Security analysis for a class of generalized Feistel ciphers

To evaluate the security of a class of generalized Feistel ciphers,the security analysis against differential and linear attacks was investigated deeply using enumeration method.If the round function is bijective,then the number of active round function for 4,8,12,16-round ciphers are not less than 2,5,8,10 respectively and the number of active round function for 4r-round(r≥2) ciphers are not less than 2r+1.So the upper bounds of maximum differential and linear characteristic probabilities for 4r-round ciphers are p2r+1 and q2r+1 if maximum differential and linear approximation probabilities for round function are p and q.