exchange.IO("signTypedData", ...)

Signs structured data according to the EIP-712 standard. A single call completes the calculation of the type hash, domain separator, struct hash, and digest, and then signs it. It is suitable for scenarios such as ERC-20 Permit, Permit2, UniswapX, CoW, and 1inch limit orders.

    
    
    
exchange.IO(k, typedData)

    
    
    
exchange.IO(k, typedData, key)

    
    
    
exchange.IO(k, domain, types, message)

    
    
    
exchange.IO(k, domain, types, message, key)

Examples

Sign a Permit for USDC on the Ethereum mainnet, and have the USDC contract verify the signature via exchange.IO("call", ...).

    javascript
    
    
function main() {
    var USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"      // Ethereum mainnet USDC
    // Spender (authorized party), fill in as needed
    var spender = "0x1111111254EEB25477B68fb85Ed929f73A960582"
    var owner = exchange.IO("address")
    var deadline = Math.floor(Date.now() / 1000) + 3600
    // nonce must equal nonces(owner) in the contract: it is no longer 0 once the wallet has used a
    // permit
    exchange.IO("abi", USDC, JSON.stringify([{ type: "function", name: "nonces",
        stateMutability: "view",
        inputs: [{ type: "address" }], outputs: [{ type: "uint256" }] }]))
    var nonce = exchange.IO("api", USDC, "nonces", owner)

    // ethers style: domain, types (without EIP712Domain), message; the primary type is inferred
    // automatically
    var domain = { name: "USD Coin", version: "2", chainId: 1, verifyingContract: USDC }
    var types = {
        Permit: [
            { name: "owner", type: "address" }, { name: "spender", type: "address" },
            { name: "value", type: "uint256" }, { name: "nonce", type: "uint256" },
            { name: "deadline", type: "uint256" }
        ]
    }
    var message = { owner: owner, spender: spender, value: "1000000", nonce: nonce,
        deadline: deadline }
    var sig = exchange.IO("signTypedData", domain, types, message)
    Log("digest:", sig.digest, "v:", sig.v, "r:", sig.r, "s:", sig.s)

    // Single-object style (MetaMask eth_signTypedData_v4 format) produces the same result
    var sig2 = exchange.IO("signTypedData", { domain: domain, types: types, primaryType: "Permit",
        message: message })
    Log("Both styles match:", sig.signature === sig2.signature)

    // Simulate USDC's permit with eth_call so the contract verifies the signature (no transaction
    // is sent)
    var calldata = "0x" + String(exchange.IO("hash", "keccak256", "raw", "hex",
        "permit(address,address,uint256,uint256,uint8,bytes32,bytes32)")).replace(/^0x/, "").slice(0, 8) +
        exchange.IO("encode", "address,address,uint256,uint256,uint8,bytes32,bytes32",
            owner, spender, "1000000", deadline, sig.v, sig.r, sig.s)
    Log("permit simulation:", exchange.IO("call", USDC,
        calldata) !== null ? "Signature valid" : GetLastError())
}

Returns

Arguments

See Also

Remarks

An error is reported when message is missing a field from the type definitions; missing fields are not zero-filled and then signed.

The private key is used only inside the exchange object; strategy code cannot access the private key.