Method and device to increase the protection of a chip card
AssigneeGemplus Card International
InventorsGilles Lisimaque, Francois Geronimi
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Abstract
The method is designed to increase the protection of a microcircuit-based memory card comprising at least one memory coupled to a data-processing element. When said data-processing element receives a command by a data signal external to the card, said method consists in making said data-processing element emit a ratification signal at an instant that is deferred, with respect to the instant at which its emission was prompted by the data signal, by a duration that is randomly variable in time. The disclosed method can be applied to microcircuit-based memory cards.
Claims8
A memory card, said memory card comprising:
- a bus, said bus permitting communication between an external device and said memory card;
- a first memory, said first memory being coupled to said bus, and said first memory having an application program stored therein;
- a second memory, said second memory being coupled to said bus;
- a circuit for generating a random delay value, said circuit being coupled to said bus;
- and
- a processing element, said processing element being coupled to said bus, and said processing element defining means
- for receiving instructions from said application program via said bus,
- for executing said application program instructions,
- for transmitting data via said bus to said second memory for storage therein,
- for receiving said random delay value via said bus, and
- for delaying transmission of an end-of-control signal from said memory card to said external device by an amount of time proportional to said random delay value.
A method to increase the security of a micro-circuit based chip card having a memory, and a data processing element receiving a data signal command from an external device, the method comprising the steps of:
- generating a random delay value following receipt of said data signal command;
- triggering a delay count to initiate a time interval;
- generating an end-of-control signal;
- incrementing said delay count;
- comparing said random delay value to said delay count;
- and
- transmitting said end-of-control signal when said delay count is equal to said random delay value.
Dependencies are inferred from the claim text.