fix(cast): do not strip 0x / hex decode message before EIP-191 hashing

[grandizzy]

Motivation

• attempts to use cast hm to create flashbot sig failed, eventually used chisel eval to generate such

chisel eval 'keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n66","'$payload_keccak'"))'

https://github.com/pcaversaccio/white-hat-frontrunning/blob/main/go.sh#L62

• fix cast to not hex decode message to hash but use it as it is to create EIP-191 final message "\x19Ethereum Signed Message:\n" + message. length + message which is then hashed

Solution

[DaniPopes]

I think this is fine, however it is a breaking change, and it might be assumed that 0x input is hex decoded like in other commands, we don't really have a consistent behavior in this regard I think

[grandizzy]

I think this is fine, however it is a breaking change, and it might be assumed that 0x input is hex decoded like in other commands, we don't really have a consistent behavior in this regard I think

yep it is a breaking change, though the command help reads

Hash a message according to EIP-191
Usage: cast hash-message [MESSAGE]

Arguments:
  [MESSAGE]  The message to hash

so it's confusing as one would expect to just hash without decoding (also atm there's no way to hash a 0x message). We could add a cast hash-decode-message for current behavior in case there are people using it as designed now, but not sure if worth, wdyt?