This module provides common interface to HMAC engines. HMAC standard is documented in RFC 2104:
H. Krawczyk et al., "HMAC: Keyed-Hashing for Message Authentication", RFC 2104, February 1997
These APIs are inspired by JCE 1.2's javax.crypto.Mac interface.
<URL:http://java.sun.com/security/JCE1.2/spec/apidoc/javax/crypto/Mac.html>