Cellular Automata And Password

This paper makes a study of the cycle and the security of cellular automata, the wayhow to design algorithms based on cellular automata and the hardware implementation ofthe algorithms. Firstly, it gives an introduction to some basic knowledge in stream cipherand cellular automata; Secondly, the algorithms based on cellular automata and theirsecurity are discussed; Thirdly, one simple cellular automata and one simple linearfeedback shift register are implemented in FPGA. And the author analyzes the advantageand the disadvantage of cellular automata in hardware; Finally, the author implements onecellular automata with simple structure, and analyzes the advantage of cellular automata insecurity.The main results are presented in this thesis are as follows:1. Based on the characteristic polynomial, a method to compute its maximal cycle lengths is presented.2. Information regarding many methods to designed stream cipher based on cellular automata and their security, and how to design stream cipher based on PCA is studied.3. One cellular automata and one linear feedback shift register are implemented in FPGA. The result is shown that: CA compares with LFSR, CA has the advantage of less delay time, faster speed, and moreover, it is easier to implement. But it needs more memory than LFSR.4. According to the study, a sequence generated by CA with simple structure has better security. Especially, the sequence has higher complexity than the sequence generated by LFSR. Moreover, those sequences from different cells can be used in parallel.