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AttestPage SHA-256 Timestamping Service
x402
AttestPage SHA-256 Timestamping Service is a paid API for AI agents from s2h6qt73jtzlgbgnnfacln2poq.srv.us, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-17).
Creates a signed, timestamped cryptographic receipt for a SHA-256 hash, proving a file or record existed unchanged at a specific point in time
Price / call$0.002
Success—
StatusUnknown
How this service works
Signs a timestamped receipt for a file's sha256, proving it existed unchanged then. US$0.002 per call; POST the hash.
Output
A signed, timestamped cryptographic receipt confirming that the submitted SHA-256 hash was attested at a specific moment in time. The receipt is verifiable: any future version of the file that produces a different hash will not match, proving tampering or alteration. With an idempotency key, retrying the same hash returns the identical original receipt rather than creating a new record.
Example use cases
Audit trail for AI-generated answers
“I need a tamper-proof timestamped receipt for this AI response before I send it to the client — here's the SHA-256: a3f1c2d4e5b6789012345678abcdef0123456789abcdef0123456789abcdef01. Add the note 'AI legal memo draft v1 sent to Acme Corp'.”
Prove software build integrity
“We're shipping version 2.4.1 of our firmware today — can you create an attestation receipt for this build hash b94d27b9934d3e08a52e52d7da7dabfac484efe04f8c8b4b5c1c4c3d2e1f0a9b with the note 'firmware-v2.4.1 release build'?”
Legal document existence proof
“I need to prove this signed contract existed before the deadline — please timestamp the SHA-256 hash 0f1e2d3c4b5a6978abcdef0123456789abcdef0123456789abcdef0123456789 with the note 'NDA signed by both parties prior to merger announcement'.”
Technical details
Endpoint
POSThttps://s2h6qt73jtzlgbgnnfacln2poq.srv.us/v1/attest?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need cryptographic, verifiable proof that a specific file, record, or piece of data existed unchanged at a given point in time — without revealing the content itself (only the hash is submitted). Prefer this over simple database logging when the proof needs to be independently verifiable and tamper-evident. Use /v1/fetch instead when you need to attest what a live web page said at a given time, as that endpoint captures and hashes the page contents itself.
Side effects
- Invalid SHA-256 format (not 64 hex characters) returns a 400 error
- Idempotency key used with a different sha256 than the original returns 409 Conflict
- Idempotency key used outside of x402 payment context returns 400
- Payment not completed or insufficient funds prevents attestation
- Note exceeds 280 character limit returns validation error
- Network timeout or service unavailability returns 5xx error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| note | string | Optional note; only its SHA-256 goes in the receipt. |
| sha256 | string | SHA-256 (hex) of the thing being attested. |
| idempotency_key | string | Optional, x402 payments only (keys are scoped to the paying address; trial and L402 calls get 400). Retries with the same key and sha256 get the same attestation (the receipt names that call own payment tx); a different sha256 gets 409. |
Tags
x402
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