POS TERMINAL, STORE COMPUTER FOR POS SYSTEM, ROUTER FOR POS SYSTEM, HOST COMPUTER FOR POS SYSTEM, POS SYSTEM, DATA PROTECTION PROCESSING METHOD AND COMPUTER READABLE RECORDING MEDIUM HAVING PROGRAM FOR MAKING COMPUTER EXECUTE THE METHOD RECORDED THEREON

摘要

PROBLEM TO BE SOLVED: To transmit and receive transmission and reception data between a POS terminal device and a host computer while sufficiently improving safety without increasing their data size in a POS system.;SOLUTION: A protection key attachment position deciding part 24 or a protection key elimination position deciding part 36 decides whether received digital data meet a prescribed additional condition. When the digital data meet the prescribed additional condition, a protection key attachment processing part 26 or a protection key elimination processing part 34 realizes encoding/ decoding by adding or subtracting a prescribed protection key value to/from the digital data received when having received the digital data a prescribed number of times after the decision.;COPYRIGHT: (C)2002,JPO