Method and arrangement for enhancing the security of critical data against manipulation

US5771348A · kind A · utility

Assignee

• Francotyp-Postalia GmbH · DE

Inventors

• Ralf Kubatzki · Berlin, DE
• Wolfgang Thiel · Köngen, DE

Key dates

• Filing date: Sep 9, 1996
• Grant date: Jun 23, 1998
• Expiry date: Sep 9, 2016

Classification

• Technology area (CPC G): Physics
• CPC primary: G07B2017/00427
• WIPO field: Control
• WIPO sector: Instruments

Abstract

In a method for enhancing the security of critical register data against manipulation, a number or a pointer that is allocated to a code word is loaded into a first non-volatile memory, and a code word is loaded into second non-volatile memories containing the critical data, whereby the code word is allocated to the last operating condition of the system, i.e. the code word has been selected on the basis of a pseudo-random sequence or as an outcome of the manufacture or a reloading of the system or before turn-off or before a voltage outage or before a standby before program interruption. A validity check of the code word is made at least at the time the system is turned on, and the old code word is replaced with a predetermined, new code word when the processor, after the validity check, recognizes the validity of the old code word with reference to the code word selected from a list with stored code words in its internal processor memory. This selection is made according to the number or the position of the pointer. The system is blocked after the time the system is turned on if the processor, after the validity check, denies the validity of the old code word with reference to th…