# FractalAI x402 Seal — Post-Quantum Provenance Attestation

> FractalAI x402 Seal — Post-Quantum Provenance Attestation is a paid API for AI agents from fractalai.net.co, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-13).

Creates a post-quantum cryptographic provenance seal (Dilithium/ML-DSA) over content, optionally anchored on-chain, with drand-sourced randomness for timestamping.

## Facts

- Endpoint: POST https://fractalai.net.co/api/x402/seal
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fractalai-x402-seal-post-quantum-provenance-attestation-41ad9851
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_b1s3_iomlNbqEAuD59HAX

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability fractalai-x402-seal-post-quantum-provenance-attestation-41ad9851 -d '<json body>'
```

Example prompt: Create a post-quantum provenance seal for my document — I need an offline-verifiable ML-DSA-65 signature with a drand timestamp and an on-chain anchor so I can prove this content existed right now without relying on any central authority.

## When to prefer this

Choose this endpoint when you need post-quantum resistant content attestation with public verifiability via drand randomness, especially when offline verification (no callback to any server) is required. Prefer over traditional SHA/ECDSA timestamping when quantum-attack resistance is a concern, when you need both a chain anchor and an offline-verifiable signature in a single call, or when your compliance framework requires NIST FIPS 204 (ML-DSA) signatures.

## Known failure modes

- Payment not settled — x402 payment flow incomplete, returns 402 with payment requirements
- Content too large or malformed — seal generation fails
- drand network unavailable — randomness round cannot be fetched, seal may be delayed
- On-chain anchoring unavailable — anchor field returns advisory note but seal remains valid
- Signature verification failure on client side — must use exact signed_message bytes, not reconstructed
- Invalid public key format — base64 decoding errors for ML-DSA-65 key (1952 bytes expected)

## How this service works

The first AI-native Layer 1 blockchain built from scratch in Rust. Post-quantum cryptography (CRYSTALS-Dilithium), Proof of Fractal Work consensus, WASM smart contracts, and 460+ RPC endpoints. Mine FRAC tokens with fractal analysis instead of hash puzzles.

## Output

Returns a JSON object containing: a provenance 'seal' object with version, content_hash, drand_round, drand_randomness, sealed_at timestamp, algorithm, base64-encoded Dilithium-2 signature, and public key; an optional on-chain 'anchor' with attestation_hash, block_number, and permalink; a 'served_signature' with an offline-verifiable ML-DSA-65 (NIST FIPS 204) signature, its public key, and the exact signed_message bytes; a 'payment' settlement receipt; and a 'verify_drand_at' URL for independently re-checking the drand round.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "kind": {
   "type": "string",
   "description": "Optional provenance kind: \"dataset\" | \"training\" | \"content\" (informational label recorded in the seal)."
  },
  "anchor": {
   "type": "boolean",
   "description": "Optional (default true): also anchor the seal hash on-chain (VAID-1) for a public, tamper-evident record. Failure to anchor never fails the seal."
  },
  "issuer": {
   "type": "string",
   "description": "Optional declaring party (recorded, informational)."
  },
  "content": {
   "type": "string",
   "description": "Arbitrary UTF-8 content to seal; we seal sha256(content). Provide content OR content_hash."
  },
  "content_hash": {
   "type": "string",
   "description": "A sha256 hex digest you already computed (e.g. of a dataset or training artifact); sealed as-is. Privacy-preserving — the content never leaves you."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "schema": {
  "type": "object",
  "required": [
   "seal"
  ],
  "properties": {
   "seal": {
    "type": "object",
    "description": "The re-verifiable provenance seal: { version, content_hash, drand_round, drand_randomness, sealed_at, algorithm, signature (base64 Dilithium-2), public_key }."
   },
   "anchor": {
    "type": "object",
    "description": "On-chain anchor receipt (attestation_hash, block_number, permalink) or a note if anchoring was unavailable. Advisory — the seal is valid without it. The anchor is Dilithium-2 (ML-DSA-44), bound to the node."
   },
   "payment": {
    "type": "object",
    "description": "Settlement receipt (scheme, network, asset, txHash, payer, settled)."
   },
   "verify_drand_at": {
    "type": "string",
    "description": "URL to independently re-check the drand round on drand.sh."
   },
   "served_signature": {
    "type": "object",
    "description": "Self-contained, OFFLINE-verifiable Dilithium-3 / ML-DSA-65 (NIST FIPS 204) signature over the canonical seal bytes: { algorithm: \"ml-dsa-65\", algorithm_label, digest (sha256 hex signed), signature (base64 ML-DSA-65, 3309 bytes), public_key (base64, 1952 bytes), signed_message (the EXACT UTF-8 bytes signed = \"FRACTALAI-x402-served-v1\\nx402-seal\\n<digest>\", route-separated, 3 lines) }. Additive — verify with ml_dsa65.verify(b64(signature), utf8(signed_message), b64(public_key)); pass signed_message verbatim, do not reconstruct it."
   }
  }
 },
 "example": {
  "seal_id": "…",
  "permalink": "https://fractalai.net.co/attestation/0x…",
  "attestation_hash": "0x…",
  "served_signature": {
   "algorithm": "ml-dsa-65"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fractalai-x402-seal-post-quantum-provenance-attestation-41ad9851/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fractalai.net.co](https://www.zero.xyz/host/fractalai.net.co/llms.txt)