Trans-cryption, Inc.

Other

Milton Goldfine

Marvin K Perlman

Robert A Montgomery

Each access attempt transmitted to an authentication agency causes the agency to produce a request identifier unique to that request. The request identifier is transmitted back to the authentication code generator of the user initiating the access attempt, and to an authentication code generator in the agency. The agency also retrieves a user identifier from a database and sends it to its authentication code generator. Both the user's authentication code generator and the agency's authentication code generator independently combine, through identical or complementary transformations, the user identifier and the request identifier to form a user authentication code and an agency authentication code. The two authentication codes are presented by a comparator, which issues a permit signal only if the comparison indicates a match between the two authentication codes. The permit signal is transmitted to a transaction control device to permit the transaction to proceed. Since the authentication code is unique to each transaction attempt, interception of an authentication code will not permit an unauthorized user to successfully initiate another transaction. As an additional security feature, the user of irreversible transformations in the authentication code generator would prevent decoding of an intercepted authentication code and would not allow an unauthorized user to derive the user identifier associated with the transaction. As required by a particular application, additional levels of security can be achieved by using encryption steps in combination with the irreversible transformations at selected points in the process.

Transaction authentication using a centrally generated transaction

A verifier for use in a personal identification system of the type in which a generator receives at least a personal account number (PAN) and a secret personal identification number (PIN) and based thereon produces digits A.sub.i 's which are present in a feedback shift register (FSR) A and digits C.sub.i 's present in a feedback shift register (FSR) C respectively. The A.sub.i 's and C.sub.i 's are mapped into D.sub.i 's which represent digits of an Offset Number which together with the PAN are recorded on the magnetic stripe of a card. To use the cards the Offset Number and the PAN are read off therefrom and an intended user enters a secret PIN. In the verifier, the PIN is operated upon to produce C.sub.i 's and the PAN is operated upon to produce A.sub.i 's. The latter together with the D.sub.i 's of the received Offset Number are mapped by a processer (201) to form C.sub.i.sup.c 's. These are compared with the C.sub.i 's by a comparator (202) to determine whether the intended card user is the rightful user.

Verifier for a personal indentification system

A personal identification system comprises a generator 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 transformed digits of a sequence of digits (IN) which have been secretly entered by one or more officers of the card-issuing institution. To generate the Offset Number the PAN is entered and transformed before being stored to initialize a first feedback shift register. The person to whom the card is to be issued enters a chosen alphanumeric sequence (PIN) secretly known only to him. The PIN, after undergoing transformation is stored to initialize a second feedback shift register. When both registers have been initialized they are reinitialized by different parts of different digits of the transformed IN. Different digits of the two registers are used to initialize a control feedback shift register which when reaching a selected state in its cycle of states controls the generator to generate the Offset Number, 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.

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Loudon, TN, United States of America

Milton Goldfine