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x402 Offer Replay Hygiene Auditor
x402
x402 Offer Replay Hygiene Auditor is a paid API for AI agents from api.blockchainmoneymap.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-02).
Audits an x402 payment offer for replay hygiene by comparing its facts against a reference offer and validating fields like nonce, signature, validity window, and payment details.
Price / call$0.01
Success—
StatusUnknown
How this service works
Choose Blockchain Money Map for human-readable public blockchain reports, x402-paid agent API services, agent workflow packs, custom agent builds, or an Agent Radar pilot preview.
Output
A JSON object containing the audit outcome, including whether the x402 offer passes replay hygiene checks, any detected field mismatches between the offer and reference, flags for missing or invalid nonce/signature/validity-window fields, and an overall hygiene assessment indicating whether the offer is safe to process or potentially replayed.
Example use cases
Detect replayed x402 micropayment offer
“I received what looks like a duplicate x402 payment offer — pay_to 0xDEF456, amount 0.01 USDC on base-mainnet, valid_from 2024-06-01T10:00:00Z to valid_until 2024-06-01T10:05:00Z, nonce present, signature present, scheme x402. Compare it against the original offer I saw yesterday with the same pay_to and amount but a different valid_until, and tell me if this is a replay attack.”
Validate nonce and signature hygiene before payment
“Before my agent pays this x402 offer, audit it for replay hygiene: pay_to 0x111AAA, amount 0.05, currency USDC, network ethereum, valid_from 2024-07-15T08:00:00Z, valid_until 2024-07-15T09:00:00Z, nonce is present, signature is present, scheme x402 — no reference offer needed, just check if the fields look clean.”
Cross-check two x402 offers for duplication
“Can you compare these two x402 offers to see if one is a replay of the other? Current offer: pay_to 0xCAFEBABE, amount 1.00, currency USDC, network base-mainnet, valid_from 2024-08-01T00:00:00Z, valid_until 2024-08-01T01:00:00Z, nonce present, signature present, scheme x402. Reference offer: same pay_to and amount, but valid_until is 2024-08-01T00:45:00Z and the resource hash is sha256:a3f1c2d4e5b6789012345678901234567890123456789012345678901234abcd.”
Technical details
Endpoint
POSThttps://api.blockchainmoneymap.com/api/x402/x402-offer-replay-hygiene-auditor?utm_source=zero.xyzWhen to prefer
Use this endpoint when your agent needs to programmatically verify that an x402 payment offer has not been replayed or tampered with before processing payment — especially when you have a reference offer to compare against. Prefer this over manual field comparison when operating in automated agent pipelines where replay attacks on micropayment offers are a security concern.
Side effects
- Missing required fields in facts object returns a validation error
- Invalid resource_hash format (not matching sha256:[64 hex chars]) causes schema rejection
- Mismatched network or currency between facts and reference_facts may flag false positives if intentional
- Mode must be set to 'audit' or the request will be rejected
- Expired or future-dated valid_from/valid_until values may cause hygiene failures
- Payment via x402 fails if USDC balance is insufficient
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| mode | — | |
| facts | object | |
| policy | object | |
| reference_facts | object |
Output
Schema · Response
{
"type": "json"
}Tags
x402
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