yes now i have came 2 know what exactly is hmac
HMAC is merely a specific type of MAC function. It works by using an underlying hash function over a message and a key. It is currently one of the predominant means to ensure that secure data is not corrupted in transit over unsecure channels (like the internet).Any hashing fuction could be used with HMAC, although more secure hashing functions are preferable. An example of a secure hash function (which is commonly used in HMACimplementations) is SHA-14.(Other common hashing functions include MD5 and RIPEND-160). As computers become more and more powerful, increasingly complex hash functions will probably be used. Furthermore, there are several generations of SHA hashing functions (SHA-256, SHA-384, and SHA-512) which are currently available but not very widely used as their added security is not yet believed to be needed in everyday transactions.
