in CBOR
4.1. Structures . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Structures
4.2. Proofs . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.2. Proofs
4.3. Usage . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.3. Usage
4.4. Profiles . . . . . . . . . . . . . . . . . . . . . . . . 9 4.4. Profiles
4.4.1. Registration Requirements . . . . . . . . . . . . . . 10 4.4.1. Registration Requirements
5. RFC9162_SHA256 . . . . . . . . . . . . . . . . . . . . . . . 10 5. RFC9162_SHA256
5.1. Verifiable Data Structure . . . . . . . . . . . . . . . . 10 5.1. Verifiable Data Structure
5.2. Inclusion Proof . . . . . . . . . . . . . . . . . . . . . 10 5.2. Inclusion Proof
5.2.1. Receipt of Inclusion . . . . . . . . . . . . . . . . 11 5.2.1. Receipt of Inclusion
5.3. Consistency Proof . . . . . . . . . . . . . . . . . . . . 13 5.3. Consistency Proof
5.3.1. Receipt of Consistency . . . . . . . . . . . . . . . 13 5.3.1. Receipt of Consistency
6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 15 6. Privacy Considerations
6.1. Log Length . . . . . . . . . . . . . . . . . . . . . . . 16 6.1. Log Length
6.2. Header Parameters . . . . . . . . . . . . . . . . . . . . 16 6.2. Header Parameters
7. Security Considerations . . . . . . . . . . . . . . . . . . . 16 7. Security Considerations
7.1. Choice of Signature Algorithms . . . . . . . . . . . . . 16 7.1. Choice of Signature Algorithms
7.2. Validity Period . . . . . . . . . . . . . . . . . . . . . 16 7.2. Validity Period
7.3. Status Updates . . . . . . . . . . . . . . . . . . . . . 16 7.3. Status Updates
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 8. IANA Considerations
8.1. COSE Header Parameter . . . . . . . . . . . . . . . . . . 17 8.1. COSE Header Parameter
8.2. Verifiable Data Structure Registries . . . . . . . . . . 18 8.2. Verifiable Data Structure Registries
8.2.1. Expert Review . . . . . . . . . . . . . . . . . . . . 18 8.2.1. Expert Review
8.2.2. COSE Verifiable Data Structure Algorithms . . . . . . 18 8.2.2. Templates and Initial Contents
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 9. References
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 20 9.1. Normative References
10.1. Normative References . . . . . . . . . . . . . . . . . . 20 9.2. Informative References
10.2. Informative References . . . . . . . . . . . . . . . . . 21 Acknowledgements
Appendix A. Implementation Status . . . . . . . . . . . . . . . 22 Contributors
A.1. Transmute Prototype . . . . . . . . . . . . . . . . . . . 22 Authors' Addresses
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
COSE Receipts are signed proofs that include metadata about certain COSE Receipts are signed proofs that include metadata about certain
states of a verifiable data structure (VDS) that are true when the states of a Verifiable Data Structure (VDS) that are true when the
COSE Receipt was issued. COSE Receipts can include proofs that a COSE Receipt was issued. COSE Receipts can include proofs that a
document is in a database (proof of inclusion), that a database is document is in a database (proof of inclusion), that a database is
append only (proof of consistency), that a smaller set of statements append only (proof of consistency), that a smaller set of statements
are contained in a large set of statements (proof of disclosure, a are contained in a large set of statements (proof of disclosure, a
special case of proof of inclusion), or proof that certain data is special case of proof of inclusion), or that certain data is not yet
not yet present in a database (proofs of non inclusion). Different present in a database (proof of non-inclusion). Different VDSs can
VDS can produce different verifiable data structure proofs (VDP). produce different Verifiable Data structure Proofs (VDP). The
The combination of representations of various VDS and VDP can combination of representations of various VDSs and VDP can
significantly increase the burden for implementers and create significantly increase the burden for implementers and create
interoperability challenges for transparency services. This document interoperability challenges for transparency services. This document
describes how to convey VDS and associated VDP types in unified COSE describes how to convey VDS and associated VDP types in unified COSE
envelopes. envelopes.
1.1. Requirements Notation 1.1. Requirements Notation
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
capitals, as shown here. capitals, as shown here.
2. New COSE Header Parameters 2. New COSE Header Parameters
This document defines three new COSE header parameters, which are This document defines three new COSE header parameters, which are
introduced up-front in this Section and elaborated on later in this introduced up front in this section and elaborated on later in this
document. document.
TBD_0 (requested assignment 394): A COSE header parameter named 394: A COSE header parameter named receipts with a value type of
receipts with a value type of array where the array contains one array where the array contains one or more COSE Receipts as
or more COSE Receipts as specified in this document. specified in this document.
TBD_1 (requested assignment 395): A COSE header parameter named vds 395: A COSE header parameter named vds (for Verifiable Data
(Verifiable Data Structure), which conveys the algorithm Structure), which conveys the algorithm identifier for a
identifier for a verifiable data structure. Correspondingly, this Verifiable Data Structure. Correspondingly, see Section 8.2.2.1
document introduces a new registry (Section 8.2.2) defining the for a registry defining the integers used to identify Verifiable
integers used to identify verifiable data structures. Data Structures.
TBD_2 (requested assignment 396): A COSE header parameter named vdp 396: A COSE header parameter named vdp (for Verifiable Data
(short for "verifiable data structure proofs"), which conveys a Structure Proofs), which conveys a map containing Verifiable Data
map containing verifiable data structure proofs organized by proof Structure Proofs organized by proof type. Correspondingly, see
type. Correspondingly, this document introduces a new registry Section 8.2.2.2 for a registry defining the integers used to
(Table 2) defining the integers used to identify verifiable data identify Verifiable Data Structure proof types.
structure proof types.
3. Terminology 3. Terminology
CDDL: Concise Data Definition Language (CDDL) is defined in CDDL: Concise Data Definition Language (CDDL) is defined in
[RFC8610]. [RFC8610].
EDN: CBOR Extended Diagnostic Notation (EDN) is defined in EDN: CBOR Extended Diagnostic Notation (EDN) is defined in
[RFC8949], where it is referred to as "diagnostic notation", and [RFC8949], where it is referred to as "diagnostic notation", and
is revised in [I-D.draft-ietf-cbor-edn-literals]. is revised in [CBOR-EDN].
Verifiable Data Structure (VDS): A data structure which supports one Verifiable Data Structure (VDS): A data structure that supports one
or more Verifiable Data Structure Proof Types. This property or more Verifiable Data Structure Proof Types. This property
describes an algorithm used to maintain a verifiable data describes an algorithm used to maintain a Verifiable Data
structure, for example a binary Merkle tree algorithm. Structure, for example, a binary Merkle tree algorithm.
Verifiable Data Structure Proofs (VDP): A data structure used to Verifiable Data Structure Proofs (VDP): A data structure used to
convey proof types for proving different properties, such as convey proof types for proving different properties, such as
authentication, inclusion, consistency, and freshness. Parameters authentication, inclusion, consistency, and freshness. Parameters
can include multiple proofs of a given type, or multiple types of can include multiple proofs of a given type or multiple types of
proof (inclusion and consistency). proof (inclusion and consistency).
Proof Type: A property that can be obtained by verifying a given Proof Type: A property that can be obtained by verifying a given
proof over one or more entries in a Verifiable Data Structure. proof over one or more entries in a Verifiable Data Structure.
For example, a VDS, such as a binary Merkle tree, can support For example, a VDS, such as a binary Merkle tree, can support
proofs of type "inclusion" where each proof confirms that a given proofs of type "inclusion" where each proof confirms that a given
entry is included in a Merkle root. entry is included in a Merkle root.
Proof Value: An encoding of a Proof Type in CBOR [RFC8949]. Proof Value: An encoding of a Proof Type in CBOR [RFC8949].
Entry: An entry in a verifiable data structure for which proofs can Entry: An entry in a Verifiable Data Structure for which proofs can
be derived. be derived.
Receipt: A COSE object, as defined in [RFC9052], containing the Receipt: A COSE object, as defined in [RFC9052], containing the
header parameters necessary to convey VDP for an associated VDS. header parameters necessary to convey VDP for an associated VDS.
4. Verifiable Data Structures in CBOR 4. Verifiable Data Structures in CBOR
This section describes representations of verifiable data structure This section describes representations of Verifiable Data Structure
proofs in [RFC8949]. For example, construction of a Merkle tree Proofs in [RFC8949]. For example, construction of a Merkle tree leaf
leaf, or an inclusion proof from a leaf to a Merkle root, might have or an inclusion proof from a leaf to a Merkle root might have several
several different representations, depending on the verifiable data different representations, depending on the Verifiable Data Structure
structure used. Differences in representations are necessary to used. Differences in representations are necessary to support
support efficient verification, unique security or privacy efficient verification, unique security or privacy properties, and
properties, and for compatibility with specific implementations. for compatibility with specific implementations. This document
This document defines two extension points for enabling verifiable defines two extension points for enabling Verifiable Data Structures
data structures with COSE and provides concrete examples for the with COSE and provides concrete examples for the structures and
structures and proofs defined in Section 2.1.3 of [RFC9162] and proofs defined in Section 2.1.3 of [RFC9162] and Section 2.1.4 of
Section 2.1.4 of [RFC9162]. The design of these structures is [RFC9162]. The design of these structures is influenced by the
influenced by the conventions established for COSE Keys. conventions established for COSE Keys.
4.1. Structures 4.1. Structures
Similar to COSE Key Types (https://www.iana.org/assignments/cose/ Similar to COSE Key Types [IANA.cose_header-parameters], different
cose.xhtml#key-type), different verifiable data structures support Verifiable Data Structures support different algorithms.
different algorithms.
This document establishes a registry of verifiable data structure This document establishes a registry of Verifiable Data Structure
algorithms, see Section 8.2.2 for details. algorithms; see Section 8.2.2.1 for details.
4.2. Proofs 4.2. Proofs
Similar to COSE Key Type Parameters Similar to COSE Key Type Parameters [IANA.cose_header-parameters], as
(https://www.iana.org/assignments/cose/cose.xhtml#key-type- EC2 keys (1: 2) require and give meaning to specific parameters, such
parameters), as EC2 keys (1: 2) keys require and give meaning to as -1 (crv), -2 (x), -3 (y), -4 (d), RFC9162_SHA256 (395: 1) supports
specific parameters, such as -1 (crv), -2 (x), -3 (y), -4 (d), both (-1) inclusion and (-2) consistency proofs.
RFC9162_SHA256 (TBD_1 (requested assignment 395) : 1) supports both
(-1) inclusion and (-2) consistency proofs.
This document establishes a registry of verifiable data structure This document establishes a registry of Verifiable Data Structure
algorithm proofs, see Table 2 for details. Proofs; see Section 8.2.2.2 for details.
Proof types are specific to their associated "verifiable data Proof types are specific to their associated "Verifiable Data
structure", for example, different Merkle trees might support Structure"; for example, different Merkle trees might support
different representations of "inclusion proof" or "consistency different representations of "inclusion proof" or "consistency
proof". Implementers should not expect interoperability across proof". Implementers should not expect interoperability across
"verifiable data structures". Security analysis MUST be conducted "Verifiable Data Structures". Security analysis MUST be conducted
prior to migrating to new structures to ensure the new security and prior to migrating to new structures to ensure the new security and
privacy assumptions are acceptable for the use case. privacy assumptions are acceptable for the use case.
4.3. Usage 4.3. Usage
This document registers a new COSE Header Parameter receipts (TBD_0 This document registers a new COSE Header Parameter receipts (394) to
(requested assignment 394)) to enable Receipts to be conveyed in the enable Receipts to be conveyed in the protected and unprotected
protected and unprotected headers of COSE Objects. headers of COSE Objects.
When the receipts header parameter is present, the verifier MUST When the receipts header parameter is present, the verifier MUST
confirm that the associated verifiable data structure and verifiable confirm that the associated Verifiable Data Structure and Verifiable
data structure proofs match entries present in the registries Data Structure Proofs match entries present in the registries
established in this specification, including values added in established in this specification, including values added in
subsequent registrations.. subsequent registrations.
Receipts MUST be tagged as COSE_Sign1. Receipts MUST be tagged as COSE_Sign1.
The following [RFC8610] definition is provided: The following definition from [RFC8610] is provided:
Signature_With_Receipt = #6.18(COSE_Sign1) Signature_With_Receipt = #6.18(COSE_Sign1)
cose.label = int / text cose.label = int / text
cose.values = any cose.values = any
Protected_Header = { Protected_Header = {
* cose.label => cose.values * cose.label => cose.values
} }
skipping to change at page 6, line 44 skipping to change at line 254
COSE_Sign1 = [ COSE_Sign1 = [
protected : bstr .cbor Protected_Header, protected : bstr .cbor Protected_Header,
unprotected : Unprotected_Header, unprotected : Unprotected_Header,
payload : bstr / nil, payload : bstr / nil,
signature : bstr signature : bstr
] ]
Receipt = Receipt_For_Inclusion / Receipt_For_Consistency Receipt = Receipt_For_Inclusion / Receipt_For_Consistency
; Note the the proof formats shown here are for RFC9162_SHA256. ; Note the proof formats shown here are for RFC9162_SHA256.
; Other verifiable data structures may have different proof formats. ; Other Verifiable Data Structures may have different proof formats.
Receipt_For_Inclusion = #6.18(Signed_Inclusion_Proof) Receipt_For_Inclusion = #6.18(Signed_Inclusion_Proof)
Signed_Inclusion_Proof = [ Signed_Inclusion_Proof = [
protected : bstr .cbor RFC9162_SHA256_Inclusion_Protected_Header protected : bstr .cbor RFC9162_SHA256_Inclusion_Protected_Header
unprotected : RFC9162_SHA256_Inclusion_Unprotected_Header unprotected : RFC9162_SHA256_Inclusion_Unprotected_Header
payload : bstr / nil payload : bstr / nil
signature : bstr signature : bstr
] ]
skipping to change at page 8, line 4 skipping to change at line 308
RFC9162_SHA256_Consistency_Protected_Header = { RFC9162_SHA256_Consistency_Protected_Header = {
&(alg: 1) => int, &(alg: 1) => int,
&(vds: 395) => int, &(vds: 395) => int,
* cose.label => cose.values * cose.label => cose.values
} }
RFC9162_SHA256_Consistency_Unprotected_Header = { RFC9162_SHA256_Consistency_Unprotected_Header = {
&(vdp: 396) => RFC9162_SHA256_Verifiable_Consistency_Proofs &(vdp: 396) => RFC9162_SHA256_Verifiable_Consistency_Proofs
* cose.label => cose.values * cose.label => cose.values
} }
RFC9162_SHA256_Verifiable_Consistency_Proofs = { RFC9162_SHA256_Verifiable_Consistency_Proofs = {
&(consistency-proof: -2) => RFC9162_SHA256_Consistency_Proofs &(consistency-proof: -2) => RFC9162_SHA256_Consistency_Proofs
} }
RFC9162_SHA256_Consistency_Proofs = [ + RFC9162_SHA256_Consistency_Proof ] RFC9162_SHA256_Consistency_Proofs = [ + RFC9162_SHA256_Consistency_Proof ]
RFC9162_SHA256_Consistency_Proof = bstr .cbor [ RFC9162_SHA256_Consistency_Proof = bstr .cbor [
tree_size_1: uint, tree_size_1: uint,
tree_size_2: uint, tree_size_2: uint,
consistency_path: [ + bstr ] consistency_path: [ + bstr ]
] ]
Figure 1: CDDL for a COSE Sign1 with attached receipts Figure 1: CDDL for a COSE Sign1 with Attached Receipts
The following informative EDN is provided: The following informative EDN is provided:
/ cose-sign1 / 18([ / cose-sign1 / 18([
/ protected / <<{ / protected / <<{
/ kid / 4 : h'bc297b51...e4edf0de', / kid / 4 : h'bc297b51...e4edf0de',
/ algorithm / 1 : -7, # ES256 / algorithm / 1 : -7, # ES256
}>>, }>>,
/ unprotected / { / unprotected / {
/ receipts / 394 : { / receipts / 394 : {
skipping to change at page 9, line 27 skipping to change at line 379
}, },
/ payload / null, / payload / null,
/ signature / h'36581f38...a5581960' / signature / h'36581f38...a5581960'
])>> ])>>
}, },
}, },
/ payload / h'0167c57c...deeed6d4', / payload / h'0167c57c...deeed6d4',
/ signature / h'2544f2ed...5840893b' / signature / h'2544f2ed...5840893b'
]) ])
Figure 2: An example COSE Signature with multiple receipts Figure 2: An Example COSE Signature with Multiple Receipts
The specific structure of COSE Receipts is dependent on the structure The specific structure of COSE Receipts is dependent on the structure
of the COSE_Sign1 payload and the verifiable data structure proofs of the COSE_Sign1 payload and the Verifiable Data Structure Proofs
contained in the COSE_Sign1 unprotected header. The CDDL definition contained in the COSE_Sign1 unprotected header. The CDDL definition
for verifiable data structure proofs is specific to each verifiable for Verifiable Data Structure Proofs is specific to each Verifiable
data structure. This document describes proofs for RFC9162_SHA256 in Data Structure. This document describes proofs for RFC9162_SHA256 in
the following sections. the following sections.
4.4. Profiles 4.4. Profiles
New verifiable data structures can require the definition of a New Verifiable Data Structures can require the definition of a
profile. The payload in such definitions SHOULD be detached. profile. The payload in such definitions SHOULD be detached.
Detached payloads force verifiers to recompute the root from the Detached payloads force verifiers to recompute the root from the
proof and protect against implementation errors where the signature proof and protect against implementation errors where the signature
is verified but the payload is incompatible with the proof. Profiles is verified but the payload is incompatible with the proof. Profiles
of proof signatures that define additional protected header of proof signatures that define additional protected header
parameters are encouraged to make their presence mandatory to ensure parameters are encouraged to make their presence mandatory to ensure
that claims are processed with their intended semantics. One way to that claims are processed with their intended semantics. One way to
include this information in the COSE structure is use of the typ include this information in the COSE structure is use of the typ
(type) Header Parameter, see [RFC9596] and the similar guidance (type) Header Parameter; see [RFC9596] and the similar guidance
provided in [RFC9597]. provided in [RFC9597].
4.4.1. Registration Requirements 4.4.1. Registration Requirements
Each verifiable data structure specification applying for inclusion Each Verifiable Data Structure specification applying for inclusion
in this registry MUST define how to encode the verifiable data in this registry MUST define how to encode the Verifiable Data
structure identifier and its proof types in CBOR. Each specification Structure identifier and its proof types in CBOR. Each specification
MUST define how to produce and consume the supported proof types. MUST define how to produce and consume the supported proof types.
See Section 5 as an example. See Section 5 as an example.
Where a specification supports a choice of hash algorithm, a separate Where a specification supports a choice of hash algorithm, a separate
IANA registration must be made for each supported algorithm. For IANA registration must be made for each supported algorithm. For
example, to provide support for SHA256 and SHA3_256 with Merkle example, to provide support for SHA256 and SHA3_256 with Merkle
Consistency and Inclusion Proofs defined respectively in Inclusion Proofs and Merkle Consistency Proofs defined, respectively,
Section 2.1.3 of [RFC9162] and Section 2.1.4 of [RFC9162], both in Section 2.1.3 of [RFC9162] and Section 2.1.4 of [RFC9162], both
"RFC9162_SHA256" and "RFC9162_SHA3_256" require entries in the "RFC9162_SHA256" and "RFC9162_SHA3_256" require entries in the
relevant IANA registries. This document only defines relevant IANA registries. This document only defines
"RFC9162_SHA256". "RFC9162_SHA256".
5. RFC9162_SHA256 5. RFC9162_SHA256
This section defines how the data structure described in Section 2.1 This section defines how the data structure described in Section 2.1
of [RFC9162] is mapped to the terminology defined in this document, of [RFC9162] is mapped to the terminology defined in this document,
using [RFC8949] and [RFC9053]. using [RFC8949] and [RFC9053].
5.1. Verifiable Data Structure 5.1. Verifiable Data Structure
The integer identifier for this Verifiable Data Structure is 1. The The integer identifier for this Verifiable Data Structure is 1. The
string identifier for this Verifiable Data Structure is string identifier for this Verifiable Data Structure is
"RFC9162_SHA256", a Merkle Tree where SHA256 is used as the hash "RFC9162_SHA256", a Merkle Tree where SHA256 is used as the hash
algorithm. See Table 2. See Section 2.1.1 of [RFC9162] (Definition algorithm (see Table 2). See Section 2.1.1 of [RFC9162] for a
of the Merkle Tree), for a complete description of this verifiable complete description of this Verifiable Data Structure.
data structure.
5.2. Inclusion Proof 5.2. Inclusion Proof
See Section 2.1.3.1 of [RFC9162] (Generating an Inclusion Proof), for See Section 2.1.3.1 of [RFC9162] for a complete description of this
a complete description of this verifiable data structure proof type. Verifiable Data Structure Proof type.
The CBOR representation of an inclusion proof for RFC9162_SHA256 is: The CBOR representation of an inclusion proof for RFC9162_SHA256 is:
inclusion-proof = bstr .cbor [ inclusion-proof = bstr .cbor [
; tree size at current Merkle root ; tree size at current Merkle root
tree-size: uint tree-size: uint
; index of leaf in tree ; index of leaf in tree
leaf-index: uint leaf-index: uint
; path from leaf to current Merkle root ; path from leaf to current Merkle root
inclusion-path: [ + bstr ] inclusion-path: [ + bstr ]
] ]
Figure 3: CBOR Encoded RFC9162 Inclusion Proof Figure 3: CBOR-Encoded Inclusion Proof for RFC9162_SHA256
The term leaf-index is used for alignment with the use established in The term leaf-index is used for alignment with the use established in
Section 2.1.3.2 of [RFC9162]. Section 2.1.3.2 of [RFC9162].
Note that [RFC9162] defines inclusion proofs only for leaf nodes, and Note that [RFC9162] defines inclusion proofs only for leaf nodes, and
that: that:
If leaf_index is greater than or equal to tree_size, then fail the | If leaf_index is greater than or equal to tree_size, then fail the
proof verification. | proof verification.
The identifying index of a leaf node is relative to all nodes in the The identifying index of a leaf node is relative to all nodes in the
tree size for which the proof was obtained. tree size for which the proof was obtained.
5.2.1. Receipt of Inclusion 5.2.1. Receipt of Inclusion
In a signed inclusion proof, the payload is the Merkle tree root that In a signed inclusion proof, the payload is the Merkle tree root that
corresponds to the log at size tree-size. The protected header for corresponds to the log at size tree-size. The protected header for
an RFC9162_SHA256 inclusion proof signature is: an RFC9162_SHA256 inclusion proof signature is:
protected-header-map = { protected-header-map = {
&(alg: 1) => int &(alg: 1) => int
&(vds: 395) => int &(vds: 395) => int
* cose-label => cose-value * cose-label => cose-value
} }
Figure 4: Protected Header for a Receipt of Inclusion Figure 4: Protected Header for a Receipt of Inclusion
* alg (label: 1): REQUIRED. Signature algorithm identifier. Value alg (label: 1): REQUIRED. Signature algorithm identifier. Value
type: int. type: int.
* vds (label: TBD_1 (requested assignment 395)): REQUIRED. vds (label: 395): REQUIRED. Verifiable Data Structure algorithm
Verifiable data structure algorithm identifier. Value type: int. identifier. Value type: int.
The unprotected header for an RFC9162_SHA256 inclusion proof The unprotected header for an RFC9162_SHA256 inclusion proof
signature is: signature is:
inclusion-proofs = [ + inclusion-proof ] inclusion-proofs = [ + inclusion-proof ]
verifiable-proofs = { verifiable-proofs = {
&(inclusion-proof: -1) => inclusion-proofs &(inclusion-proof: -1) => inclusion-proofs
} }
unprotected-header-map = { unprotected-header-map = {
&(vdp: 396) => verifiable-proofs &(vdp: 396) => verifiable-proofs
* cose-label => cose-value * cose-label => cose-value
} }
Figure 5: A Verifiable Data Structure Proofs in an Unprotected Header Figure 5: A Verifiable Data Structure Proofs in an Unprotected Header
* vdp (label: TBD_2 (requested assignment 396)): REQUIRED. vdp (label: 396): REQUIRED. Verifiable Data Structure Proofs.
Verifiable data structure proofs. Value type: Map. Value type: Map.
* inclusion-proof (label: -1): REQUIRED. Inclusion proofs. Value inclusion-proof (label: -1): REQUIRED. Inclusion proofs. Value
type: Array of bstr. type: Array of bstr.
The payload of an RFC9162_SHA256 inclusion proof signature is the The payload of an RFC9162_SHA256 inclusion proof signature is the
Merkle tree hash as defined in [RFC9162]. Merkle tree hash as defined in [RFC9162].
An EDN example for a Receipt containing an inclusion proof for An EDN example for a Receipt containing an inclusion proof for
RFC9162_SHA256 with a detached payload (see Section 4.4) is: RFC9162_SHA256 with a detached payload (see Section 4.4) is:
/ cose-sign1 / 18([ / cose-sign1 / 18([
/ protected / <<{ / protected / <<{
skipping to change at page 13, line 8 skipping to change at line 541
}, },
/ payload / null, / payload / null,
/ signature / h'de24f0cc...9a5ade89' / signature / h'de24f0cc...9a5ade89'
]) ])
Figure 6: Receipt of Inclusion Figure 6: Receipt of Inclusion
The VDS in the protected header is necessary to understand the The VDS in the protected header is necessary to understand the
inclusion proof structure in the unprotected header. inclusion proof structure in the unprotected header.
The inclusion proof and signature are verified in order. First the The inclusion proof and signature are verified in order. First, the
verifier applies the inclusion proof to a possible entry (set member) verifier applies the inclusion proof to a possible entry (set member)
bytes. If this process fails, the inclusion proof may have been bytes. If this process fails, the inclusion proof may have been
tampered with. If this process succeeds, the result is a Merkle tampered with. If this process succeeds, the result is a Merkle
root, which in the attached as the COSE Sign1 payload. Second the root, which in the attached as the COSE Sign1 payload. Second, the
verifier checks the signature of the COSE Sign1. If the resulting verifier checks the signature of the COSE Sign1. If the resulting
signature verifies, the Receipt has proved inclusion of the entry in signature can be verified, the Receipt has proved inclusion of the
the verifiable data structure. If the resulting signature does not entry in the Verifiable Data Structure. If the resulting signature
verify, the signature may have been tampered with. cannot be verified, the signature may have been tampered with.
5.3. Consistency Proof 5.3. Consistency Proof
See Section 2.1.4.1 of [RFC9162] (Generating a Consistency Proof), See Section 2.1.4.1 of [RFC9162] for a complete description of this
for a complete description of this verifiable data structure proof Verifiable Data Structure Proof type.
type.
The cbor representation of a consistency proof for RFC9162_SHA256 is: The cbor representation of a consistency proof for RFC9162_SHA256 is:
consistency-proof = bstr .cbor [ consistency-proof = bstr .cbor [
; older Merkle root tree size ; older Merkle root tree size
tree-size-1: uint tree-size-1: uint
; newer Merkle root tree size ; newer Merkle root tree size
tree-size-2: uint tree-size-2: uint
; path from older Merkle root to newer Merkle root. ; path from older Merkle root to newer Merkle root.
consistency-path: [ + bstr ] consistency-path: [ + bstr ]
] ]
Figure 7: CBOR Encoded RFC9162 Consistency Proof Figure 7: CBOR-Encoded Consistency Proof for RFC9162_SHA256
5.3.1. Receipt of Consistency 5.3.1. Receipt of Consistency
In a signed consistency proof, the newer Merkle tree root (proven to In a signed consistency proof, the newer Merkle tree root (proven to
be consistent with an older Merkle tree root) is an attached payload be consistent with an older Merkle tree root), is an attached payload
and corresponds to the log at size tree-size-2. and corresponds to the log at size tree-size-2.
The protected header for an RFC9162_SHA256 consistency proof The protected header for an RFC9162_SHA256 consistency proof
signature is: signature is:
protected-header-map = { protected-header-map = {
&(alg: 1) => int &(alg: 1) => int
&(vds: 395) => int &(vds: 395) => int
* cose-label => cose-value * cose-label => cose-value
} }
Figure 8: Protected Header for a Receipt of Consistency Figure 8: Protected Header for a Receipt of Consistency
* alg (label: 1): REQUIRED. Signature algorithm identifier. Value alg (label: 1): REQUIRED. Signature algorithm identifier. Value
type: int. type: int.
* vds (label: TBD_1 (requested assignment 395)): REQUIRED. vds (label: 395): REQUIRED. Verifiable Data Structure algorithm
Verifiable data structure algorithm identifier. Value type: int. identifier. Value type: int.
The unprotected header for an RFC9162_SHA256 consistency proof The unprotected header for an RFC9162_SHA256 consistency proof
signature is: signature is:
consistency-proofs = [ + consistency-proof ] consistency-proofs = [ + consistency-proof ]
verifiable-proofs = { verifiable-proofs = {
&(consistency-proof: -2) => consistency-proofs &(consistency-proof: -2) => consistency-proofs
} }
unprotected-header-map = { unprotected-header-map = {
&(vdp: 396) => verifiable-proofs &(vdp: 396) => verifiable-proofs
* cose-label => cose-value * cose-label => cose-value
} }
* vdp (label: TBD_2 (requested assignment 396)): REQUIRED. vdp (label: 396): REQUIRED. Verifiable Data Structure Proofs.
Verifiable data structure proofs. Value type: Map. Value type: Map.
* consistency-proof (label: -2): REQUIRED. Consistency proofs. consistency-proof (label: -2): REQUIRED. Consistency proofs. Value
Value type: Array of bstr. type: Array of bstr.
The payload of an RFC9162_SHA256 consistency proof signature is: The The payload of an RFC9162_SHA256 consistency proof signature is: The
newer Merkle tree hash as defined in [RFC9162]. newer Merkle tree hash as defined in [RFC9162].
An example EDN for a Receipt containing a consistency proof for An EDN example for a Receipt containing a consistency proof for
RFC9162_SHA256 with a detached payload (see Section 4.4) is: RFC9162_SHA256 with a detached payload (see Section 4.4) is:
/ cose-sign1 / 18([ / cose-sign1 / 18([
/ protected / <<{ / protected / <<{
/ algorithm / 1 : -7, # ES256 / algorithm / 1 : -7, # ES256
/ vds / 395 : 1, # RFC9162 SHA-256 / vds / 395 : 1, # RFC9162 SHA-256
}>>, }>>,
/ unprotected / { / unprotected / {
/ proofs / 396 : { / proofs / 396 : {
/ consistency / -2 : [ / consistency / -2 : [
skipping to change at page 15, line 30 skipping to change at line 647
h'249efab6...b7614ccd', h'249efab6...b7614ccd',
h'85dd6293...38914dc1' h'85dd6293...38914dc1'
]>> ]>>
], ],
}, },
}, },
/ payload / null, / payload / null,
/ signature / h'94469f73...52de67a1' / signature / h'94469f73...52de67a1'
]) ])
Figure 9: Example consistency receipt Figure 9: Example Consistency Receipt
The VDS in the protected header is necessary to understand the The VDS in the protected header is necessary to understand the
consistency proof structure in the unprotected header. consistency proof structure in the unprotected header.
The signature and consistency proof are verified in order. The signature and consistency proof are verified in order.
First the verifier checks the signature on the COSE Sign1. If the First, the verifier checks the signature on the COSE Sign1. If the
verification fails, the consistency proof is not checked. Second the verification fails, the consistency proof is not checked. Second,
consistency proof is checked by applying a previous inclusion proof, the consistency proof is checked by applying a previous inclusion
to the consistency proof. If the verification fails, the append only proof to the consistency proof. If the verification fails, the
property of the verifiable data structure is not assured. This append only property of the Verifiable Data Structure is not assured.
approach is specific to RFC9162_SHA256, different verifiable data This approach is specific to RFC9162_SHA256; different Verifiable
structures may not support consistency proofs. It is recommended Data Structures may not support consistency proofs. It is
that implementations return a single boolean result for Receipt recommended that implementations return a single boolean result for
verification operations, to reduce the chance of accepting a valid Receipt-verification operations to reduce the chance of accepting a
signature over an invalid consistency proof. valid signature over an invalid consistency proof.
6. Privacy Considerations 6. Privacy Considerations
The privacy considerations section of [RFC9162] and [RFC9053] apply The privacy considerations section of [RFC9162] and [RFC9053] apply
to this document. to this document.
6.1. Log Length 6.1. Log Length
Some structures and proofs leak the size of the log at the time of Some structures and proofs leak the size of the log at the time of
inclusion. In the case that a log only stores certain kinds of inclusion. In the case that a log only stores certain kinds of
skipping to change at page 16, line 23 skipping to change at line 688
6.2. Header Parameters 6.2. Header Parameters
Additional header parameters can reveal information about the Additional header parameters can reveal information about the
transparency service or its log entries. The receipt producer MUST transparency service or its log entries. The receipt producer MUST
perform a privacy analysis for all mandatory fields in profiles based perform a privacy analysis for all mandatory fields in profiles based
on this specification. on this specification.
7. Security Considerations 7. Security Considerations
See the security considerations section of: See the Security Considerations sections of:
* [RFC9162] * [RFC9162]
* [RFC9053] * [RFC9053]
7.1. Choice of Signature Algorithms 7.1. Choice of Signature Algorithms
A security analysis ought to be performed to ensure that the digital A security analysis ought to be performed to ensure that the digital
signature algorithm alg has the appropriate strength to secure signature algorithm alg has the appropriate strength to secure
receipts. receipts.
It is recommended to select signature algorithms that share It is recommended to select signature algorithms that share
cryptographic components with the verifiable data structure used, for cryptographic components with the Verifiable Data Structure used; for
example: Both RFC9162_SHA256 and ES256 depend on the sha-256 hash example, both RFC9162_SHA256 and ES256 depend on the sha-256 hash
function. function.
7.2. Validity Period 7.2. Validity Period
In some cases, receipts MAY include strict validity periods, for In some cases, receipts MAY include strict validity periods, for
example, activation not too far in the future, or expiration, not too example, activation not too far in the future or expiration not too
far in the past. See the iat, nbf, and exp claims in [RFC8392], for far in the past. See the iat, nbf, and exp claims in [RFC8392] for
one way to accomplish this. The details of expressing validity one way to accomplish this. The details of expressing validity
periods are out of scope for this document. periods are out of scope for this document.
7.3. Status Updates 7.3. Status Updates
In some cases, receipts should be "revocable" or "suspendible", after In some cases, receipts should be "revocable" or "suspendable" after
being issued, regardless of their validity period. The details of being issued, regardless of their validity period. The details of
expressing statuses are out of scope for this document. expressing statuses are out of scope for this document.
8. IANA Considerations 8. IANA Considerations
8.1. COSE Header Parameter 8.1. COSE Header Parameter
IANA is requested to add the COSE header parameters defined in IANA has added the COSE header parameters defined in Section 2, and
Section 2, as listed in Table 1, to the "COSE Header Parameters" as listed in Table 1, to the "COSE Header Parameters" subregistry
registry [IANA.cose_header-parameters] in the 'Integer values from [IANA.cose_header-parameters] in the "CBOR Object Signing and
256 to 65535' range ('Specification Required' Registration Encryption (COSE)" registry group. These COSE header parameters fall
Procedure). The Value Registry for "vds" is the COSE Verifiable Data in the 'Integer values from 256 to 65535' range (with a Specification
Structure registry. The map labels in the "vdp" are assigned from Required registration procedure (see [RFC8126])). The Value Registry
the COSE Verifiable Data Structure Proofs registry. listed for "vds" is the "COSE Verifiable Data Structure Algorithm"
subregistry. The map labels in the "vdp" are assigned from the "COSE
Verifiable Data Structure Proofs" subregistry.
+========+=============+=====+============+=============+=========+ +==========+=======+=======+============+==============+===========+
|Name | Label |Value| Value | Description |Reference| | Name | Label | Value | Value | Description | Reference |
| | |Type | Registry | | | | | | Type | Registry | | |
+========+=============+=====+============+=============+=========+ +==========+=======+=======+============+==============+===========+
|receipts| TBD_0 |array| | Priority |RFCthis, | | receipts | 394 | array | | Priority | RFC 9942, |
| | (requested | | | ordered |Section 2| | | | | | ordered | Section 2 |
| | assignment: | | | sequence of | | | | | | | sequence of | |
| | 394) | | | CBOR | | | | | | | CBOR encoded | |
| | | | | encoded | | | | | | | Receipts | |
| | | | | Receipts | | +----------+-------+-------+------------+--------------+-----------+
+--------+-------------+-----+------------+-------------+---------+ | vds | 395 | int | COSE | Algorithm | RFC 9942, |
|vds | TBD_1 |int | COSE | Algorithm |RFCthis, | | | | | Verifiable | identifier | Section 2 |
| | (requested | | Verifiable | identifier |Section 2| | | | | Data | for | |
| | assignment: | | Data | for | | | | | | Structure | Verifiable | |
| | 395) | | Structure | verifiable | | | | | | | Data | |
| | | | | data | | | | | | | Structures | |
| | | | | structures, | | | | | | | that is used | |
| | | | | used to | | | | | | | to produce | |
| | | | | produce | | | | | | | Verifiable | |
| | | | | verifiable | | | | | | | Data | |
| | | | | data | | | | | | | Structure | |
| | | | | structure | | | | | | | Proofs | |
| | | | | proofs | | +----------+-------+-------+------------+--------------+-----------+
+--------+-------------+-----+------------+-------------+---------+ | vdp | 396 | map | map key in | Location for | RFC 9942, |
|vdp | TBD_2 |map | map key in | Location |RFCthis, | | | | | COSE | Verifiable | Section 2 |
| | (requested | | COSE | for |Section 2| | | | | Verifiable | Data | |
| | assignment: | | Verifiable | verifiable | | | | | | Data | Structure | |
| | 396) | | Data | data | | | | | | Structure | Proofs in | |
| | | | Structure | structure | | | | | | Proofs | COSE Header | |
| | | | Proofs | proofs in | | | | | | | Parameters | |
| | | | | COSE Header | | +----------+-------+-------+------------+--------------+-----------+
| | | | | Parameters | |
+--------+-------------+-----+------------+-------------+---------+
Table 1: Newly registered COSE Header Parameters Table 1: Newly Registered COSE Header Parameters
8.2. Verifiable Data Structure Registries 8.2. Verifiable Data Structure Registries
IANA established the COSE Verifiable Data Structure Algorithms and IANA established the "COSE Verifiable Data Structure Algorithms" and
COSE Verifiable Data Structure Proofs registries under a "COSE Verifiable Data Structure Proofs" subregistries under a
Specification Required policy as described in Section 4.6 of Specification Required policy as described in Section 4.6 of
[RFC8126]. [RFC8126].
8.2.1. Expert Review 8.2.1. Expert Review
Expert reviewers should take into consideration the following points: Expert reviewers (see [RFC8126]) should take into consideration the
following points:
* Experts are advised to assign the next available positive integer * Experts are advised to assign the next available positive integer
for verifiable data structures. for Verifiable Data Structures.
* Point squatting should be discouraged. Reviewers are encouraged * Point squatting should be discouraged. Reviewers are encouraged
to get sufficient information for registration requests to ensure to get sufficient information for registration requests to ensure
that the usage is not going to duplicate one that is already that the usage is not going to duplicate one that is already
registered, and that the point is likely to be used in registered and that the point is likely to be used in deployments.
deployments.
* Specifications are required for all point assignments. Early * Specifications are required for all point assignments. early
Allocation is permissible, see Section 2 of [RFC7120]. allocation is permissible, see Section 2 of [RFC7120].
* It is not permissible to assign points in COSE Verifiable Data * It is not permissible to assign points in COSE Verifiable Data
Structure Algorithms, for which no corresponding COSE Verifiable Structure Algorithms for which no corresponding COSE Verifiable
Data Structure Proofs entry exists, and vice versa. Data Structure Proofs entry exists, and vice versa.
* The Change Controller for related registrations of structures and * The change controller for related registrations of structures and
proofs should be the same. proofs should be the same.
8.2.2. COSE Verifiable Data Structure Algorithms 8.2.2. Templates and Initial Contents
Registration Template: 8.2.2.1. COSE Verifiable Data Structure Algorithms Registry
* Name: This is a descriptive name for the verifiable data structure Registration Template:
that enables easier reference to the item. Name:
This is a descriptive name for the Verifiable Data Structure
that enables easier reference to the item.
* Value: This is the value used to identify the verifiable data Value:
structure. This is the value used to identify the Verifiable Data
Structure.
* Description: This field contains a brief description of the Description:
verifiable data structure. This field contains a brief description of the Verifiable Data
Structure.
* Reference: This contains a pointer to the public specification for Reference:
the verifiable data structure. This contains a pointer to the public specification for the
Verifiable Data Structure.
* Change Controller: For Standards Track RFCs, list the "IETF". For Change Controller:
others, give the name of the responsible party. Other details For Standards Track RFCs, list the "IETF". For others, give
(e.g., postal address, email address, home page URI) may also be the name of the responsible party. Other details (e.g., postal
included. address, email address, home page URI) may also be included.
Initial contents: +================+=======+===============+============+===========+
| Name | Value | Description | Change | Reference |
| | | | Controller | |
+================+=======+===============+============+===========+
| Reserved | 0 | Reserved | | RFC 9942 |
+----------------+-------+---------------+------------+-----------+
| RFC9162_SHA256 | 1 | SHA256 Binary | IETF | Section |
| | | Merkle Tree | | 2.1 of |
| | | | | [RFC9162] |
+----------------+-------+---------------+------------+-----------+
+================+=======+===========================+==============+ Table 2: COSE Verifiable Data Structure Algorithms Initial
| Name | Value | Description | Reference | Registry Contents
+================+=======+===========================+==============+
| Reserved | 0 | Reserved | Reserved |
+----------------+-------+---------------------------+--------------+
| RFC9162_SHA256 | 1 | SHA256 Binary | Section 2.1 |
| | | Merkle Tree | of [RFC9162] |
+----------------+-------+---------------------------+--------------+
Table 2: COSE Verifiable Data Structure Algorithms 8.2.2.2. COSE Verifiable Data Structure Proofs Registry
Registration Template: Registration Template:
Verifiable Data Structure:
This value used identifies the related Verifiable Data
Structure.
* Verifiable Data Structure: This value used identifies the related Name:
verifiable data structure. This is a descriptive name for the proof type that enables
easier reference to the item.
* Name: This is a descriptive name for the proof type that enables
easier reference to the item.
* Label: This is the value used to identify the verifiable data
structure proof type.
* CBOR Type: This contains the CBOR type for the value portion of
the label.
* Description: This field contains a brief description of the proof
type.
* Reference: This contains a pointer to the public specification for Label:
the proof type. This is the value used to identify the Verifiable Data
Structure Proof type.
* Change Controller: For Standards Track RFCs, list the "IETF". For CBOR Type:
others, give the name of the responsible party. Other details This contains the CBOR type for the value portion of the label.
(e.g., postal address, email address, home page URI) may also be
included.
Initial contents: Description:
This field contains a brief description of the proof type.
+============+=============+=====+=======+=============+===========+ Reference:
| Verifiable | Name |Label| CBOR | Description | Reference | This contains a pointer to the public specification for the
| Data | | | Type | | | proof type.
| Structure | | | | | |
+============+=============+=====+=======+=============+===========+
| 1 | inclusion |-1 | array | Proof of | RFCthis, |
| | proofs | | (of | inclusion | Section |
| | | | bstr) | | 5.2 |
+------------+-------------+-----+-------+-------------+-----------+
| 1 | consistency |-2 | array | Proof of | RFCthis, |
| | proofs | | (of | append only | Section |
| | | | bstr) | property | 5.3 |
+------------+-------------+-----+-------+-------------+-----------+
Table 3: COSE Verifiable Data Structure Proofs Change Controller:
For Standards Track RFCs, list the "IETF". For others, give
the name of the responsible party. Other details (e.g., postal
address, email address, home page URI) may also be included.
9. Acknowledgements +==========+===========+=====+=====+===========+==========+=========+
|Verifiable|Name |Label|CBOR |Description|Change |Reference|
|Data | | |Type | |Controller| |
|Structure | | | | | | |
+==========+===========+=====+=====+===========+==========+=========+
|1 |inclusion |-1 |array|Proof of |IETF |RFC 9942,|
| |proofs | |(of |inclusion | |Section |
| | | |bstr)| | |5.2 |
+----------+-----------+-----+-----+-----------+----------+---------+
|1 |consistency|-2 |array|Proof of |IETF |RFC 9942,|
| |proofs | |(of |append only| |Section |
| | | |bstr)|property | |5.3 |
+----------+-----------+-----+-----+-----------+----------+---------+
We would like to thank Maik Riechert, Jon Geater, Michael B. Jones, Table 3: COSE Verifiable Data Structure Proofs Initial Registry
Mike Prorock, Ilari Liusvaara, Amaury Chamayou, for their Contents
contributions (some of which substantial) to this draft and to the
initial set of implementations.
10. References 9. References
10.1. Normative References 9.1. Normative References
[IANA.cose_header-parameters] [IANA.cose_header-parameters]
IANA, "COSE Header Parameters", IANA, "COSE Header Parameters",
<https://www.iana.org/assignments/cose>. <https://www.iana.org/assignments/cose>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data [RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/rfc/rfc8610>. June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object [RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949, Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020, DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/rfc/rfc8949>. <https://www.rfc-editor.org/info/rfc8949>.
[RFC9053] Schaad, J., "CBOR Object Signing and Encryption (COSE): [RFC9053] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Initial Algorithms", RFC 9053, DOI 10.17487/RFC9053, Initial Algorithms", RFC 9053, DOI 10.17487/RFC9053,
August 2022, <https://www.rfc-editor.org/rfc/rfc9053>. August 2022, <https://www.rfc-editor.org/info/rfc9053>.
[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/rfc/rfc9162>. December 2021, <https://www.rfc-editor.org/info/rfc9162>.
[RFC9596] Jones, M.B. and O. Steele, "CBOR Object Signing and [RFC9596] Jones, M.B. and O. Steele, "CBOR Object Signing and
Encryption (COSE) "typ" (type) Header Parameter", Encryption (COSE) "typ" (type) Header Parameter",
RFC 9596, DOI 10.17487/RFC9596, June 2024, RFC 9596, DOI 10.17487/RFC9596, June 2024,
<https://www.rfc-editor.org/rfc/rfc9596>. <https://www.rfc-editor.org/info/rfc9596>.
[RFC9597] Looker, T. and M.B. Jones, "CBOR Web Token (CWT) Claims in [RFC9597] Looker, T. and M.B. Jones, "CBOR Web Token (CWT) Claims in
COSE Headers", RFC 9597, DOI 10.17487/RFC9597, June 2024, COSE Headers", RFC 9597, DOI 10.17487/RFC9597, June 2024,
<https://www.rfc-editor.org/rfc/rfc9597>. <https://www.rfc-editor.org/info/rfc9597>.
10.2. Informative References
[BCP205] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 9.2. Informative References
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/rfc/rfc7942>.
[I-D.draft-ietf-cbor-edn-literals] [CBOR-EDN] Bormann, C., "CBOR Extended Diagnostic Notation (EDN)",
Bormann, C., "CBOR Extended Diagnostic Notation (EDN)",
Work in Progress, Internet-Draft, draft-ietf-cbor-edn- Work in Progress, Internet-Draft, draft-ietf-cbor-edn-
literals-19, 16 October 2025, literals-20, 2 March 2026,
<https://datatracker.ietf.org/doc/html/draft-ietf-cbor- <https://datatracker.ietf.org/doc/html/draft-ietf-cbor-
edn-literals-19>. edn-literals-20>.
[RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code [RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code
Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January
2014, <https://www.rfc-editor.org/rfc/rfc7120>. 2014, <https://www.rfc-editor.org/info/rfc7120>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>. <https://www.rfc-editor.org/info/rfc8126>.
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig, [RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392, "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/rfc/rfc8392>. May 2018, <https://www.rfc-editor.org/info/rfc8392>.
[RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE): [RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", STD 96, RFC 9052, Structures and Process", STD 96, RFC 9052,
DOI 10.17487/RFC9052, August 2022, DOI 10.17487/RFC9052, August 2022,
<https://www.rfc-editor.org/rfc/rfc9052>. <https://www.rfc-editor.org/info/rfc9052>.
Appendix A. Implementation Status
Note to RFC Editor: Please remove this section as well as references
to [BCP205] before AUTH48.
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [BCP205].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [BCP205], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
A.1. Transmute Prototype
An open-source implementation was initiated and is maintained by the Acknowledgements
Transmute Industries Inc. - Transmute. An application demonstrating
the concepts is available at COSE SCITT Receipts (https://github.com/
transmute-industries/cose?tab=readme-ov-file#transparent-statement)
Implementation URL: https://github.com/transmute-industries/cose We would like to thank Maik Riechert, Jon Geater, Michael B. Jones,
Maturity: The code's level of maturity is considered to be Mike Prorock, Ilari Liusvaara, and Amaury Chamayou for their
"prototype". Coverage and Version Compatibility: The current version contributions (some of which substantial) to this document and to the
('main') implements the verifiable data structure algorithm, initial set of implementations.
inclusion proof and consistency proof concepts of this draft.
License: The project and all corresponding code and data maintained
on GitHub are provided under the Apache License, version 2. Contact:
Orie Steele (orie@transmute.industries)
Contributors Contributors
Amaury Chamayou Amaury Chamayou
Microsoft Microsoft
United Kingdom United Kingdom
Email: amaury.chamayou@microsoft.com Email: amaury.chamayou@microsoft.com
Steve Lasker Steve Lasker
Email: stevenlasker@hotmail.com Email: stevenlasker@hotmail.com
Robert Martin Robert Martin
MITRE Corporation MITRE Corporation
United States United States of America
Email: ramartin@mitre.org Email: ramartin@mitre.org
Monty Wiseman Monty Wiseman
United States of America United States of America
Email: mwiseman32@acm.org Email: mwiseman32@acm.org
Roy Williams Roy Williams
United States of America United States of America
Email: roywill@msn.com Email: roywill@msn.com
Authors' Addresses Authors' Addresses
Orie Steele Orie Steele
Tradeverifyd Tradeverifyd
United States United States of America
Email: orie@or13.io Email: orie@or13.io
Henk Birkholz Henk Birkholz
Fraunhofer SIT Fraunhofer SIT
Rheinstrasse 75 Rheinstrasse 75
64295 Darmstadt 64295 Darmstadt
Germany Germany
Email: henk.birkholz@ietf.contact Email: henk.birkholz@ietf.contact
Antoine Delignat-Lavaud Antoine Delignat-Lavaud
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