Simpler verification of externally-created ECDSA signatures in Solidity

Question

I just want to use ecrecover to verify with a public key that the corresponding private key signed a message passed through a variable in solidity. What's the simple way to do this? I have inserted ??? into my solidity where I don't know how to use ecrecover.

ie: client end:

message: "solidity has poor documentation"

bob's private key: "2j3940"

bob's public key: "0x3jhr32"

signed message: "3cj0239roi3409i34234"

solidity end:

function verifyMessage(message, signedMessage, publicKey){

    bool verified = False;

    if (????){
        verified = True;
    }

    return(verified);
}

expected use:

input:
verifyMessage("solidity has poor documentation","3cj0239roi3409i34234","0x3jhr32")

output:
True

Here is another question talking about the same issue, but I am unable to use their implementation: Verification of externally-created ECDSA signatures

Answer 1

Check out Openzeppelin ECDSA: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/cryptography/ECDSA.sol. They have a recover function where you can input the signature as a string.

// SPDX-License-Identifier: MIT
pragma solidity 0.8.13;

import {ECDSA} from "https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/cryptography/ECDSA.sol";

contract MySignatureTest {
    using ECDSA for bytes32;
    
    function verifyMessage(bytes32 messageHash, bytes memory signedMessage, address account) external pure returns (bool) {
        return messageHash
            .toEthSignedMessageHash()
            .recover(signedMessage) == account;
    }
}