The sign method calculates an Ethereum specific signature with:

sign(keccak256("\\x19Ethereum Signed Message:\\n" + len(message) + message))).

By adding a prefix to the message makes the calculated signature recognizable as an Ethereum specific signature. This prevents misuse where a malicious dapp can sign arbitrary data (e.g. transaction) and use the signature to impersonate the victim.

🚧

NOTE: the address to sign with must be unlocked.

Parameters

Typed data is a JSON object containing type information, domain separator parameters and the message object.

"params": [
    "0x0d8e461687b7d06f86ec348e0c270b0f279855f0",
    {
        "types": {
            "EIP712Domain": [
                {
                    "name": "name",
                    "type": "string"
                },
                {
                    "name": "version",
                    "type": "string"
                },
                {
                    "name": "chainId",
                    "type": "uint256"
                },
                {
                    "name": "verifyingContract",
                    "type": "address"
                }
            ],
            "Person": [
                {
                    "name": "name",
                    "type": "string"
                },
                {
                    "name": "wallet",
                    "type": "address"
                }
            ],
            "Mail": [
                {
                    "name": "from",
                    "type": "Person"
                },
                {
                    "name": "to",
                    "type": "Person"
                },
                {
                    "name": "contents",
                    "type": "string"
                }
            ]
        },
        "primaryType": "Mail",
        "domain": {
            "name": "Ether Mail",
            "version": "1",
            "chainId": 1,
            "verifyingContract": "0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC"
        },
        "message": {
            "from": {
                "name": "Cow",
                "wallet": "0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826"
            },
            "to": {
                "name": "Bob",
                "wallet": "0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB"
            },
            "contents": "Hello, Bob!"
        }
    }
]

Result

Signature. As in eth_sign it is a hex encoded 129 byte array starting with 0x. It encodes the r, s and v parameters from appendix F of the yellow paper in big-endian format. Bytes 0…64 contain the r parameter, bytes 64…128 the s parameter and the last byte the v parameter. Note that the v parameter includes the chain id as specified in EIP-155.

Example

Request

curl <your-endpoint> \
    -X POST \
    -H "Content-Type: application/json" \
    -d '{"jsonrpc":"2.0","method":"eth_sign","params":["0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826", {"types":{"EIP712Domain":[{"name":"name","type":"string"},{"name":"version","type":"string"},{"name":"chainId","type":"uint256"},{"name":"verifyingContract","type":"address"}],"Person":[{"name":"name","type":"string"},{"name":"wallet","type":"address"}],"Mail":[{"name":"from","type":"Person"},{"name":"to","type":"Person"},{"name":"contents","type":"string"}]},"primaryType":"Mail","domain":{"name":"Ether Mail","version":"1","chainId":1,"verifyingContract":"0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC"},"message":{"from":{"name":"Cow","wallet":"0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826"},"to":{"name":"Bob","wallet":"0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB"},"contents":"Hello, Bob!"}}],"id":1}'

Return

{
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x772e1f106f5333f2fc12d486057bad24145d84ae53fc44932bb5c767379a6cc412c8624af160f473403d15125cdc7b3de1129f725a71074e7eb011cc242300511b"
}