SkeinMac
Implementation of the Skein parameterised MAC function in 256, 512 and 1024 bit block sizes,
based on the ThreefishEngineThreefish tweakable block cipher.
1024 bit block size - Skein-1024
256 bit block size - Skein-256
512 bit block size - Skein-512
Constructs a Skein MAC with an internal state size and output size.
Optionally initialises the Skein digest with the provided parameters.