04974193 is referenced by 36 patents and cites 5 patents.

Dependent on a variable start value (s), a random number according to the relationship v=f (K;s) is generated from a ciphering algorithm (f) implemented in the microprocessor of the chip card and from a stored secret cipher (K). This random number can be intermediately stored in a register and, when generating a new random number, can be logically operated with a variable input quantity (for example, with the variable start value (s), to form a modified variable start value (s'), for use in establishing protected communications between the chip card and a user terminal having a chip card reader.

Title
Circuit arrangement for protecting access to a data processing system with the assistance of a chip card
Application Number
7/164477
Publication Number
4974193
Application Date
March 4, 1988
Publication Date
November 27, 1990
Inventor
Dietrich Kruse
Ottobrunn
DE
Annette Gabriele Kersten
Wiesbaden
DE
Albrecht Beutelspacher
Ottobrunn
DE
Agent
Hill Van Santen Steadman & Simpson
Assignee
Siemens Aktiengesellschaft
DE
IPC
G06K 5/00
G06F 3/00
View Original Source