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Single-Use Cryptographic Attestation Seal
x402
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.
Price / call$0.05
Success—
StatusUnknown
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.
Example use cases
Sealing an agent-generated research report
“Generate a single-use cryptographic seal for attestation ID 'research-yield-analysis-007' issued to 'dao-treasury-agent', valid for 7200 seconds, so the DAO can verify that research report came from our agent and wasn't tampered with before they act on it.”
Proving task completion for a smart contract
“I need a tamper-evident seal for deliverable 'contract-audit-v2' issued to 'settlement-escrow-agent', with a TTL of 1800 seconds — the escrow won't release funds until the counterparty checks this cryptographic proof that we produced the audit.”
Non-repudiable proof for a hired agent's output
“Issue a single-use seal for attestation ID 'due-diligence-run-42' issued to 'client-review-agent', valid for 86400 seconds, so my client has an independent cryptographic receipt proving my agent produced that due diligence report at this exact time.”
Technical details
Endpoint
POSThttps://api.craigmbrown.com/v1/services/attestation.single-use-sealWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| issued_to | string | |
| ttl_seconds | integer | |
| attestation_id | string |
Output
Schema · Response
{
"type": "json",
"schema": {
"type": "object",
"properties": {
"seal": {
"type": "object"
},
"redeem_hint": {
"type": "string"
},
"attestation_id": {
"type": "string"
}
}
},
"example": {
"seal": {}
}
}Tags
x402
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