Study On Hash Function Construction Based On Message Network

With the popularity and rapid development of Internet, computer network has fully come into our daily life. The network has brought us convenience, but also a serious threat. At present, the traditional Hash functions are also facing enormous challenges, because MD5 and SHA-1 algorithms have been successfully broken by the Professor Wang Xiaoyun's team, and have aroused wide attention from the scholars of international cryptography. Since the chaotic system is a nonlinear deterministic system, but with initial sensitivity, and capable of producing seemingly random trajectory, it has been widely used in the field of information security. In recent years, the good characteristics of chaotic systems have been used in the construction of hash function, which has become a hot topic in the scholars of cryptography.The mainly contributions of this dissertation are as follows:Firstly, the Cryptography, hash and chaotic theory are briefly introduced, and several typical hash algorithms and chaotic systems are summarized. Moreover, hash functions based on chaotic system and common constructing methods are analyzed.Secondly, through analyzing the hash function on the basis of spatiotemporal chaos, it is found that spatiotemporal chaos model diffuses the slight change slowly, because of the disturbance of coupling terms.Thirdly, the hash function based on message network is proposed. There is an inevitable relation between the message's transmission speed and the topology of the network. In order to improve the diffusion speed of tiny changes, a hash function construction is proposed, which is based on the weighted complex network with some topology structure. Numerous simulations are given to verify the properties of the approved algorithms.