Verifiable AI Refusal Events using SCITT
draft-kamimura-scitt-refusal-events-02
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | TOKACHI KAMIMURA | ||
| Last updated | 2026-01-29 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
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| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
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draft-kamimura-scitt-refusal-events-02
Supply Chain Integrity, Transparency, and Trust T. Kamimura
Internet-Draft VeritasChain Standards Organization
Intended status: Informational 30 January 2026
Expires: 3 August 2026
Verifiable AI Refusal Events using SCITT
draft-kamimura-scitt-refusal-events-02
Abstract
This document defines a claim set for recording AI content refusal
events. The claim set specifies the semantic content and correlation
rules for refusal audit trails, independent of any particular
serialization format. The claims are designed to be carried within
SCITT Signed Statements and verified using SCITT Receipts.
This specification addresses claim semantics and verification
requirements; it does not mandate a specific encoding. A CDDL
definition is provided for CBOR-based implementations, and equivalent
JSON representations are shown in an appendix for illustration.
This specification provides auditability of logged refusal decisions.
It does not define content moderation policies, classification
criteria, or what AI systems should refuse.
About This Document
This note is to be removed before publishing as an RFC.
The latest version of this document, along with implementation
resources and examples, can be found at
<https://github.com/veritaschain/cap-spec>.
Discussion of this document takes place on the SCITT Working Group
mailing list (scitt@ietf.org).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 3 August 2026.
Copyright Notice
Copyright (c) 2026 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Motivation . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3. Limitations . . . . . . . . . . . . . . . . . . . . . . . 5
1.4. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Mapping to SCITT . . . . . . . . . . . . . . . . . . . . 6
3. Claim Set Definition . . . . . . . . . . . . . . . . . . . . 6
3.1. Common Claims . . . . . . . . . . . . . . . . . . . . . . 6
3.2. ATTEMPT Claims . . . . . . . . . . . . . . . . . . . . . 7
3.3. DENY Claims . . . . . . . . . . . . . . . . . . . . . . . 7
3.4. GENERATE Claims . . . . . . . . . . . . . . . . . . . . . 8
3.5. ERROR Claims . . . . . . . . . . . . . . . . . . . . . . 8
3.6. Completeness Invariant . . . . . . . . . . . . . . . . . 8
3.7. Timing Requirements . . . . . . . . . . . . . . . . . . . 9
4. CDDL Definition . . . . . . . . . . . . . . . . . . . . . . . 9
5. SCITT Integration . . . . . . . . . . . . . . . . . . . . . . 11
5.1. Encoding as Signed Statements . . . . . . . . . . . . . . 11
5.2. Registration . . . . . . . . . . . . . . . . . . . . . . 11
5.3. Verification . . . . . . . . . . . . . . . . . . . . . . 12
5.4. Registration Policy Considerations . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7.1. Threat Model . . . . . . . . . . . . . . . . . . . . . . 13
7.2. Omission Attacks . . . . . . . . . . . . . . . . . . . . 13
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7.3. Log Equivocation . . . . . . . . . . . . . . . . . . . . 13
7.4. Replay Attacks . . . . . . . . . . . . . . . . . . . . . 14
7.5. Dictionary Attacks on Hashes . . . . . . . . . . . . . . 14
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 14
8.1. Harmful Content . . . . . . . . . . . . . . . . . . . . . 14
8.2. Actor Privacy . . . . . . . . . . . . . . . . . . . . . . 14
8.3. Correlation Risks . . . . . . . . . . . . . . . . . . . . 15
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. Risk Category Taxonomy (Non-Normative) . . . . . . . 16
Appendix B. Deployment Considerations (Non-Normative) . . . . . 17
B.1. Basic Deployment . . . . . . . . . . . . . . . . . . . . 17
B.2. Regulated Deployment . . . . . . . . . . . . . . . . . . 18
B.3. High-Assurance Deployment . . . . . . . . . . . . . . . . 18
Appendix C. JSON Representation Example (Non-Normative) . . . . 18
C.1. ATTEMPT Example . . . . . . . . . . . . . . . . . . . . . 18
C.2. DENY Example . . . . . . . . . . . . . . . . . . . . . . 19
Appendix D. Evidence Pack Format (Non-Normative) . . . . . . . . 19
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 20
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
AI systems capable of generating content increasingly implement
safety mechanisms to refuse requests deemed harmful, illegal, or
policy-violating. However, these refusal decisions typically leave
no verifiable audit trail. When a system refuses to generate
content, the event vanishes—there is no receipt, no log entry
accessible to external parties, and no mechanism for third-party
verification.
This document defines a claim set for recording such refusal events.
The claim set specifies:
* The semantic meaning of each claim
* Correlation rules linking attempts to outcomes
* A completeness invariant for audit trail integrity
* Privacy-preserving approaches using cryptographic hashes
The claims are designed to be carried within SCITT Signed Statements
[I-D.ietf-scitt-architecture] and verified using SCITT Receipts.
This document does not mandate a specific serialization;
implementations may use CBOR, JSON, or other formats as appropriate
for their deployment context.
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1.1. Motivation
The January 2026 Grok incident demonstrated the need for verifiable
refusal records. The AI system generated millions of harmful images
while the provider claimed moderation systems were functioning.
External parties had no mechanism to verify whether refusals actually
occurred or whether claimed safeguards were enforced.
This creates several problems:
* Regulators cannot independently verify that AI providers enforce
stated policies
* Providers cannot prove to external auditors that specific requests
were refused
* Third parties investigating incidents have no way to establish
refusal without trusting provider claims
SCITT provides the infrastructure—Signed Statements, Transparency
Services, and Receipts—to address this gap. This document defines
the claim semantics for AI refusal events that can be carried within
that infrastructure.
1.2. Scope
This document defines:
* A claim set for ATTEMPT and Outcome events
* Semantic definitions for each claim
* A completeness invariant for correlation
* A CDDL grammar for CBOR representation
* Integration guidance for SCITT Transparency Services
This document does NOT define:
* Content moderation policies
* Classification algorithms or risk scoring
* Mandatory serialization formats
* Transparency Service behavior beyond standard SCITT
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* Regulatory compliance requirements
This specification is an application profile for SCITT, defining
domain-specific claim semantics. It does not extend or modify SCITT
architecture.
1.3. Limitations
This specification provides auditability of refusal decisions that
are logged, not cryptographic proof that no unlogged generation
occurred. An AI system that bypasses logging entirely cannot be
detected by this mechanism alone.
Transparency Services do not enforce the completeness invariant
defined in this document; such checks are performed by verifiers at
the application level using the claim semantics defined herein.
1.4. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Terminology
This document uses terminology from [I-D.ietf-scitt-architecture].
The following terms are specific to this specification:
Generation Request A request submitted to an AI system to produce
content.
Refusal Event A decision by an AI system to decline a generation
request.
ATTEMPT A claim set recording that a generation request was
received.
DENY A claim set recording that a generation request was refused.
References the corresponding ATTEMPT.
GENERATE A claim set recording successful content generation.
References the corresponding ATTEMPT.
ERROR A claim set recording system failure during processing.
References the corresponding ATTEMPT.
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Outcome Any of DENY, GENERATE, or ERROR.
Completeness Invariant The property that every logged ATTEMPT has
exactly one corresponding Outcome.
Verifiable Refusal Record An ATTEMPT claim set, a DENY claim set,
and Receipts proving their registration with a Transparency
Service.
2.1. Mapping to SCITT
This specification maps directly to SCITT primitives:
+===================+==========================+
| This Document | SCITT Primitive |
+===================+==========================+
| ATTEMPT claim set | Signed Statement payload |
+-------------------+--------------------------+
| Outcome claim set | Signed Statement payload |
+-------------------+--------------------------+
| AI System | Issuer |
+-------------------+--------------------------+
| Inclusion proof | Receipt |
+-------------------+--------------------------+
Table 1
3. Claim Set Definition
This section defines the claims for refusal events. Claims are
specified by their semantic meaning; encoding is deployment-specific.
Section 4 provides a CDDL grammar for CBOR representation.
3.1. Common Claims
The following claims appear in all event types:
event-type (REQUIRED) One of: "ATTEMPT", "DENY", "GENERATE",
"ERROR". Identifies the event category.
event-id (REQUIRED) Unique identifier for this event. UUIDv7
[RFC9562] is RECOMMENDED for temporal ordering.
timestamp (REQUIRED) Time of event occurrence. In CBOR, MUST be
either tag 0 (RFC 3339 date-time string) or tag 1 (epoch-based
integer/float). Untagged integers representing Unix epoch seconds
are also permitted.
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issuer (REQUIRED) Identifier of the AI system that created this
event. SHOULD be a URI.
3.2. ATTEMPT Claims
An ATTEMPT records receipt of a generation request. It MUST be
created before any safety evaluation begins.
prompt-hash (REQUIRED) Cryptographic hash of the prompt content.
MUST use SHA-256 or stronger. The original prompt MUST NOT be
stored.
input-type (REQUIRED) Type of input: "text", "image", "text+image",
"audio", "video", or "multimodal".
reference-input-hashes (OPTIONAL) Array of hashes for non-text
inputs (images, audio, etc.).
session-id (OPTIONAL) Session identifier for correlation across
requests.
actor-hash (OPTIONAL) Pseudonymized hash of the requesting entity.
model-id (OPTIONAL) Identifier of the AI model processing the
request.
policy-id (OPTIONAL) Identifier of the content policy being applied.
The requirement to create ATTEMPT before safety evaluation prevents
selective logging where only "safe" requests are recorded.
3.3. DENY Claims
A DENY records refusal of a generation request.
attempt-id (REQUIRED) The event-id of the corresponding ATTEMPT.
This establishes the correlation required by the completeness
invariant.
risk-category (OPTIONAL) Category of policy violation. Values are
deployment-specific; Appendix A provides a non-normative taxonomy.
risk-score (OPTIONAL) Confidence score, 0.0 to 1.0.
refusal-reason (OPTIONAL) Human-readable reason. SHOULD NOT contain
prompt content.
human-override (OPTIONAL) Boolean indicating human reviewer
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involvement.
3.4. GENERATE Claims
A GENERATE records successful content generation.
attempt-id (REQUIRED) The event-id of the corresponding ATTEMPT.
output-hash (OPTIONAL) Hash of the generated content, for
correlation with downstream provenance (e.g., C2PA manifests).
3.5. ERROR Claims
An ERROR records system failure, not a policy decision.
attempt-id (REQUIRED) The event-id of the corresponding ATTEMPT.
error-code (OPTIONAL) Machine-readable error identifier.
error-message (OPTIONAL) Human-readable error description.
ERROR does not indicate policy enforcement. A high ERROR rate may
indicate operational issues or adversarial inputs.
3.6. Completeness Invariant
The completeness invariant is the core integrity property:
For every ATTEMPT with event-id A that is registered with a
Transparency Service, there MUST exist exactly one Outcome (DENY,
GENERATE, or ERROR) with attempt-id equal to A.
Formally:
|{ATTEMPT}| = |{DENY}| + |{GENERATE}| + |{ERROR}|
where each Outcome references exactly one ATTEMPT, and no ATTEMPT is
referenced by multiple Outcomes.
Violations indicate:
* ATTEMPT without Outcome: incomplete logging or in-progress request
* Outcome without ATTEMPT: fabricated outcome or logging failure
* Multiple Outcomes per ATTEMPT: data integrity failure
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Verifiers SHOULD check this invariant when auditing event streams.
Transparency Services do not enforce this invariant; it is an
application-level semantic constraint.
3.7. Timing Requirements
To maintain audit trail integrity:
* ATTEMPT MUST be created before safety evaluation begins
* Outcome SHOULD be created promptly after decision
* Outcome timestamp MUST be greater than or equal to ATTEMPT
timestamp
Some scenarios require delayed outcomes (human review, system
recovery). Implementations SHOULD document expected latency bounds.
4. CDDL Definition
This section provides a CDDL [RFC8610] grammar for CBOR-based
representation of the claim set. This grammar is RECOMMENDED for
implementations using CBOR encoding within SCITT Signed Statements.
Implementations using other encodings (e.g., JSON) SHOULD maintain
semantic equivalence with this definition.
; Refusal Event Claim Set
; draft-kamimura-scitt-refusal-events-02
refusal-event = attempt-event / outcome-event
; Common claims (appear in all events)
common-claims = (
event-type: event-type-value,
event-id: uuid,
timestamp: time,
issuer: tstr
)
event-type-value = "ATTEMPT" / "DENY" / "GENERATE" / "ERROR"
; ATTEMPT event
attempt-event = {
common-claims,
prompt-hash: hash-value,
input-type: input-type-value,
? reference-input-hashes: [+ hash-value],
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? session-id: uuid,
? actor-hash: hash-value,
? model-id: tstr,
? policy-id: tstr,
* tstr => any ; extension point
}
input-type-value = "text" / "image" / "text+image" /
"audio" / "video" / "multimodal"
; Outcome events
outcome-event = deny-event / generate-event / error-event
deny-event = {
common-claims,
attempt-id: uuid,
? risk-category: tstr,
? risk-score: float16 .le 1.0,
? refusal-reason: tstr,
? human-override: bool,
* tstr => any
}
generate-event = {
common-claims,
attempt-id: uuid,
? output-hash: hash-value,
* tstr => any
}
error-event = {
common-claims,
attempt-id: uuid,
? error-code: tstr,
? error-message: tstr,
* tstr => any
}
; Supporting types
uuid = bstr .size 16 / tstr ; binary or string representation
hash-value = bstr / tstr ; raw bytes or prefixed string
time = #6.0(tstr) / #6.1(number) / uint ; tag 0 (date-time string),
; tag 1 (epoch), or raw uint
Notes on the CDDL definition:
* Extension points (* tstr => any) allow deployment-specific claims
without breaking interoperability
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* UUID may be binary (16 bytes) or string (RFC 9562 format)
* Hash values may be raw bytes or prefixed strings (e.g.,
"sha256:...")
* Timestamps support CBOR tag 0 (RFC 3339 date-time string), tag 1
(epoch-based number), or untagged epoch seconds
The claim names defined in this specification (e.g., "event-type",
"prompt-hash") represent semantic labels. Implementations MAY use
alternative key representations (such as short integer labels for
CBOR efficiency) provided the semantic meaning is preserved and
documented.
5. SCITT Integration
This section describes how refusal event claim sets integrate with
SCITT infrastructure.
5.1. Encoding as Signed Statements
A refusal event claim set is carried as the payload of a SCITT Signed
Statement:
* The claim set is serialized (CBOR RECOMMENDED)
* The serialized bytes become the COSE_Sign1 [RFC9052] payload
* The Issuer is the AI system's signing identity
* Content-Type SHOULD indicate the claim set format
For CBOR-encoded claim sets, the Content-Type "application/cbor" or a
more specific media type MAY be used.
5.2. Registration
After creating a Signed Statement, the Issuer SHOULD register it with
a SCITT Transparency Service via SCRAPI [I-D.ietf-scitt-scrapi].
The Transparency Service returns a Receipt proving inclusion.
Issuers SHOULD store Receipts for future verification requests.
Registration timing affects audit trail integrity:
* Prompt registration provides stronger temporal guarantees
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* Batched registration may be acceptable for non-time-critical
audits
5.3. Verification
A Verifiable Refusal Record consists of:
1. ATTEMPT Signed Statement and Receipt
2. DENY Signed Statement and Receipt
3. Verification that attempt-id in DENY equals event-id in ATTEMPT
Verifiers confirm:
* Both Receipts are valid for the Transparency Service
* Both Signed Statements have valid Issuer signatures
* The attempt-id correlation is correct
* Timestamps are consistent (Outcome >= ATTEMPT)
This demonstrates that a refusal was logged. It does not prove that
no unlogged generation occurred.
5.4. Registration Policy Considerations
A Transparency Service MAY apply a Registration Policy that
validates:
* Required claims are present
* Timestamp is within acceptable bounds
* Issuer is authorized (if restricted)
Transparency Services SHOULD NOT attempt to enforce the completeness
invariant; this is an application-level verification performed by
auditors.
6. IANA Considerations
This document has no IANA actions at this time.
Future revisions may request:
* Registration of a media type for refusal event claim sets
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* Establishment of a registry for event-type values
* Establishment of a registry for risk-category values
The working group should consider whether standardized registries
would benefit interoperability, or whether deployment-specific
vocabularies are sufficient.
7. Security Considerations
7.1. Threat Model
This specification assumes:
* The AI system (Issuer) is partially trusted: expected to log
events but may have bugs or be compromised
* The Transparency Service is partially trusted: provides append-
only guarantees but may be compromised
* Verifiers are trusted to perform completeness checks
This specification does NOT protect against:
* An AI system that bypasses logging entirely
* Collusion between Issuer and Transparency Service
7.2. Omission Attacks
An adversary controlling the AI system might omit events to hide
policy violations. The completeness invariant provides detection for
logged events: auditors can identify ATTEMPTs without Outcomes.
However, if an ATTEMPT is never logged, this specification cannot
detect the omission. Complete prevention requires external
mechanisms (trusted execution, attestation [RFC9334]) outside this
specification's scope.
7.3. Log Equivocation
A malicious Transparency Service might present different views to
different parties. Mitigations include:
* Gossiping of Signed Tree Heads between verifiers
* Registration with multiple Transparency Services
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* External anchoring to public ledgers
7.4. Replay Attacks
Replay of old events is mitigated by:
* UUIDv7 temporal ordering
* Timestamp verification against registration time
* Receipt binding to specific log position
7.5. Dictionary Attacks on Hashes
An adversary with a dictionary of prompts could attempt to identify
which prompt was used by hash comparison. Mitigations include:
* Access controls on event queries
* Rate limiting
* Time-limited retention
8. Privacy Considerations
8.1. Harmful Content
Refusal events may be triggered by harmful content. To prevent the
audit log from becoming a repository of harmful content:
* prompt-hash stores only a hash, not the original
* refusal-reason SHOULD NOT quote prompt content
* Reference images are stored as hashes only
8.2. Actor Privacy
actor-hash provides pseudonymization. Implementations SHOULD:
* Use pseudonymous identifiers by default
* Maintain separate access-controlled identity mappings
* Support crypto-shredding for data deletion
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8.3. Correlation Risks
Event metadata may enable correlation attacks:
* Timestamps reveal activity patterns
* session-id links requests
* model-id reveals system usage
Implementations SHOULD apply appropriate access controls.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", STD 96, RFC 9052,
DOI 10.17487/RFC9052, August 2022,
<https://www.rfc-editor.org/info/rfc9052>.
[RFC9562] Davis, K., Peabody, B., and P. Leach, "Universally Unique
IDentifiers (UUIDs)", RFC 9562, DOI 10.17487/RFC9562, May
2024, <https://www.rfc-editor.org/info/rfc9562>.
[I-D.ietf-scitt-architecture]
Birkholz, H., Delignat-Lavaud, A., and C. Fournet, "An
Architecture for Trustworthy and Transparent Digital
Supply Chains", Work in Progress, Internet-Draft, draft-
ietf-scitt-architecture, 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-scitt-
architecture>.
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[I-D.ietf-scitt-scrapi]
Steele, O., "SCITT Reference APIs", Work in Progress,
Internet-Draft, draft-ietf-scitt-scrapi, 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-scitt-
scrapi>.
9.2. Informative References
[RFC6962] Laurie, B., Langley, A., and E. Kasper, "Certificate
Transparency", RFC 6962, DOI 10.17487/RFC6962, June 2013,
<https://www.rfc-editor.org/info/rfc6962>.
[RFC9334] Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
W. Pan, "Remote ATtestation procedureS (RATS)
Architecture", RFC 9334, DOI 10.17487/RFC9334, January
2023, <https://www.rfc-editor.org/info/rfc9334>.
[CAP-SRP] VeritasChain Standards Organization, "CAP-SRP: Content/
Creative AI Profile - Safe Refusal Provenance",
https://github.com/veritaschain/cap-spec, 2026.
Appendix A. Risk Category Taxonomy (Non-Normative)
This appendix provides an example taxonomy for risk-category values.
This taxonomy is non-normative; deployments MAY use different values
appropriate to their context.
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+=========================+==================================+
| Category | Description |
+=========================+==================================+
| CSAM_RISK | Child sexual abuse material |
+-------------------------+----------------------------------+
| NCII_RISK | Non-consensual intimate imagery |
+-------------------------+----------------------------------+
| MINOR_SEXUALIZATION | Sexualization of minors |
+-------------------------+----------------------------------+
| REAL_PERSON_DEEPFAKE | Unauthorized realistic depiction |
+-------------------------+----------------------------------+
| VIOLENCE_EXTREME | Graphic violence |
+-------------------------+----------------------------------+
| HATE_CONTENT | Discriminatory content |
+-------------------------+----------------------------------+
| TERRORIST_CONTENT | Terrorism-related material |
+-------------------------+----------------------------------+
| SELF_HARM_PROMOTION | Self-harm encouragement |
+-------------------------+----------------------------------+
| COPYRIGHT_VIOLATION | Clear IP infringement |
+-------------------------+----------------------------------+
| COPYRIGHT_STYLE_MIMICRY | Artist style imitation |
+-------------------------+----------------------------------+
| OTHER | Other policy violations |
+-------------------------+----------------------------------+
Table 2
A future revision may define an IANA registry for risk categories if
interoperability requires standardized values.
Appendix B. Deployment Considerations (Non-Normative)
This appendix provides guidance for deployments with varying
assurance requirements. These are not conformance tiers; all
deployments MUST satisfy the normative requirements in Section 3.
B.1. Basic Deployment
Suitable for voluntary transparency:
* Log ATTEMPT and Outcome events locally
* Register with Transparency Service periodically (daily)
* Retain events for 6+ months
* Provide Evidence Packs on request
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B.2. Regulated Deployment
Suitable for regulatory compliance (e.g., EU AI Act):
* Register events promptly (within minutes)
* Implement continuous completeness monitoring
* Retain events for 2+ years
* Provide programmatic audit API
* Document latency bounds and retention policies
B.3. High-Assurance Deployment
Suitable for maximum accountability:
* Register events in real-time (within seconds)
* Use HSM for signing keys
* Register with multiple Transparency Services
* Implement external anchoring (blockchain, multiple TSAs)
* Retain events for 5+ years
* Support 24-hour incident response
Appendix C. JSON Representation Example (Non-Normative)
This appendix shows equivalent JSON representations of the claim sets
defined in Section 3. These examples are for illustration; the
normative definition is the CDDL in Section 4.
C.1. ATTEMPT Example
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{
"event-type": "ATTEMPT",
"event-id": "019467a1-0001-7000-0000-000000000001",
"timestamp": 1738159425,
"issuer": "urn:example:ai-service:img-gen-prod",
"prompt-hash": "sha256:7f83b1657ff1fc53b92dc18148a1d65d...",
"input-type": "text+image",
"reference-input-hashes": [
"sha256:9f86d081884c7d659a2feaa0c55ad015..."
],
"session-id": "019467a1-0001-7000-0000-000000000000",
"actor-hash": "sha256:e3b0c44298fc1c149afbf4c8996fb924...",
"model-id": "img-gen-v4.2.1",
"policy-id": "content-safety-v2"
}
C.2. DENY Example
{
"event-type": "DENY",
"event-id": "019467a1-0001-7000-0000-000000000002",
"timestamp": 1738159426,
"issuer": "urn:example:ai-service:img-gen-prod",
"attempt-id": "019467a1-0001-7000-0000-000000000001",
"risk-category": "NCII_RISK",
"risk-score": 0.94,
"refusal-reason": "Content policy violation detected"
}
Appendix D. Evidence Pack Format (Non-Normative)
An Evidence Pack is a self-contained collection of events suitable
for regulatory submission or third-party audit. This format is
deployment-specific and not required for conformance.
A typical Evidence Pack contains:
* Manifest with metadata and checksums
* Serialized events (CBOR or JSON Lines)
* Receipts from Transparency Services
* Completeness verification results
* Public keys for signature verification
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The CAP-SRP specification [CAP-SRP] defines a detailed Evidence Pack
format for content AI applications.
Acknowledgements
The authors thank the SCITT Working Group for feedback on earlier
revisions, particularly regarding SCITT charter scope and the
distinction between claim semantics and payload formats.
This work builds upon transparency log concepts from Certificate
Transparency [RFC6962] and the SCITT architecture.
Author's Address
TOKACHI KAMIMURA
VeritasChain Standards Organization
Japan
Email: standards@veritaschain.org
URI: https://veritaschain.org
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