# Agent Embassy Document Certification

> Agent Embassy Document Certification is a paid API for AI agents from aemb.pro, paid per call via x402, $0.25/call, status unknown (last checked 2026-10-12).

Certifies a document hash on-chain with a cryptographic receipt, proving an agent performed an action at a specific time without revealing document contents.

## Facts

- Endpoint: POST https://aemb.pro/v1/cert?utm_source=zero.xyz
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent-embassy-document-certification-16a96556
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_nYcc_arafMb-mUdzGPMKc

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 agent-embassy-document-certification-16a96556 -d '<json body>'
```

Example prompt: Certify this document hash for me — SHA256 is `a3f1b2c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5e6f7a8b9c0d1e2`, label it 'Q2 financial report', and use idempotency key `550e8400-e29b-41d4-a716-446655440000` so I get a verifiable receipt proving it existed right now.

## When to prefer this

Choose this endpoint when an AI agent needs cryptographic proof that a specific document or artifact existed and was certified at a precise point in time — without revealing the document itself. Ideal for audit trails, compliance workflows, agent accountability, and provenance tracking where privacy matters. The idempotency mechanism makes it safe to replay in unreliable networks. Prefer over generic blockchain notarization when you need a structured receipt with chain-of-custody metadata and x402 micropayment-native billing.

## Known failure modes

- Invalid SHA256 hash (not 64 lowercase hex chars) — rejected with validation error
- Idempotency key reuse with published/known example key — rejected as invalid
- Duplicate idempotency key returns original receipt unchanged, not an error
- Payment failure via x402 protocol — 402 response, no receipt issued
- Document name exceeding 200 characters — validation error
- Malformed UUID v4 idempotency key — rejected

## How this service works

Agents pay for work and prove what happened.

## Output

Returns a JSON receipt containing: a unique receipt ID (e.g. `emb_9f8e7d6c5b4a`), certification status (`certified`), the payer's account address, receipt version (`embassy-receipt/2`), and a chain-of-custody array documenting the full lifecycle — request, authorization, action, proof, and liability boundary — providing cryptographic proof that the document hash was recorded at a specific point in time.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "document_hash": {
   "type": "string",
   "description": "SHA256 hash of your document as 64 lowercase hex characters. We never see the document itself."
  },
  "document_name": {
   "type": "string",
   "description": "Optional label for your document (max 200 chars), recorded on the receipt"
  },
  "idempotency_key": {
   "type": "string",
   "description": "Idempotency key: UUID v4, client-generated, one per logical request. Replaying the same key on this tool returns the original receipt — the action is not re-run, and the first request's receipt wins even if you resend different inputs. Published example keys are rejected. Keys are scoped per tool and per payer account: a key never returns another wallet's receipt."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "tool": "cert",
  "chain": [
   "request",
   "authorization",
   "action",
   "proof",
   "liability_boundary"
  ],
  "status": "certified",
  "account": "0x1111111111111111111111111111111111111111",
  "receipt_id": "emb_9f8e7d6c5b4a",
  "receipt_version": "embassy-receipt/2"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent-embassy-document-certification-16a96556/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from aemb.pro](https://www.zero.xyz/host/aemb.pro/llms.txt)