An algorithm for cryptanalysis of certain keystream generators suitable for high-speed software and hardware implementations

An algorithm for cryptanalysis of certain keystream generators is proposed. The developed algorithm has the following two advantages over other report ed ones: it is more powerful, and it can be implemented by a high-speed sof tware or a simple hardware suitable for high parallel architectures. The al gorithm is based on error-correction of information bits only (of the corre sponding binary block code) with a novel method for construction of the par ity-checks, and the employed error-correction procedure is an APP based thr eshold decoding. Ex perimental and theoretical analyses of the algorithm pe rformance are presented, and its complexity is evaluated. The proposed algo rithm is compared with recently proposed improved fast correlation attacks based on convolutional codes and turbo decoding. The underlying principles, performance and complexity are compared, and the gain obtained with the no vel approach is pointed out.