Research And Design Of Hash Functions

The Hash function is an important branch of cryptology. It has a wide range of applications indigital signature, authentication, message authention and many other fields. In1989, MD2algorithmdesigned by Rivest is the initial model of Hash function. It subsequently appeared MD4, MD5,HAVAL, RIPEMD, SHA-0, SHA-1, SHA-2algorithm. In2009, the NIST collectioned the SHA-3function. In2010December, the NIST announced the final five algorithm of SHA-3: BLAKE，Gr stl，JH，Keccak，Skein. In2012, the NIST will hold the finals and publish the final algorithm.SHA-1still palys an important role in modern society. However, in2005, Wang X. useddifferential attack SHA-1algorithm to reduce the deciphered from280to263, so it has been unable tomeet the safety requirements of modern cryptography. This article improve SHA-1from the fouraspects: transforming the original logical function, transforming register initial value, transformingeach wheel constant and modification algorithm iterative process. The dependenced test, step test andavalancheavalanche effect factor test show that the safety of the improved algorithm is improved.Efficiency test shows that the efficiency of the improved algorithm is without reducing.SHA-2algorithm is a series of algorithm included SHA-224, SHA-256, SHA-384, SHA-512,which is based on SHA-1and according to the actual situation by NIST in2002. We improve theSHA-2algorithm, represented by SHA-256, from the improved of compression function and iterativeprocess reform. By compared the attack before and after shows the improved algorithm is improved insafety. Efficiency test shows that, the improved algorithm in efficiency is improved without reducing.The article analyzes the efficiency of packet length and iterative structure, and referrs theWhirlpool structure design method, and Constructed Hash function AWF. The confusion and diffusiontest, dependence test and avalanche factor tests show this function meet the security requiremens ofthe modern Hash function. Analysis and test show that AWF can resist the existing Hash functionattacks. On efficiency, on a single core platform, the AWF algorithm is about0.6times of SHA-2algorithm; on dual core platform, AWF slightly better than the SHA-2algorithm; on the quad platformefficiency of AWF is about two times of SHA-2algorithm. In monocytes dual quad platform, theefficiency of AWF is about two times of Whirlpool. in eight nuclear platform, it has not muchdifference between AWF and Whirlpool in efficiency.