Cryptanalysis And Research On The Collision Of Hash Functions In Cryptography

Hash function plays an important part in modern cryptography. It's a basic tool for message integrity, authentication and digital signature, and it is widely used in the field of information security, e-commerce and e-government. In this thesis, the collision attack to hash functions is studied.We adopt the differential cryptanalysis which is one of the most effective ways to cryptanalyze the collision of hash functions. By the cryptanalysis of the hash function collision, more suggestions can be provided to design secure hash functions.First of all, the research background, related progress and the significance are described in the thesis. Secondly, the basic knowledge of hash function is summarized comprehensively. Thirdly, depth research and analysis are carried out for differential cryptanalysis, including the choice of input differential message, the search of differential path, the determination of sufficient condition and the modification technology of message. Meanwhile, putting the MD4 algorithm as the attack target, a better near collision and a new differential path are found respectively, an automatic searching differential path algorithm is programmed as well. Finally, the collision of FORK-256 compression algorithm proposed by Korean scholar recently is cryptanalyzed.