The Design And Analysis Of Feedforward Stream Cipher

In this paper we study the feedforward stream cipher on analysis and design which are two contrary directions.Recently linear approaching analysis and correlation analysis are two important attack methods against the feedforward stream cipher,and it is a valuable work in cipher analysis and design to find new analysis ways or to improve the success probability of those now existing attack methods.First we introduce the essential thoughts of linear approaching analysis and correlation analysis,and give an reformative algorithm after studying two improved correlation analysis methods.Theoretical analysis and experiment indicate that the new algorithm does well in improving the success probability.especially to the case of multi-output feedforward network.Following the new algorithm we design a new feedforward network by selecting from a multi-output one,then discuss the output sequence's cipher characteristics.We prove in thoery that it is strictly balanced.has large period.high linear complexity and also has controlled security,at the same time experiment data show the new sequence has almost ideal run path properties.