摘要

An improved one-dimensional cellular automata is designed in which the key space is large with pseudo random series on a shift map and perturbed terms and thus data expansion is avoided. Random triggering rules are involved. There is no complex computation, but a large amount of information can be processed every time. The stream cipher generated by the automata is proved to be of ideal randomness and avalanche effect with rapid dispersion velocity of errors. Empirical results show that the stream cipher is perfectly random. both globally and locally. The chi-square test( confidence 95%) on a set of stream cipher with a length of 24000 and its 400 time iterations shows that the passing rates of frequencies and series are above 95% and 100%, respectively. To test the sensitivity of the data, 1 bit is changed at any position of the key stream and the average variation rate of total bits is 49.99%, ranging from 49% to 51% ( theoretical value is 50%), and variance is 1.193.10(-5), which means that the automata is a good encryption technique.