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AFAIK, to verify a message, I need three things - message, signer wallet address and signature which is the signed message. Like when I use MyEtherWallet signing tool.

But in function isValidSignature, there's a hash of bytes32 type.

function isValidSignature(bytes32 hash, bytes memory signature) external view returns (bytes4 magicValue);

How do I actually get the hash and what is the algorithm used (MD5, SHA, etc)? I'm actually using this SignatureChecker library now but can't see to know how I can generate the hash.

1 Answer 1

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The hash necessary for the function isValidSignature is the hash of the message and the values that is used for signature.

The Solidity code for signing a message is as follows, the value in the variable digest is the hash used for verification.

bytes32 digest = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32",
  bytes32(uint256(uint160(address))), 
  bytes32(message));

The code was taken from the following article, which provides more details.

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