Applications Of Cellular Automata Theory In A Stream Cipher

With the development of the computer network technique, especially internet, problem of data confidentiality, integrity and authentication of electronic data has already become an important task. Cryptography is the kernel technology of information security. From the foundation of morden cryptography, each ocountry in the world has been exploring and developing the self-dependent techqiues of cryptography to ensure benfits of society and contry during the process of informatization. Cellular automata(CA) is a discrete dynamic system composed of time, space and status, whose inherent characteristics of simplicity of component unit, locality of interaction , high parallelism of information processing as well as complicated dynamic property makes CA much suitable for cryptograph application. It becomes one of the most promising kernel techniques in the self-independent research of the cryptograph.According to status quo of cellular automata, this paper presents two high quality pseudo random generators based on controllable coupled and two-Dimensional CA with a trapezoidal structure in stream cipher.Main contributions of this dissertation are summarized as follows:(1)A novel cellular automata(CA)-coupling and controllable CA(CCCA) is proposed in this paper. According to character of CCCA, a pseudo random generating method based on CCCA is presented. Randomness test results on CCCA pseudorandom number generators (PRNGs) show that they are better than one-dimensional CA PRNGs and can be comparable to two-dimensional ones. Meanwhile it keeps the structure simplicity of one-dimensional CA. This novel CCCA is widely used in symmetrical cryptography.(2)A novel cellular automata(CA)- two-Dimensional controllable CA with a trapezoidal structure is proposed in this paper. According to characteristics of two-Dimensional controllable CA, a pseudo random generating method based on two-Dimensional controllable CA with a trapezoidal structure is presented. Simulation demonstrates that pseudo random bit sequence generator based on the two-dimensional controllable CA with a trapezoidal structure is easily implemented, and can generate high speed bit sequence and excellent statistical properties.