The Design And Analysis Of Stream Cipher

The content of paper mainly includes two parts. First, we study the random evaluating indexs of random sequences—linear complexity. And we get three usefull conclusions. Second, we analyse the design of stream cipher based on S-boxes, and advance a design scheme of highly security S-boxes. Then, we advance a stream cipher arithmetic based on S-boxes, and show the experiment results about all designs. The results of author mainly includes:1. discussed the random evaluating indexs—linear complexity. The author mainly discusses the linear complexity and k-Error linear complexity of a binary sequence with the period N = npv(n is a positive integer, p is an odd prime, gcd (n ,p) =1), and show three important conclusions: A necessary and sufficient condition for LC k (SN)< LC(SN), Distributing of linear complexity about periodic sequence and a general upper bound for ( )N2. Advanced a design methods of S-boxes. Based on IDEA arithmetic, advanced a fast algorithm of produced S-boxes. The algorithm is simple and implements by software and hard easily.3. Dependent on the theory of"evolution"which Darwin advanced. We have advanced a evolutional idea of"S-boxes pool", and show evolutional method and evolutional algorithm. We utilize the experiments of computer to control evolutional process. The results of experiments show, we have designed a highly security S-boxes.4. Making use of the highly security S-boxes, we have finally finished the design of stream cipher algorithm based on S-boxes. we show the completely stream cipher algorithm, and have given the arranging scheme of key. The algorithm is asily implemented by software and hard, and the speed of initialization is very fast.