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An AAP attestation token is a Mnemom-signed JWS (JSON Web Signature) committing to a canonical card’s identity tuple — (agent_id, content_hash, version, composed_at, card_kind). Any consumer holding the public key from <api>/v1/.well-known/jwks.json can verify it offline, without ever holding a Mnemom credential. The attestation is the cryptographic glue between three Phase 5 surfaces:

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Wire format

JWS Compact Serialization (RFC 7515):

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What it commits to

The payload binds the identity. A change to any of these fields produces a different attestation: The token doesn’t carry the card body — consumers fetch the body separately (via /v1/agents/{id}/a2a-agent-card or GET /v1/agents/{id}/state) and check the body’s content_hash matches the attestation’s content_hash.

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Verification

The full verification flow (mnemom verify-card executes this for you):
  1. Fetch <iss>/v1/.well-known/jwks.json.
  2. Locate the key with kid matching the token’s header.
  3. Verify the Ed25519 signature.
  4. Check iss matches the expected issuer (https://mnemom.ai for production).
  5. Check now() < exp (the verifier may apply a small clock-skew grace; default 60 seconds).
  6. Check the canonical card body’s content_hash matches the attestation’s content_hash.
If you’d benefit from a code reference, the runtime verifier lives at mnemom-api/src/attestation/verifier.ts and the CLI verifier at mnemom-platform/cli/src/commands/verify-card.ts.

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Key rotation + JWKS lifetime

The JWKS includes the active key plus recently-retired keys still inside their verification window. Once the retirement window plus the token-TTL plus a small grace has elapsed, the retired key drops out of the JWKS. AAP signing-key rotation is a Mnemom-platform operation, performed by Mnemom staff on a scheduled cadence (and on demand for incident response) — it is not a customer- or operator-callable endpoint. You don’t rotate the platform’s AAP signing keys yourself; the rotation, retirement window, and key publication are managed for you. What you can rely on: the retired key remains verifiable for any token signed before its retired_at timestamp, and the current public keys are always discoverable from the published JWKS. (To rotate your own agent’s API key — a different operation — see Agent key rotation.)

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Relationship to the transparency log

Tokens are short-lived (1-hour TTL by default). The durable record is the transparency log: every canonical card identity ever composed has a row in card_attestations with the full signed token + a Merkle inclusion proof. Beyond the token’s expiry, consumers query the log — not the token.

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See also