# AOTrust Time Attestation

> AOTrust Time Attestation is a paid API for AI agents from api.aotrust.link, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-30).

Creates a cryptographically signed timestamp bound to a SHA-256 payload hash, anchored in a cumulative Merkle log for tamper-evident proof of existence at a point in time.

## Facts

- Endpoint: POST https://api.aotrust.link/v1/attest/time?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/aotrust-time-attestation-c0cc364b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_P86pw3jRRbHO7HOlQXeaH

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 aotrust-time-attestation-c0cc364b -d '<json body>'
```

Example prompt: I need a signed time attestation anchoring this SHA-256 hash to the AOTrust Merkle log to prove it existed right now: a3f1c2d4e5b6789012345678901234567890abcdef1234567890abcdef123456.

## When to prefer this

Choose this endpoint when you need a lightweight, low-cost cryptographic proof that a specific payload hash existed at a known point in time, anchored in a verifiable Merkle log. Prefer it over blockchain-based timestamping when you want fast, cheap attestation without full on-chain transaction overhead, and when you plan to retrieve a full evidence bundle (PDR + inclusion proof) later via the sibling AOTrust Evidence Bundle endpoint.

## Known failure modes

- Invalid payload_hash format (not 64 lowercase hex characters) — returns 400 validation error
- Payment failure or insufficient USDC balance — returns 402 Payment Required
- Rate limiting or quota exceeded — returns 429 Too Many Requests
- Merkle log anchor service temporarily unavailable — returns 503
- Duplicate hash submission may return the same or a new attestation depending on policy

## How this service works

Signed time attestation: timestamp bound to a payload hash, anchored in the cumulative Merkle log

## Output

A signed time attestation object containing the timestamp bound to the submitted payload hash, a cryptographic signature, and an anchor reference in AOTrust's cumulative Merkle log — enabling third-party verification that the hash existed at that moment in time.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "payload_hash": {
   "type": "string",
   "pattern": "^[0-9a-f]{64}$",
   "description": "sha256 hex of the payload"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/aotrust-time-attestation-c0cc364b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.aotrust.link](https://www.zero.xyz/host/api.aotrust.link/llms.txt)