Is It Possible To Sign Interface.encodeFunctionData() With _signTypedData

[preston4896]

Hello 👋. I have been trying to implement a Forwarder smart contract that calls a function on a target contract. This Forwarder contract requires that the users to sign an EIP 712 message that contains the encoded function signature with parameters, essentially a bytes type on Solidity, which can also simply be retrieved on ethers js using Interface.encodeFunctionData().

The following snippets are my current implementation.

Smart Contract

bytes32 eip712_hashedMessage = keccak256(
  abi.encode(
    keccak256("Forwarder(bytes functionSig)"), // typehash
    keccak256(functionSig) // functionSig is of bytes type, can be obtained using encodeFunctionData() from ethers.js
  )
)

After the EIP712 message has been verified, the contract simply does a CALL to the target contract.

(bool success, bytes memory data) = address(target).call(abi.encodePacked(functionSig))

Ethers.js

const setGreeterSig = ['function setGreeting(string memory _greeting)']
const setGreeterIFace= new utils.Interface(setGreeterSig);
function encodeSetGreeter(greeting: string): string {
  return setGreeterIFace.encodeFunctionData('setGreeting', [greeting]);
}

const type = {
  Forwarder: [
    {name: "functionSig", type: "bytes"}
  ]
}

const value = {
  functionSig: encodeSetGreeter("Hello, World!")
}

const signature = signer._signTypedData(domain, type, value);

The contract couldn't recover the correct signer address. I am not sure what I am doing wrong here, I would really appreciate anyone pointing out my possible mistakes here.

I have also tried using toUtf8Bytes(encodeSetGreeter()), it didn't work either.

[preston4896]

Never mind it turns out it was a mistake on my part. FYI, we can pass in the encoded function signature as it is, no toUtf8Bytes conversion necessary. :)