<?xml version='1.0'encoding='utf-8'?>encoding='UTF-8'?> <!DOCTYPE rfc [ <!ENTITY nbsp " "> <!ENTITY zwsp "​"> <!ENTITY nbhy "‑"> <!ENTITY wj "⁠"> ]> <rfc xmlns:xi="http://www.w3.org/2001/XInclude" ipr="trust200902" docName="draft-ietf-scitt-architecture-22" number="9943" updates="" obsoletes="" xml:lang="en" category="std" consensus="true" submissionType="IETF" tocInclude="true" sortRefs="true" symRefs="true" version="3"><!-- xml2rfc v2v3 conversion 2.46.0 --><front> <title abbrev="SCITT Architecture">An Architecture for Trustworthy and Transparent Digital Supply Chains</title> <seriesInfoname="Internet-Draft" value="draft-ietf-scitt-architecture-22"/>name="RFC" value="9943"/> <author initials="H." surname="Birkholz" fullname="Henk Birkholz"> <organization abbrev="Fraunhofer SIT">Fraunhofer SIT</organization> <address> <postal> <street>Rheinstrasse 75</street> <city>Darmstadt</city> <code>64295</code> <country>Germany</country> </postal><email>henk.birkholz@sit.fraunhofer.de</email><email>henk.birkholz@ietf.contact</email> </address> </author> <author initials="A." surname="Delignat-Lavaud" fullname="Antoine Delignat-Lavaud"> <organization>Microsoft Research</organization> <address> <postal> <street>21 Station Road</street> <city>Cambridge</city> <code>CB1 2FB</code><country>UK</country><country>United Kingdom</country> </postal> <email>antdl@microsoft.com</email> </address> </author> <author initials="C." surname="Fournet" fullname="Cedric Fournet"> <organization>Microsoft Research</organization> <address> <postal> <street>21 Station Road</street> <city>Cambridge</city> <code>CB1 2FB</code><country>UK</country><country>United Kingdom</country> </postal> <email>fournet@microsoft.com</email> </address> </author> <author initials="Y." surname="Deshpande" fullname="Yogesh Deshpande"> <organization>ARM</organization> <address> <postal> <street>110 Fulbourn Road</street> <city>Cambridge</city> <code>CB1 9NJ</code><country>UK</country><country>United Kingdom</country> </postal> <email>yogesh.deshpande@arm.com</email> </address> </author> <author initials="S." surname="Lasker" fullname="Steve Lasker"> <organization/> <address> <email>stevenlasker@hotmail.com</email> </address> </author> <dateyear="2025" month="October" day="10"/> <area>Security</area> <workgroup>SCITT</workgroup> <keyword>Internet-Draft</keyword>year="2026" month="March"/> <area>SEC</area> <workgroup>scitt</workgroup> <!-- [rfced] Please insert any keywords (beyond those that appear in the title) for use on https://www.rfc-editor.org/search. --> <keyword>example</keyword> <abstract><?line 156?><t>Traceability in supply chains is a growing security concern. While verifiable data structures have addressed specific issues, such as equivocation over digital certificates, they lack a universal architecture for all supply chains. This document defines such an architecture for single-issuer signed statement transparency. It ensuresextensibility,extensibility and interoperability between different transparencyservices, andservices as well as compliance with various auditing procedures and regulatory requirements.</t> </abstract> <note removeInRFC="true"> <name>About This Document</name> <t> Status information for this document may be found at <eref target="https://datatracker.ietf.org/doc/draft-ietf-scitt-architecture/"/>. </t> <t> Discussion of this document takes place on the SCITT Working Group mailing list (<eref target="mailto:scitt@ietf.org"/>), which is archived at <eref target="https://mailarchive.ietf.org/arch/browse/scitt/"/>. Subscribe at <eref target="https://www.ietf.org/mailman/listinfo/scitt/"/>. </t> <t>Source for this draft and an issue tracker can be found at <eref target="https://github.com/ietf-wg-scitt/draft-ietf-scitt-architecture"/>.</t> </note> </front> <middle> <?line 163?> <section anchor="sec-introduction"> <name>Introduction</name> <t>This document defines an architecture, a base set of extensible message structures, and associated flows to make signed content transparent via verifiable data structures maintained by corresponding transparency services. The goal of the transparency enabled by the Supply Chain Integrity, Transparency, and Trust (SCITT) architecture is to enhance auditability and accountability for single-issuer signed content (statements) that are about supply chain commodities (artifacts).</t> <t>Registering signed statements with a transparency service is akin to a notarization procedure. TransparencyservicesServices (TSs) confirm a policy is met before recording the statement on the ledger. The SCITT ledger represents a linear and irrevocable history of statements made. Once the signed statement is registered, the transparency service issues a receipt.</t> <t>Similar approaches have been implemented for specific classes of artifacts, such as Certificate Transparency (CT) <xref target="RFC9162"/>. The SCITT approach follows a more generic paradigm than previous approaches. This "content-agnostic" approach allows SCITT transparency services to be either integrated in existing solutions orto bean initial part of new emerging systems. Extensibility is a vital feature of the SCITT architecture, so that requirements from various applications can be accommodated while always ensuring interoperability with respect to registration procedures and corresponding auditability and accountability. For simplicity, the scope of this document is limited to use cases originating from the software supply chaindomain, butdomain. However, the specification defined is applicable to any other type of supply chain statements (also referred to asvalue-add graphs),"value-add graphs"), for example, statements about hardware supply chains.</t> <t>This document also defines message structures for signed statements and transparent statements, which embedCOSECBOR Object Signing and Encryption (COSE) receipts <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>,target="RFC9942"/>, i.e., signed verifiable data structure proofs). These message structures are based on the Concise Binary Object Representation (CBOR) Standard <xref target="STD94"/> and corresponding signing is facilitated via theCBOR Object Signing and EncryptionCOSE Standard <xref target="STD96"/>. The message structures are defined using the Concise Data Definition Language (CDDL) <xref target="RFC8610"/>. The signed statements and receiptsareare, respectively, basedrespectivelyon the COSE_Sign1 specification in Section <xref section="4.2"sectionFormat="of"sectionFormat="bare" target="RFC9052"/> of RFC 9052 <xref target="STD96"/> and on COSE receipts <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>.target="RFC9942"/>. The application-domain-agnostic nature of COSE_Sign1 and its extensibility through COSE Header Parameters are prerequisites for implementing the interoperable message layer defined in this document.</t> <t>In summary, this specification supports relying parties obtaining proof that signed statements were recorded and checked for their validity at the time they were registered. How these statements are managed orstored,stored as well as how participating entities discover and notify each other of changes isout-of-scopeout of scope of this document.</t> <section anchor="sec-requirements-notation"> <name>Requirements Notation</name><t>The<t> The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>", "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as described inBCP 14BCP 14 <xref target="RFC2119"/> <xref target="RFC8174"/> when, and only when, they appear in all capitals, as shownhere.</t> <?line -18?>here. </t> </section> </section> <section anchor="sec-software-supply-chain-scope"> <name>Software Supply Chain Scope</name> <t>To illustrate the applicability of the SCITT architecture and its messages, this section details the exemplary context ofsoftware supply chainSoftware Supply Chain (SSC) use cases. The building blocks provided by the SCITT architecture are not restricted tosoftware supply chainSSC use cases.Software supply chainsSSCs serve asauseful application guidance and first usagescenario.</t>scenarios.</t> <section anchor="sec-generic-ssc-problem-statement"> <name>Generic SSC Problem Statement</name> <t>Supply chain security is a prerequisite to protecting consumers and minimizing economic, public health, and safety threats. Supply chain security has historically focused on risk management practices to safeguard logistics, meet regulatory requirements, forecast demand, and optimize inventory. While these elements are foundational to a healthy supply chain, an integrated cyber-security-based perspective of thesoftware supply chainsSSCs remains broadly undefined. Recently, the global community has experienced numerous supply chain attacks targeting weaknesses insoftware supply chains.SSCs. As illustrated in <xref target="lifecycle-threats"/>,a software supply chainan SSC attack may leverage one or more life-cycle stages and directly or indirectly target the component.</t> <!--[rfced] We had the following questions related to SVG used throughout the document: a) Please review our update to Figure 1 from "3rd-party" to "third-party". It looks like making this change may have affected the spacing of that sentence. Please regenerate. b) We note that the text within at least one (maybe more) of the SVG figures is not able to be selected. Is it possible to modify the SVG using your preferred SVG editing software to improve the rendering of the string in the SVG? Here is an example of SVG where the strings within the SVG are selectable and searchable: https://www.rfc-editor.org/rfc/rfc9576.html#figure-1 --> <figure anchor="lifecycle-threats"> <name>Example SSC Life-Cycle Threats</name> <artset> <artwork type="svg"><svg xmlns="http://www.w3.org/2000/svg" version="1.1" height="752" width="520" viewBox="0 0 520 752" class="diagram" text-anchor="middle" font-family="monospace" font-size="13px"> <path d="M 8,80 L 8,144" fill="none" stroke="black"/> <path d="M 8,176 L 8,240" fill="none" stroke="black"/> <path d="M 8,272 L 8,336" fill="none" stroke="black"/> <path d="M 8,368 L 8,432" fill="none" stroke="black"/> <path d="M 8,464 L 8,528" fill="none" stroke="black"/> <path d="M 8,560 L 8,624" fill="none" stroke="black"/> <path d="M 8,656 L 8,720" fill="none" stroke="black"/> <path d="M 56,48 L 56,80" fill="none" stroke="black"/> <path d="M 56,144 L 56,176" fill="none" stroke="black"/> <path d="M 56,240 L 56,272" fill="none" stroke="black"/> <path d="M 56,336 L 56,368" fill="none" stroke="black"/> <path d="M 56,432 L 56,464" fill="none" stroke="black"/> <path d="M 56,528 L 56,560" fill="none" stroke="black"/> <path d="M 56,624 L 56,656" fill="none" stroke="black"/> <path d="M 104,80 L 104,144" fill="none" stroke="black"/> <path d="M 104,176 L 104,240" fill="none" stroke="black"/> <path d="M 104,272 L 104,336" fill="none" stroke="black"/> <path d="M 104,368 L 104,432" fill="none" stroke="black"/> <path d="M 104,464 L 104,528" fill="none" stroke="black"/> <path d="M 104,560 L 104,624" fill="none" stroke="black"/> <path d="M 104,656 L 104,720" fill="none" stroke="black"/> <path d="M 8,80 L 104,80" fill="none" stroke="black"/> <path d="M 8,144 L 104,144" fill="none" stroke="black"/> <path d="M 8,176 L 104,176" fill="none" stroke="black"/> <path d="M 8,240 L 104,240" fill="none" stroke="black"/> <path d="M 8,272 L 104,272" fill="none" stroke="black"/> <path d="M 8,336 L 104,336" fill="none" stroke="black"/> <path d="M 8,368 L 104,368" fill="none" stroke="black"/> <path d="M 8,432 L 104,432" fill="none" stroke="black"/> <path d="M 8,464 L 104,464" fill="none" stroke="black"/> <path d="M 8,528 L 104,528" fill="none" stroke="black"/> <path d="M 8,560 L 104,560" fill="none" stroke="black"/> <path d="M 8,624 L 104,624" fill="none" stroke="black"/> <path d="M 8,656 L 104,656" fill="none" stroke="black"/> <path d="M 8,720 L 104,720" fill="none" stroke="black"/> <g class="text"> <text x="60" y="36">Dependencies</text> <text x="208" y="36">Malicious</text> <text x="288"y="36">3rd-party</text>y="36">third-party</text> <text x="360" y="36">package</text> <text x="404" y="36">or</text> <text x="448" y="36">version</text> <text x="52" y="116">Code</text> <text x="212" y="116">Compromise</text> <text x="284" y="116">source</text> <text x="344" y="116">control</text> <text x="208" y="196">Malicious</text> <text x="284" y="196">plug-ins</text> <text x="52" y="212">Commit</text> <text x="208" y="212">Malicious</text> <text x="276" y="212">commit</text> <text x="196" y="292">Modify</text> <text x="248" y="292">build</text> <text x="296" y="292">tasks</text> <text x="332" y="292">or</text> <text x="360" y="292">the</text> <text x="400" y="292">build</text> <text x="472" y="292">environment</text> <text x="56" y="308">Build</text> <text x="196" y="308">Poison</text> <text x="240" y="308">the</text> <text x="280" y="308">build</text> <text x="364" y="308">agent/compiler</text> <text x="196" y="324">Tamper</text> <text x="244" y="324">with</text> <text x="288" y="324">build</text> <text x="336" y="324">cache</text> <text x="212" y="388">Compromise</text> <text x="276" y="388">test</text> <text x="320" y="388">tools</text> <text x="60" y="404">Test</text> <text x="224" y="404">Falsification</text> <text x="292" y="404">of</text> <text x="324" y="404">test</text> <text x="376" y="404">results</text> <text x="184" y="484">Use</text> <text x="216" y="484">bad</text> <text x="268" y="484">packages</text> <text x="56" y="500">Package</text> <text x="212" y="500">Compromise</text> <text x="288" y="500">package</text> <text x="364" y="500">repository</text> <text x="196" y="580">Modify</text> <text x="256" y="580">release</text> <text x="312" y="580">tasks</text> <text x="56" y="596">Release</text> <text x="196" y="596">Modify</text> <text x="248" y="596">build</text> <text x="292" y="596">drop</text> <text x="336" y="596">prior</text> <text x="372" y="596">to</text> <text x="416" y="596">release</text> <text x="52" y="692">Deploy</text> <text x="196" y="692">Tamper</text> <text x="244" y="692">with</text> <text x="308" y="692">versioning</text> <text x="368" y="692">and</text> <text x="412" y="692">update</text> <text x="472" y="692">process</text> </g> </svg> </artwork> <artwork type="ascii-art"><![CDATA[ Dependencies Malicious3rd-partythird-party package or version | | +-----+-----+ | | | Code | Compromise source control | | +-----+-----+ | +-----+-----+ | | Malicious plug-ins | Commit | Malicious commit | | +-----+-----+ | +-----+-----+ | | Modify build tasks or the build environment | Build | Poison the build agent/compiler | | Tamper with build cache +-----+-----+ | +-----+-----+ | | Compromise test tools | Test | Falsification of test results | | +-----+-----+ | +-----+-----+ | | Use bad packages | Package | Compromise package repository | | +-----+-----+ | +-----+-----+ | | Modify release tasks | Release | Modify build drop prior to release | | +-----+-----+ | +-----+-----+ | | | Deploy | Tamper with versioning and update process | | +-----------+ ]]></artwork> </artset> </figure> <t>DevSecOps, as defined in <xref target="NIST.SP.800-204C"/>, often depends on third-party and open-source software. These dependencies can be quite complex throughout the supply chain, so checking provenance and traceability throughout theirlifecyclelife cycle is difficult. There is a need for manageable auditability and accountability of digital products. Typically, the range of types of statements about digital products (and their dependencies) is vast, heterogeneous, and can differ between community policy requirements. Taking the type and structure of all statements about digital products into account might not be possible. Examples of statements may include commit signatures, build environment and parameters,software billSoftware Bill ofmaterials,Materials (SBOM), static and dynamic application security testing results, fuzz testing results, release approvals, deployment records, vulnerability scan results, and patch logs.In consequence,Consequently, instead of trying to understand and describe the detailed syntax and semantics of every type of statement about digital products, the SCITT architecture focuses on ensuring statement authenticity, ensuring visibility/transparency, and intends to provide scalable accessibility. Threats and practical issues can also arise from unintendedside-effectsside effects of using security techniques outside their proper bounds. Forinstanceinstance, digital signatures may fail to verify past their expiry date even though the signed item itself remains completely valid. Or a signature may verify even though the information it is securing is now found unreliable but fine-grained revocation is too hard.</t> <t>Lastly, where data exchange underpins serious business decision-making, it is important to hold the producers of those data to a higher standard of auditability. The SCITT architecture provides mechanisms and structures for ensuring that the makers of authoritative statements can be held accountable and not hide or shred the evidence when it becomes inconvenient later.</t> <t>The following use cases illustrate the scope of SCITT and elaborate on the generic problem statement above.</t> </section> <section anchor="sec-eclectic-ssc-use-cases"> <name>Eclectic SSC Use Cases</name> <t>The three following use cases are a specialization derived from the generic problem statement above.</t> <section anchor="sec-security-analysis-of-a-software-product"> <name>Security Analysis of a Software Product</name> <t>A released software product is often accompanied by a set of complementary statements about its security properties. This gives enough confidence to both producers and consumers that the released software meets the expected security standards and is suitable to use.</t> <t>Subsequently, multiple security researchers often run sophisticated security analysis tools on the same product. The intention is to identify any security weaknesses or vulnerabilities in the package.</t> <t>Initially, a particular analysis can identify a simple weakness in a software component. Over a period of time, a statement from athird-partythird party illustrates that the weakness is exposed in a way that represents an exploitable vulnerability. The producer of the software product provides a statement that confirms the linking of a software component vulnerability with the software product by issuing a product vulnerability disclosure report and alsoissuesissuing an advisory statement on how to mitigate the vulnerability. At first, the producer provides an updated software product that still uses the vulnerable software component but shields the issue in a fashion that inhibits exploitation. Later, a second update of the software product includes a security patch to the affected software component from the software producer. Finally, a third update includes a new release (updated version) of the formerly insecure software component. For this release, both the software product and the affected software component are deemed secure by the producer and consumers.</t> <t>A consumer of a released software wants to:</t> <ul spacing="normal"> <li>know where to get these security statements from producers andthird-partiesthird parties related to the software product in a timely and unambiguous fashion</li> <li>attribute them to an authoritative issuer</li> <li>associate the statements in a meaningful manner via a set of well-known semantic relationships</li> <li>consistently, efficiently, and homogeneously check their authenticity</li> </ul> <t>SCITT provides a standardized way to:</t> <ul spacing="normal"> <li>know the various sources of statements</li> <li>express the provenance and historicity of statements</li> <li>relate and link various heterogeneous statements in a simple fashion</li> <li>check that the statement comes from a source with authority to issue that statement</li> <li>confirm that sources provide a complete history of statements related to a given component</li> </ul> </section> <section anchor="sec-promotion-of-a-software-component-by-multiple-entities"> <name>Promotion of a Software Component by Multiple Entities</name> <t>A software component (e.g., a library or software product), open-source or commercial, is often initially released by a single trustedproducer,producer who can choose to attach a statement of authenticity to it. As that component becomes used in a growing range of other products, providers other than the original trusted producer oftenre-distribute,re-distribute or release their own version of that component.</t> <t>Some providers include it as part of their releaseproduct/packageproduct or package bundle and provide the package with proof of authenticity using their issuer authority. Some packages include the original statement of authenticity, and some do not. Over time, some providers no longer offer the exact same software component source code but pre-compiled software component binaries. Some sources do not provide the exact same softwarecomponent,component but include patches and fixes produced bythird-parties,third parties as these emerge faster than solutions from the original producer. Due to complex distribution and promotion life-cycle scenarios, the original software component takes myriad forms.</t> <t>A consumer of a released software wants to:</t> <ul spacing="normal"> <li>understand if a particular provider is a trusted originating producer or an alternative party</li> <li>know if and how the source, or resulting binary, of a promoted software component differs from the original software component</li> <li>check the provenance and history of a software component's source back to its origin</li> <li>assess whether to trust a component or product based on a downloaded package location and source supplier</li> </ul> <t>SCITT provides a standardized way to:</t> <ul spacing="normal"> <li>reliably discern if a provider is the original, trusted producer or is a trustworthy alternative provider or is an illegitimate provider</li> <li>track the provenance path from an original producer to a particular provider</li> <li>check the trustworthiness of a provider</li> <li>check the integrity of modifications or transformations applied by a provider</li> </ul> </section> <section anchor="sec-software-integrator-assembling-a-software-product-for-a-vehicle"> <name>Software Integrator Assembling a Software Product for a Vehicle</name> <t>Software Integration is a complex activity.This typicallyTypically, it involves getting various software components from multiplesuppliers,suppliers and producing an integrated package deployed as part of device assembly. For example, car manufacturers source integrated software for their vehicles from third parties that integrate software components from various sources. Integration complexity creates a higher risk of security vulnerabilities to the delivered software.</t> <t>Consumers of integrated software want:</t> <ul spacing="normal"> <li>a list of all components present in a software product</li> <li>the ability to identify and retrieve all components from a secure and tamper-proof location</li> <li>verifiable proofs on build process and build environment with all supplier tiers to ensureend to endend-to-end build quality and security</li> </ul> <t>SCITT provides a standardized way to:</t> <ul spacing="normal"> <li>provide a tiered and transparent framework that allows for verification of integrity and authenticity of the integrated software at both component and product level before installation</li> <li>provide valid annotations on build integrity to ensure conformance</li> </ul> </section> </section> </section> <section anchor="terminology"> <name>Terminology</name> <t>The terms defined in this section have special meaning in the context ofSupply Chain Integrity, Transparency, and Trust,SCITT and are used throughout this document.</t> <t>This document has been developed in coordination with the COSE,OAUTHOAUTH, and RATSWGworking groups (WGs) and uses terminology common to theseworking groupsWGs asmuchoften as possible.</t><t>When<t>The terms "header", "payload", and "to-be-signed bytes" are defined in <xref target="STD96"/>.</t> <t>The term "claim" is defined in <xref target="RFC8392"/>.</t> <!--[rfced] We had the following questions/comments related to the Terminology section: a) We have moved the following paragraph to appear directly before the list of terms defined in this document as the terms borrowed from other documents (e.g., "header") are not capitalized in the text. We have also changed "corresponding" to "following" for clarity. Please review and let us know any objections. Original: When used in text, the corresponding terms are capitalized. To ensure readability, only a core set of terms is included in thissection.</t> <t>Thesection. Current: When used in text, the following terms"header", "payload",are capitalized. To ensure readability, only a core set of terms is included in this section. b) Related to the paragraph above in part (a): Note that several of the terms in the Terminology list are not consistently capped throughout the rest of the document. For example, should "attestation" be capped within the Attestation definition (occurs two times lowercase)? Here is a list of terms that appear in lowercase in the body of the document: append-only artifact attestation equivocation issuer (see also single-issuer) non-equivocation receipt (see related cluster-wide query as this affects both documents) registration relying party (or parties) signed statement statement transparent statement transparency service (or services) verifiable data structure (see related question about abbreviation use) We suggest the following possible ways forward: -Cap the terms on their introduction (i.e., <dt>) in the list in the Terminology section only: lowercase when used in prose. Remove the sentence about these terms being capped from the Terminology section (from (a) above). -Cap the terms consistently throughout the document. Leave the sentence from (a) as is. -Leave the variation between capitalization and"to-be-signed bytes"lowercase if there is meaning involved (e.g., when capped it has this definition but when lowercase it does not) and update the sentence in (a) to explain the meaning behind the variation. NOTE: Generally, we believe over-capitalizing nouns can get distracting to readers, but we understand the desire to match past use or add meaning, etc. Our main goal is to ensure the reader understands your intent. c) The only term that seems to be out of alphabetical order in this is "Attestation". May we move this term to fit in the A's? d) We note that [RFC8392] uses "CWT Claims Set" rather than "CWT Claim Set". Please review and let us know what/if any updates are necessary. Current: In SCITT Statements and Receipts, the iss Claim is a member of the COSE header parameter 15: CWT Claims defined in<xref target="STD96"/>.</t> <t>The[RFC9597], which embeds a CWT Claim Set [RFC8392] within the protected header of a COSE Envelope. e) Section 4 is titled "Definition of Transparency". Does this seem like something that should be grouped with "Terminology" (i.e., should it be Section 3.1)? f) Section 5.1.1.1: Should this pointer to the definition of "trust anchor" be replaced by an entry in the Terminology section instead? We note that the term"claim"was already used at the end of Section 5.1.1. Original: Transparency Services MUST maintain a list of trust anchors (see definition of trust anchor in [RFC4949]) in order to check the signatures of Signed Statements, either separately, or inside Registration Policies. g) Section 9.4: Should this pointer to the definition of cryptoperiod be replaced by an entry in the Terminology section instead? Original: * rotate their keys at a cryptoperiod (defined in [RFC4949]) appropriate for the key algorithm and domain-specific regulations h) Please see our cluster-wide questions related to discrepancies between the definitions that appear in both documents in this cluster. --> <t>When used in text, the following terms are capitalized. To ensure readability, only a core set of terms isdefinedincluded in<xref target="RFC8392"/>.</t>this section.</t> <dl anchor="mybody"> <dt>Append-only Log:</dt> <dd> <t>a Statement Sequence comprising the entire registration history of the Transparency Service. To make the Append-only property verifiable and transparent, the Transparency Service defines how Signed Statements are made available to Auditors.</t> </dd> <dt>Artifact:</dt> <dd> <t>a physical or non-physical item that is moving along a supply chain.</t> </dd> <dt>Auditor:</dt> <dd> <t>an entity that checks the correctness and consistency of all Transparent Statements, or the transparent Statement Sequence, issued by a Transparency Service. An Auditor is an example of a specialized Relying Party.</t> </dd> <dt>Client:</dt> <dd> <t>an application making protected Transparency Service resource requests on behalf of the resource owner and with its authorization.</t> </dd> <dt>Envelope:</dt> <dd> <t>metadata, created by the Issuer to produce a Signed Statement. The Envelope contains the identity of the Issuer and information about the Artifact, enabling Transparency Service Registration Policies to validate the Signed Statement. A Signed Statement is a COSE Envelope wrapped around a Statement, binding the metadata in the Envelope to the Statement. In COSE, an Envelope consists of a protected header (included in the Issuer's signature) and an unprotected header (not included in the Issuer's signature).</t> </dd> <dt>Equivocation:</dt> <dd> <t>a state where a Transparency Service provides inconsistent proofs to Relying Parties, containing conflicting claims about the Signed Statement bound at a given position in the Verifiable Data Structure.</t> </dd> <dt>Issuer:</dt> <dd> <t>an identifier representing an organization, device, user, or entity securing Statements about supply chain Artifacts. An Issuer may be the owner or author ofArtifacts,Artifacts or an independent third party such as an Auditor,reviewerreviewer, oranendorser. In SCITT Statements and Receipts, the <tt>iss</tt> Claim is a member of the COSE header parameter <tt>15: CWT Claims</tt> defined in <xref target="RFC9597"/>, which embeds aCWTCBOR Web Token (CWT) Claim Set <xref target="RFC8392"/> within the protected header of a COSE Envelope. This document uses the terms"Issuer","Issuer" and "Subject" as described in <xreftarget="RFC8392"/>, howevertarget="RFC8392"/>; however, the usage is consistent with the broader interpretation of these terms in bothJOSEJSON Object Signing and Encryption (JOSE) and COSE, and the guidance in <xref target="RFC8725"/> generally applies the COSE equivalent terms with consistent semantics.</t> </dd> <dt>Non-equivocation:</dt> <dd> <t>a state where all proofs provided by the Transparency Service to Relying Parties are produced from a single Verifiable Data Structure describing a unique sequence of Signed Statements and are therefore consistent <xref target="EQUIVOCATION"/>. Over time, an Issuer may register new Signed Statements about an Artifact in a Transparency Service with new information. However, the consistency of a collection of Signed Statements about the Artifact can be checked by all Relying Parties.</t> </dd> <dt>Receipt:</dt> <dd> <t>a cryptographic proof that a Signed Statement is included in the Verifiable Data Structure. See <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>target="RFC9942"/> for implementations. Receipts are signed proofs of verifiable data-structure properties. Receipt Profiles implemented by a Transparency Service <bcp14>MUST</bcp14> support inclusion proofs and <bcp14>MAY</bcp14> support other proof types, such as consistency proofs.</t> </dd> <dt>Registration:</dt> <dd> <t>the process of submitting a Signed Statement to a Transparency Service, applying the Transparency Service's Registration Policy, adding to the Verifiable Data Structure, and producing a Receipt.</t> </dd> <dt>Registration Policy:</dt> <dd> <t>thepre-conditionprecondition enforced by the Transparency Service before registering a Signed Statement, based on information in the non-opaque header and metadata contained in its COSE Envelope.</t> </dd> <dt>Relying Party:</dt> <dd> <t>Relying Partiesconsumesconsume Transparent Statements, verifying their proofs and inspecting the Statement payload, either before using correspondingArtifacts,Artifacts or later to audit an Artifact's provenance on the supply chain.</t> </dd> <dt>Signed Statement:</dt> <dd> <t>an identifiable and non-repudiable Statement about an Artifact signed by an Issuer. In SCITT, Signed Statements are encoded as COSE signed objects; the <tt>payload</tt> of the COSE structure contains the issued Statement.</t> </dd> <dt>Attestation:</dt> <dd> <t><xref target="NIST.SP.1800-19"/> defines "attestation"as "Theas:</t> <blockquote><t>The process of providing a digital signature for a set of measurements securely stored in hardware, and then having the requester validate the signature and the set ofmeasurements."measurements.</t></blockquote> <!--[rfced] Can you let us know how "NIST guidance "Software Supply Chain Security Guidance EO 14028" is different from [NIST_E014028]? This currently reads as if the reference is using itself. Original: NIST guidance "Software Supply Chain Security Guidance EO 14028" uses the definition from<xref target="NIST_EO14028"/>,[NIST_EO14028], which states that an "attestation" is "The issue of a statement, based on a decision, that fulfillment of specified requirements has been demonstrated.".ItThe related reference entry: [NIST_EO14028] NIST, "Software Supply Chain Security Guidance Under Executive Order (EO) 14028 Section 4e", 4 February 2022, <https://www.nist.gov/system/files/documents/2022/02/04/ software-supply-chain-security-guidance-under-EO-14028- section-4e.pdf>. Perhaps: [NIST_EO14028] states that an "attestation" is: The issue of a statement, based on a decision, that fulfillment of specified requirements has been demonstrated. --> <t>NIST guidance "Software Supply Chain Security Guidance EO 14028" uses the definition from <xref target="NIST_EO14028"/>, which states that an "attestation" is:</t><blockquote> <t>The issue of a statement, based on a decision, that fulfillment of specified requirements has been demonstrated.</t></blockquote> <t>It is often useful for the intended audience to qualify the term "attestation" in their specific context to avoid confusion and ambiguity.</t> </dd> <dt>Statement:</dt> <dd> <t>any serializable information about an Artifact. To helpinterpretation ofinterpret Statements, they must be tagged with a relevant media type (as specified in <xref target="RFC6838"/>). A Statement may representa Software Bill Of Materials (SBOM)an SBOM that lists the ingredients of a software Artifact, contains an endorsement or attestation about an Artifact,indicateindicates the End of Life (EOL),redirectionredirects to a newer version, or contains any content an Issuer wishes to publish about an Artifact. Additional Statements about an Artifact are correlated by the Subject Claim as defined in the IANA CWT registry <xref target="IANA.cwt"/>registryand used as a protected header parameter as defined in <xref target="RFC9597"/>. The Statement is considered opaque to TransparencyService,Service and <bcp14>MAY</bcp14> be encrypted.</t> </dd> <dt>Statement Sequence:</dt> <dd> <t>a sequence of Signed Statements captured by a Verifiable Data Structure. See Verifiable Data Structure.</t> </dd> <dt>Subject:</dt> <dd> <t>an identifier, defined by the Issuer,whichthat represents the organization, device, user, entity, or Artifact about which Statements (and Receipts) are made and by which a logical collection of Statements can be grouped. It is possible that there are multiple Statements about the same Artifact. In these cases, distinct Issuers (<tt>iss</tt>) might agree to use the <tt>sub</tt> CWT Claim, defined in <xref target="RFC8392"/>, to create a coherent sequence of Signed Statements about the sameArtifactArtifact, and Relying Parties can leverage <tt>sub</tt> to ensure completeness and Non-equivocation across Statements by identifying all Transparent Statements associated to a specific Subject.</t> </dd> <dt>Transparency Service:</dt> <dd> <t>an entity that maintains and extends the Verifiable Data Structure and endorses its state. The identity of a Transparency Service is captured by a public key that must be known by Relying Parties in order to validate Receipts.</t> </dd> <dt>Transparent Statement:</dt> <dd> <t>a Signed Statement that is augmented with a Receipt created via Registration in a Transparency Service. The Receipt is stored in the unprotected header of COSE Envelope of the Signed Statement. A Transparent Statement remains a valid Signed Statement and may be registered again in a different Transparency Service.</t> </dd> <dt>Verifiable Data Structure:</dt> <dd> <t>a data structurewhichthat supports one or more proof types, such as "inclusion proofs" or "consistency proofs", for Signed Statements as they are Registered to a Transparency Service. SCITT supports multiple Verifiable Data Structures and Receipt formats as defined in <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>,target="RFC9942"/>, accommodating different Transparency Service implementations.</t> </dd> </dl> </section> <section anchor="sec-definition-of-transparency"> <name>Definition of Transparency</name> <t>In this document, the definition of transparency is intended to build over abstract notions of Append-only Logs and Receipts. Existing transparency systems such asCertificate TransparencyCT <xref target="RFC9162"/> are instances of this definition. SCITT supports multiple Verifiable Data Structures, as defined in <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>.</t>target="RFC9942"/>.</t> <t>A Signed Statement is an identifiable and non-repudiable Statement made by an Issuer. The Issuer selects additional metadata and attaches a proof of endorsement (in most cases, a signature) using the identity key of the Issuer that binds the Statement and its metadata. Signed Statements can be made transparent by attaching a proof of Registration by a TransparencyService,Service in the form of a Receipt. Receipts demonstrate inclusion of Signed Statements in the Verifiable Data Structure of a Transparency Service. By extension, the Signed Statement may say an Artifact (for example, a firmware binary) is transparent if it comes with one or more Transparent Statements from its author or owner, though the context should make it clear what type of SignedStatementsStatement is expected for a given Artifact.</t> <t>Transparency does not prevent dishonest or compromised Issuers, but it holds them accountable. Any Artifact that may beverified,verified is subject to scrutiny and auditing by other parties. The Transparency Service provides a history of Statements, which may be made by multiple Issuers, enabling Relying Parties to make informed decisions.</t> <t>Transparency is implemented by providing a consistent, append-only, cryptographically verifiable, publicly available record of entries. Implementations of Transparency Services may protect their registered sequence of Signed Statements and Verifiable Data Structure using a combination of trusted hardware, consensus protocols, and cryptographic evidence. A Receipt is a signature over one or more Verifiable Data Structure Proofs that a Signed Statement is registered in the Verifiable Data Structure. It is universally verifiable without online access to the TS. Requesting a Receipt can result in the production of a new Receipt for the same Signed Statement. A Receipt's verification key, signing algorithm, validity period, header parameters or other claims <bcp14>MAY</bcp14> change each time a Receipt is produced.</t> <t>Anyone with access to the Transparency Service can independently verify its consistency and review the complete list of Transparent Statements registered by each Issuer.</t><t>Reputable<t>Thus, reputable Issuers arethusincentivized to carefully review their Statements before signing them to produce Signed Statements. Similarly, reputable Transparency Services are incentivized to secure their Verifiable Data Structure, as any inconsistency can easily be pinpointed by any Auditor with read access to the Transparency Service.</t> <t>The building blocks specified in this document enable the unequivocal and auditable production of statements about software supply chain artifacts. The extensible design of the SCITT architecture potentially allows future usage with other supply chains in different domains, forexampleexample, advanced manufacturing or food supply.</t> <t>SCITT is a generalization ofCertificate Transparency (CT)CT <xref target="RFC9162"/>, which can be interpreted as a transparency architecture for the supply chain of X.509 certificates. Considering CT in terms of SCITT:</t> <ul spacing="normal"><li>CAs<li>Certificate Authorities (CAs) (Issuers) sign the ASN.1DER encodedDER-encoded tbsCertificate structure to produce an X.509 certificate (Signed Statements)</li> <li>CAs submit the certificates to one or more CT logs (Transparency Services)</li> <li>CT logs produce Signed Certificate Timestamps (Transparent Statements)</li> <li>Signed Certificate Timestamps, Signed Tree Heads, and their respective consistency proofs are checked by Relying Parties</li> <li>The Verifiable Data Structure can be checked by Auditors</li> </ul> </section> <section anchor="sec-architecture-overview"> <name>Architecture Overview</name> <t>The SCITT architecture enables Transparency Services in a given application domain to implement a collectivebaseline,baseline by providing a set of common formats and protocols for issuing and registering Signed Statements and auditing Transparent Statements.</t> <t>In order to accommodate as many Transparency Service implementations as possible, this document only specifies the format of Signed Statements (which must be used by all Issuers) and a very thin wrapper format for Receipts, which specifies the Transparency Service identity and the agility parameters for the Signed Inclusion Proofs. The remaining details of the Receipt's contents are specified in <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>.</t>target="RFC9942"/>.</t> <t><xref target="fig-concept-relationship"/> illustrates the roles and processes that comprise a Transparency Service independent of any one use case:</t> <ul spacing="normal"> <li>Issuers that use their credentials to create Signed Statements aboutArtifacts</li>Artifacts.</li> <li>Transparency Services that evaluate Signed Statements against RegistrationPolicies,Policies producing Receipts upon successful Registration. The returned Receipt may be combined with the Signed Statement to create a Transparent Statement.</li> <li> <t>Relying Parties that: </t> <ul spacing="normal"> <li>collect Receipts of Signed Statements for subsequent registration of Transparent Statements;</li> <li>retrieve Transparent Statements for analysis of Statements about Artifacts themselves(e.g.(e.g., verification);</li> <li>or replay all the Transparent Statements to check for the consistency and correctness of the Transparency Service's Verifiable Data Structure(e.g. auditing)</li>(e.g., auditing).</li> </ul> </li> </ul> <t>In addition, <xref target="fig-concept-relationship"/> illustrates multiple Transparency Services and multiple Receipts as a single Signed Statement <bcp14>MAY</bcp14> be registered with one or more Transparency Service. 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Statement | .+ | | '------+-----' .-------. | | Service +-+ | | .---------+ Receipt +<--' +--+------------+ | | | |.-----. | +. | Transparency | | | | | '+------' | | | | v v '---+ Receipt +<------+ Service | | .--+-----+--. '-------' +--------+-----+ | | Transparent | | | | Statement +-------. .----------)------' '-----+-----' | | | v v v v .--------+---------. .--+--------------+--. .------+----------. / Collect Receipts / / Verify Transparent / / Replay Log / '--+---------------+ / Statement / '-+---------------+ | Relying Party | '----+---------------+ | Relying Party | +---------------+ | Relying Party | +---------------+ +---------------+ ]]></artwork> </artset> </figure> <t>The subsequent sections describe the main concepts, namely Transparency Service, Signed Statements, Registration, and Transparent Statements in more detail.</t> <section anchor="sec-transparency-service"> <name>Transparency Service</name> <t>Transparency Services <bcp14>MUST</bcp14> produce COSE Receipts <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>.</t> <t>Typicallytarget="RFC9942"/>.</t> <t>Typically, a Transparency Service has a single Issuer identitywhichthat is present in the <tt>iss</tt> Claim of Receipts for that service.</t> <t>Multi-tenant support can be enabled through the use of identifiers in the <tt>iss</tt>Claim,Claim; for example, <tt>ts.example.</tt> may have a distinct Issuer identity for eachsub domain,subdomain, such as <tt>tenant1.ts.example.</tt> and <tt>tenant2.ts.example.</tt>.</t> <section anchor="sec-registration-policies"> <name>Registration Policies</name> <t>Registration Policies refer to additional checks over and above the Mandatory Registration Checks that are performed before a Signed Statement is registered to the Verifiable Data Structure. To enableaudit-ability,auditability, Transparency Services <bcp14>MUST</bcp14> maintain Registration Policies. The presence of an explicit transparent registration policy, even if it allows all authenticated submissions, facilitates service audit, and enables potential future changes to that policy.</t> <t>Beyond the mandatory Registration checks, the scope of additional checks, including no additional checks, is up to the implementation.</t> <t>This specification leaves implementation,encodingencoding, and documentation of Registration Policies and trust anchors to the operator of the Transparency Service.</t> <section anchor="sec-mandatory-registration-checks"> <name>Mandatory Registration Checks</name> <t>During Registration, a Transparency Service <bcp14>MUST</bcp14> syntactically check the Issuer of the Signed Statement by cryptographically verifying the COSE signature according to <xref target="STD96"/>. The Issuer identity <bcp14>MUST</bcp14> be bound to the Signed Statement by including an identifier in the protected header. If the protected header includes multiple identifiers, all those that are registered by the Transparency Service <bcp14>MUST</bcp14> be checked.</t> <t>Transparency Services <bcp14>MUST</bcp14> maintain a list of trust anchors (see definition of trust anchor in <xref target="RFC4949"/>) in order to check the signatures of SignedStatements,Statements eitherseparately,separately or inside Registration Policies. Transparency Services <bcp14>MUST</bcp14> authenticate Signed Statements as part of a Registration Policy. For instance, a trust anchor could be an X.509 root certificate (directly or its thumbprint), a pointer to an OpenID Connect identity provider, or any other trust anchor that can be referenced in a COSE header parameter.</t> <t>When using X.509 Signed Statements, the Transparency Service <bcp14>MUST</bcp14> build and validate a complete certification path from an Issuer's certificate to one of the root certificates currently registered as a trust anchor by the Transparency Service. The protected header of the COSE_Sign1 Envelope <bcp14>MUST</bcp14> include either the Issuer's certificate as <tt>x5t</tt> or the chain including the Issuer's certificate as <tt>x5chain</tt>, as defined in <xref target="RFC9360"/>. If <tt>x5t</tt> is included in the protected header, an <tt>x5chain</tt> with a leaf certificate corresponding to the <tt>x5t</tt> value <bcp14>MAY</bcp14> be included in the unprotected header.</t> <t>Registration Policies and trust anchors <bcp14>MUST</bcp14> be made Transparent and available to all Relying Parties of the Transparency Service by Registering them as Signed Statements on the Verifiable Data Structure.</t> <t>The Transparency Service <bcp14>MUST</bcp14> apply the Registration Policy that was most recently committed to the Verifiable Data Structure at the time of Registration.</t> </section> <section anchor="sec-auditability-of-registration"> <name>Auditability of Registration</name> <t>The operator of a Transparency Service <bcp14>MAY</bcp14> update the Registration Policy or the trust anchors of a Transparency Service at any time.</t> <t>Transparency Services <bcp14>MUST</bcp14> ensure that for any Signed Statement they register, enough information is made available to Auditors to reproduce the Registration checks that were defined by the Registration Policies at the time of Registration. At a minimum, this consists of the Signed Statements themselves, any additional collateral data required to perform their authentication, and the applicable Registration Policy at the time of Registration.</t> </section> </section> <section anchor="ts-initialization"> <name>Initialization and Bootstrapping</name> <t>Since the mandatory Registration checks rely on having registered Signed Statements for the Registration Policy and trust anchors, Transparency Services <bcp14>MUST</bcp14> support at least one of the three following bootstrapping mechanisms:</t> <ul spacing="normal"><li>Pre-configured<li>Preconfigured Registration Policy and trust anchors;</li> <li>Acceptance of a first Signed Statement whose payload is a valid Registration Policy, without performing Registrationchecks</li>checks; or</li> <li>An out-of-band authenticated managementinterface</li>interface.</li> </ul> </section> <section anchor="sec-verifiable-data-structure"> <name>Verifiable Data Structure</name> <t>The security properties are determined by the choice of the Verifiable Data Structure(<xref target="I-D.draft-ietf-cose-merkle-tree-proofs"/>)(see <xref target="RFC9942"/>) used by the Transparency Service implementation. This verifiable data structure <bcp14>MUST</bcp14> support the following security requirements:</t> <dl> <dt>Append-Only:</dt> <dd> <t>a property required for a verifiable data structure to be applicable to SCITT, ensuring that the Statement Sequence cannot be modified, deleted, or reordered.</t> </dd> <dt>Non-equivocation:</dt> <dd> <t>there is no fork in the registered sequence of Signed Statements accepted by the Transparency Service and committed to the Verifiable Data Structure. Everyone with access to its content sees the same ordered collection of Signed Statements and can check that it is consistent with any Receipts they have verified.</t> </dd> <dt>Replayability:</dt> <dd> <t>the Verifiable Data Structure includes sufficient information to enable authorized actors with access to its content to check that each data structure representing each Signed Statement has been correctly registered.</t> </dd> </dl> <t>In addition to Receipts, some verifiable data structures might support additional proof types, such as proofs ofconsistency,consistency or proofs of non-inclusion.</t> <t>Specific verifiable data structures, such those describes in <xref target="RFC9162"/> and <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>,target="RFC9942"/>, and the review of their security requirements for SCITT are out of scope for this document.</t> </section> <section anchor="sec-adjacent-services"> <name>Adjacent Services</name> <t>Transparency Services can be deployedalong sidealongside other database or object storage technologies. For example, a Transparency Service that supports a software package management system, might be referenced from the APIs exposed for package management. It can also provide the ability to request a fresh Receipt for a given softwarepackage,package or a list of Signed Statements associated with that package.</t> </section> </section> </section> <section anchor="signed-statements"> <name>Signed Statements</name> <t>This specification prioritizes conformance to <xref target="STD96"/> and its required and optional properties. Signed Statements produced by Issuers must be COSE_Sign1 messages, as defined by <xref target="STD96"/>. Profiles andimplementation specificimplementation-specific choices should be used to determine admissibility of conforming messages. This specification is left intentionally open to allow implementations to make Registration restrictions that make the most sense for their operational use cases.</t> <t>There are many types of Statements (such asSBOMs,an SBOM, malware scans, audit reports, policy definitions) that Issuers may want to turn into Signed Statements. An Issuer must first decide on a suitable format (<tt>3</tt>: payload type) to serialize the Statement payload. For a software supply chain, payloads describing the software Artifacts may include:</t> <!--[rfced] In the following list, we will update to have the citation follow the text unless we hear objection. Original: * [CoSWID] Concise Software Identification Tags format * [CycloneDX] Bill of Materials format * [in-toto] Supply chain description metadata * [SPDX-CBOR] Software component description format * [SPDX-JSON] Software component description format * [SLSA] Supply-chain Levels for Software Artifacts * [SWID] Software Identification Tag format --> <ul spacing="normal"> <li> <xreftarget="CoSWID"/>target="RFC9393"/> Concise Software Identification Tags format</li> <li> <xref target="CycloneDX"/> Bill of Materials format</li> <li> <xref target="in-toto"/> Supply chain description metadata</li> <li> <xref target="SPDX-CBOR"/> Software component description format</li> <li> <xref target="SPDX-JSON"/> Software component description format</li> <li> <xref target="SLSA"/> Supply-chain Levels for Software Artifacts</li> <li> <xref target="SWID"/> Software Identification Tag format</li> </ul> <t>Issuers can produce Signed Statements about different Artifacts under the same Identity. Issuers and Relying Parties must be able to recognize the Artifact to which the Statements pertain by looking at the Signed Statement. The <tt>iss</tt> and <tt>sub</tt> Claims, within the <tt>CWT Claims</tt> protected header, are used to identify the Artifact the Statement pertains to. (See Subjectunderin <xreftarget="terminology"/> Terminology.)</t>target="terminology"/>.)</t> <t>Issuers <bcp14>MAY</bcp14> use different signing keys (identified by <tt>kid</tt> in the<xref target="STD96"/>protectedheader)header from <xref target="STD96"/>) for different Artifacts or sign all Signed Statements under the same key.</t> <t>An Issuer can make multiple Statements about the same Artifact. For example, an Issuer can make amended Statements about the same Artifact as their view changes over time.</t> <t>Multiple Issuers can make different, evenconflicting Statements,conflicting, Statements about the same Artifact. Relying Parties can choose which Issuers they trust.</t> <t>Multiple Issuers can make the same Statement about a single Artifact, affirming multiple Issuers agree.</t> <t>Additionally, an <tt>x5chain</tt> that corresponds to either <tt>x5t</tt> or <tt>kid</tt> identifying the leaf certificate in the included certification path <bcp14>MAY</bcp14> be included in the unprotected header of the COSE Envelope.</t> <ul spacing="normal"> <li>When using x.509 certificates, support for either <tt>x5t</tt> or <tt>x5chain</tt> in the protected header is <bcp14>REQUIRED</bcp14> to implement.</li> <li>Support for <tt>kid</tt> in the protected header and <tt>x5chain</tt> in the unprotected header is <bcp14>OPTIONAL</bcp14> to implement.</li> </ul> <t>When <tt>x5t</tt> or <tt>x5chain</tt> is present in the protected header, <tt>iss</tt> <bcp14>MUST</bcp14> be a string that meets URI requirements defined in <xref target="RFC8392"/>. The <tt>iss</tt> value's length <bcp14>MUST</bcp14> be between 1 and 8192 characters in length.</t> <t>The <tt>kid</tt> header parameter <bcp14>MUST</bcp14> be present when neither <tt>x5t</tt> nor <tt>x5chain</tt> is present in the protected header. Key discovery protocols areout-of-scopeout of scope of this document.</t> <t>The protected header of a Signed Statement and a Receipt <bcp14>MUST</bcp14> include the <tt>CWT Claims</tt> header parameter as specified in <xref section="2" sectionFormat="of" target="RFC9597"/>. The <tt>CWT Claims</tt> value <bcp14>MUST</bcp14> include the <tt>Issuer Claim</tt> (Claim label 1) and the <tt>Subject Claim</tt> (Claim label 2) <xref target="IANA.cwt"/>.</t> <t>A Receipt is a Signed Statement (COSE_Sign1) with additional Claims in its protected header related to verifying the inclusion proof in its unprotected header. See <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>.</t>target="RFC9942"/>.</t> <section anchor="sec-signed-statement-examples"> <name>Signed Statement Examples</name> <t><xref target="fig-signed-statement-cddl"/> illustrates a normative CDDL definition <xref target="RFC8610"/> for the protected header and unprotected header of Signed Statements and Receipts.</t> <t>The SCITT architecture specifies the minimal mandatory labels. Implementation-specific Registration Policies may define additional mandatory labels.</t> <figure anchor="fig-signed-statement-cddl"> <name>CDDLdefinitionDefinition for Signed Statements and Receipts</name> <sourcecodetype="cddl">type="cddl"><![CDATA[ Signed_Statement = #6.18(COSE_Sign1) Receipt = #6.18(COSE_Sign1) COSE_Sign1 = [ protected : bstr .cbor Protected_Header, unprotected : Unprotected_Header, payload : bstr / nil, signature : bstr ] Protected_Header = {&(CWT_Claims:&(CWT_Claims: 15)=>=> CWT_Claims ?&(alg:&(alg: 1)=>=> int ?&(content_type:&(content_type: 3)=>=> tstr / uint ?&(kid:&(kid: 4)=>=> bstr ?&(x5t:&(x5t: 34)=>=> COSE_CertHash ?&(x5chain:&(x5chain: 33)=>=> COSE_X509 * label=>=> any } CWT_Claims = {&(iss:&(iss: 1)=>=> tstr&(sub:&(sub: 2)=>=> tstr * label=>=> any } Unprotected_Header = { ?&(x5chain:&(x5chain: 33)=>=> COSE_X509 ?&(receipts:&(receipts: 394)=>=> [+ Receipt] * label=>=> any } label = int /tstr </sourcecode>tstr]]></sourcecode> </figure> <t><xref target="fig-signed-statement-edn"/> illustrates an instance of a Signed Statement in Extended Diagnostic Notation (EDN), with a payload that is detached. Detached payloads support largeStatements,Statements and ensure Signed Statements can integrate with existing storage systems.</t> <figure anchor="fig-signed-statement-edn"><name>CBOR Extended<name>CBOR-Extended Diagnostic NotationexampleExample of a Signed Statement</name> <sourcecodetype="cbor-diag">type="cbor-diag"><![CDATA[ 18( / COSE_Sign1 / [ h'a4012603...6d706c65', / Protected / {}, / Unprotected / nil, / Detached payload / h'79ada558...3a28bae4' / Signature / ]) </sourcecode>)]]></sourcecode> </figure> <t><xref target="fig-signed-statement-protected-header-edn"/> illustrates the decoded protected header of the Signed Statement in <xref target="fig-signed-statement-edn"/>. It indicates the Signed Statement is securing a JSON contenttype,type and identifying the content with the <tt>sub</tt> Claim "vendor.product.example".</t> <figure anchor="fig-signed-statement-protected-header-edn"><name>CBOR Extended<name>CBOR-Extended Diagnostic NotationexampleExample of a Signed Statement's Protected Header</name> <sourcecodetype="cbor-diag">type="cbor-diag"><![CDATA[ { / Protected / 1: -7, / Algorithm / 3: application/example+json, / Content type / 4: h'50685f55...50523255', / Key identifier / 15: { / CWT Claims / 1: software.vendor.example, / Issuer / 2: vendor.product.example, / Subject / }} </sourcecode>}]]></sourcecode> </figure> </section> <section anchor="sec-signing-large-or-sensitive-statements"> <name>Signing Large or Sensitive Statements</name><t>Statements<t>Statement payloads might be too large or too sensitive to be sent to a remote Transparency Service. 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transform="rotate(90,56,680)"/> <polygon class="arrowhead" points="64,584 52,578.4 52,589.6 " fill="black" transform="rotate(90,56,584)"/> <polygon class="arrowhead" points="64,456 52,450.4 52,461.6 " fill="black" transform="rotate(270,56,456)"/> <polygon class="arrowhead" points="64,104 52,98.4 52,109.6 " fill="black" transform="rotate(90,56,104)"/> <polygon class="arrowhead" points="48,200 36,194.4 36,205.6 " fill="black" transform="rotate(90,40,200)"/> <g class="text"> <text x="76" y="52">Artifact</text> <text x="60" y="132">Hash</text> <text x="196" y="180">OR</text> <text x="296" y="180">Payload</text> <text x="72" y="228">Statement</text> <text x="104" y="292">...</text> <text x="164" y="292">Producer</text> <text x="232" y="292">Network</text> <text x="280" y="292">...</text> <text x="192" y="324">...</text> <text x="104" y="356">...</text> <text x="164" y="356">Issuer</text> <text x="224" y="356">Network</text> <text x="272" y="356">...</text> <text x="52" y="420">Identity</text> <text x="168" y="420">(iss,</text> <text x="212" y="420">x5t)</text> <text x="52" y="436">Document</text> <text x="48" y="500">Private</text> <text x="96" y="500">Key</text> <text x="268" y="548">Header</text> <text x="76" y="628">Sign</text> <text x="220" y="628">To</text> <text x="244" y="628">Be</text> <text x="284" y="628">Signed</text> <text x="336" y="628">Bytes</text> <text x="60" y="708">COSE_Sign1</text> </g> </svg> </artwork> <artwork type="ascii-art"><![CDATA[ .----+-----. | Artifact | '+-+-------' | | .-' v | .--+-------. | | Hash +-+ | '----------' | /\ '-. | / \ .----------. | +-->+ OR +-->+ Payload | v | \ / '--------+-' .+--------. | \/ | | Statement +--+ | '---------' | | | ... Producer Network ... | ... ... Issuer Network ... | | | .---------. | | Identity | (iss, x5t) | | Document +--------------------+ | `----+----` | | ^ | | .----+-------. | | | Private Key | | | '----+-------' v | | .----+---. | | | Header | | | '----+---' | v v v .-+-----------. .------+------+--. / / / \ / Sign +<------+ To Be Signed Bytes | / / \ / '-----+-------' '----------------' v .----+-------. | COSE_Sign1 | '------------' ]]></artwork> </artset> </section> <section anchor="sec-registration-of-signed-statements"> <name>Registration of Signed Statements</name> <t>To register a Signed Statement, the Transparency Service performs the following steps:</t> <ol spacing="normal" type="1"> <li><strong>Client authentication:</strong> A<!--[rfced] Section 6.3 (in the numbered list): Points 1-3 began with a phrase enclosed in <strong> followed by a colon; but points 4 and 5 did not have text following the part in <strong>. Please see our formatting updates where we: - got rid of <strong>, - got rid of the colons, and - added a blank line after the text that was in <strong> We believe that the current version of this list looks more parallel (each entry is the step performed followed by any further info if it exists) and might be easier for the reader's eyes (especially in the text file). Please review and let us know if we've not correctly captured your intent. --> <t>Client Authentication</t> <t>A Client authenticates with the Transparency Service before registering Signed Statements on behalf of one or more Issuers. Authentication and authorization areimplementation-specificimplementation specific and out of scope of the SCITTarchitecture.</li>architecture.</t></li> <li><strong>TS<t>TS Signed Statement Verification andValidation:</strong> TheValidation</t><t>The Transparency Service <bcp14>MUST</bcp14> perform signature verification per Section <xref section="4.4"sectionFormat="of"sectionFormat="bare" target="RFC9052"/> of RFC 9052 <xref target="STD96"/> and <bcp14>MUST</bcp14> verify the signature of the Signed Statement with the signature algorithm and verification key of the Issuer per <xref target="RFC9360"/>. The Transparency Service <bcp14>MUST</bcp14> also check that the Signed Statement includes the required protected headers. The Transparency Service <bcp14>MAY</bcp14> validate the Signed Statement payload in order to enforcedomain specificdomain-specific registration policies that apply to specific contenttypes.</li>types.</t></li> <li><strong>Apply<t>Apply RegistrationPolicy:</strong> ThePolicy</t><t>The Transparency Service <bcp14>MUST</bcp14> check the attributes required by a Registration Policy are present in the protected headers. Custom Signed Statements are evaluated given the current Transparency Service state and the entire Envelope and may use information contained in the attributes of namedpolicies.</li>policies.</t></li> <li><strong>Register<t>Register the SignedStatement</strong></li>Statement</t></li> <li><strong>Return<t>Return theReceipt</strong>, whichReceipt</t> <t>This <bcp14>MAY</bcp14> be asynchronous from Registration. The Transparency Service <bcp14>MUST</bcp14> be able to provide a Receipt for all registered Signed Statements. Details about generating Receipts are described in <xreftarget="Receipt"/>.</li>target="Receipt"/>.</t></li> </ol> <t>The last two steps may be shared between a batch of Signed Statements registered in the Verifiable Data Structure.</t> <t>A Transparency Service <bcp14>MUST</bcp14> ensure that a Signed Statement is registered before releasing its Receipt.</t> <t>A Transparency Service <bcp14>MAY</bcp14> accept a Signed Statement with content in its unprotectedheader,header and <bcp14>MAY</bcp14> use values from that unprotected header during verification and registration policy evaluation.</t> <t>However, the unprotected header of a Signed Statement <bcp14>MUST</bcp14> be set to an empty map before the Signed Statement can be included in a Statement Sequence.</t> <t>The same Signed Statement may be independently registered in multiple Transparency Services, producingmultiple,multiple independent Receipts. The multiple Receipts may be attached to the unprotected header of the SignedStatement,Statement creating a Transparent Statement.</t> <t>An Issuer that knows of a changed state of quality for anArtifact,Artifact <bcp14>SHOULD</bcp14> Register a new SignedStatement,Statement using the same <tt>15</tt> CWT <tt>iss</tt> and <tt>sub</tt> Claims.</t> </section> </section> <section anchor="Receipt"> <name>Transparent Statements</name> <t>The Client (which is not necessarily the Issuer) that registers a Signed Statement and receives a Receipt can produce a Transparent Statement by adding the Receipt to the unprotected header of the Signed Statement. Client applications <bcp14>MAY</bcp14> register Signed Statements on behalf of one or more Issuers. Client applications <bcp14>MAY</bcp14> request Receipts regardless of the identity of the Issuer of the associated Signed Statement.</t> <t>When a Signed Statement is registered by a Transparency Service a Receipt becomes available. When a Receipt is included in a SignedStatementStatement, a Transparent Statement is produced.</t> <t>Receipts are based on Signed Inclusion Proofs as described in COSE Receipts <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/> thattarget="RFC9942"/>, which also provides the COSE header parameter semantics for label 394.</t> <t>The Registration time is recorded as the timestamp when the Transparency Service added the Signed Statement to its Verifiable Data Structure.</t> <t><xref target="fig-transparent-statement-cddl"/> illustrates a normative CDDL definition of Transparent Statements. See <xref target="fig-signed-statement-cddl"/> for the CDDL rule that defines 'COSE_Sign1' as specified in Section <xref section="4.2"sectionFormat="of" target="STD96"/></t>sectionFormat="bare" target="RFC9052"/> of RFC 9052 <xref target="STD96"/>.</t> <figure anchor="fig-transparent-statement-cddl"> <name>CDDLdefinitionDefinition for a Transparent Statement</name> <sourcecodetype="cddl">type="cddl"><![CDATA[ Transparent_Statement = #6.18(COSE_Sign1) Unprotected_Header = {&(receipts:&(receipts: 394)=>=> [+ Receipt]} </sourcecode>}]]></sourcecode> </figure> <t><xref target="fig-transparent-statement-edn"/> illustrates a Transparent Statement with a detachedpayload,payload and two Receipts in its unprotected header. The type of label 394 <tt>receipts</tt> in the unprotected header is a CBOR array that can contain one or more Receipts (each entry encoded as a.cbor encoded Receipts).</t>.cbor-encoded Receipt).</t> <figure anchor="fig-transparent-statement-edn"><name>CBOR Extended<name>CBOR-Extended Diagnostic NotationexampleExample of a Transparent Statement</name> <sourcecodetype="cbor-diag">type="cbor-diag"><![CDATA[ 18( / COSE_Sign1 / [ h'a4012603...6d706c65', / Protected / { / Unprotected / 394: [ / Receipts (2) / h'd284586c...4191f9d2' / Receipt 1 / h'c624586c...8f4af97e' / Receipt 2 / ] }, nil, / Detached payload / h'79ada558...3a28bae4' / Signature / ]) </sourcecode>)]]></sourcecode> </figure> <t><xref target="fig-receipt-edn"/> illustrates one of the decodedReceiptReceipts from <xref target="fig-transparent-statement-edn"/>. The Receipt contains inclusion proofs for verifiable data structures. The unprotected header contains verifiable data structure proofs. See the protected header for details regarding the specific verifiable data structure used. Per the COSE Verifiable Data Structure Algorithms Registry documented in <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>,target="RFC9942"/>, the COSE key type RFC9162_SHA256 is value <tt>1</tt>. Labels identify inclusion proofs (<tt>-1</tt>) and consistency proofs (<tt>-2</tt>).</t> <figure anchor="fig-receipt-edn"><name>CBOR Extended<name>CBOR-Extended Diagnostic NotationexampleExample of a Receipt</name> <sourcecodetype="cbor-diag">type="cbor-diag"><![CDATA[ 18( / COSE_Sign1 / [ h'a4012604...6d706c65', / Protected / { / Unprotected / -222: { / Proofs / -1: [ / Inclusion proofs (1) / h'83080783...32568964', / Inclusion proof 1 / ] }, }, nil, / Detached payload / h'10f6b12a...4191f9d2' / Signature / ]) </sourcecode>)]]></sourcecode> </figure> <t><xref target="fig-receipt-protected-header-edn"/> illustrates the decoded protected header of the Transparent Statement in <xref target="fig-transparent-statement-edn"/>. <!--[rfced] The parentheses at the end of these sentences make them read strangely (how does it relate to the rest of the sentence?). Please review: Original: The verifiable data structure (-111) uses 1 from (RFC9162_SHA256). and The structure of this inclusion proof is specific to the verifiable data structure used (RFC9162_SHA256). --> The verifiable data structure (<tt>-111</tt>) uses <tt>1</tt> from (RFC9162_SHA256).</t> <figure anchor="fig-receipt-protected-header-edn"><name>CBOR Extended<name>CBOR-Extended Diagnostic NotationexampleExample of a Receipt's Protected Header</name> <sourcecodetype="cbor-diag">type="cbor-diag"><![CDATA[ { / Protected / 1: -7, / Algorithm / 4: h'50685f55...50523255', / Key identifier / -111: 1, / Verifiable Data Structure / 15: { / CWT Claims / 1: transparency.vendor.example, / Issuer / 2: vendor.product.example, / Subject / }} </sourcecode>}]]></sourcecode> </figure> <t><xref target="fig-receipt-inclusion-proof-edn"/> illustrates the decoded inclusion proof from <xref target="fig-receipt-edn"/>. This inclusion proof indicates that the size of the Verifiable Data Structure was <tt>8</tt> at the time the Receipt was issued. The structure of this inclusion proof is specific to the verifiable data structure used (RFC9162_SHA256).</t> <figure anchor="fig-receipt-inclusion-proof-edn"><name>CBOR Extended<name>CBOR-Extended Diagnostic NotationexampleExample of a Receipt's Inclusion Proof</name> <sourcecodetype="cbor-diag">type="cbor-diag"><![CDATA[ [ / Inclusion proof 1 / 8, / Tree size / 7, / Leaf index / [ / Inclusion hashes (3) / h'c561d333...f9850597' / Intermediate hash 1 / h'75f177fd...2e73a8ab' / Intermediate hash 2 / h'0bdaaed3...32568964' / Intermediate hash 3 / ]] </sourcecode>]]]></sourcecode> </figure> <section anchor="validation"> <name>Validation</name> <t>Relying Parties <bcp14>MUST</bcp14> apply the verification process as described in Section <xref section="4.4"sectionFormat="of" target="STD96"/>,sectionFormat="bare" target="RFC9052"/> of RFC 9052 <xref target="STD96"/> when checking the signature of Signed Statements and Receipts.</t> <t>A Relying Party <bcp14>MUST</bcp14> trust the verification key or certificate and the associated identity of at least one Issuer of a Receipt.</t> <t>A Relying Party <bcp14>MAY</bcp14> decide to verify only a single Receipt that is acceptable to them and not check the signature on the Signed Statement or Receiptswhichthat rely on verifiable data structureswhichthey do not understand.</t> <t>APIs exposing verification logic for Transparent Statements may provide more details than a single boolean result. For example, an API may indicate if the signature on the Receipt or Signed Statement is valid, if Claims related to the validity period are valid, or if the inclusion proof in the Receipt is valid.</t> <t>Relying Parties <bcp14>MAY</bcp14> be configured to re-verify the Issuer's Signed Statement locally.</t> <t>In addition, Relying Parties <bcp14>MAY</bcp14> apply arbitrary validation policies after the Transparent Statement has been verified and validated. Such policies may use as input all information in the Envelope, the Receipt, and the Statement payload, as well as any local state.</t> </section> </section> <section anchor="sec-privacy-considerations"> <name>Privacy Considerations</name> <t>Interactions with Transparency Services are expected to use appropriately strong encryption and authorization technologies.</t> <t>The Transparency Service is trusted with the confidentiality of the Signed Statements presented for Registration. Issuers and Clients are responsible for verifying that the Transparency Service's privacy and security posture is suitable for the contents of the Signed Statements they submit prior to Registration. Issuers must carefully review the inclusion of private, confidential, orpersonally identifiable informationPersonally Identifiable Information (PII) in their Statements against the Transparency Service's privacy posture.</t> <t>In somedeploymentsdeployments, a special role such as an Auditor might require and be given access to both the Transparency Service and related Adjacent Services.</t><t>Transparency<!--[rfced] Please carefully review our edits to this text to ensure we have maintained your intended meaning. Original: Transparency Services can leverage Verifiable Data Structures which only retain cryptographic metadata (e.g. a hash), rather than the complete Signed Statement, as part of a defense in depth approach to maintaining confidentiality. Current: Transparency Services can leverage Verifiable Data Structures that only retain cryptographic metadata (e.g., a hash) rather than the complete Signed Statement as part of an in-depth defensive approach to maintaining confidentiality. --> <t>Transparency Services can leverage Verifiable Data Structures that only retain cryptographic metadata (e.g., a hash) rather than the complete Signed Statement as part of an in-depth defensive approach to maintaining confidentiality. By analyzing the relationship between data stored in the Transparency Service and data stored in Adjacent Services, it is possible to perform metadata analysis, which could reveal the order in which artifacts were built, signed, and uploaded.</t> </section> <section anchor="SecConSec"> <name>Security Considerations</name> <t>SCITT provides the following security guarantees:</t> <ol spacing="normal" type="1"> <li>Statements made by Issuers about supply chain Artifacts are identifiable and can beauthenticated</li>authenticated.</li> <li>Statement provenance and history can be independently and consistentlyaudited</li>audited.</li> <li>Issuers can efficiently prove that their Statement is logged by a TransparencyService</li>Service.</li> </ol> <t>The first guarantee is achieved by requiring Issuers to sign their Statements. The second guarantee is achieved by proving a Signed Statement is present in a Verifiable Data Structure. The third guarantee is achieved by the combination of both of these steps.</t> <t>In addition to deciding whether to trust a Transparency Service, Relying Parties can use the history of registered Signed Statements to decide which Issuers they choose to trust. This decision process is out of scope of this document.</t> <section anchor="sec-ordering-of-signed-statements"> <name>Ordering of Signed Statements</name> <t>Statements are signed prior to submitting to a SCITT Transparency service. Unless advertised in the Transparency Service Registration Policy, the Relying Party cannot assume that the ordering of Signed Statements in the Verifiable Data Structure matches the ordering of their issuance.</t> </section> <section anchor="sec-accuracy-of-statements"> <name>Accuracy of Statements</name> <t>Issuers can make false Statements either intentionally or unintentionally; registering a Statement only proves it was produced by an Issuer. A registered Statement may be superseded by a subsequently submitted Signed Statement from the same Issuer, with the same subject in the <tt>CWT Claims</tt> protected header. Other Issuers may make new Statements to reflect new or corrected information. Relying Parties may choose to include or exclude Statements from Issuers to determine the accuracy of a collection of Statements.</t> </section> <section anchor="sec-issuer-participation"> <name>Issuer Participation</name> <t>Issuers can refuse to register their Statements with a TransparencyService,Service or selectively submit some but not all the Statements they issue. It is important for Relying Parties not to accept Signed Statements for which they cannot discover Receipts issued by a Transparency Service they trust.</t> </section> <section anchor="sec-key-management"> <name>Key Management</name> <t>Issuers and Transparency Services <bcp14>MUST</bcp14>:</t> <ul spacing="normal"> <li>carefully protect their private signing keys</li> <li>avoid using keys for more than one purpose</li> <li>rotate their keys at a cryptoperiod (defined in <xref target="RFC4949"/>) appropriate for thekey algorithmkey-algorithm and domain-specific regulations</li> </ul> <section anchor="sec-verifiable-data-structure-1"> <name>Verifiable Data Structure</name> <t>The security considerations for specific Verifiable Data Structures are out of scope for this document. See <xreftarget="I-D.draft-ietf-cose-merkle-tree-proofs"/>target="RFC9942"/> for the generic security considerations that apply to Verifiable Data Structure and Receipts.</t> </section> <section anchor="sec-key-compromise"> <name>Key Compromise</name> <t>It is important for Issuers and Transparency Services to clearly communicate when keys arecompromised,compromised so that Signed Statements can be rejected by Transparency Services or Receipts can be ignored by Relying Parties. Transparency Services whose receipt signing keys have been compromised can roll back their Statement Sequence to a point before compromise, establish new credentials, and usethemthe new credentials to issue fresh Receipts going forward. Issuers are encouraged to follow existing best practices if their credentials are compromised. Revocation strategies for compromised keys are out of scope for this document.</t> </section> <section anchor="sec-bootstrapping"> <name>Bootstrapping</name> <t>Bootstrapping mechanisms that solely rely on Statement registration to set and update registration policy can be audited without additional implementation-specificknowledge, andknowledge; therefore, they arethereforepreferable. Mechanisms that rely onpre-configuredpreconfigured values and do not allow updates are unsuitable for use in long-lived servicedeployments,deployments in which the ability to patch a potentially faulty policy is essential.</t> </section> </section> <section anchor="MediaTypeSecConSec"> <name>Implications ofMedia-TypeMedia Type Usage</name> <t>The Statement (scitt-statement+cose) and Receipt (scitt-receipt+cose) media types describe the expected content of COSE envelope headers. The payload media type ('content type') is included in the COSE envelope header. <xref target="STD96"/> describes the security implications of reliance on this header parameter.</t> <t>Both media types describe COSE_Sign1 messages, which include asignature,signature and therefore provide integrity protection.</t> </section> <section anchor="sec-cryptographic-agility"> <name>Cryptographic Agility</name> <t>Because the SCITT Architecture leverages <xref target="STD96"/> for Statements and Receipts, it benefits from the format's cryptographic agility.</t> </section> <section anchor="sec-threat-model"> <name>Threat Model</name> <t>This section provides a generic threat model for SCITT, describing its residual security properties when some of its actors (Issuers, Transparency Services, and Auditors) are either corrupt or compromised.</t> <t>SCITT primarily supports checking of Signed Statement authenticity, both from the Issuer (authentication) and from the Transparency Service (transparency). Issuers and Transparency Services can both be compromised.</t> <t>The SCITT Architecture does not require trust in a single centralized Transparency Service. Different actors may rely on different Transparency Services, each registering a subset of Signed Statements subject to their own policy. Running multiple, independent Transparency Services provides different organizations to represent consistent or divergent opinions. It is the role of the relying party to decide which Transparency Services and Issuers they choose to trust for their scenario.</t> <t>In both cases, the SCITT architecture provides generic,universally-verifiableuniversally verifiable cryptographic proofs to hold Issuers or Transparency Services accountable. On one hand, this enables valid actors to detect and disambiguate malicious actors who employ Equivocation with Signed Statements to different entities. On the other hand, their liability and the resulting damage to their reputation are applicationspecific,specific and out of scope of the SCITT architecture.</t> <t>Relying Parties and Auditors need not be trusted by other actors. So long as actors maintain proper control of their signing keys and identity infrastructure they cannot "frame" an Issuer or a Transparency Service for Signed Statements they did not issue or register.</t> </section> </section> <!--[rfced] FYI - the RPC will communicate any changes to Sections 10.1 and 10.2 to IANA for them to update the following registries respectively to exactly match the document once AUTH48 completes. https://www.iana.org/assignments/media-types/application/scitt-statement+cose https://www.iana.org/assignments/media-types/application/scitt-receipt+cose, --> <section anchor="sec-iana-considerations"> <name>IANA Considerations</name> <t>IANAis requested to register:</t> <ul spacing="normal"> <li>the media type application/scitt-statement+cose inhas registered the"Media Types" registry, see below.</li> <li>thefollowing mediatype application/scitt-receipt+cosetypes in the"Media Types" registry, see below.</li> </ul> <section anchor="sec-media-type-applicationscitt-statementcose-registration"> <name>Media Type application/scitt-statement+cose Registration</name> <t>IANA is requested to add the following Media-Type to"application" subregistry of the "Media Types" registry group <xref target="IANA.media-types"/>:</t> <ul spacing="normal"> <li>application/scitt-statement+cose (see <xreftarget="IANA.media-types"/>.</t>target="sec-media-type-applicationscitt-statementcose-registration"/>)</li> <li>application/scitt-receipt+cose (see <xref target="sec-media-type-applicationscitt-receiptcose-registration"/>)</li> </ul> <section anchor="sec-media-type-applicationscitt-statementcose-registration"> <name>Registration of application/scitt-statement+cose</name> <table anchor="new-media-types-scitt-statement"> <name>SCITT Signed Statement Media Type Registration</name> <thead> <tr> <th align="left">Name</th> <th align="left">Template</th> <th align="left">Reference</th> </tr> </thead> <tbody> <tr> <td align="left">scitt-statement+cose</td> <td align="left">application/scitt-statement+cose</td> <td align="left"> <xref target="signed-statements"/> ofRFCthis</td>RFC 9943</td> </tr> </tbody> </table><dl spacing="compact"><dl> <dt>Type name:</dt> <dd> <t>application</t> </dd> <dt>Subtype name:</dt> <dd> <t>statement+cose</t> </dd> <dt>Required parameters:</dt> <dd><t>n/a</t><t>N/A</t> </dd> <dt>Optional parameters:</dt> <dd><t>n/a</t><t>N/A</t> </dd> <dt>Encoding considerations:</dt> <dd> <t>binary (CBOR data item)</t> </dd> <dt>Security considerations:</dt> <dd> <t><xref target="MediaTypeSecConSec"/> ofRFCthis</t>RFC 9943</t> </dd> <dt>Interoperability considerations:</dt> <dd> <t>none</t> </dd> <dt>Published specification:</dt> <dd><t>RFCthis</t><t>RFC 9943</t> </dd> <dt>Applications that use this media type:</dt> <dd> <t>Used to provide an identifiable and non-repudiable Statement about an Artifact signed by an Issuer.</t> </dd> <dt>Fragment identifier considerations:</dt> <dd><t>n/a</t><t>N/A</t> </dd> <dt>Additional information:</dt><dd> <dl><dd><t><br/></t> <dl spacing="compact"> <dt>Deprecated alias names for this type:</dt> <dd> <t>N/A</t> </dd> <dt>Magic number(s):</dt> <dd> <t>N/A</t> </dd> <dt>File extension(s):</dt> <dd> <t>.scitt</t> </dd> <dt>Macintosh file type code(s):</dt> <dd> <t>N/A</t> </dd> </dl> </dd> <dt>Personand& email address to contact for further information:</dt> <dd><t>iesg@ietf.org</t>iesg@ietf.org </dd> <dt>Intended usage:</dt> <dd> <t>COMMON</t> </dd> <dt>Restrictions on usage:</dt> <dd> <t>none</t> </dd> <dt>Author/Change controller:</dt> <dd> <t>IETF</t> </dd> </dl> </section> <section anchor="sec-media-type-applicationscitt-receiptcose-registration"><name>Media Type<name>Registration of application/scitt-receipt+cose Registration</name> <table anchor="new-media-types-receipt"> <name>SCITT Receipt Media Type Registration</name> <thead> <tr> <th align="left">Name</th> <th align="left">Template</th> <th align="left">Reference</th> </tr> </thead> <tbody> <tr> <td align="left">scitt-receipt+cose</td> <td align="left">application/scitt-receipt+cose</td> <td align="left"> <xref target="Receipt"/> ofRFCthis</td>RFC 9943</td> </tr> </tbody> </table><dl spacing="compact"><dl> <dt>Type name:</dt> <dd> <t>application</t> </dd> <dt>Subtype name:</dt> <dd> <t>receipt+cose</t> </dd> <dt>Required parameters:</dt> <dd><t>n/a</t><t>N/A</t> </dd> <dt>Optional parameters:</dt> <dd><t>n/a</t><t>N/A</t> </dd> <dt>Encoding considerations:</dt> <dd> <t>binary (CBOR data item)</t> </dd> <dt>Security considerations:</dt> <dd> <t><xref target="MediaTypeSecConSec"/> ofRFCthis</t>RFC 9943</t> </dd> <dt>Interoperability considerations:</dt> <dd> <t>none</t> </dd> <dt>Published specification:</dt> <dd><t>RFCthis</t><t>RFC 9943</t> </dd> <dt>Applications that use this media type:</dt> <dd> <t>Used to establish or verify transparency over Statements. Typically emitted by a TransparencyService,Service for the benefit of Relying Parties wanting to ensure Non-equivocation over all or part of a Statement Sequence.</t> </dd> <dt>Fragment identifier considerations:</dt> <dd><t>n/a</t><t>N/A</t> </dd> <dt>Additional information:</dt><dd> <dl><dd><t><br/></t> <dl spacing="compact"> <dt>Deprecated alias names for this type:</dt> <dd> <t>N/A</t> </dd> <dt>Magic number(s):</dt> <dd> <t>N/A</t> </dd> <dt>File extension(s):</dt> <dd> <t>.receipt</t> </dd> <dt>Macintosh file type code(s):</dt> <dd> <t>N/A</t> </dd> </dl> </dd> <dt>Personand& email address to contact for further information:</dt> <dd><t>iesg@ietf.org</t>iesg@ietf.org </dd> <dt>Intended usage:</dt> <dd> <t>COMMON</t> </dd> <dt>Restrictions on usage:</dt> <dd> <t>none</t> </dd> <dt>Author/Change controller:</dt> <dd> <t>IETF</t> </dd> </dl> </section> <section anchor="sec-coap-content-format-registrations"> <name>CoAP Content-Format Registrations</name> <t>IANAis requested to registerhas registered the following Content-Format numbers in the "CoAP Content-Formats"sub-registry,subregistry within the "Constrained RESTful Environments (CoRE) Parameters"Registryregistry group <xref target="IANA.core-parameters"/> in the 256-9999Range:</t>range:</t> <table anchor="new-content-formats"> <name>SCITT Content-Formats Registration</name> <thead> <tr> <thalign="left">Content-Type</th>align="left">Content Type</th> <th align="left">Content Coding</th> <th align="left">ID</th> <th align="left">Reference</th> </tr> </thead> <tbody> <tr> <td align="left">application/scitt-statement+cose</td> <td align="left">-</td> <td align="left">277</td> <tdalign="left">RFCthis</td>align="left">RFC 9943</td> </tr> <tr> <td align="left">application/scitt-receipt+cose</td> <td align="left">-</td> <td align="left">278</td> <tdalign="left">RFCthis</td>align="left">RFC 9943</td> </tr> </tbody> </table> </section> </section> </middle> <back> <displayreference target="RFC9393" to="CoSWID"/> <references anchor="sec-combined-references"> <name>References</name> <references anchor="sec-normative-references"> <name>Normative References</name><reference anchor="RFC6838"> <front> <title>Media Type Specifications and Registration Procedures</title> <seriesInfo name="DOI" value="10.17487/RFC6838"/> <seriesInfo name="RFC" value="6838"/> <seriesInfo name="BCP" value="13"/> <author fullname="N. Freed" initials="N." surname="Freed"/> <author fullname="J. Klensin" initials="J." surname="Klensin"/> <author fullname="T. Hansen" initials="T." surname="Hansen"/> <date month="January" year="2013"/> <abstract> <t>This document defines procedures for the specification and registration of media types for use in HTTP, MIME, and other Internet protocols. This memo documents an Internet Best Current Practice.</t> </abstract> </front> </reference> <reference anchor="RFC8392"> <front> <title>CBOR Web Token (CWT)</title> <seriesInfo name="DOI" value="10.17487/RFC8392"/> <seriesInfo name="RFC" value="8392"/> <author fullname="M. Jones" initials="M." surname="Jones"/> <author fullname="E. Wahlstroem" initials="E." surname="Wahlstroem"/> <author fullname="S. Erdtman" initials="S." surname="Erdtman"/> <author fullname="H. Tschofenig" initials="H." surname="Tschofenig"/> <date month="May" year="2018"/> <abstract> <t>CBOR Web Token (CWT) is a compact means of representing claims to be transferred between two parties. The claims in a CWT are encoded in the Concise Binary Object Representation (CBOR), and CBOR Object Signing and Encryption (COSE) is used for added application-layer security protection. A claim is a piece of information asserted about a subject and is represented as a name/value pair consisting of a claim name and a claim value. CWT is derived from JSON Web Token (JWT) but uses CBOR rather than JSON.</t> </abstract> </front> </reference> <reference anchor="RFC8610"> <front> <title>Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures</title> <seriesInfo name="DOI" value="10.17487/RFC8610"/> <seriesInfo name="RFC" value="8610"/> <author fullname="H. Birkholz" initials="H." surname="Birkholz"/> <author fullname="C. Vigano" initials="C." surname="Vigano"/> <author fullname="C. Bormann" initials="C." surname="Bormann"/> <date month="June" year="2019"/> <abstract> <t>This document proposes a notational convention to express Concise Binary Object Representation (CBOR) data structures (RFC 7049). Its main goal is to provide an easy and unambiguous way to express structures for protocol messages and data formats that use CBOR or JSON.</t> </abstract> </front> </reference> <reference anchor="STD94"> <front> <title>Concise Binary Object Representation (CBOR)</title> <seriesInfo name="DOI" value="10.17487/RFC8949"/> <seriesInfo name="RFC" value="8949"/> <seriesInfo name="STD" value="94"/> <author fullname="C. Bormann" initials="C." surname="Bormann"/> <author fullname="P. Hoffman" initials="P." surname="Hoffman"/> <date month="December" year="2020"/> <abstract> <t>The Concise Binary Object Representation (CBOR) is a data format whose design goals include the possibility of extremely small code size, fairly small message size, and extensibility without the need for version negotiation. These design goals make it different from earlier binary serializations such as ASN.1 and MessagePack.</t> <t>This document obsoletes RFC 7049, providing editorial improvements, new details, and errata fixes while keeping full compatibility with the interchange format of RFC 7049. It does not create a new version of the format.</t> </abstract> </front> </reference> <reference anchor="STD96"> <front> <title>CBOR Object Signing and Encryption (COSE): Structures and Process</title> <seriesInfo name="DOI" value="10.17487/RFC9052"/> <seriesInfo name="RFC" value="9052"/> <seriesInfo name="STD" value="96"/> <author fullname="J. Schaad" initials="J." surname="Schaad"/> <date month="August" year="2022"/> <abstract> <t>Concise Binary Object Representation (CBOR) is a data format designed for small code size and small message size. There is a need to be able to define basic security services for this data format. This document defines the CBOR Object Signing and Encryption (COSE) protocol. This specification describes how to create and process signatures, message authentication codes, and encryption using CBOR for serialization. This specification additionally describes how to represent cryptographic keys using CBOR.</t> <t>This document, along with RFC 9053, obsoletes<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.6838.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8392.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8610.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml9/reference.STD.94.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml9/reference.STD.96.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9360.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9597.xml"/> <!-- [RFC9942] draft-ietf-cose-merkle-tree-proofs-18 companion doc RFC8152.</t> </abstract> </front> </reference> <reference anchor="RFC9360"> <front> <title>CBOR Object Signing and Encryption (COSE): Header Parameters for Carrying and Referencing X.509 Certificates</title> <seriesInfo name="DOI" value="10.17487/RFC9360"/> <seriesInfo name="RFC" value="9360"/> <author fullname="J. Schaad" initials="J." surname="Schaad"/> <date month="February" year="2023"/> <abstract> <t>The CBOR Object Signing and Encryption (COSE) message structure uses references to keys in general. For some algorithms, additional properties are defined that carry parameters relating to keys as needed. The COSE Key structure is used for transporting keys outside of COSE messages. This document extends the way that keys can be identified and transported by providing attributes that refer to or contain X.509 certificates.</t> </abstract> </front> </reference>9942 --> <referenceanchor="RFC9597">anchor="RFC9942" target="https://www.rfc-editor.org/info/rfc9942"> <front> <title>CBORWeb Token (CWT) Claims in COSE Headers</title> <seriesInfo name="DOI" value="10.17487/RFC9597"/> <seriesInfo name="RFC" value="9597"/> <author fullname="T. Looker" initials="T." surname="Looker"/> <author fullname="M.B. Jones" initials="M.B." surname="Jones"/> <date month="June" year="2024"/> <abstract> <t>This document describes how to include CBOR Web Token (CWT) claims in the header parameters of any CBORObject Signing and Encryption (COSE)structure. This functionality helps to facilitate applications that wish to make use of CWT claims in encrypted COSE structures and/or COSE structures featuring detached signatures, while having some of those claims be available before decryption and/or without inspecting the detached payload. Another use case is using CWT claims with payloads that are not CWT Claims Sets, including payloads that are not CBOR at all.</t> </abstract> </front> </reference> <reference anchor="I-D.draft-ietf-cose-merkle-tree-proofs"> <front> <title>COSE (CBOR Object Signing and Encryption)Receipts</title><seriesInfo name="Internet-Draft" value="draft-ietf-cose-merkle-tree-proofs-17"/><authorfullname="Orie Steele"initials="O."surname="Steele">surname="Steele" fullname="Orie Steele"> <organization>Tradeverifyd</organization> </author> <authorfullname="Henk Birkholz"initials="H."surname="Birkholz">surname="Birkholz" fullname="Henk Birkholz"> <organization>Fraunhofer SIT</organization> </author> <authorfullname="Antoine Delignat-Lavaud"initials="A."surname="Delignat-Lavaud">surname="Delignat-Lavaud" fullname="Antoine Delignat-Lavaud"> <organization>Microsoft</organization> </author> <authorfullname="Cedric Fournet"initials="C."surname="Fournet">surname="Fournet" fullname="Cedric Fournet"> <organization>Microsoft</organization> </author> <dateday="10" month="September" year="2025"/> <abstract> <t> COSE (CBOR Object Signing and Encryption) Receipts prove properties of a verifiable data structure to a verifier. Verifiable data structures and associated proof types enable security properties, such as minimal disclosure, transparency and non-equivocation. Transparency helps maintain trust over time, and has been applied to certificates, end to end encrypted messaging systems, and supply chain security. This specification enables concise transparency oriented systems, by building on CBOR (Concise Binary Object Representation) and COSE. The extensibility of the approach is demonstrated by providing CBOR encodings for Merkle inclusion and consistency proofs. </t> </abstract>month='March' year='2026'/> </front> <seriesInfo name="RFC" value="9942"/> <seriesInfo name="DOI" value="10.17487/RFC9942"/> </reference> <reference anchor="IANA.cwt" target="https://www.iana.org/assignments/cwt"> <front> <title>CBOR Web Token (CWT) Claims</title> <author> <organization>IANA</organization> </author> </front> </reference><reference anchor="RFC2119"> <front> <title>Key words for use in RFCs to Indicate Requirement Levels</title> <seriesInfo name="DOI" value="10.17487/RFC2119"/> <seriesInfo name="RFC" value="2119"/> <seriesInfo name="BCP" value="14"/> <author fullname="S. Bradner" initials="S." surname="Bradner"/> <date month="March" year="1997"/> <abstract> <t>In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.</t> </abstract> </front> </reference> <reference anchor="RFC8174"> <front> <title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title> <seriesInfo name="DOI" value="10.17487/RFC8174"/> <seriesInfo name="RFC" value="8174"/> <seriesInfo name="BCP" value="14"/> <author fullname="B. Leiba" initials="B." surname="Leiba"/> <date month="May" year="2017"/> <abstract> <t>RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.</t> </abstract> </front> </reference><xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/> <reference anchor="IANA.media-types" target="https://www.iana.org/assignments/media-types"> <front> <title>Media Types</title> <author> <organization>IANA</organization> </author> </front> </reference> <reference anchor="IANA.core-parameters" target="https://www.iana.org/assignments/core-parameters"> <front> <title>Constrained RESTful Environments (CoRE) Parameters</title> <author> <organization>IANA</organization> </author> </front> </reference> </references> <references anchor="sec-informative-references"> <name>Informative References</name> <reference anchor="NIST.SP.1800-19" target="https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.1800-19.pdf"> <front> <title>Trustedcloud :security practice guidecloud: Security Practice Guide for VMwarehybrid cloud infrastructureHybrid Cloud Infrastructure as aserviceService (IaaS)environments</title> <seriesInfo name="DOI" value="10.6028/NIST.SP.1800-19"/> <seriesInfo name="NIST Special Publications (General)" value="1800-19"/>Environments</title> <author fullname="Michael Bartock" surname="Bartock"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Donna Dodson" surname="Dodson"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Murugiah Souppaya" surname="Souppaya"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Daniel Carroll" surname="Carroll"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Robert Masten" surname="Masten"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Gina Scinta" surname="Scinta"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Paul Massis" surname="Massis"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Hemma Prafullchandra" surname="Prafullchandra"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Jason Malnar" surname="Malnar"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Harmeet Singh" surname="Singh"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Rajeev Ghandi" surname="Ghandi"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Laura E Storey" surname="Storey"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Raghuram Yeluri" surname="Yeluri"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Tim Shea" surname="Shea"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Michael Dalton" surname="Dalton"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Rocky Weber" surname="Weber"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Karen Scarfone" surname="Scarfone"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Anthony Dukes" surname="Dukes"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Jeff Haskins" surname="Haskins"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Carlos Phoenix" surname="Phoenix"> <organization>Information Technology Laboratory</organization> </author> <author fullname="Brenda Swarts" surname="Swarts"> <organization>Information Technology Laboratory</organization> </author><author> <organization>National Institute of Standards and Technology (U.S.)</organization> <address> <postal> <country>US</country> <city>Gaithersburg</city> </postal> </address> </author><date day="20" month="April" year="2022"/><abstract> <t>A cloud workload is an abstraction of the actual instance of a functional application that is virtualized or containerized to include compute, storage, and network resources. Organizations need to be able to monitor, track, apply, and enforce their security and privacy policies on their cloud workloads, based on business requirements, in a consistent, repeatable, and automated way. The goal of this project is to develop a trusted cloud solution that will demonstrate how trusted compute pools leveraging hardware roots of trust can provide the necessary security capabilities. These capabilities not only provide assurance that cloud workloads are running on trusted hardware and in a trusted geolocation or logical boundary, but also improve the protections for the data in the workloads and in the data flows between workloads. The example solution leverages modern commercial off-the-shelf technology and cloud services to address lifting and shifting a typical multi-tier application between an organization-controlled private cloud and a hybrid/public cloud over the internet.</t> </abstract></front> <seriesInfo name="DOI" value="10.6028/NIST.SP.1800-19"/> <seriesInfo name="NIST SP" value="1800-19"/> </reference> <reference anchor="NIST.SP.800-204C" target="https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-204C.pdf"> <front> <title>Implementation of DevSecOps for amicroservices-based applicationMicroservices-based Application withservice mesh</title>Service Mesh</title> <seriesInfo name="DOI" value="10.6028/NIST.SP.800-204C"/> <seriesInfo name="NIST Special Publications (General)" value="800-204C"/> <author fullname="Ramaswamy Chandramouli" surname="Chandramouli"> <organization>Information Technology Laboratory</organization> </author><author> <organization>National Institute of Standards and Technology (U.S.)</organization> <address> <postal> <country>US</country> <city>Gaithersburg</city> </postal> </address> </author><dateday="8"month="March" year="2022"/><abstract> <t>Cloud-native applications have evolved into a standardized architecture consisting of multiple loosely coupled components called microservices (often typically implemented as containers) that are supported by an infrastructure for providing application services, such as service mesh. Both of these components are usually hosted on a container orchestration and resource management platform. In this architecture, the entire set of source code involved in the application environment can be divided into five code types: 1) application code (which embodies the application logic), 2) application services code (for services such as session establishment, network connection, etc.), 3) infrastructure as code (for provisioning and configuring computing, networking, and storage resources), 4) policy as code (for defining runtime policies such as zero trust expressed as a declarative code), 5) and observability as code (for the continuous monitoring of an application runtime state). Due to security, business competitiveness, and the inherent structure of loosely coupled application components, this class of applications needs a different development, deployment, and runtime paradigm. DevSecOps (consisting of acronyms for Development, Security, and Operations, respectively) has been found to be a facilitating paradigm for these applications with primitives such as continuous integration, continuous delivery, and continuous deployment (CI/CD) pipelines. These pipelines are workflows for taking the developer s source code through various stages, such as building, testing, packaging, deployment, and operations supported by automated tools with feedback mechanisms. The objective of this document is to provide guidance for the implementation of DevSecOps primitives for cloud-native applications with the architecture and code types described above. The benefits of this approach for high security assurance and for enabling continuous authority to operate (C-ATO) are also discussed.</t> </abstract></front> <seriesInfo name="NIST SP" value="800-204C"/> <seriesInfo name="DOI" value="10.6028/NIST.SP.800-204C"/> </reference> <reference anchor="NIST_EO14028" target="https://www.nist.gov/system/files/documents/2022/02/04/software-supply-chain-security-guidance-under-EO-14028-section-4e.pdf"> <front> <title>Software Supply Chain Security Guidance Under Executive Order (EO) 14028 Section 4e</title> <author><organization/><organization>NIST</organization> </author> <date year="2022" month="February" day="04"/> </front> </reference><reference anchor="RFC4949"> <front> <title>Internet Security Glossary, Version 2</title> <seriesInfo name="DOI" value="10.17487/RFC4949"/> <seriesInfo name="RFC" value="4949"/> <seriesInfo name="FYI" value="36"/> <author fullname="R. Shirey" initials="R." surname="Shirey"/> <date month="August" year="2007"/> <abstract> <t>This Glossary provides definitions, abbreviations, and explanations of terminology for information system security. The 334 pages of entries offer recommendations to improve the comprehensibility of written material that is generated in the Internet Standards Process (RFC 2026). The recommendations follow the principles that such writing should (a) use the same term or definition whenever the same concept is mentioned; (b) use terms in their plainest, dictionary sense; (c) use terms that are already well-established in open publications; and (d) avoid terms that either favor a particular vendor or favor a particular technology or mechanism over other, competing techniques that already exist or could be developed. This memo provides information for the Internet community.</t> </abstract> </front> </reference> <reference anchor="RFC8725"> <front> <title>JSON Web Token Best Current Practices</title> <seriesInfo name="DOI" value="10.17487/RFC8725"/> <seriesInfo name="RFC" value="8725"/> <seriesInfo name="BCP" value="225"/> <author fullname="Y. Sheffer" initials="Y." surname="Sheffer"/> <author fullname="D. Hardt" initials="D." surname="Hardt"/> <author fullname="M. Jones" initials="M." surname="Jones"/> <date month="February" year="2020"/> <abstract> <t>JSON Web Tokens, also known as JWTs, are URL-safe JSON-based security tokens that contain a set of claims that can be signed and/or encrypted. JWTs are being widely used and deployed as a simple security token format in numerous protocols and applications, both in the area of digital identity and in other application areas. This Best Current Practices document updates RFC 7519 to provide actionable guidance leading to secure implementation and deployment of JWTs.</t> </abstract> </front> </reference> <reference anchor="RFC9162"> <front> <title>Certificate Transparency Version 2.0</title> <seriesInfo name="DOI" value="10.17487/RFC9162"/> <seriesInfo name="RFC" value="9162"/> <author fullname="B. Laurie" initials="B." surname="Laurie"/> <author fullname="E. Messeri" initials="E." surname="Messeri"/> <author fullname="R. Stradling" initials="R." surname="Stradling"/> <date month="December" year="2021"/> <abstract> <t>This document describes version 2.0 of the Certificate Transparency (CT) protocol for publicly logging the existence of Transport Layer Security (TLS) server certificates as they are issued or observed, in a manner that allows anyone to audit certification authority (CA) activity and notice the issuance of suspect certificates as well as to audit the certificate logs themselves. The intent is that eventually clients would refuse to honor certificates that do not appear in a log, effectively forcing CAs to add all issued certificates to the logs.</t> <t>This document obsoletes RFC 6962. It also specifies a new TLS extension that is used to send various CT log artifacts.</t> <t>Logs are network services that implement the protocol operations for submissions and queries that are defined in this document.</t> </abstract> </front> </reference> <reference anchor="CoSWID"> <front> <title>Concise Software Identification Tags</title> <seriesInfo name="DOI" value="10.17487/RFC9393"/> <seriesInfo name="RFC" value="9393"/> <author fullname="H. Birkholz" initials="H." surname="Birkholz"/> <author fullname="J. Fitzgerald-McKay" initials="J." surname="Fitzgerald-McKay"/> <author fullname="C. Schmidt" initials="C." surname="Schmidt"/> <author fullname="D. Waltermire" initials="D." surname="Waltermire"/> <date month="June" year="2023"/> <abstract> <t>ISO/IEC 19770-2:2015 Software Identification (SWID) tags provide an extensible XML-based structure to identify and describe individual software components, patches, and installation bundles. SWID tag representations can be too large for devices with network and storage constraints. This document defines a concise representation of SWID tags: Concise SWID (CoSWID) tags. CoSWID supports a set of semantics and features that are similar to those for SWID tags, as well as new semantics that allow CoSWIDs to describe additional types of information, all in a more memory-efficient format.</t> </abstract> </front> </reference><xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.4949.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.8725.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9162.xml"/> <xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9393.xml"/> <reference anchor="CycloneDX" target="https://cyclonedx.org/specification/overview/"> <front> <title>CycloneDX</title> <author> <organization/> </author><date>n.d.</date></front> </reference> <reference anchor="in-toto" target="https://in-toto.io/"> <front> <title>in-toto</title> <author> <organization/> </author><date>n.d.</date></front> </reference> <reference anchor="SLSA" target="https://slsa.dev/"> <front> <title>SLSA</title> <author> <organization/> </author><date>n.d.</date></front> </reference> <!-- [rfced] The reference entries for [SPDX-CBOR] and [SPDX-JSON] are identical. Should these references be condensed down into one reference? Or are these references meant to point to specific parts of the SPDX Specification? Current: [SPDX-CBOR] "SPDX Specification", <https://spdx.dev/use/specifications/>. [SPDX-JSON] "SPDX Specification", <https://spdx.dev/use/specifications/>. --> <reference anchor="SPDX-CBOR" target="https://spdx.dev/use/specifications/"> <front> <title>SPDX Specification</title> <author> <organization/> </author><date>n.d.</date></front> </reference> <reference anchor="SPDX-JSON" target="https://spdx.dev/use/specifications/"> <front> <title>SPDX Specification</title> <author> <organization/> </author><date>n.d.</date></front> </reference> <reference anchor="SWID" target="https://csrc.nist.gov/Projects/Software-Identification-SWID/guidelines"> <front> <title>SWID Specification</title> <author><organization/><organization>NIST</organization> </author><date>n.d.</date></front> </reference> <reference anchor="EQUIVOCATION" target="https://www.read.seas.harvard.edu/~kohler/class/08w-dsi/chun07attested.pdf"> <front> <title>Attested Append-Only Memory: Making Adversaries Stick to their Word</title> <author fullname="Byung-Gon Chun"/> <author fullname="Petros Maniatis"/> <author fullname="Scott Shenker"/> <author fullname="John Kubiatowicz"/> <date day="14" month="October" year="2007"/> </front> <refcontent>ACM SIGOPS Operating Systems Review, vol. 41, no. 6, pp. 189-204</refcontent> <seriesInfo name="DOI" value="10.1145/1323293.1294280"/><author> <organization/> </author> <date>n.d.</date> </front></reference> </references> </references> <section anchor="contributors" numbered="false" toc="include" removeInRFC="false"> <name>Contributors</name> <contact initials="O." surname="Steele" fullname="Orie Steele"> <organization>Tradeverifyd</organization> <address> <postal> <country>UnitedStates</country>States of America</country> </postal> <email>orie@or13.io</email> </address> </contact> <t>Orie contributed to improving the generalization of COSE building blocks and document consistency.</t> <contact initials="A." surname="Chamayou" fullname="Amaury Chamayou"> <organization>Microsoft</organization> <address> <postal> <country>United Kingdom</country> </postal> <email>amaury.chamayou@microsoft.com</email> </address> </contact> <t>Amaury contributed elemental parts to finalize normative language on registration behavior and the single-issuer design, as well as overall document consistency</t> <contact initials="D." surname="Brooks" fullname="Dick Brooks"> <organization>Business CyberGuardian (TM)</organization>Guardian</organization> <address> <postal> <country>UnitedStates</country>States of America</country> </postal> <email>dick@businesscyberguardian.com</email> </address> </contact> <t>Dick contributed to the software supply chain use cases.</t> <contact initials="B." surname="Knight" fullname="Brian Knight"> <organization>Microsoft</organization> <address> <postal> <country>UnitedStates</country>States of America</country> </postal> <email>brianknight@microsoft.com</email> </address> </contact> <t>Brian contributed to the software supply chain use cases.</t> <contact initials="R. A." surname="Martin" fullname="Robert Martin"> <organization>MITRE Corporation</organization> <address> <postal> <country>UnitedStates</country>States of America</country> </postal> <email>ramartin@mitre.org</email> </address> </contact> <t>Robert contributed to the software supply chain use cases.</t> </section></back><!--[rfced] We had the following questions/comments related to abbreviation use throughout the document: a) FYI - We have added expansions for abbreviations upon first use per Section 3.6 of RFC 7322 ("RFC Style Guide"). Please review each expansion in the document carefully to ensure correctness. b) FYI - We have updated to use an abbreviation (instead of its expanded form) after first use in accordance with the guidance at https://www.rfc-editor.org/styleguide/part2/#exp_abbrev. Please let us know any objections. c) Does TS refer to Transparency Service, Transparent Statement, or something else? After first use, we suggest using TS as described in (b) above. d) This document uses both: verifiable data structure proofs and Verifiable Data Structure Proofs We will capitalize on first use and introduce the VDP abbreviation as was used in draft-ietf-cose-merkle-tree-proofs-18 for use thereafter unless we hear objection. e) As one of the T's in SCITT stands for transparency, is "SCITT transparency" redundant? Original: This "content-agnostic" approach allows SCITT transparency services... --> <!--[rfced] We had the following questions related to terminology use throughout the document (see also our cluster-wide terminology questions that impact terms used in both documents in C557): a) As the large majority of instances appear as shown on the right, we will update to use that form consistently throughout the body of the text unless we hear objection: SCITT Architecture vs. SCITT architecture x.509 vs. X.509 b) Should the following terms be made consistent throughout? If so, please let us know the preferred form: Mandatory Registration Checks vs. mandatory Registration checks c) We see that this document uses the term "proof type". This term is defined in draft-ietf-cose-merkle-tree-proofs-18. Should there be any type of citation pointing the reader to the Terminology section of that document for more information? d) Most instances of "iss" refer to it as a Claim. Should these sentences be updated as follow? Original: When x5t or x5chain is present in the protected header, iss MUST be a string that meets URI requirements defined in [RFC8392]. The iss value's length MUST be between 1 and 8192 characters in length. Perhaps: When x5t or x5chain is present in the protected header, the iss Claim MUST be a string that meets URI requirements defined in [RFC8392]. The iss Claim value's length MUST be between 1 and 8192 characters in length. e) We note that Section 2.2.3 uses both "integrated software" and "Software Integration". Please review if these should be made consistent and if capitalization is necessary. f) We see the following various treatment for media type names (with respect to quotation marks, parentheses, word ordering, etc.): ('content type') media type (scitt-receipt+cose) media type media type application/scitt-receipt+cose media type application/scitt-statement+cose May we make these consistent? g) Should the iss Claims mentioned in the first sentence below be in quotation marks to match the quotations used for the sub Claim in the second sentence below? Original: Multi-tenant support can be enabled through the use of identifiers in the iss Claim, for example, ts.example. may have a distinct Issuer identity for each sub domain, such as tenant1.ts.example. and tenant2.ts.example.. Original: It indicates the Signed Statement is securing a JSON content type, and identifying the content with the sub Claim "vendor.product.example". --> <!-- [rfced] See a list below of terms enclosed in <tt> in this document. We note that some of the terms enclosed in <tt> appear elsewhere in the document without <tt> (e.g., payload, receipts). <tt>-111</tt> <tt>15: CWT Claims</tt> <tt>15</tt> <tt>-1</tt> <tt>1</tt> <tt>-2</tt> <tt>3</tt> <tt>8</tt> <tt>CWT Claims</tt> <tt>iss</tt> Claim <tt>Issuer Claim</tt> <tt>kid</tt> <tt>payload</tt> <tt>receipts</tt> <tt>Subject Claim</tt> <tt>sub</tt> CWT Claim <tt>tenant1.ts.example.</tt> <tt>tenant2.ts.example.</tt> <tt>ts.example.</tt> <tt>x5chain</tt> <tt>x5t</tt> Please review to ensure the usage of <tt> is correct and consistent. 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Updates of this nature typically result in more precise language, which is helpful for readers. Note that our script did not flag any words in particular, but this should still be reviewed as a best practice. --> </back> </rfc>