Gemalto Sa

Gemplus

Ludovic Rousseau

David Naccache

Pierre Girard

Pascal Guterman

Alexandre Benoit

Christophe Bidan

A method for preventing secret code manipulation in a data processing device, such as a smart card, to which a presented code is applied. Prior to implementation of a code transforming function in the processing device, the secret code is transformed into a transformed secret code in the card. For each use of the card, the presented code is transformed into a transformed presented code in accordance with the implemented transformation function. A comparison of the transformed secret code with the transformed secret code in the card is then performed.

Access control to data processing means

A method for managing an original executable code downloaded into a reprogrammable computer on-board system such as a microprocessor card. The code includes a cryptographic signature and is executable by the microprocessor once the validity of the signature has been checked. Off the card, a modified executable code corresponding to the original code and adapted to a pre-defined specific use is identified. A software component is calculated, which when applied to the original code, enables the modified code to be reconstructed. The software component is signed, and the signed original code and the signed software component are downloaded into the card. On the card, the signature of the original code and the software component are checked, and the software component is applied to the original code in order to reconstruct the modified code for the execution of the same by the microprocessor.

Method for managing an executable code downloaded in a reprogrammable on-board system

In a method for monitoring the flow of execution of a series of instructions of a computer program, a sequence of instructions are transmitted to the processor to execute the monitored program. These instructions are analyzed, and the result of the analysis are verified by referring to reference data recorded with the program. The reference data can include a value predetermined in such a way as to correspond to the result of the analysis produced during the monitoring process only if all the instructions have been actually analyzed during the program flow. The invention also concerns a device for monitoring the program execution, a program device, and a programming device operating according to the monitoring principles.

Growing community of inventors

Aubagne, France

Ludovic Rousseau