Fault Attack Detection Using Look-Up Table Sub-Table Relations
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Solution Overview
Problem
Existing methods for detecting fault attacks during cryptographic operations, such as duplication of circuitry or increased computation time, are costly and complex, necessitating a more efficient approach.
Innovation Solution
A method and circuitry using look-up tables with sub-tables that verify fixed relations between data values, employing exclusive OR operations and comparators to detect faults, allowing for continued cryptographic operations only if the relations are valid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If duplication of circuitry is used to detect fault attacks, then reliability is improved, but device complexity and chip area increase
Solution Approach 1:
The patent uses software-based copying by executing the same cryptographic operation twice using the same circuitry, generating two output data blocks that are then compared to detect faults, eliminating the need for physical circuit duplication
Solution Approach 2:
The system performs self-verification by comparing its own output data blocks to detect faults, using the same circuitry to execute operations and verify results without requiring separate dedicated verification circuitry
2Reliability
If additional verification operations are performed, then reliability is improved, but computation time increases
Solution Approach 1:
The patent performs verification by comparing only the relevant output data blocks from the two cryptographic operations, rather than verifying all possible outputs, thereby reducing the verification overhead while maintaining adequate fault detection capability
Solution Approach 2:
The system executes the cryptographic operation twice in parallel to generate two output data blocks before performing verification, allowing the verification step to operate on pre-computed data rather than requiring sequential verification
Data Source
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AI summary
The invention concerns a method of detecting a fault attack during a cryptographic operation using at least one look-up table, said look-up table comprising a plurality of sub-tables each having a same number of values of a fixed bit length, a fixed relation existing between values at same locations in each sub-table, the method comprising: performing a load operation to retrieve from said look-up table data values (B_1(Xi) to B_4(Xi)) from a same location in each of said sub-tables; verifying that said fixed relation exists between at least two of said data values; and generating an output signal based on said verification.