| 摘要 |
PURPOSE:To improve security against forgery by erasing a storage area so as to make only area corresponding to write information incapable of reproduction, and rewriting a data stored in other area than an erased part. CONSTITUTION:An account adjusting means 26 is operated by a hook command FS, and whenever a message data SP is supplied, ''1'' is subtracted from the balance data SUM, and a new SUM is derived. Subsequently, whenever a quotient data X is subtracted by ''1'', a position data ARD is supplied to an erasion positioning means 27 and a scratch head is driven, and also a command SS is supplied to a data erasing means 28 and a data area 13 is scratched. Next, when the command FS is released or the new SUM goes to ''0'', the means 26 supplies the SUM to a storage means 29 and also an operating means 30. The means 30 generates a check data CD from the SUM, and thereafter, devides it by a constant (a) and devives a surplus data Y, supplies a command RS to a write head means 31 and positions a write head at a data area 14, supplies the surplus data Y and the check data CD to a means 32, rewrites it, and thereafter, supplies a command SD to a means 25 and discharges a card 10. |
