A new Hash Function Based on Combination of Existing Digest Algorithms

Hash functions were introduced in cryptology as a tool to protect the authenticity of information. SHA-1, MD5, and RIPEMD are among the most commonly-used hash function message digest algorithms. Nowadays scientists have found weaknesses in a number of hash functions, including MD5, SHA and RIPEMD so the purpose of this paper is combination of some function to reinforce these functions. Recent works have presented collision attacks on SHA-1, MD5 hash functions so the natural response to overcome this threat was assessing the weak points of these protocols that actually depend on collision resistance for their security, and potentially schedule an upgrade to a stronger hash function. Other options involve altering the protocol in some way. This work suggests a different option. We present several simple message pre-processing techniques and show how the techniques can be combined with MD5 or SHA-1 so that applications are no longer vulnerable to the known collision attacks.