exthereum/blockchain

Question:: BitHelper - sha3 vs keccak

dkataskin opened this issue · 5 comments

dkataskin commented

Hello sirs, I looked into implementation of BitHelper and I see that keccakf1600 is used. While the algorithm is the same keccakf1600 package contains NIST SHA3 implementation and it's different from original Keccak and Ethereum is using original Keccak.

Shouldn't BitHelper be utilizing keccak hash instead of sha3? SHA3 can be reversed to to Keccak by changing padding and there is a fork that does that for keccakf1600.

hayesgm commented

To be honest, I haven't verified our usage of SHA3 with the official Ethereum tests yet. If you would suggest a change to the algorithm that you believe we should make, I'd be happy to discuss and/or look over a PR.

Here's a good example of an official Eth test case that covers the expected result of a SHA3: https://github.com/ethereum/tests/blob/e8ba92a9e20a252d215cbc95d314eba22b1d79c5/src/GeneralStateTestsFiller/stSolidityTest/TestCryptographicFunctionsFiller.json#L43

hayesgm commented

You're right that the current implementation does not look to match those tests as is, e.g.:

iex> BitHelper.kec("teststring") |> :binary.decode_unsigned |> inspect(base: :hex)
0xA52EF463EDB03558BE0598FB9A3AE67E0FC41C44BD0B1D4392B354D1E817FEA8
dkataskin commented

I suggest doing the following:

or if you just fork erlang-keccakf1600 under exthereum I can prepare pull requests with required changes and tests

hayesgm commented

FYI, right now we're using https://hex.pm/packages/keccakf1600_orig to solve this issue.

dkataskin commented

@hayesgm thank you, I guess the issue can be closed then.