| 摘要 |
PURPOSE:To perform a ticket examining processing in a short period of time and to prevent the forgery of a card by providing a key table in which plural sub keys prepared based on a prescribed common key are stored beforehand on a transmission side. CONSTITUTION:When an user possessing the card C enters a ticket examining passage and brings the card C close to a communication area 4, a polling signal is received. A CPU 23 prepares the cipher text of data stored in a plain text data part 24b by using the sub keys Kc.Ko-Kc.Kn of respective layers stored in the key table 24c according to the program of a system program data part 24a and transmits it through a communication control part 21 to a main body side. The main body which receives the cipher text stores the cipher text in a RAM 7, then demodulates it by using the sub keys prepare based on the common key Kc stored beforehand in the RAM 7 (or a ROM 6) and decodes the data such as the valid period of the card C or the like. When passing can be permitted as the result of decoding, a door is opened. |
