MICROPROCESSOR CARDS HAVING PROTECTION CIRCUITS THAT PREVENT POWER ANALYSIS ATTACKS, AND METHODS OF OPERATING SAME

摘要

A microprocessor card includes an integrated circuit device (14) containing secure information. The card includes a protection circuit (16) configured to protect the integrated circuit device, preventing unauthorized extraction of the secure information by the use of a power analysis technique. This is accomplished by maintaining at substantially uniform voltage at least one power line (28) electrically connected to the integrated circuit device. The uniform voltage masks the operations performed by the integrated circuit device (14) vis-à-vis an external hardware capable of performing an attack. In particular, a variable capacitor (24) is incorporated to provide a displacement current to the power line (28) and the integrated circuit device, and the capacitance of this capacitor is progressively decreased at a rate appropriate to maintain a voltage. constant on the feed line (28). / P