Design and analysis of a highly secure stream cipher based on linear feedback shift register

Linear feedback shift register (LFSR) based stream ciphers are popular because of their low hardware implementation costs. The nonlinear combination generators and clock-controlled generators are two very commonly used schemes in LFSR based stream ciphers. FPGA implementation of these two schemes has been done to obtain an idea about the hardware complexity of the two schemes. The fast correlation attack and edit distance attack, which are the fastest of the reported attacks on the nonlinear combination generators and clock-controlled generators respectively, have been implemented. A new model for LFSR based keystream generation has been proposed by combining the two existing schemes. The proposed model is based on the detailed comparative study and cryptanalysis of the two existing schemes mentioned.