On the linear consistency test (LCT) in cryptanalysis with applications

Abstract

In this paper, we give at first a precise estimation for the consistency probability of a system of linear algebraic equations Ax = b with random m × n coefficient matrix A, m > n, and fixed non-zero right side b. A new test in cryptanalysis is then formulated on the basis of the estimation and applied to at-tack the multiplexing generator of Jennings (1980) and the multiple-speed gen-erator of Massey-Rueppel (1984). Some security remarks concerning the perfect linear cipher of the latter authors are also made.