Apparatus and method for providing resilience to attacks on reset of the apparatus
First Claim
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1. An apparatus for enhancing resilience to attacks, comprising:
- a plurality of storage elements forming a remapping group of storage elementsupdate circuitry configured to receive obscuring data, and responsive to a reset event to store in each of said at least one storage element a data value that is dependent on a current value of the obscuring data;
modification circuitry configured to modify a value of a control signal dependent on the remapping group of storage elements in order to generate a modified value for the control signal; and
processing circuitry configured to operate in dependence on the modified value of the control signal,wherein the modification circuitry is configured to use the value of the control signal to identify a storage element within said remapping group, and to output the data value stored in the identified storage element as the modified value of the control signal.
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Abstract
An apparatus and method are provided for enhancing resilience to attacks on reset of the apparatus. The apparatus comprises at least one storage element, and update circuitry that is configured to receive obscuring data, and which is responsive to a reset event to store in each of the at least one storage element a data value that is dependent on the current value of the obscuring data. For each such storage element, this ensures that the data value stored in that storage element is unpredictable following each reset event, thereby preventing the reproducibility of certain steps that would typically be taken by an attacker during an attack on the apparatus.
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Citations
16 Claims
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1. An apparatus for enhancing resilience to attacks, comprising:
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a plurality of storage elements forming a remapping group of storage elements update circuitry configured to receive obscuring data, and responsive to a reset event to store in each of said at least one storage element a data value that is dependent on a current value of the obscuring data; modification circuitry configured to modify a value of a control signal dependent on the remapping group of storage elements in order to generate a modified value for the control signal; and processing circuitry configured to operate in dependence on the modified value of the control signal, wherein the modification circuitry is configured to use the value of the control signal to identify a storage element within said remapping group, and to output the data value stored in the identified storage element as the modified value of the control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of updating within an apparatus a plurality of storage elements forming a remapping group of storage elements in order to enhance resilience to attacks, comprising:
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receiving obscuring data; responsive to a reset event, storing in each of said plurality of storage element a data value that is dependent on a current value of the obscuring data; modifying a value of a control signal dependent on the remapping group of storage elements in order to generate a modified value for the control signal; and operating processing circuitry in dependence on the modified value of the control signal; wherein the modifying step uses the value of the control signal to identify a storage element within said remapping group, and to output the data value stored in the identified storage element as the modified value of the control signal.
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16. An apparatus for enhancing resilience to attacks, comprising:
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a plurality of storage element means forming a remapping group of storage element mean; update means for receiving obscuring data, and responsive to a reset event, for storing in each of said plurality of storage element means a data value that is dependent on a current value of the obscuring data; modification means for modifying a value of a control signal dependent on the remapping group of storage element means in order to generate a modified value for the control signal; and processing means for operating in dependence on the modified value of the control signal; wherein the modification means uses the value of the control signal to identify a storage element means within said remapping group, and to output the data value stored in the identified storage element means as the modified value of the control signal.
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Specification