This Ruby extension implements the SHA-3 ([Keccak](http://keccak.noekeon.org/)) cryptographic hashing algorithm. It is based on the reference C implementation, version 3.2. The exposed interface is almost identical to that of the `digest` standard library.
Keccak supports 5 hash lengths: 224-bit, 256-bit, 384-bit, 512-bit and variable length. Variable length is not supported by this Ruby extension. Unless the user specifies otherwise, this Ruby extension assumes 512-bit.