Pseudo-random key generation for secure HMAC-MD5

Cryptographic hash functions had been very significant primitives to the cryptography. They have been utilized widely in cryptographic applications and most important of them is their use in the composition of efficient Message Authentication Codes (MACs). The cryptanalysis of hashing algorithms used in Hash Message Authentication Code(HMAC) like SHA-1 and MD5 have found many attacks against them. But this does not mean that if the underlying hashing algorithms are breakable then HMAC is also breakable. It is infeasible for the attacker to break HMAC because he would not be able to generate message sets offline without predicting the key K. The goal of this paper is to improve the strength of Hash Message Authentication Code (HMAC), so that its resistance increases to the Birthday Attack and Exhaustive key Search Attack. The secret key used in calculation of HMAC is shared among the sender and the recipient. We generated the Secret key with the help of a pseudorandom MD6 hashing function so that it becomes more secure and hard to envisage by forgery.