TRANSMISSION TERMINAL, RECEPTION TERMINAL AND PASSWORD KEY SYNCHRONIZATION SYSTEM IN PACKET COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a password key synchronization system guaranteeing the synchronism of a password key used in a transmission station and a reception station even if the password key is periodically changed when one transmission station uses plural channels an one logic channel. SOLUTION: In the password key synchronization system, the transmission terminal assembles and transmits plural packets with data ciphered by using a password key and the reception terminal decodes ciphered data in plural packets by using the password key. The transmission terminal has a means which periodically changes the password key used for ciphering, a means ciphering data included in the packet transmitted by using the present password key at every logic channel, a means giving a password key identifier showing the password key used for ciphering data at every transmission packet. The reception terminal is provided with a decoding means decoding data in the packet received by the password key shown by the password key identifier in the received packet.