The editing generator and its cryptanalysis

In this paper1, we present a new pseudo-random sequence generator, constructed by using two ternary linear feedback shift registers (LFSR). This new generator is called an editing generator which is a combined model of the clock-control generator (viewed as insertion) and the shrinking generator (viewed as deletion). It is shown that the editing generator has good properties of randomness, such as large periods, high linear spans, large ratio of linear span per symbol, and small unbias of occurrences of symbols. Given that a portion of a key stream is exposed, two different attacks for recovering the initial states of the two LFSRs are analyzed, which are the parity-check attack, the unconstraint embedding attack (analogous to the binary case). The analysis shows that the edited sequences resist to both the attacks. Index words: Pseudo-random sequences, LFSR, cryptanalysis.