How to get r, s and v values for ecrecover using Solidity?

Question

I've seen some answers showing how to get r, s, v values using web3.js but how to retrieve them using Solidity? Assuming I enter the signature into the contract.

Answer 1

This is the code you can use:

function splitSignature(
        bytes memory sig
    ) public pure returns (bytes32 r, bytes32 s, uint8 v) {
        require(sig.length == 65, "invalid signature length");

        assembly {
            /*
            First 32 bytes stores the length of the signature

            add(sig, 32) = pointer of sig + 32
            effectively, skips first 32 bytes of signature

            mload(p) loads next 32 bytes starting at the memory address p into memory
            */

            // first 32 bytes, after the length prefix
            r := mload(add(sig, 32))
            // second 32 bytes
            s := mload(add(sig, 64))
            // final byte (first byte of the next 32 bytes)
            v := byte(0, mload(add(sig, 96)))
        }

        // implicitly return (r, s, v)
    }

Full code : https://github.com/Zartaj0/BasicSignature/blob/main/Hardhat/contracts/Verify.sol