Signing message using web3 and using ethers gives different result. Why?

Question

I'm encoding a message using ethers' solidityPackedKeccak256()

const encodedMessage = ethers.solidityPackedKeccak256(
            ["address", "uint256", "uint256"],
            [deployer.address, TOKEN_ID, NONCE],
        );

I'm signing this message using -

1. web3

    const { signature: signatureWeb3 } = web3.eth.accounts.sign(
                encodedMessage,
                HARDHAT_PRIVATE_KEY,
            );
   

2. ethers

    const signatureEthers = await deployer.signMessage(encodedMessage);
   

Their outputs are -

web3 =  0xc5b8d6ae2203e7f90257162289e552fac04b5708d4fe6b4360e86c2855db059314357f66bf89a2f72858980aa390607598defcb5382fea437ac4da3f725a9b231b
ethers =  0xaf7cb82eee6050746f299888ccc2a888d6801bff3701975ed5a73c73238b12a624fa575c9f8222ecaed25d2071c108477c84ac79572ceedf226f7a010f24511d1c

The message for both functions is same. So Why are both signatures different? How do I get the same result from ethers as web3's?

Answer 1

You are using two different cryptography to sign the transactions on web3 and ethers.

Web3 soliditySha3() and for ethers solidityPackedKeccak256()

Instead you should implement web3.utils.keccak256() and ethers.utils.keccak256() to receive the same outputs signing ✍🏽 the message.