HMAC stands for Hash based Message Authentication Code, which is a key related hash operation Krawezyk, M. Bellare, R. Canetti proposed a method for message authentication based on Hash functions and keys in 1996, which was published as RFC2104 in 1997 and widely used in IPSec and other network protocols such as SSL. It has now become a de facto Internet security standard. It can be bundled with any iterative hash function for use