eth_signTypedData_v4

Signs typed structured data according to EIP-712. This is the recommended method for signing structured data as it provides better security and user experience.

Parameters

Index	Type	Description
0	`string`	Address to sign with
1	`string`	JSON string of typed data

Returns

string - The signature (65-byte hex string)

Typed Data Structure


interface TypedData {
  types: {
    EIP712Domain: Array<{ name: string; type: string }>
    [typeName: string]: Array<{ name: string; type: string }>
  }
  primaryType: string
  domain: {
    name?: string
    version?: string
    chainId?: number
    verifyingContract?: string
    salt?: string
  }
  message: Record<string, any>
}

Example


const typedData = {
  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: 'My dApp',
    version: '1',
    chainId: 1,
    verifyingContract: '0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC'
  },
  message: {
    from: {
      name: 'Alice',
      wallet: '0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826'
    },
    to: {
      name: 'Bob',
      wallet: '0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB'
    },
    contents: 'Hello, Bob!'
  }
}
 
const signature = await window.$onekey.ethereum.request({
  method: 'eth_signTypedData_v4',
  params: [accounts[0], JSON.stringify(typedData)]
})
 
console.log('Signature:', signature)

Permit Signature (ERC-2612)


const permitData = {
  types: {
    EIP712Domain: [
      { name: 'name', type: 'string' },
      { name: 'version', type: 'string' },
      { name: 'chainId', type: 'uint256' },
      { name: 'verifyingContract', type: 'address' }
    ],
    Permit: [
      { name: 'owner', type: 'address' },
      { name: 'spender', type: 'address' },
      { name: 'value', type: 'uint256' },
      { name: 'nonce', type: 'uint256' },
      { name: 'deadline', type: 'uint256' }
    ]
  },
  primaryType: 'Permit',
  domain: {
    name: 'USD Coin',
    version: '2',
    chainId: 1,
    verifyingContract: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48'
  },
  message: {
    owner: accounts[0],
    spender: '0xSpenderAddress...',
    value: '1000000000', // 1000 USDC
    nonce: 0,
    deadline: Math.floor(Date.now() / 1000) + 3600
  }
}
 
const signature = await window.$onekey.ethereum.request({
  method: 'eth_signTypedData_v4',
  params: [accounts[0], JSON.stringify(permitData)]
})

Errors

Code	Message	Description
4001	User rejected the request	User denied the signature request
-32602	Invalid params	Invalid typed data structure

Notes

The typed data must be a valid JSON string
chainId in domain should match the connected chain
User will see a human-readable representation of the data
Specified by EIP-712