Resilient Function based Sequence Generator-RFSG

The main focus of this paper is to apply suitable combiner function for cryptographic use which possesses multiple cryptographic properties such as balanced, correlation immune and high algebraic degree. Resilient function which is the generalization of correlation immune Boolean function is thus considered. In this paper we presents RFSG, a new sequence generator which uses (q, m+1, m, 1) resilient function over GF(2 2 ) as a combiner function and linear feedback shift registers. The feedback polynomials with large number of taps increase the computational complexity of cipher and polynomials with low taps allow the fast correlation attack and distinguishing attack to recover the initial state. In the light of these constraints the feedback polynomials of eight taps are considered. These polynomials are primitive polynomials having period of maximal length. RFSG uses a key and initialization vector of 64 bits, and produces one bit of key stream per iteration. The internal state of generator is 128-bits and its period is (2 128 1). RFSG has good cryptographic properties and guaranteed randomness. Its security is analyzed with respect to strict avalanche criteria and fast correlation attack and found to be invulnerable to these attacks. Software and hardware implementation complexities have also been placed briefly, making these suitable candidates for realization of higher throughputs.