Recovering the MSS-sequence via CA

A cryptographic sequence generator, the modified self-shrinking generator (MSSG), was recently designed as a novel version of the self-shrinking generator. Taking advantage of the cryptographic properties of the irregularly decimated generator class, the MSSG was mainly created to be used in stream cipher applications and hardware implementations. Nevertheless, in this work it is shown that the MSSG output sequence, the so-called modified self-shrunken sequence, is generated as one of the output sequences of a linear model based on Cellular Automata that use rule 60 for their computations. Thus, the linearity of these structures can be advantageous exploited to recover the complete modified self-shrunken sequence from a number of intercepted bits.