FHE Accelerator Bootstrapping With Compressed Auxiliary Data
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Solution Overview
Problem
The bootstrapping process in Fully Homomorphic Encryption (FHE) schemes is computationally complex and requires significant memory resources, making it impractical for real-time commercial applications.
Innovation Solution
Optimize the bootstrapping process by reducing auxiliary data used for bootstrapping and loading it into the internal memory of an FHE accelerator only once, utilizing techniques such as matrix diagonal compression, sparse-to-dense key-switching key compression, and key reuse, while maintaining an optimal memory-computation balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bootstrapping process is executed frequently to maintain decryption accuracy, then the reliability of the FHE scheme is improved, but the execution time and computational overhead increase significantly
Solution Approach 1:
The patent pre-computes and stores auxiliary data (including trigonometric tables, key switching keys, and decomposition data) in a compressed format before the actual FHE execution. This preliminary preparation allows the bootstrapping process to execute faster during runtime by retrieving pre-processed data rather than computing it on-the-fly, thus reducing the time penalty of frequent bootstrapping operations while maintaining decryption accuracy
2Quantity of substance
If the auxiliary data for bootstrapping is stored in full form, then the completeness of the data is improved, but the memory resources required increase significantly
Solution Approach 1:
The patent applies compression techniques to transform the auxiliary data from its original uncompressed form into a compressed representation. Specifically, it uses matrix diagonal compression for the trigonometric tables and sparse-to-dense key switching key compression, which significantly reduces the memory footprint while preserving all necessary information for the bootstrapping process to function correctly
3Device complexity
If the bootstrapping process is optimized to reduce memory usage, then the device complexity is reduced, but the computational overhead during execution may increase
Solution Approach 1:
The patent performs computationally intensive compression operations on the auxiliary data during an offline setup phase, transforming the data into a compact format that requires minimal memory resources. Although this pre-processing requires computational effort, it is executed once during system initialization rather than during each bootstrapping operation, thereby reducing the ongoing computational energy consumption during actual FHE execution
Data Source
AI summary
A method and system of the device may include obtaining hardware constraints of an FHE accelerator configured to execute the FHE program. In addition, the device may include selecting an optimal bootstrapping configuration that corresponds to the hardware constraints. The device may include identifying repetitive data patterns in the auxiliary data to be used in the bootstrapping process. Moreover, the device may include reducing the auxiliary data by applying at least one auxiliary data optimization technique based on the repetitive data patterns. Also, the device may include modifying the FHE program to include an instruction to load at least a portion of the reduced auxiliary data into an internal memory of the FHE accelerator, where the at least a portion of the reduced auxiliary data is loaded to the internal memory once prior to the execution of the plurality of bootstrapping processes.