Shared-Data ALU Interface for Side-Channel-Resilient Cryptography
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Solution Overview
Problem
Lattice-based cryptographic schemes like Falcon are vulnerable to physical side-channel attacks and fault injection, and existing countermeasures are complex, costly, and have high overhead, making them difficult to implement effectively.
Innovation Solution
Implement countermeasure control circuitry that splits sensitive variables into random, multiple secret shares for processing in an arithmetic logic unit (ALU), then recombines them, and uses blinding techniques for integer-to-floating-point conversions to reduce power and electromagnetic leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing countermeasures are implemented to protect against physical side-channel attacks, then security is improved, but implementation complexity and overhead increase significantly
Solution Approach 1:
The patent introduces an ALU interface unit as an intermediary component between the arithmetic logic unit and the external interface. This unit mediates all data flow through the ALU, implementing security functions (sharing, recombining, blinding) at the interface level rather than requiring complex modifications throughout the entire cryptographic processing system. The interface unit acts as a security gateway that protects against side-channel attacks while maintaining low implementation complexity.
2Speed
If sensitive variables are processed directly in the ALU, then processing speed is maintained, but vulnerability to side-channel attacks increases
Solution Approach 1:
The patent applies segmentation by dividing sensitive cryptographic variables into multiple shares before processing. The ALU interface unit shares input variables into separate components that are processed independently through the ALU. This segmentation prevents the ALU from directly processing complete sensitive values, thereby eliminating side-channel leakage while maintaining processing speed because the segmented operations can be executed efficiently in parallel or sequence without complex cryptographic overhead.
Solution Approach 2:
The patent implements preliminary action by performing sharing and blinding operations on variables before they enter the ALU. The ALU interface unit prepares the data in a protected form (shared and blinded representations) prior to ALU processing. This preliminary protection ensures that when the ALU operates at full speed, it is processing already-secured data, preventing side-channel attacks without requiring post-processing security measures that would reduce speed.
3Reliability
If sharing and recombining operations are implemented, then protection against side-channel attacks is achieved, but computational overhead increases
Solution Approach 1:
The patent implements self-service by designing the ALU interface unit to automatically perform sharing, recombining, and blinding operations as part of its standard data flow management. These security functions are integrated into the interface unit's core operations rather than being separate computational steps. The interface unit serves its own security needs by managing the sharing state of variables throughout processing, eliminating the need for additional computational overhead from external security management logic.
Data Source
AI summary
Examples include techniques for a physical side-channel resilient arithmetic logic unit (ALU) The examples include use of circuitry to input a shared representation of a value having a plurality of shares to the ALU. Then, at the ALU, recombine the shared representation of the value to a single representation of the value and use the single representation to generate a result value or operate on the shared representation of the value to generate a shared representation of the result value. If the result value is based on operating on the single representation of the value, the result value is split to a shared representation of the result value. The shared representation of the result value can be output from the ALU and stored to at least one register from among a plurality of registers.