{"uid":"cap_0bToKKn0kMhQpNcYhc6Zk","slug":"signalharness-eip-191-message-hash-972e76a5","name":"SignalHarness EIP-191 Message Hash","description":"Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.","url":"https://signalharness.ai/api/agent/services/message_hash_eip191/invoke","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"message_hash_request":{"type":"string","maxLength":65536,"minLength":2}}},"responseSchema":{"type":"json","example":{"replay":false,"result":{"warnings":["Hashing does not sign or prove authorship."],"service_id":"message_hash_eip191","message_hash":"{\"encoding\":\"utf8\",\"hash\":\"0x43c3ce76740c0da4b23274e62f830220acfc4cb8d66dc3c373c6f58db8620442\"}","evidence_scope":"caller_supplied_data"},"status":"succeeded","receipt":{"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","usage":[],"status":"succeeded","network":"eip155:8453","artifacts":[],"endedAtMs":0,"latencyMs":0,"paymentId":"example-payment","receiptId":"example-receipt","requestId":"example-request","serviceId":"message_hash_eip191","executionId":"example-execution","startedAtMs":0,"amountAtomic":"5000","resultSha256":"8f11719349cff4ac11654fa2d877a1171776a9cc3eee1fc4857fac9b56d1829f","serviceVersion":"1.0.0","settlementReference":"0x0000000000000000000000000000000000000000000000000000000000000000"},"artifacts":[],"requestId":"example-request","executionId":"example-execution"}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.005","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.005/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.005","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_X9UJY57PLRmaf2omfAh7-","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.005","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Computes the EIP-191 Ethereum personal sign message hash for a given input string","exampleAgentPrompt":"Can you compute the EIP-191 personal sign hash for this message: 'Authorize wallet connection for user 0xAbC123 at timestamp 1720000000'?","exampleUseCases":[{"title":"Wallet signature verification prep","prompt":"I need the EIP-191 message hash for 'Login nonce: a3f9b2c1d4e5 for user alice@example.com' so I can verify an Ethereum wallet signature on my backend."},{"title":"Smart contract off-chain signing","prompt":"Can you hash this message using EIP-191 personal sign format: 'Approve transfer of 500 USDC to 0xDeadBeef00000000000000000000000000000000 on 2024-07-05'?"},{"title":"Auth token hash for dApp login","prompt":"Hash the string 'dapp-session:user=0x1234567890abcdef&expires=1720100000' with EIP-191 so I know what digest MetaMask will actually sign."}],"resultDescription":"Returns the EIP-191-prefixed keccak256 hash (message_hash) of the supplied input string, along with a list of any warnings about the input, the evidence_scope indicating data provenance, a replay-detection flag, and a full execution receipt including payment ID, network (Base), amount charged in atomic USDC units, and result SHA-256 for integrity verification.","failureModes":["Input string too short (below minLength of 2) — validation error returned","Input string exceeds 65536 characters — request rejected","Malformed JSON body — HTTP 400","Payment failure or insufficient USDC balance — HTTP 402 with payment details","Service unavailable — HTTP 5xx with error message"],"whenToPreferThis":"Choose this endpoint when you need a deterministic, auditable EIP-191 personal_sign message hash computed as a paid, receipted API call with on-chain payment provenance on Base — useful when you need cryptographic evidence of what was hashed and by whom, rather than computing locally. Prefer local computation for high-volume or latency-sensitive use cases; use this when auditability, receipts, or agent-native x402 payment rails are required.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-13T13:07:10.200Z","isFirstParty":false}