Access-controlled data storage medium
AssigneeGiesecke & Devrient GmbH
InventorsHarald Vater, Hermann Drexler, Eric Johnson
Life of this patent
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Abstract
The invention relates to a data carrier having a semiconductor chip. In order to prevent an attacker from determining secret data of the chip from intercepted signal patterns of the chip, security-relevant operations are performed only with commands or command strings of the operating program whose use does not permit the processed data to be inferred from the signal patterns.
Claims17
A data carrier comprising:
- a semiconductor chip having:
- at least one memory;
- an operating program stored in said memory;
- and
- a plurality of operating program commands contained in said operating program, each command causing signals detectable from outside the semiconductor chip during execution of the command within the semiconductor chip, wherein:
- the operating program is arranged to execute a plurality of operations;
- for at least a first subset of said plurality of operations, a total result achieved by execution of the first subset does not depend on an order of execution of at least a first portion of operations of the first subset of said plurality of operations, the first subset of said plurality of operations including at least one of said plurality of operations;
- the order of execution of the first subset of said plurality of operations is varied at least when the first subset of said plurality of operations contains one or more security-relevant operations;
- and
- for at least a second subset of said plurality of operations, a total result achieved by execution of the second subset depends on an order of execution of at least a second portion of operations of the second subset of said plurality of operations, and the order of execution of the second portion of the operations of the second subset is not varied, the second subset of said plurality of operations including at least one of said plurality of operations.
A method for protecting secret data stored in a memory of a semiconductor chip of a data carrier, said secret data serving as input data for one or more of a plurality of operations executed on the semiconductor chip, the execution of the one or more of a plurality of operations causing signals detectable from outside of the data carrier, the signals being dependent on the one or more of a plurality of operations and on the input data for the one or more of a plurality of operations, said method comprising the steps of:
- executing the plurality of operations in such a manner that,
- for at least a first subset of said plurality of operations, a total result achieved by execution of more than one operations of the first subset does not depend on an order of execution of at least a first portion of operations of the first subset of said plurality of operations, the first subset of said plurality of operations including at least one of said plurality of operations, and
- for at least a second subset of said plurality of operations, a total result achieved by execution of the second subset depends on an order of execution of at least a second portion of operations of the second subset of said plurality of operations, the order of executions of the second portion of the operations of the second subset is not varied, the second subset of said plurality of operations including at least one of said plurality of operations;
- and
- varying the order of execution of the first subset of said plurality of operations at least when the first subset of said plurality of operations contains one or more security-relevant operations.
Dependencies are inferred from the claim text.