



RATS                                                      B. Tsyrulnikov
Internet-Draft                                                 Cyntrisec
Intended status: Informational                              1 March 2026
Expires: 2 September 2026


Attested Inference Receipt (AIR): A COSE/CWT Profile for Confidential AI
                               Inference
          draft-tsyrulnikov-rats-attested-inference-receipt-00

Abstract

   This document defines the Attested Inference Receipt (AIR), a
   COSE_Sign1 envelope carrying CWT claims profiled per the Entity
   Attestation Token (EAT) framework.  An AIR receipt binds model
   identity, input/output hashes, platform attestation metadata, and
   operational telemetry into a single signed artifact suitable for
   audit, compliance, and third-party verification of a confidential AI
   inference event.

   AIR v1 targets single-inference receipts emitted by workloads running
   inside hardware-isolated Trusted Execution Environments (TEEs).  It
   supports AWS Nitro Enclaves and Intel TDX measurement formats, with
   extension points for additional platforms.  Pipeline chaining and
   multi-inference receipts are out of scope for this version.

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
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   This Internet-Draft will expire on 2 September 2026.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Goals . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.2.  Non-Goals . . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   5
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  AIR v1 Receipt Format . . . . . . . . . . . . . . . . . . . .   6
     4.1.  COSE_Sign1 Envelope . . . . . . . . . . . . . . . . . . .   6
     4.2.  Protected Header  . . . . . . . . . . . . . . . . . . . .   6
     4.3.  Unprotected Header  . . . . . . . . . . . . . . . . . . .   7
     4.4.  Payload: CWT Claims Map . . . . . . . . . . . . . . . . .   7
     4.5.  CDDL Schema . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Claim Semantics . . . . . . . . . . . . . . . . . . . . . . .   8
     5.1.  Standard CWT/EAT Claims . . . . . . . . . . . . . . . . .   8
       5.1.1.  iss (Issuer) -- key 1 . . . . . . . . . . . . . . . .   8
       5.1.2.  iat (Issued At) -- key 6  . . . . . . . . . . . . . .   9
       5.1.3.  cti (CWT ID) -- key 7 . . . . . . . . . . . . . . . .   9
       5.1.4.  eat_profile -- key 265  . . . . . . . . . . . . . . .   9
       5.1.5.  eat_nonce -- key 10 . . . . . . . . . . . . . . . . .   9
     5.2.  AIR Private Claims  . . . . . . . . . . . . . . . . . . .   9
       5.2.1.  model_id -- key -65537  . . . . . . . . . . . . . . .   9
       5.2.2.  model_version -- key -65538 . . . . . . . . . . . . .   9
       5.2.3.  model_hash -- key -65539  . . . . . . . . . . . . . .  10
       5.2.4.  request_hash -- key -65540  . . . . . . . . . . . . .  10
       5.2.5.  response_hash -- key -65541 . . . . . . . . . . . . .  10
       5.2.6.  attestation_doc_hash -- key -65542  . . . . . . . . .  10
       5.2.7.  enclave_measurements -- key -65543  . . . . . . . . .  10
       5.2.8.  policy_version -- key -65544  . . . . . . . . . . . .  11
       5.2.9.  sequence_number -- key -65545 . . . . . . . . . . . .  11
       5.2.10. execution_time_ms -- key -65546 . . . . . . . . . . .  11
       5.2.11. memory_peak_mb -- key -65547  . . . . . . . . . . . .  12
       5.2.12. security_mode -- key -65548 . . . . . . . . . . . . .  12
       5.2.13. model_hash_scheme -- key -65549 . . . . . . . . . . .  12
   6.  EAT Profile Declaration . . . . . . . . . . . . . . . . . . .  12
   7.  Verification Procedure  . . . . . . . . . . . . . . . . . . .  14
     7.1.  Layer 1: Parse  . . . . . . . . . . . . . . . . . . . . .  14
     7.2.  Layer 2: Cryptographic Verification . . . . . . . . . . .  14
     7.3.  Layer 3: Claim Validation . . . . . . . . . . . . . . . .  15



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     7.4.  Layer 4: Policy Evaluation  . . . . . . . . . . . . . . .  15
   8.  Relationship to Other Work  . . . . . . . . . . . . . . . . .  16
     8.1.  draft-messous-eat-ai  . . . . . . . . . . . . . . . . . .  16
     8.2.  SCITT . . . . . . . . . . . . . . . . . . . . . . . . . .  16
     8.3.  RATS Architecture . . . . . . . . . . . . . . . . . . . .  16
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
     9.1.  Receipt Integrity . . . . . . . . . . . . . . . . . . . .  17
     9.2.  Algorithm Pinning . . . . . . . . . . . . . . . . . . . .  17
     9.3.  Replay Protection . . . . . . . . . . . . . . . . . . . .  17
     9.4.  Model Hash Limitations  . . . . . . . . . . . . . . . . .  18
     9.5.  Attestation Document Not Verified by Receipt  . . . . . .  18
     9.6.  Signing Key Binding . . . . . . . . . . . . . . . . . . .  18
     9.7.  TEE Compromise  . . . . . . . . . . . . . . . . . . . . .  18
     9.8.  Clock Integrity . . . . . . . . . . . . . . . . . . . . .  18
     9.9.  Deterministic Encoding  . . . . . . . . . . . . . . . . .  19
     9.10. Closed Claims Map . . . . . . . . . . . . . . . . . . . .  19
   10. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  19
     10.1.  Input/Output Hashes  . . . . . . . . . . . . . . . . . .  19
     10.2.  Correlation Metadata . . . . . . . . . . . . . . . . . .  19
     10.3.  Nonce Privacy  . . . . . . . . . . . . . . . . . . . . .  19
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
   12. Implementation Status . . . . . . . . . . . . . . . . . . . .  20
     12.1.  Reference Implementation (Rust)  . . . . . . . . . . . .  20
     12.2.  Python Interop Verifier  . . . . . . . . . . . . . . . .  22
     12.3.  E2E Validation . . . . . . . . . . . . . . . . . . . . .  22
   13. Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .  22
     13.1.  Valid Receipt Walkthrough  . . . . . . . . . . . . . . .  22
     13.2.  Invalid Receipt Categories . . . . . . . . . . . . . . .  23
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  24
     14.1.  Normative References . . . . . . . . . . . . . . . . . .  24
     14.2.  Informative References . . . . . . . . . . . . . . . . .  25
   Appendix A.  Full CDDL Schema . . . . . . . . . . . . . . . . . .  26
   Appendix B.  Golden Vector Summary  . . . . . . . . . . . . . . .  27
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  28
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  28

1.  Introduction

   Regulated industries increasingly deploy machine learning models on
   cloud infrastructure but lack a standardized, interoperable mechanism
   to prove what happened during a specific inference.  Existing
   attestation frameworks such as RATS [RFC9334] establish platform
   identity and code integrity, but they do not produce per-inference
   evidence binding a model, its inputs and outputs, and the platform
   state into a single verifiable artifact.






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   The Attested Inference Receipt (AIR) fills this gap.  An AIR receipt
   is a COSE_Sign1 [RFC9052] envelope whose payload is a CWT [RFC8392]
   claims set profiled as an EAT [RFC9711].  The receipt is signed with
   Ed25519 [RFC8032] by the workload running inside a Trusted Execution
   Environment (TEE).  A verifier can confirm the receipt's integrity,
   the signing algorithm, and the claim values using only widely
   available COSE/CWT libraries and the workload's Ed25519 public key.

   AIR v1 is scoped to a single inference: one request processed by one
   model inside one attested workload produces one receipt.  Pipeline
   chaining, multi-stage proofs, and integration with transparency logs
   (such as SCITT [SCITT]) are deferred to future versions.

   AIR v1 defines the per-inference receipt as the base primitive.
   Future AIR profiles may define aggregation mechanisms for high-
   throughput deployments (for example, Merkle-root commitments over
   multiple inference events) while preserving the same verification
   semantics.  Such aggregation mechanisms are out of scope for AIR v1.

1.1.  Goals

   The goals of AIR v1 are:

   1.  Define a receipt wire format using existing IETF standards
       (COSE_Sign1, CWT, EAT).

   2.  Bind model identity (cryptographic hash), input/output hashes,
       attestation metadata, and operational telemetry in a single
       signed envelope.

   3.  Support verification by any party with access to the Ed25519
       public key, without TEE-specific tooling.

   4.  Provide a portable measurement map that accommodates multiple TEE
       platforms (currently Nitro PCR and Intel TDX MRTD/RTMR).

   5.  Establish extension points for future platforms and claims
       without breaking v1 verifiers.

1.2.  Non-Goals

   AIR v1 explicitly does not:

   *  Define a transport protocol or session management scheme.

   *  Specify attestation document verification procedures (these are
      platform-specific).




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   *  Prove data deletion or model correctness.

   *  Provide regulatory certification or compliance guarantees.

   *  Define pipeline chaining or multi-inference receipts.

2.  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.

3.  Terminology

   Attested Inference Receipt (AIR):  A COSE_Sign1 signed CWT/EAT
      artifact emitted by a workload after processing a single AI
      inference request inside a TEE.  The receipt binds model identity,
      input/output hashes, attestation metadata, and operational
      telemetry.

   Confidential Workload:  The software executing inside a TEE that
      loads a model, processes inference requests, and generates AIR
      receipts.  In RATS [RFC9334] terminology, the confidential
      workload acts as the Attester.

   Verifier:  An entity that validates an AIR receipt's signature, claim
      values, and policy constraints.  In RATS [RFC9334] terminology,
      this maps to the Verifier role.

   Relying Party:  An entity that consumes the verification result to
      make trust decisions (e.g., an auditor, compliance officer, or end
      user).  In RATS [RFC9334] terminology, this maps to the Relying
      Party role.

   Endorser:  The TEE hardware vendor (e.g., AWS for Nitro, Intel for
      TDX) whose attestation infrastructure anchors trust in the
      platform measurements carried by the receipt.

   Measurement Map:  The enclave_measurements claim containing platform-
      specific register values (PCRs for Nitro, MRTD/RTMRs for TDX) that
      identify the workload code and configuration.

   Receipt:  In this document, "receipt" always refers to an AIR






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      receipt.  Note that this differs from the SCITT usage of "receipt"
      (which refers to a countersigned statement from a transparency
      service).  The two are complementary: a future version could
      register an AIR receipt with a SCITT transparency service and
      receive a SCITT receipt in return.

4.  AIR v1 Receipt Format

4.1.  COSE_Sign1 Envelope

   An AIR v1 receipt is a tagged COSE_Sign1 structure (CBOR tag 18) as
   defined in [RFC9052] Section 4.2:

   COSE_Sign1 = [
     protected   : bstr,          ; serialized protected header
     unprotected : map,            ; unprotected header map
     payload     : bstr,           ; serialized CWT claims map
     signature   : bstr .size 64   ; Ed25519 signature
   ]

   The signature covers Sig_structure1 = ["Signature1", protected,
   external_aad, payload] where external_aad is empty (h'').

   Verifiers MUST reject untagged COSE_Sign1 structures.  The CBOR tag
   18 is mandatory.

4.2.  Protected Header

   The protected header is a CBOR map containing exactly two entries:

            +=======+==============+=======+=================+
            | Label | Name         | Value | Description     |
            +=======+==============+=======+=================+
            |     1 | alg          |    -8 | EdDSA (Ed25519) |
            +-------+--------------+-------+-----------------+
            |     3 | content type |    61 | application/cwt |
            +-------+--------------+-------+-----------------+

                                 Table 1

   Verifiers MUST reject receipts where alg is not -8 or where content
   type is not 61.  Additional protected header parameters are not
   defined in v1 and MUST NOT be present.

   The signing algorithm is Ed25519 with verify_strict semantics per
   [RFC8032] Section 5.1.7.  Verifiers MUST reject non-canonical S
   values (S >= L where L is the Ed25519 group order).




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4.3.  Unprotected Header

   The unprotected header MUST be empty for AIR v1 receipts.  The CDDL
   permits an optional kid (label 4, type bstr) for forward
   compatibility, but the reference implementation rejects non-empty
   unprotected headers because unprotected header parameters are not
   covered by the COSE signature and can be tampered in transit.

   Verifiers SHOULD reject receipts with non-empty unprotected headers.

4.4.  Payload: CWT Claims Map

   The payload is a CBOR-encoded CWT claims map.  The map uses
   deterministic encoding per [RFC8949] Section 4.2.1 (shorter encoded
   key sorts first, then bytewise lexicographic comparison).

   The claims map is closed: verifiers MUST reject maps containing
   unknown integer keys.  Duplicate keys MUST be rejected.

4.5.  CDDL Schema

   The following CDDL [RFC8610] defines the complete wire shape:

   air-receipt = #6.18([
     protected:   bstr .cbor air-protected-header,
     unprotected: air-unprotected-header,
     payload:     bstr .cbor air-claims,
     signature:   bstr .size 64
   ])

   air-protected-header = {
     1 => -8,          ; alg: EdDSA (Ed25519)
     3 => 61,          ; content type: application/cwt
   }

   air-unprotected-header = {
     ? 4 => bstr,      ; kid: key identifier (reserved)
   }

   air-claims = {
     ; --- Standard CWT/EAT claims ---
     1   => tstr,                  ; iss: issuer
     6   => uint,                  ; iat: issued-at (Unix seconds)
     7   => bstr .size 16,         ; cti: CWT ID (UUID v4, 16 bytes)
     265 => "https://spec.cyntrisec.com/air/v1",  ; eat_profile
     ? 10 => bstr,                 ; eat_nonce (optional)

     ; --- AIR private claims ---



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     -65537 => tstr,               ; model_id
     -65538 => tstr,               ; model_version
     -65539 => sha256-hash,        ; model_hash
     -65540 => sha256-hash,        ; request_hash
     -65541 => sha256-hash,        ; response_hash
     -65542 => sha256-hash,        ; attestation_doc_hash
     -65543 => enclave-measurements, ; enclave_measurements
     -65544 => tstr,               ; policy_version
     -65545 => uint,               ; sequence_number
     -65546 => uint,               ; execution_time_ms
     -65547 => uint,               ; memory_peak_mb
     -65548 => tstr,               ; security_mode
     ? -65549 => tstr,             ; model_hash_scheme (optional)
   }

   sha256-hash = bstr .size 32
   sha384-hash = bstr .size 48

   enclave-measurements = nitro-measurements / tdx-measurements

   nitro-measurements = {
     "pcr0"             => sha384-hash,
     "pcr1"             => sha384-hash,
     "pcr2"             => sha384-hash,
     ? "pcr8"           => sha384-hash,
     "measurement_type" => "nitro-pcr",
   }

   tdx-measurements = {
     "pcr0"             => sha384-hash,   ; MRTD
     "pcr1"             => sha384-hash,   ; RTMR0
     "pcr2"             => sha384-hash,   ; RTMR1
     "measurement_type" => "tdx-mrtd-rtmr",
   }

   The full CDDL is also provided in Appendix A.

5.  Claim Semantics

5.1.  Standard CWT/EAT Claims

5.1.1.  iss (Issuer) -- key 1

   A text string identifying the issuing entity (e.g., "cyntrisec.com").
   The value is operator-assigned and opaque to the receipt format.
   Verifiers MAY check against an expected issuer allowlist.





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5.1.2.  iat (Issued At) -- key 6

   An unsigned integer representing the Unix timestamp (seconds since
   epoch) when the inference completed.  Verifiers apply a freshness
   check: now - max_age <= iat <= now + clock_skew.  Verifiers SHOULD
   reject future timestamps.

5.1.3.  cti (CWT ID) -- key 7

   A 16-byte binary string containing a UUID v4 encoded as raw bytes
   (not the 36-character string form).  Each receipt MUST have a unique
   cti.  Verifiers maintaining replay state SHOULD track observed cti
   values.

5.1.4.  eat_profile -- key 265

   The fixed string value "https://spec.cyntrisec.com/air/v1".
   Verifiers MUST reject receipts with unknown eat_profile values.  The
   value is an identifier, not a dereference requirement.  Verifiers
   MUST NOT require network retrieval of this URI during validation.

5.1.5.  eat_nonce -- key 10

   An optional binary string (8-64 bytes per [RFC9711] Section 4.1)
   provided by the client to bind the receipt to a specific request
   session.  If the verifier supplied a nonce, it MUST check that
   eat_nonce matches.  This is the primary replay resistance mechanism
   when verifier-side cti deduplication is not feasible.

5.2.  AIR Private Claims

   AIR uses negative integer keys in the CWT private-use range to avoid
   collision with IANA-registered claims.  Keys -65537 through -65548
   are assigned and required.  Key -65549 is assigned and optional.
   Keys -65550 through -65599 are reserved for v1.x extensions.

5.2.1.  model_id -- key -65537

   A text string containing the human-readable model identifier (e.g.,
   "minilm-l6-v2").  Operator-assigned, opaque.  Not cryptographic; use
   model_hash for binding.

5.2.2.  model_version -- key -65538

   A text string containing the human-readable model version (e.g.,
   "1.0.0").  Operator-assigned, opaque.





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5.2.3.  model_hash -- key -65539

   A 32-byte SHA-256 [FIPS180-4] hash of the model weights.  This is the
   cryptographic binding between the receipt and a specific model
   artifact.  Verifiers MUST compare against a known-good hash when
   model identity matters.  The model_hash MUST NOT be all zeros.

5.2.4.  request_hash -- key -65540

   A 32-byte SHA-256 hash of the inference request payload.  Binds the
   receipt to a specific input.  Clients holding the original request
   can recompute and compare.

5.2.5.  response_hash -- key -65541

   A 32-byte SHA-256 hash of the inference response payload.  Binds the
   receipt to a specific output.

5.2.6.  attestation_doc_hash -- key -65542

   A 32-byte SHA-256 hash of the platform attestation document (e.g.,
   Nitro COSE attestation document, TDX quote).  Links the receipt to
   TEE evidence without embedding the (potentially large) attestation
   document itself.

   Note: AIR v1 does not define attestation document verification.
   Verifiers SHOULD independently obtain and verify the attestation
   document, then compare its hash.

5.2.7.  enclave_measurements -- key -65543

   A map containing platform-specific measurement registers.  The map
   structure depends on the measurement_type field within it.

5.2.7.1.  Nitro PCR Variant (measurement_type = "nitro-pcr")

       +====================+=========+==========+================+
       | Field              | Type    | Required | Description    |
       +====================+=========+==========+================+
       | "pcr0"             | bstr 48 | Yes      | PCR0 (SHA-384) |
       +--------------------+---------+----------+----------------+
       | "pcr1"             | bstr 48 | Yes      | PCR1 (SHA-384) |
       +--------------------+---------+----------+----------------+
       | "pcr2"             | bstr 48 | Yes      | PCR2 (SHA-384) |
       +--------------------+---------+----------+----------------+
       | "pcr8"             | bstr 48 | No       | PCR8 (SHA-384) |
       +--------------------+---------+----------+----------------+
       | "measurement_type" | tstr    | Yes      | "nitro-pcr"    |



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       +--------------------+---------+----------+----------------+

                                 Table 2

5.2.7.2.  TDX MRTD/RTMR Variant (measurement_type = "tdx-mrtd-rtmr")

       +====================+=========+==========+=================+
       | Field              | Type    | Required | Description     |
       +====================+=========+==========+=================+
       | "pcr0"             | bstr 48 | Yes      | MRTD (SHA-384)  |
       +--------------------+---------+----------+-----------------+
       | "pcr1"             | bstr 48 | Yes      | RTMR0 (SHA-384) |
       +--------------------+---------+----------+-----------------+
       | "pcr2"             | bstr 48 | Yes      | RTMR1 (SHA-384) |
       +--------------------+---------+----------+-----------------+
       | "measurement_type" | tstr    | Yes      | "tdx-mrtd-rtmr" |
       +--------------------+---------+----------+-----------------+

                                  Table 3

   The TDX registers are mapped to pcr0/pcr1/pcr2 field names for cross-
   platform verifier simplicity.  The measurement_type field
   disambiguates the actual register semantics.

   All pcr0/pcr1/pcr2 values MUST be exactly 48 bytes.  Verifiers MUST
   reject receipts where any required measurement register is the wrong
   length.  The measurement_type MUST be one of the defined values;
   unknown types MUST be rejected.

5.2.8.  policy_version -- key -65544

   A text string identifying the version of the policy governing the
   workload (e.g., "policy-2026.02").  Informational.

5.2.9.  sequence_number -- key -65545

   An unsigned integer that increases monotonically within a single
   workload session.  Resets on workload restart.  Verifiers processing
   a stream of receipts SHOULD check monotonicity; gaps indicate missed
   receipts within a session.

5.2.10.  execution_time_ms -- key -65546

   An unsigned integer representing the wall-clock inference time in
   milliseconds.  Informational; anomalously low or high values may
   indicate issues but are not a verification failure.





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5.2.11.  memory_peak_mb -- key -65547

   An unsigned integer representing the peak memory usage during
   inference in megabytes.  Informational.

5.2.12.  security_mode -- key -65548

   A text string identifying the security mode of the workload (e.g.,
   "GatewayOnly", "FullAttestation").  Informational.  Verifiers MAY
   require a specific security mode.

5.2.13.  model_hash_scheme -- key -65549

   An optional text string declaring how model_hash was computed,
   enabling verifiers to reproduce the hash from model artifacts.

   Defined scheme values:

    +===================+=============================================+
    | Scheme            | Description                                 |
    +===================+=============================================+
    | "sha256-single"   | SHA-256 of a single model weights file      |
    +-------------------+---------------------------------------------+
    | "sha256-concat"   | SHA-256 of deterministically concatenated   |
    |                   | weight files (lexicographic filename order) |
    +-------------------+---------------------------------------------+
    | "sha256-manifest" | SHA-256 of a self-describing manifest       |
    |                   | listing per-file hashes                     |
    +-------------------+---------------------------------------------+

                                  Table 4

   If present, verifiers MUST recognize the scheme value.  Unknown
   schemes MUST be rejected (fail-closed).  If absent, verifiers SHOULD
   treat model_hash as opaque (can still compare against a known-good
   hash, but cannot independently reproduce it).

   New scheme values MAY be registered in v1.x minor updates.
   Implementations MUST NOT invent unregistered scheme values.

6.  EAT Profile Declaration

   This section consolidates the mandatory profile positions per
   [RFC9711] Section 6.3.







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   1.   *Profile identifier*: URI "https://spec.cyntrisec.com/air/v1"
        (carried in eat_profile, key 265).  This URI is used as an
        opaque identifier and does not imply that validation depends on
        a hosted verifier service.

   2.   *Encoding*: CBOR only ([RFC8949]).  JSON serialization is not
        defined.

   3.   *Envelope*: COSE_Sign1 ([RFC9052] Section 4.2), CBOR tag 18.
        Untagged COSE_Sign1 MUST be rejected.

   4.   *Payload content type*: COSE content_type = 61 (application/
        cwt).  The payload is a CWT claims map.

   5.   *HTTP media type*: application/eat+cwt ([RFC9782]).  Receivers
        SHOULD accept both application/cwt and application/eat+cwt.

   6.   *Signing algorithm*: Ed25519 only (COSE alg = -8). verify_strict
        required (canonical S per [RFC8032] Section 5.1.7).  No
        algorithm negotiation in v1.

   7.   *Detached bundles*: Not supported in v1.  The attestation
        document is referenced by hash (attestation_doc_hash), not
        embedded.

   8.   *Key identification*: Out of band.  The verifier obtains the
        Ed25519 public key through a platform-specific channel (e.g.,
        attestation document, key registry).  Optional kid in the
        unprotected header is reserved but currently rejected by the
        reference implementation.

   9.   *Mandatory claims*: 16 required claims: iss, iat, cti,
        eat_profile, model_id, model_version, model_hash, request_hash,
        response_hash, attestation_doc_hash, enclave_measurements,
        policy_version, sequence_number, execution_time_ms,
        memory_peak_mb, security_mode.

   10.  *Optional claims*: 2 optional claims: eat_nonce (replay
        resistance), model_hash_scheme (hash computation method).

   11.  *Freshness*: iat carries the execution timestamp (Unix seconds).
        Verifiers apply max_age + clock_skew policy. eat_nonce provides
        optional challenge-response replay resistance ([RFC9711]
        Section 4.1, 8-64 bytes).

   12.  *Deterministic encoding*: Required.  Map keys sorted per
        [RFC8949] Section 4.2.1 (shorter encoded form first, then
        bytewise lexicographic).



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   13.  *Closed claims map*: The claims map is closed.  Unknown integer
        keys MUST be rejected.  Duplicate keys MUST be rejected.

   14.  *Unprotected header*: MUST be empty.  All header parameters are
        carried in the protected header.  The CDDL permits an optional
        kid (label 4) for forward compatibility, but unprotected
        parameters are not signed and can be tampered in transit.

   15.  *Private claim keys*: Keys -65537 through -65549 are assigned in
        the CWT private-use range ([RFC8392]).  No IANA registration is
        required.  Keys -65550 through -65599 are reserved for v1.x
        extensions.

7.  Verification Procedure

   The AIR v1 verification procedure is organized into four layers.
   Each layer MUST complete successfully before proceeding to the next.
   If any check fails, the verifier MUST reject the receipt and SHOULD
   report the specific failure.

7.1.  Layer 1: Parse

   1.  Decode the input as CBOR.  Confirm the outer structure is tagged
       with CBOR tag 18.

   2.  Decode the COSE_Sign1 array (4 elements).

   3.  Confirm the receipt size does not exceed 65,536 bytes.

   4.  Decode the protected header.  Confirm it is a well-formed CBOR
       map.

   5.  Confirm alg (label 1) in the protected header is -8 (EdDSA).
       Reject receipts with any other algorithm.

   6.  Confirm content type (label 3) in the protected header is 61
       (application/cwt).

   7.  Decode the payload.  Confirm it is a well-formed CBOR map.

   8.  Confirm eat_profile (key 265) equals
       "https://spec.cyntrisec.com/air/v1".  Reject receipts with
       unknown profile values.

7.2.  Layer 2: Cryptographic Verification

   1.  Construct Sig_structure1 = ["Signature1", protected, h'',
       payload].



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   2.  Verify the Ed25519 signature over Sig_structure1 using the
       provided public key.  The verification MUST use verify_strict
       semantics (reject non-canonical S values).

7.3.  Layer 3: Claim Validation

   1.   Confirm cti (key 7) is exactly 16 bytes.

   2.   Confirm iat (key 6) is a non-zero unsigned integer.

   3.   Confirm model_hash (key -65539) is exactly 32 bytes and not all
        zeros.

   4.   Confirm all required text string claims (iss, model_id,
        model_version, policy_version, security_mode) are non-empty and
        within reasonable bounds (implementation-defined, RECOMMENDED
        maximum 1024 bytes each).

   5.   Confirm enclave_measurements (key -65543) is a map.

   6.   Confirm measurement_type within enclave_measurements is one of
        the defined values ("nitro-pcr" or "tdx-mrtd-rtmr").

   7.   Confirm all pcr0/pcr1/pcr2 values are exactly 48 bytes.

   8.   If measurement_type is "tdx-mrtd-rtmr", confirm pcr8 is absent.
        TDX measurement maps MUST NOT contain pcr8.

   9.   If model_hash_scheme (key -65549) is present, confirm it is one
        of the defined values ("sha256-single", "sha256-concat",
        "sha256-manifest").  Unknown values MUST be rejected.

   10.  Confirm the claims map contains no unknown integer keys and no
        duplicate keys.

7.4.  Layer 4: Policy Evaluation

   Policy checks are configurable per verifier deployment.  The
   following checks are defined:

   *FRESH* (timestamp bounds):  If configured, verify now - max_age <=
      iat <= now + clock_skew.

   *NONCE* (challenge binding):  If the verifier supplied a nonce,
      verify eat_nonce matches.

   *MODEL* (expected model):  If configured, verify model_hash and/or
      model_id match expected values.



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   *PLATFORM* (expected platform):  If configured, verify
      measurement_type matches expected value.

   *REPLAY* (deduplication):  If the verifier maintains a seen-cti
      store, reject duplicate cti values.

   Verifiers SHOULD document which Layer 4 policies they enforce.

8.  Relationship to Other Work

8.1.  draft-messous-eat-ai

   [I-D.messous-eat-ai] defines an EAT profile for autonomous AI agents,
   including model identification, training metadata, and performance
   metrics.  AIR v1 is complementary: where draft-messous-eat-ai focuses
   on broad AI agent provenance metadata (potentially including training
   and evaluation details), AIR v1 focuses narrowly on per-inference
   execution evidence from a confidential workload.  A future version of
   AIR could adopt registered claim keys from draft-messous-eat-ai once
   they stabilize, replacing the current private-use integer keys.

8.2.  SCITT

   The Supply Chain Integrity, Transparency and Trust [SCITT] framework
   uses "receipt" to mean a countersigned statement from a transparency
   service.  In AIR, "receipt" means a workload-signed inference proof.
   The two are complementary: an AIR receipt could be registered as a
   SCITT statement, and the resulting SCITT receipt (countersignature
   from the transparency service) would provide independent
   auditability.  This document uses "AIR receipt" consistently to avoid
   ambiguity.

8.3.  RATS Architecture

   AIR receipts fit the RATS [RFC9334] architecture as follows:

   *  The confidential workload is the *Attester* (it generates evidence
      in the form of receipts).

   *  The receipt consumer is the *Verifier* (it validates signatures
      and claims).

   *  The end user, auditor, or compliance officer is the *Relying
      Party* (they consume verification results).

   *  The TEE hardware vendor (AWS, Intel) is the *Endorser* (their
      attestation infrastructure anchors trust).




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   AIR v1 is a workload-emitted artifact, not a verifier-emitted
   attestation result.  It is distinct from IETF EAR (EAT Attestation
   Result), which is produced by a verifier after evaluating platform
   evidence.  In a complete deployment, an EAR might reference an AIR
   receipt as part of the evidence it evaluated.

9.  Security Considerations

9.1.  Receipt Integrity

   The Ed25519 signature over the COSE Sig_structure1 protects the
   protected header and all claims against tampering.  The unprotected
   header is not covered by the signature; AIR v1 requires it to be
   empty (Section 4.3).

9.2.  Algorithm Pinning

   AIR v1 pins the signing algorithm to Ed25519 (alg = -8).  The
   algorithm identifier is carried in the protected header and is
   therefore signed.  This prevents algorithm confusion attacks where an
   attacker substitutes a weaker algorithm.

9.3.  Replay Protection

   Replay protection in AIR v1 is a shared responsibility:

   *  The cti claim provides a unique receipt identifier.  Verifiers
      maintaining state SHOULD track observed cti values and reject
      duplicates.

   *  The eat_nonce claim (optional) provides challenge-response
      freshness.  When present, it binds the receipt to a specific
      verifier-supplied challenge, preventing replay to other verifiers.

   *  The sequence_number claim provides monotonicity within a session.
      Gaps indicate missed receipts.

   Verifiers not maintaining state and not using eat_nonce have limited
   replay protection (only iat-based freshness).  Deployments requiring
   strong replay resistance MUST use at least one of cti deduplication
   or eat_nonce.










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9.4.  Model Hash Limitations

   The model_hash claim (SHA-256 of model weights) proves byte-level
   identity, not model correctness, bias, or safety.  Two distinct
   models with identical hashes are computationally infeasible, but a
   model with a correct hash may still produce harmful or incorrect
   outputs.

   The model_hash_scheme claim (Section 5.2.13) declares how the hash
   was computed.  Unknown scheme values MUST be rejected.  This prevents
   a verifier from accepting a hash computed with an unrecognized method
   that might weaken integrity guarantees.

9.5.  Attestation Document Not Verified by Receipt

   The attestation_doc_hash claim is a SHA-256 hash of the platform
   attestation document.  AIR v1 does not embed or verify the
   attestation document.  Verifiers requiring TEE assurance MUST
   independently obtain and verify the attestation document using
   platform-specific procedures (e.g., Nitro COSE verification against
   the AWS root CA, Intel TDX DCAP verification against Intel PCS).

9.6.  Signing Key Binding

   AIR v1 does not define how the Ed25519 signing key relates to the TEE
   attestation.  Implementations SHOULD:

   1.  Generate the Ed25519 key inside the TEE at startup.

   2.  Include the public key in the platform attestation document
       (e.g., Nitro public_key user data field, TDX REPORTDATA).

   3.  Provide the attestation document alongside the receipt for end-
       to-end verification.

9.7.  TEE Compromise

   AIR v1 assumes the TEE hardware is correct (Trust Assumption TA-1).
   A hardware vulnerability, firmware bug, or supply chain compromise
   affecting the TEE breaks all AIR guarantees.  AIR v1 does not define
   revocation mechanisms for compromised platforms.

9.8.  Clock Integrity

   The iat claim depends on the workload's system clock.  On AWS Nitro,
   the enclave uses the host clock (no independent time source).  On
   Intel TDX, the CVM has a TSC but it is subject to frequency scaling.
   AIR v1 freshness checks are only as accurate as the platform clock.



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9.9.  Deterministic Encoding

   AIR v1 requires deterministic CBOR encoding ([RFC8949]
   Section 4.2.1).  This ensures that the same claims always produce the
   same payload bytes, preventing signature-valid variants of the same
   receipt.  Implementations MUST sort map keys per the CBOR
   deterministic encoding rules.

9.10.  Closed Claims Map

   The claims map is closed: unknown integer keys MUST be rejected.
   This prevents downgrade attacks where an attacker adds unrecognized
   claims that a naive verifier might silently accept as benign.

10.  Privacy Considerations

10.1.  Input/Output Hashes

   The request_hash and response_hash claims contain SHA-256 hashes, not
   plaintext inputs or outputs.  However, for low-entropy inputs (e.g.,
   binary classification queries, yes/no questions), an adversary with
   knowledge of the input space could brute-force the hash to recover
   the original input.  Deployments handling sensitive low-entropy data
   SHOULD consider whether receipt exposure risks input recovery.

10.2.  Correlation Metadata

   AIR receipts contain timestamps (iat), sequence numbers, and
   identifiers (cti, iss) that could be used to correlate activity
   across receipts.  In privacy-sensitive deployments, operators SHOULD
   consider whether the combination of receipt metadata enables unwanted
   profiling.

10.3.  Nonce Privacy

   The eat_nonce claim, when present, may leak correlation data if the
   same nonce is reused across sessions or if the nonce encodes client-
   identifying information.  Verifiers SHOULD use random nonces and
   avoid embedding client identifiers in nonce values.

11.  IANA Considerations

   This document has no IANA actions at this time.








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   AIR v1 uses negative integer keys in the CWT private-use range (keys
   -65537 through -65549).  If AIR gains adoption, a future version may
   request registration of these claims in the CWT Claims registry
   established by [RFC8392].  The eat_profile URI
   ("https://spec.cyntrisec.com/air/v1") follows the EAT profile naming
   conventions in [RFC9711] but is not registered in any IANA registry.

   The HTTP media type application/eat+cwt referenced in Section 6 is
   registered by [RFC9782].

12.  Implementation Status

   Note to RFC Editor: Please remove this section before publication.

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting, per
   [RFC7942].

12.1.  Reference Implementation (Rust)

   Organization:  Cyntrisec

   Implementation:  EphemeralML (common/src/air_receipt.rs, common/src/
      air_verify.rs)

   Description:  Full AIR v1 emitter and 4-layer verifier.  Generates
      COSE_Sign1 receipts with deterministic CBOR encoding and Ed25519
      signing.  Verifier implements all four layers (parse, crypto,
      claims, policy) with structured error codes.

   Maturity:  Deployment-validated.  Emitted in E2E paths on three
      platforms.

   Coverage:  575 tests passing (including 16 AIR v1 conformance vector
      tests).

   Performance snapshot (non-normative):  2026-03-01 AWS build-host
      microbenchmark aggregate (air_v1_aws_build_bench_5runs_2026-03-01)
      measured crypto and verifier costs on an AWS c6i.xlarge Linux host
      after compiling ephemeralml-verify from source (valid AIR vector
      size 599 bytes).  Values below are 5-run median and p95:










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   +=======================+===========+===========+==================+
   | Metric                |    Median |       p95 | Notes            |
   +=======================+===========+===========+==================+
   | SHA-256 (1 KB)        |  0.931 us |  0.931 us | OpenSSL 3.2.2    |
   |                       |           |           | speed conversion |
   +-----------------------+-----------+-----------+------------------+
   | SHA-256 (4 KB)        |  3.227 us |  3.227 us | OpenSSL 3.2.2    |
   |                       |           |           | speed conversion |
   +-----------------------+-----------+-----------+------------------+
   | Ed25519 sign          | 31.763 us | 31.887 us | OpenSSL 3.2.2    |
   |                       |           |           | speed            |
   +-----------------------+-----------+-----------+------------------+
   | Ed25519 verify        |   102.512 |   103.338 | OpenSSL 3.2.2    |
   |                       |        us |        us | speed            |
   +-----------------------+-----------+-----------+------------------+
   | AIR verify (Rust CLI, | 1,533.100 | 1,558.608 | Includes process |
   | process-per-call)     |        us |        us | spawn overhead   |
   +-----------------------+-----------+-----------+------------------+

                                 Table 5

   Estimated receipt emission crypto path for a 1 KB request + 4 KB
   response plus a 1 KB attestation hash and Ed25519 signing is 36.852
   us median (36.958 us p95) per inference on this host.

   Separate retest run (non-normative):  A second 5-run retest on the
      same AWS instance class (air_v1_aws_retest_bench_5runs_2026-03-01)
      reproduced SHA-256 and Ed25519 primitive timings within
      approximately 1%, and reproduced the receipt emission crypto
      estimate at 37.035 us median (+0.5% versus the baseline snapshot).
      The Rust CLI process-per-call verify metric increased by +14.7% in
      the retest; this metric includes process fork/exec/linker overhead
      and is environment-sensitive.  For this reason, AIR v1 performance
      interpretation should prioritize the per-inference crypto path
      estimate rather than CLI process-per-call latency.

   Environment-sensitivity check (non-normative):  A separate run on GCP
      n2-standard-4 (Intel Xeon @ 2.80 GHz, OpenSSL 3.0.13, Ubuntu
      24.04) measured the emit crypto path at 62.178 us median.  The
      absolute values differ from AWS due to OpenSSL version (3.0 vs 3.2
      assembly paths) and CPU generation, not protocol logic.  This
      confirms the AIR crypto path remains in tens of microseconds
      across tested environments.

   These measurements are environment-specific and informative only; AIR
   v1 does not define performance requirements.

   Contact:  borys@cyntrisec.com



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12.2.  Python Interop Verifier

   Organization:  Cyntrisec (same team, separate Python implementation)

   Implementation:  scripts/interop_test.py

   Description:  Minimal Python verifier using pycose and cbor2
      libraries.  Validates COSE_Sign1 structure, Ed25519 signature, and
      claim presence.

   Maturity:  Test/interop.

12.3.  E2E Validation

   The reference implementation has been validated end-to-end on three
   confidential computing platforms:

   +============================================+========+============+
   | Platform                                   | Status | Date       |
   +============================================+========+============+
   | AWS Nitro Enclaves (m6i)                   | PASS   | 2026-02-28 |
   +--------------------------------------------+--------+------------+
   | GCP Confidential Space TDX (c3-standard-4) | PASS   | 2026-02-27 |
   +--------------------------------------------+--------+------------+
   | GCP Confidential Space GPU H100 CC (a3-    | PASS   | 2026-02-27 |
   | highgpu-1g)                                |        |            |
   +--------------------------------------------+--------+------------+

                                 Table 6

13.  Examples

13.1.  Valid Receipt Walkthrough

   The following describes a valid AIR v1 receipt in diagnostic
   notation.  This corresponds to the v1-nitro-no-nonce golden vector.

   The COSE_Sign1 envelope (tagged with CBOR tag 18):

   18([
     h'A2012703183D',           / protected: {1: -8, 3: 61} /
     {},                         / unprotected: empty /
     h'B0...',                   / payload: CWT claims map /
     h'<64 bytes>'               / signature: Ed25519 /
   ])

   The protected header decodes to:




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   {
     1: -8,    / alg: EdDSA /
     3: 61     / content type: application/cwt /
   }

   The payload (CWT claims map) includes 16 required claims plus the EAT
   profile:

 {
   1: "cyntrisec.com",                          / iss /
   6: 1740000000,                               / iat /
   7: h'<16 bytes UUID v4>',                    / cti /
   265: "https://spec.cyntrisec.com/air/v1",    / eat_profile /
   -65537: "minilm-l6-v2",                      / model_id /
   -65538: "1.0.0",                             / model_version /
   -65539: h'<32 bytes SHA-256>',               / model_hash /
   -65540: h'<32 bytes SHA-256>',               / request_hash /
   -65541: h'<32 bytes SHA-256>',               / response_hash /
   -65542: h'<32 bytes SHA-256>',               / attestation_doc_hash /
   -65543: {                                    / enclave_measurements /
     "pcr0": h'<48 bytes SHA-384>',
     "pcr1": h'<48 bytes SHA-384>',
     "pcr2": h'<48 bytes SHA-384>',
     "measurement_type": "nitro-pcr"
   },
   -65544: "policy-2026.02",                    / policy_version /
   -65545: 1,                                   / sequence_number /
   -65546: 77,                                  / execution_time_ms /
   -65547: 0,                                   / memory_peak_mb /
   -65548: "FullAttestation"                    / security_mode /
 }

   Verification with the corresponding Ed25519 public key succeeds
   through all four layers.

13.2.  Invalid Receipt Categories

   The specification includes 8 invalid golden vectors covering failure
   modes across all verification layers:












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        +========================+=======+========================+
        | Vector                 | Layer | Expected Failure       |
        +========================+=======+========================+
        | wrong-key              | L2    | SIG_FAILED             |
        +------------------------+-------+------------------------+
        | wrong-alg              | L1    | BAD_ALG                |
        +------------------------+-------+------------------------+
        | zero-model-hash        | L3    | ZERO_MODEL_HASH        |
        +------------------------+-------+------------------------+
        | bad-measurement-length | L3    | BAD_MEASUREMENT_LENGTH |
        +------------------------+-------+------------------------+
        | nonce-mismatch         | L4    | NONCE_MISMATCH         |
        +------------------------+-------+------------------------+
        | model-hash-mismatch    | L4    | MODEL_HASH_MISMATCH    |
        +------------------------+-------+------------------------+
        | platform-mismatch      | L4    | PLATFORM_MISMATCH      |
        +------------------------+-------+------------------------+
        | stale-iat              | L4    | TIMESTAMP_STALE        |
        +------------------------+-------+------------------------+

                                  Table 7

   Complete vector files (JSON with hex-encoded COSE bytes, expected
   failure codes, and policy overrides) are available in the reference
   implementation repository.

14.  References

14.1.  Normative References

   [FIPS180-4]
              National Institute of Standards and Technology, "Secure
              Hash Standard (SHS)", August 2015,
              <https://csrc.nist.gov/publications/detail/fips/180/4/
              final>.

   [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/rfc/rfc2119>.

   [RFC8032]  Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
              Signature Algorithm (EdDSA)", RFC 8032,
              DOI 10.17487/RFC8032, January 2017,
              <https://www.rfc-editor.org/rfc/rfc8032>.






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   [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/rfc/rfc8174>.

   [RFC8392]  Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
              "CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
              May 2018, <https://www.rfc-editor.org/rfc/rfc8392>.

   [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/rfc/rfc8610>.

   [RFC8949]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/rfc/rfc8949>.

   [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/rfc/rfc9052>.

   [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/rfc/rfc9334>.

   [RFC9711]  Lundblade, L., Mandyam, G., O'Donoghue, J., and C.
              Wallace, "The Entity Attestation Token (EAT)", RFC 9711,
              DOI 10.17487/RFC9711, April 2025,
              <https://www.rfc-editor.org/rfc/rfc9711>.

14.2.  Informative References

   [I-D.messous-eat-ai]
              Messous, A., Morand, L., and P. C. Liu, "Entity
              Attestation Token (EAT) Profile for Autonomous AI Agents",
              2026.

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,
              <https://www.rfc-editor.org/rfc/rfc7942>.






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   [RFC9782]  Lundblade, L., Birkholz, H., and T. Fossati, "Entity
              Attestation Token (EAT) Media Types", RFC 9782,
              DOI 10.17487/RFC9782, May 2025,
              <https://www.rfc-editor.org/rfc/rfc9782>.

   [SCITT]    "Supply Chain Integrity, Transparency and Trust (SCITT)",
              n.d., <https://datatracker.ietf.org/wg/scitt/about/>.

Appendix A.  Full CDDL Schema

   This appendix reproduces the complete CDDL schema from Section 4.5
   for convenience.

   ; Attested Inference Receipt (AIR) v1 -- CDDL Schema
   ; Status: v1.0 FROZEN
   ; References: RFC 9052, RFC 8392, RFC 9711, RFC 8949, RFC 8610

   air-receipt = #6.18([
     protected:   bstr .cbor air-protected-header,
     unprotected: air-unprotected-header,
     payload:     bstr .cbor air-claims,
     signature:   bstr .size 64
   ])

   air-protected-header = {
     1 => -8,          ; alg: EdDSA (Ed25519)
     3 => 61,          ; content type: application/cwt
   }

   air-unprotected-header = {
     ? 4 => bstr,      ; kid: key identifier (reserved)
   }

   air-claims = {
     ; --- Standard CWT/EAT claims ---
     1   => tstr,                  ; iss: issuer
     6   => uint,                  ; iat: issued-at (Unix seconds)
     7   => bstr .size 16,         ; cti: CWT ID (UUID v4, 16 bytes)
     265 => "https://spec.cyntrisec.com/air/v1",  ; eat_profile
     ? 10 => bstr,                 ; eat_nonce (optional)

     ; --- AIR private claims ---
     -65537 => tstr,               ; model_id
     -65538 => tstr,               ; model_version
     -65539 => sha256-hash,        ; model_hash
     -65540 => sha256-hash,        ; request_hash
     -65541 => sha256-hash,        ; response_hash
     -65542 => sha256-hash,        ; attestation_doc_hash



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     -65543 => enclave-measurements, ; enclave_measurements
     -65544 => tstr,               ; policy_version
     -65545 => uint,               ; sequence_number
     -65546 => uint,               ; execution_time_ms
     -65547 => uint,               ; memory_peak_mb
     -65548 => tstr,               ; security_mode

     ; --- Optional claims (v1.0) ---
     ? -65549 => tstr,             ; model_hash_scheme
   }

   sha256-hash = bstr .size 32
   sha384-hash = bstr .size 48

   enclave-measurements = nitro-measurements / tdx-measurements

   nitro-measurements = {
     "pcr0"             => sha384-hash,
     "pcr1"             => sha384-hash,
     "pcr2"             => sha384-hash,
     ? "pcr8"           => sha384-hash,
     "measurement_type" => "nitro-pcr",
   }

   tdx-measurements = {
     "pcr0"             => sha384-hash,   ; MRTD
     "pcr1"             => sha384-hash,   ; RTMR0
     "pcr2"             => sha384-hash,   ; RTMR1
     "measurement_type" => "tdx-mrtd-rtmr",
   }

Appendix B.  Golden Vector Summary

   The reference implementation includes 10 golden test vectors (2
   valid, 8 invalid) generated with a deterministic Ed25519 key pair:

   *  Seed:
      2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a2a

   *  Public key:
      197f6b23e16c8532c6abc838facd5ea789be0c76b2920334039bfa8b3d368d61

   Vectors are JSON files containing the COSE_Sign1 bytes (hex-encoded),
   expected verification outcomes, and policy overrides for Layer 4
   tests.  They are available in the repository under vectors/.

   Valid vectors:




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   *  v1-nitro-no-nonce.json: Nitro measurements, no eat_nonce
      (canonical golden vector).

   *  v1-tdx-with-nonce.json: TDX measurements, with eat_nonce (tests
      nonce binding and TDX measurement variant).

   Invalid vectors exercise specific failure modes across all four
   verification layers:

   *  v1-wrong-key.json (L2: SIG_FAILED)

   *  v1-wrong-alg.json (L1: BAD_ALG)

   *  v1-zero-model-hash.json (L3: ZERO_MODEL_HASH)

   *  v1-bad-measurement-length.json (L3: BAD_MEASUREMENT_LENGTH)

   *  v1-nonce-mismatch.json (L4: NONCE_MISMATCH)

   *  v1-model-hash-mismatch.json (L4: MODEL_HASH_MISMATCH)

   *  v1-platform-mismatch.json (L4: PLATFORM_MISMATCH)

   *  v1-stale-iat.json (L4: TIMESTAMP_STALE)

Acknowledgments

   The author thanks the RATS working group for the foundational
   architecture ([RFC9334]), the EAT editors for the profiling framework
   ([RFC9711]), and the COSE editors for the signing structures
   ([RFC9052]).  The measurement of confidential computing overhead
   referenced in this document was performed on AWS Nitro Enclaves and
   GCP Confidential Space (Intel TDX).

Author's Address

   Borys Tsyrulnikov
   Cyntrisec
   Email: borys@cyntrisec.com












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