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EIP-191 Ethereum Message Hash (personal_sign digest)
x402
EIP-191 Ethereum Message Hash (personal_sign digest) is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-01).
Computes the EIP-191 prefixed hash of a message string — the exact digest that Ethereum wallets sign during personal_sign
Price / call$0.001
Success—
StatusUnknown
How this service works
EIP-191 digest of a message (what personal_sign actually signs) — Genesis402 / UnyKorn Operator Network
Output
Returns a JSON object confirming success, the type field 'eth-message-hash', and the computed EIP-191 digest (the keccak256 hash of the '\x19Ethereum Signed Message:\n{len}{message}' prefixed payload), along with a payment receipt including transaction hash, USD amount, and receipt ID.
Example use cases
Verify off-chain signature authenticity
“I need to verify that a user actually signed my login challenge message. Can you compute the EIP-191 personal_sign hash for 'Login to MyApp: nonce=7f3a9c' so I can compare it against the signature they submitted?”
Debug Ethereum signing flow
“My dApp's signature verification is failing — what EIP-191 hash does personal_sign actually produce for the message 'Authorize withdrawal of 100 USDC on 2024-06-01'? I want to check if my backend is computing it correctly.”
Prepare message digest for smart contract
“I'm writing a smart contract that checks personal_sign signatures. Can you give me the EIP-191 prefixed hash for the string 'Transfer approved: user=0xABCD, amount=500' so I can hardcode the expected digest in my test?”
Technical details
Endpoint
POSThttps://twin.unykorn.org/eth-message-hash?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need to reproduce or verify the exact hash that an Ethereum wallet computes during a personal_sign (eth_sign) operation — without running a local Ethereum node or wallet. Ideal for off-chain signature verification, backend authentication systems, smart contract testing, and debugging signing flows where you need to confirm the prefixed keccak256 digest independently.
Side effects
- Message exceeds 49152 character limit — request rejected
- Malformed JSON body or missing message field — 400 error
- Payment not received or insufficient — 402 error
- Service unavailable on the UnyKorn network — 503 or timeout
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| params | object |
Output
Schema · Response
{
"type": "json",
"example": {
"ok": true,
"type": "eth-message-hash",
"receipt": {
"tx_hash": "0x<64hex>",
"amount_usd": 0.001,
"receipt_id": "g402-<16hex>"
},
"generated_at": "<iso8601>"
}
}Tags
x402
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