> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mnemom.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Attestation Token Schema

> Canonical wire format for AAP attestation tokens (v1). JWS Compact serialization, EdDSA-signed payload conforming to mnemom-contracts/attestation-token/v1.yaml.

The canonical wire format for [AAP attestation tokens](/concepts/aap-attestation). Mirrors [`mnemom-contracts/attestation-token/v1.yaml`](https://github.com/mnemom/mnemom-contracts/blob/main/attestation-token/v1.yaml).

## Envelope

JWS Compact Serialization (RFC 7515):

```
<base64url(header)>.<base64url(payload)>.<base64url(signature)>
```

## Header

Fixed shape:

```json theme={null}
{
  "alg": "EdDSA",
  "kid": "<key_id>",
  "typ": "AAP-Attestation/v1"
}
```

| Field | Constraint                                                                                                |
| ----- | --------------------------------------------------------------------------------------------------------- |
| `alg` | Always `"EdDSA"` (Ed25519).                                                                               |
| `kid` | Key identifier; matches a `kid` in [`/v1/.well-known/jwks.json`](/concepts/aap-attestation#verification). |
| `typ` | Always `"AAP-Attestation/v1"`. Mirrored in the payload for defense-in-depth.                              |

## Payload

JSON object conforming to JSON Schema 2020-12. All required fields below; `additionalProperties: false`.

| Field               | Type                               | Required | Description                                                                                                                        |
| ------------------- | ---------------------------------- | -------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| `typ`               | const `"AAP-Attestation/v1"`       | yes      | Mirrors the header `typ`.                                                                                                          |
| `iss`               | string (URI)                       | yes      | Issuer — always `https://mnemom.ai` for production. Verifiers reject other issuers.                                                |
| `sub`               | string                             | yes      | Subject — the Mnemom `agent_id` (e.g., `smolt-e2ca60ef`).                                                                          |
| `iat`               | integer (Unix seconds)             | yes      | Issued-at, UTC. Verifiers reject `iat > now() + clock_skew_grace` (default 60s).                                                   |
| `exp`               | integer (Unix seconds)             | yes      | Expiry, UTC. Default TTL is `iat + 3600` (1 hour).                                                                                 |
| `content_hash`      | string (`^[0-9a-f]{64}$`)          | yes      | SHA-256 hex of the canonical card body at attestation time.                                                                        |
| `version`           | integer (≥ 1)                      | yes      | Monotone canonical-card version at attestation time.                                                                               |
| `composed_at`       | string (date-time)                 | yes      | ISO-8601 UTC timestamp at which the canonical card was composed.                                                                   |
| `card_kind`         | enum `"alignment" \| "protection"` | yes      | Which canonical card the token attests to.                                                                                         |
| `smolt_id`          | string (`^smolt-[a-z0-9]+$`)       | no       | Optional convenience claim for consumers binding on smolt-id.                                                                      |
| `historic_backfill` | const `true`                       | no       | Present (and only `true`) on tokens minted by the one-shot backfill script for canonical cards that pre-date the transparency log. |

## Signature

Ed25519 signature over the byte string `<base64url(header)>.<base64url(payload)>`. Base64url-encoded; **no padding**, **no whitespace**, **no line wrapping** (per RFC 7515 §3.1).

## Beyond expiry

Tokens are short-lived. After `exp`, the embedded token is no longer cryptographically valid for new use, but the [transparency log](/concepts/transparency-log) preserves it indefinitely. Consumers wanting to verify a historic posture query the log via `mnemom verify-card --at <ISO>`; the JWS inside the log row continues to verify against the JWKS as long as the signing key remains in the JWKS (active or retired-within-window).

## Editorial source

Schema authored at [`mnemom-contracts/attestation-token/v1.yaml`](https://github.com/mnemom/mnemom-contracts/blob/main/attestation-token/v1.yaml). Runtime consumers:

* [`mnemom-api/src/attestation/signer.ts`](https://github.com/mnemom/mnemom-api/blob/main/src/attestation/signer.ts) — issuer
* [`mnemom-api/src/attestation/verifier.ts`](https://github.com/mnemom/mnemom-api/blob/main/src/attestation/verifier.ts) — server-side verifier
* [`mnemom-platform/cli/src/commands/verify-card.ts`](https://github.com/mnemom/mnemom-platform/blob/main/cli/src/commands/verify-card.ts) — offline verifier CLI

## See also

* [AAP attestation concept](/concepts/aap-attestation)
* [Transparency log schema](/specifications/transparency-log-schema)
* [`mnemom verify-card` guide](/guides/verify-card)