Signing an Uint8Array (etherjs v6 => viem)

[armand-git]

Hi,
With ethereum V6, i do that :

const hashToSign = ethers.solidityPackedKeccak256(
    ['address', 'uint256', 'uint256', 'uint256'],
    [
        myContratAddress,
        nonce,
        tokenId,
        amount
    ]
);

const signature = await signer.signMessage(ethers.getBytes(hashToSign));

With viem, i (want to) do that :

const hashToSign = keccak256(encodePacked(['address', 'uint256', 'uint256', 'uint256'],
                                    [
                                        myContractAddress,
                                        BigInt(nonce),
                                        BigInt(tokenId),
                                        amount
                                    ]
const signature = await walletClient!.signMessage({ message: hashToSign });

My Back recover with Web3js :

    const message = web3.utils.soliditySha3(
        { type: 'address', value: myContractAddress },
        { type: 'uint256', value: nonce },
        { type: 'uint256', value: tokenId },
        { type: 'uint256', value: amount.toString() }
    );
    const recovered = web3.eth.accounts.recover(message!, signature);

The back recovers correctly ether (and my contract also), but not viem (bad signer address).
The twice hashToSign have exactly sames values.
viem signing need a string, not an array.
I try to use a signTypedData, but with no results.
I try to cast 'message' to Uint8Array with toBytes and then to string, with no results (the twice Uint8Array ethers.getBytes(hashToSign) and from getBytes are exactly same)

Note : If I add an arbitrary prefix like this :
const signature = await walletClient!.signMessage({ message: 'someprefix' + hashToSign });
And I add the same prefix in my back like that :
const recovered = web3.eth.accounts.recover('someprefix' + message!, signature);
It's working ! But i can't use this solution, my smartcontrat doesn't need 'someprefix', and wait message with a fixed 32 length.

My solidity code :

bytes32 message = prefixed(keccak256(abi.encodePacked(this, nonce, tokenId, price)));
(address recovered, ECDSA.RecoverError error) = ECDSA.tryRecover(message, vendorSigning);

// ...

function prefixed(bytes32 hash) internal pure returns (bytes32) {
    return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
}

Can one help me please ?

[ygtdmn]

were you able to find answers?

[armand-git]

Hi!
Yes!

Here an example I use for identification : My backend send a nonce to be signed.

First create yours types like this :

export const MyBackendDomain = {
    name: 'MyBackendDomain',
    version: '1'
} as const;

export const MyBackendTypes = {
    linkWallet: [
        { name: 'action', type: 'string' },
        { name: 'account', type: 'address' },
        { name: 'nonce', type: 'uint256' },
    ],
    otherType: [
        { name: 'params1', type: 'string' },
        { name: 'params2', type: 'address' },
        { name: 'params3', type: 'string' },
    ],
} as const;

On your front, use signTypedData :

  const { address: userAccount } = useAccount();
  const { data: walletClient } = useWalletClient();

  /* (...) */
  const signature = await walletClient.signTypedData({
      domain: MyBackendDomain,
      types: MyBackendTypes,
      primaryType: 'linkWallet',
      message: {
          action: 'identification',
          account: userAccount,
          nonce: BigInt(nonce)
      }
  });

On your back :

   const isValid = await verifyTypedData({
                  address: userAccount,
                  domain: MyBackendDomain,
                  types: MyBackendTypes,
                  primaryType: 'linkWallet',
                  message: {
                      action: 'identification',                  
                      account: userAccount,
                      nonce: BigInt(nonce),
                  },
                  signature,
              });

I rewrite this code for this example, i hop no error comes on
Mores infos https://viem.sh/docs/utilities/verifyTypedData.html