| 摘要 |
PURPOSE:To surely prevent the wrong use of a card by equalizing the processing time required for collation of a personal identification number whether the collation results in coincidence or not and eliminating the possibility of decoding of the personal identification number. CONSTITUTION:When input of a personal identification number PIN is confirmed by a central controller 17, the number PIN in an input buffer 20 is given to a comparator 26 and is compared with a personal identification number PIN' in a secret zone of a storage memory 24 by the comparator 26. If they coincide with each other, a reinput number RTN of the memory 24 is set to '0', and a coincidence instruction of the number PIN is transferred to an output buffer 22. If the comparison results in disaccord, the reinput number RTN of the secret zone of the memory 24 is counted up by +1 and is measured by a timer 25. When the number of times of reinput exceeds a prescribed value, the counting operation of the timer is stopped to execute the card invalidating processing. Thus, the time required for the processing is equalized whether the comparison results in coincidence or not. |
