# Genesis402 Signed Proof Receipt

> Genesis402 Signed Proof Receipt is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.25/call, status unknown (last checked 2026-10-02).

Generates a cryptographically signed proof receipt attesting that a specific text, claim, or content hash existed at a given time, anchored to the Genesis402/UnyKorn operator network

## Facts

- Endpoint: POST https://twin.unykorn.org/prove?utm_source=zero.xyz
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/genesis402-signed-proof-receipt-3f064e94
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VBKf3hFmfF5KOwf8jo5I4

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 genesis402-signed-proof-receipt-3f064e94 -d '<json body>'
```

Example prompt: Create a signed proof receipt for the claim 'I published the whitepaper titled Decentralized Trust Framework on 2025-06-01' under the subject 'alice@example.com', and include the SHA-256 hash a3f1c2e4b5d6789012345678abcdef1234567890abcdef1234567890abcdef12.

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-use cryptographic proof-of-existence or attestation receipt without setting up a blockchain wallet or smart contract. It is ideal for agents that need to certify claims, timestamps, or document hashes on behalf of users in compliance, legal, or provenance workflows. Prefer it over general notary services when the x402 micropayment model fits your agent's payment infrastructure and you need a structured machine-readable receipt.

## Known failure modes

- Text exceeds 16,384 character limit — request rejected with validation error
- SHA-256 hash does not match the 64-character hex pattern — schema validation failure
- Claim string exceeds 512 character limit — truncation or rejection
- Subject string exceeds 200 character limit — validation error
- Payment not completed or x402 payment header missing/invalid — 402 Payment Required response
- Operator network unavailable — 503 or timeout with no receipt issued
- Duplicate submission may produce a distinct receipt with a different timestamp, not idempotent

## How this service works

Signed proof receipt (genesis402-receipt-v1) — Genesis402 / UnyKorn Operator Network

## Output

A signed proof receipt (genesis402-receipt-v1) containing a cryptographic attestation from the UnyKorn Operator Network, confirming the existence and content of the submitted text, claim, and/or SHA-256 hash at the time of the call, bound to the provided subject identifier. The receipt serves as a verifiable, tamper-evident record.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "params": {
   "type": "object",
   "properties": {
    "text": {
     "type": "string",
     "maxLength": 16384
    },
    "claim": {
     "type": "string",
     "maxLength": 512
    },
    "sha256": {
     "type": "string",
     "pattern": "^[0-9a-f]{64}$"
    },
    "subject": {
     "type": "string",
     "maxLength": 200
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "type": "prove",
  "verify": {
   "keys": "/prove/keys",
   "source": "https://github.com/FTHTrading/402-truth"
  },
  "receipt": {
   "tx_hash": "0x<64hex>",
   "amount_usd": 0.25,
   "receipt_id": "g402-<16hex>"
  },
  "proofReceipt": {
   "issuer": {
    "alg": "ed25519",
    "keyId": "g402-key-<16hex>"
   },
   "receiptId": "g402_rcpt_<12hex>",
   "truthLabels": [
    "ATTESTED",
    "VERIFIED"
   ],
   "receiptVersion": "genesis402-receipt-v1"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/genesis402-signed-proof-receipt-3f064e94/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from twin.unykorn.org](https://www.zero.xyz/host/twin.unykorn.org/llms.txt)