Apparatus and method for checking an error detection functionality of a data processor
First Claim
1. A chip card or smart card security controller comprisinga data processor having an arithmetic logic unit configured to calculate an output datum based on at least one an input datum,an error detector configured to check the output datum for an error based on the output datum and the at least one input datum, and, if an error is present, generates an error signal;
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each time the controller switches to the checking mode,influences the arithmetic logic unit, the error detector or the input datum such that the error detector detects an error and, if no error signal is received in response to the influencing, output an alarm signal indicating an incorrect execution of the error detection functionality; and
subsequently, cause the error detector to check the output datum with regard to an error without influencing the arithmetic logic unit, the error detector and the input datum, and output the alarm signal, if the controller receives a further error signal from the error detector in response to the causing,a circuit adapted to execute a security reset in response to receiving the alarm signal, and adapted to perform one of a termination of a program currently running on the chip card, a security reset and a renewal of an instruction initiating the calculation of the arithmetic logic unit, in response to receiving the error signal via the error signal output.
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Abstract
An apparatus for checking an error detection functionality of a data processing circuit, comprising an arithmetic logic unit, which provides an output datum based on an input datum, and an error detection circuit that executes the error detection functionality and detects an error based on the output datum during correct execution of the error detection functionality, and generates an error signal, if an error is present, which comprises a control circuit that passes the error signal through to an error signal output in a normal operating mode, and blocks the error signal in a checking mode, does not let the error signal pass to the error signal output, influences the arithmetic logic unit, the error detection circuit or the input datum such that the error detection circuit detects an error during correct execution of the error detection functionality, and, if no error signal is received in response to influencing, outputs an alarm signal indicating an incorrect execution of the error detection functionality.
30 Citations
10 Claims
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1. A chip card or smart card security controller comprising
a data processor having an arithmetic logic unit configured to calculate an output datum based on at least one an input datum, an error detector configured to check the output datum for an error based on the output datum and the at least one input datum, and, if an error is present, generates an error signal; - and
a controller configured to alternately switch between a normal operating mode and a checking mode, pass the error signal through to an error signal output in the normal operating mode, and blocks the error signal in a checking mode, in order to not let the error signal pass through to the error signal output; each time the controller switches to the checking mode, influences the arithmetic logic unit, the error detector or the input datum such that the error detector detects an error and, if no error signal is received in response to the influencing, output an alarm signal indicating an incorrect execution of the error detection functionality; and subsequently, cause the error detector to check the output datum with regard to an error without influencing the arithmetic logic unit, the error detector and the input datum, and output the alarm signal, if the controller receives a further error signal from the error detector in response to the causing, a circuit adapted to execute a security reset in response to receiving the alarm signal, and adapted to perform one of a termination of a program currently running on the chip card, a security reset and a renewal of an instruction initiating the calculation of the arithmetic logic unit, in response to receiving the error signal via the error signal output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A digital memory medium comprising a program with program code for performing the method comprising:
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calculating, performed by an arithmetic logic unit, an output datum based on at least one an input datum, checking, performed by an error detector, the output datum for an error based on the output datum and the at least one input datum, and, if an error is present, generate an error signal, and alternately switching between a normal operating mode and a checking mode, passing the error signal through to an error signal output in the normal operating mode, and blocking the error signal in a checking mode, in order to not let the error signal pass through to the error signal output; each time the checking mode is switched to, influencing the arithmetic logic unit, the error detector or the input datum such that the error detector detects an error and, if no error signal is received in response to the influencing, outputting an alarm signal indicating an incorrect execution of the error detection functionality; and subsequently, causing the error detector to check the output datum with regard to an error without influencing the arithmetic logic unit, the error detector and the input datum, and outputting the alarm signal, if the controller receives a further error signal from the error detector in response to the causing, executing a security reset in response to receiving the alarm signal, and performing one of a termination of a program currently running on the chip card, a security reset and a renewal of an instruction initiating the calculation of the arithmetic logic unit, in response to receiving the error signal via the error signal output.
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10. A method, comprising:
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calculating, performed by an arithmetic logic unit, an output datum based on at least one an input datum, checking, performed by an error detector, the output datum for an error based on the output datum and the at least one input datum, and, if an error is present, generate an error signal, and alternately switching between a normal operating mode and a checking mode, passing the error signal through to an error signal output in the normal operating mode, and blocking the error signal in a checking mode, in order to not let the error signal pass through to the error signal output; each time the checking mode is switched to, influencing the arithmetic logic unit, the error detector or the input datum such that the error detector detects an error and, if no error signal is received in response to the influencing, outputting an alarm signal indicating an incorrect execution of the error detection functionality; and subsequently, causing the error detector to check the output datum with regard to an error without influencing the arithmetic logic unit, the error detector and the input datum, and outputting the alarm signal, if the controller receives a further error signal from the error detector in response to the causing, executing a security reset in response to receiving the alarm signal, and performing one of a termination of a program currently running on the chip card, a security reset and a renewal of an instruction initiating the calculation of the arithmetic logic unit, in response to receiving the error signal via the error signal output.
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Specification