Fast approximation of anti-random sequence generator for stream ciphering

Stream ciphering is an essential coding method for delay sensitive traffic such as voice and video. In this method the source sequence is combined with the output of a key stream generator using XOR The strength and robustness of this ciphering method lays in complexity of the key stream generator. A well-known method for generating key stream is pseudo-random number generator) which is based on LFSR. Recently the anti-random sequence has attained attraction and shown to have better statistical properties compared to pseudo-random numbers, so it appears be suitable for stream ciphering. The existing methods for generating anti-random numbers are highly time and memory consuming. This paper presents an approximate method for generating anti-random sequence, which is very simple and does not need large capacity of memory, while preserves the properties of the sequence. Moreover, we show that our method presents enough statistical complexity to fulfill the required security for stream ciphering.