Q: What is this?
A: This is an implementation of the Keccak hash function.

Q: What is a hash function?
A: A deterministic procedure which seems difficult to invert.

Q: What do you mean "seems difficult"?
A: Broadly speaking, there is no proof that common hash functions *are*
   difficult to invert. Rather, we don't know efficient ways to invert them.

Q: What is Keccak?
A: https://keccak.team/keccak.html

Q: What are the advantages of Keccak over other hash functions?
A: Keccak has a few nice features (list not exhaustive):
   - Keccak can take in arbitrarily large input, and return arbitrarily
     large output.
   - It's possible to trade security for speed, and vice versa.

Q: How does Keccak work?
A: Basically, Keccak loads bits into a large Rubik's cube, permutes those bits
   in convoluted ways, and reads back bits from the Rubik's cube.
To contain a Keccak implementation.