| 摘要 |
PURPOSE:To obtain a card legality deciding method comparatively prevented from disturbance by encoding and decoding writable data in the 2nd recording part on the basis of the data in the 1st recording part inherently included in a card. CONSTITUTION:To write data in the card C, the card C is inserted into a card device, the data in the 1st recording part 3 of the card C are read out by a recording data reading head 5 and the value of a medium variable (m) is stored in an encoding part 10 of a function operating part AU1 through the 1st reading data processing part 8. When the data (x) to be recorded are inputted to the encoding part 10 of the function arithmetic part AU1, conversion is executed by a previously fixed function f(x, m). Recording data converted by the encoding part 10 are written in the 2nd recording part 2 of the card C by a writing head 6 through a writing data processing part 11. To decide the legality of the data read out from the card C, the data in the 1st and 2nd recording parts 2, 3, the medium variable (m) is extracted and the data (y) are converted as reversed function f<-1>(y, m). |
