# Single-Use Cryptographic Attestation Seal

> Single-Use Cryptographic Attestation Seal is a paid API for AI agents from api.craigmbrown.com, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Issues a single-use cryptographic seal proving a specific deliverable was produced by a specific agent at a specific time and has not been altered since.

## Facts

- Endpoint: POST https://api.craigmbrown.com/v1/services/attestation.single-use-seal
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/single-use-cryptographic-attestation-seal-d849135e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_RA39zLt5JpL-3MDJzks7w

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 single-use-cryptographic-attestation-seal-d849135e -d '<json body>'
```

Example prompt: Create a single-use cryptographic seal for attestation ID 'report-2024-q4-001', issued to counterparty 'acme-corp-agent', valid for 3600 seconds, so they can independently verify this deliverable came from me and hasn't been altered.

## When to prefer this

Choose this endpoint when you need a counterparty-verifiable, tamper-evident cryptographic receipt for a specific agent-produced deliverable — especially in agentic workflows where non-repudiation, auditability, or escrow release depends on independent proof of origin and integrity. Prefer this over generic hashing or logging when the counterparty needs a self-contained, independently checkable artifact without trusting your infrastructure.

## Known failure modes

- Invalid or missing attestation_id returns an error
- TTL value out of acceptable range rejected
- issued_to field malformed or empty causes rejection
- Seal already redeemed — single-use seals cannot be reused
- Expired seal returns invalid on redemption check
- Payment failure via x402 prevents seal issuance

## How this service works

A single-use cryptographic seal proving a specific deliverable was produced by a specific agent at a specific time and has not been altered since — the receipt a counterparty can independently check.

## Output

Returns a seal object containing the cryptographic proof, a redeem_hint string explaining how the counterparty can independently verify the seal, and the attestation_id confirming which deliverable was sealed. The seal is single-use and expires after the specified TTL.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "issued_to": {
   "type": "string"
  },
  "ttl_seconds": {
   "type": "integer"
  },
  "attestation_id": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "schema": {
  "type": "object",
  "properties": {
   "seal": {
    "type": "object"
   },
   "redeem_hint": {
    "type": "string"
   },
   "attestation_id": {
    "type": "string"
   }
  }
 },
 "example": {
  "seal": {}
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/single-use-cryptographic-attestation-seal-d849135e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.craigmbrown.com](https://www.zero.xyz/host/api.craigmbrown.com/llms.txt)