CIPHERING DEVICE, DECIPHERING DEVICE, CIPHERING METHOD, DECIPHERING METHOD AND COMMUNICATION SYSTEM USING THE SAME

摘要

PROBLEM TO BE SOLVED: To make decoding difficult and to securely synchronize passwords by generating a password key based on information which is set at every connection of a communication line between a base station and a moving station. SOLUTION: Ciphering is executed by using the key generated in a key generation part 200. The key generation part generates the password key based on information or the like which are set every time when the communication line is connected between the base station and the moving station. The password keys taking dynamic values different in every communication connection or every arbitrary time are made by generating the key from information. Random numbers outputted from a random number generation circuit part 202 are fed back and used as initial values for generating the next random numbers. The generated random numbers and data to be transmitted are operated in an exclusive OR operation part 203 and a password sentence of generated.