Personal indentification system.

摘要

A personal identification system comprises a generator (10) which generates an Offset Number which is recorded on the magnetic stripe of a card, together with the account number (PAN) of the person to whom the card is to be issued. The generator stores (15) transformed digits of a sequence of digits (IN) which have been secretly entered (16) by one or more officers of the card-issuing institution. To generate the Offset Number the PAN is entered (21) and transformed (23) before being stored to initialize a first feedback shift register (25). The person to whom the card is to be issued enters (27) a chosen alphanumeric sequence (PIN) secretly known only to him. The PIN, after undergoing transformation (28) is stored to initialize a second feedback shift register (30). When both registers have been initialized they are reinitialized by different parts of different digits of transformed IN. Different digits of the two registers are used to initialize a control feedback shift register (35) which when reaching a selected state in its cycle of states controls the generator to generate the Offset Number (46), based on a selected mapping of the digits, then present, in the first and second feedback shift registers. To use the card it is entered into a verifier. Therein the PAN and Offset Number on the magnetic stripe are read out. The intended user enters a PIN, and the verifier, like the generator, generates an Offset Number. Only if the PIN entered into the verifier is identical to that entered into the generator, does the verifier produce an Offset Number identical to that read off the card, thereby indicating that the card user is the one to whom the card was issued.