Payments: JS validation

Validate signature belongs to the signing address

To validate the signature belongs to the signing address, we can use the method recover from web3.account.recover:

function checkSignatureMatch(signingAddress, transaction, signature) {
  var expectedSigningAddress = web3.eth.accounts.recover(transaction, signature);
  var isEqual = expectedSigningAddress === signingAddress;
  return isEqual;
}