AES Engine Two-Way Parity Checking for Low-Overhead Fault Detection
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Solution Overview
Problem
Current fault detection methods for AES encryption systems, such as duplication and single parity, incur high overhead or inadequate fault coverage, necessitating a low-cost solution with reliable fault detection capabilities.
Innovation Solution
Implementing a two-way parity fault detection system throughout the AES datapath, including segmentation of data into 8-bit segments, computation, and comparison of output and input parity bits at critical steps to detect faults during encryption and decryption, with optional duplication of control logic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If duplication method is used for fault detection, then reliability is improved, but area overhead increases significantly
Solution Approach 1:
The data path is segmented into multiple sections, and parity bits are computed at different segmentation points. This allows fault detection without duplicating the entire system, reducing area overhead while maintaining reliability through distributed parity checking across segmented data flows.
Solution Approach 2:
Instead of duplicating the entire AES engine, the patent creates simplified copies of only the parity computation logic at strategic points. This selective copying approach maintains fault detection capability while minimizing the additional area required compared to full duplication.
2Area of stationary object
If single parity method is used for fault detection, then area overhead is reduced, but fault coverage becomes inadequate
Solution Approach 1:
The patent extends single parity checking into multiple dimensions by computing parity bits at different stages of the encryption process and combining these checks. This multi-stage parity approach achieves 99.9% fault coverage without requiring area-intensive duplication, effectively adding temporal and spatial dimensions to the parity checking process.
3Reliability
If two-way parity detection is implemented throughout AES datapath, then fault detection coverage reaches 99.9%, but device complexity increases
Solution Approach 1:
The complex two-way parity detection system is divided into manageable segments corresponding to different stages of the AES algorithm. Each segment handles specific parity computations independently, making the overall complex system easier to implement, verify, and maintain while achieving comprehensive fault coverage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves 99.9% fault detection coverage with significantly reduced area overhead compared to conventional duplication methods, effectively preventing error propagation and ensuring reliable operation.
Implementation Method 1
The logic unit includes an arithmetic unit for computing parity data created based on XOR operation from an encryption key
Data Source
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AI summary
A method of improving the operation of a processor executing a cryptographic process, by automatically detecting faults during both encryption and decryption operations by the cryptographic process, comprises segmenting the data to be encrypted and encrypting the data segments using a complex non-linear algorithm that can lead to faults; computing an output parity bit from a selected step of the algorithm for a selected data segment, based on the input value of that segment; comparing the actual output parity bit of the selected segment with the computed output parity bit for that segment; and determining whether a fault exists, based on whether the actual output parity bit matches the computed output parity bit for the selected segment.