Maryam Hematti - Razi University Of Kermanshah
Arash Ahmadi - Razi University Of Kermanshah
Vahab Makki - Razi University Of Kermanshah

Producing pseudo-random sequence with large period, output complexity and high security has been one of the important topics in security and encryption discussion. Different structures such as linear feedback shift register (LFSRs) and nonlinear feedback shift register (NFSRs) have been used in these systems. Large period in output sequence is almost the most important parameter in designing pseudo-random number generators, because in cryptography we need full length sequences with a very large period and in this paper a new structure consists of two NFSRs is proposed, that can generate random numbers with better output quality. With this approach we can produce a pseudo-random sequence with larger period compared to a single NFSR. Output signal shows a good autocorrelation function. The output autocorrelation graph is δ-like. Because of using different NFSRs with different feedback functions in this structure, it also has more output complexity, too. Output has an appropriate random characteristic and with some improvements could be used in cryptographic systems.

NFSRs, Period, Pseudo-random Number Generator