EIP 712 Signatures

[brunoalano]

Hello,

It's possible to some way sign EIP 712 messages (structured messages)? Ethers.js has a signer. _signTypedData which can be used, but when using useSigner(), I can't access this method.

[jasheal]

_signTypedData appears to work but it seems like it's only v1 which has been flagged as insecure.

Would be interested to know how to use v4 using wagmi

[brunoalano]

Got it working using the following:

import type { VoidSigner } from "@ethersproject/abstract-signer";
import { useNetwork, useSigner } from "wagmi";

const [{ data: signer }] = useSigner();

const domain = {
  name: "Ether Mail",
  version: "1",
  chainId: networkData.chain.id,
  verifyingContract: "0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC",
};

// The named list of all type definitions
const types = {
  Person: [
    { name: "name", type: "string" },
    { name: "wallet", type: "address" },
  ],
  Mail: [
    { name: "from", type: "Person" },
    { name: "to", type: "Person" },
    { name: "contents", type: "string" },
  ],
};

// The data to sign
const value = {
  from: {
    name: "Cow",
    wallet: "0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826",
  },
  to: {
    name: "Bob",
    wallet: "0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB",
  },
  contents: "Hello, Bob!",
};

const signature = await (signer as VoidSigner)._signTypedData(domain, types, value);

[jasheal]

Yes, I believe this is v1 which is not recommended to use.

https://docs.metamask.io/guide/signing-data.html#sign-typed-data-v1

[jasheal]

my bad it is v4!

https://github.com/ethers-io/ethers.js/blob/master/packages/providers/src.ts/json-rpc-provider.ts#L271