A new class of nonlinear functions for running-key generators: Extended abstract

Abstract

A systematic approach to the design of running-key generators in stream cipher systems is proposed using a new class of nonlinear functions based on integer arithmetic operations. This approach is applicable to both feedforward- and feedback-types running-key generators. Most practical nonlinear functions that use only one addition and one multiplication are fully analyzed. Cryptographic properties, such as 0-1 balance, linear complexity, and correlation, of the key-sequence generated by this scheme are examined and several important criteria for determining the parameters of such generators are derived. This approach will prove valuable in designing running-key generators.