Encryption Device Using Composite Field Inverse Calculation
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Solution Overview
Problem
Conventional techniques for implementing the AES cipher in hardware face challenges due to the large number of logical steps in the randomized 8-bit inverse element calculation unit, making them inefficient and unsuitable for certain hardware implementations with strict RAM capacity limits.
Innovation Solution
An encryption device is designed with a simplified structure that reduces the number of logical steps by performing inverse element calculations in a composite field GF(((2^2)^2)^2), using a first randomization unit to generate masked input data and an output mask value, and an output data processing unit to produce encrypted text, thereby minimizing the circuit complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional randomized inverse element calculation is implemented in hardware, then encryption security against power analysis attacks is improved, but the number of logical steps increases making it inefficient
Solution Approach 1:
The patent changes the mathematical field parameter from conventional GF(2^8) to composite field GF(((2^2)^2)^2). This parameter change fundamentally alters the calculation approach, reducing the number of logical steps from 11 to 7 while maintaining the security property of randomization against power analysis attacks.
Solution Approach 2:
The patent segments the inverse element calculation into distinct modular components within the composite field structure. By dividing the calculation into separate transformation stages (GF(2^8) to GF((2^2)^2) to GF(((2^2)^2)^2)), each stage can be optimized independently, reducing overall complexity and logical steps.
2Reliability
If conventional masking methods are used to prevent power analysis attacks, then security is improved, but device complexity increases due to additional RAM requirements
Solution Approach 1:
The patent extracts the randomization function from separate storage structures (RAM tables) and integrates it directly into the calculation logic of the inverse element computation. By embedding the masking capability within the arithmetic operations themselves, the design eliminates external memory dependencies and reduces overall device complexity.
Solution Approach 2:
The composite field calculation unit serves multiple functions simultaneously: it performs the mathematical inversion operation, applies randomization for security, and manages mask values internally. This multi-functionality consolidates what would otherwise require separate dedicated circuits, reducing overall device complexity.
Data Source
AI summary
An encryption circuit is provided which generates encrypted text from plain text using a key. The encryption circuit includes a randomized 8-bit inverse element calculation circuit which receives randomized input data that is obtained by adding, to input data on which predetermined processing is performed with the key, a predetermined input mask value determined depending on a random number, and which generates randomized output data that is obtained by adding, to an inverse element of the input data, an output mask value that is an inverse element of the input mask value, wherein the encryption circuit generates the encrypted text from the generated randomized output data.