The sha256.py in the attack repo matches https://github.com/thomdixon/pysha2/blob/master/sha2/sha256.py https://github.com/thomdixon/pysha2/blob/master/sha2/sha

The sha256.py in the attack repo matches https://github.com/thomdixon/pysha2/blob/master/sha2/sha256.py https://github.com/thomdixon/pysha2/blob/master/sha2/sha256..... up to whitespace. I have not sure that it matches the NIST spec, but it matches wikipedia on emptystring...