QAP-Based Homomorphic Encryption One-Way Computational System Design

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Solution Overview

Problem

Current fully homomorphic encryption (HE) schemes face challenges in achieving practical, noise-free computations due to exponential overhead and inability to conduct blind evaluations without secret disclosure, relying on approximated solutions and high computational costs.

Innovation Solution

A method for designing a one-way computational system in quotient algebra partition-based homomorphic encryption (QAPHE) that constructs fault-tolerant encodes using tensor-product operators, correction operators, and permutations to achieve exact solutions with modest computational overhead, enabling blind evaluations and secure computations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If noise reduction methods are used in lattice-based HE schemes, then computation can be performed on encrypted data, but exponential overhead is required and only approximated solutions are obtained

Engineering Contradiction:
Improvecomputation accuracyVSAvoidcomputational overhead
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the computational process into distinct phases: encoding the function as a QAP instance, performing homomorphic evaluation, and decoding results. This segmentation allows each phase to be optimized independently, avoiding the exponential overhead of traditional lattice-based noise reduction while maintaining computation accuracy through structured algebraic operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the fundamental parameters of the HE system by transitioning from lattice-based cryptography to QAP-based cryptography. This parameter change enables exact arithmetic operations on encrypted data without requiring noisy approximation corrections, thereby eliminating exponential computational overhead while maintaining reliability.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If traditional HE schemes are used, then encrypted computation is enabled, but algorithms and operators are revealed during computation (no blind evaluation)

Engineering Contradiction:
ImprovesecurityVSAvoidsecret disclosure
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent introduces QAP instances and evaluation circuits as intermediaries between the encrypted data and the computation process. These intermediaries allow the computation to be performed on encrypted representations without exposing the underlying algorithms or operators, enabling blind evaluation while maintaining security through the cryptographic structure of QAPHE.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Measurement precision

If fault tolerant encoding is used in QAPHE, then exact solutions can be obtained, but computational complexity increases

Engineering Contradiction:
Improvesolution exactnessVSAvoidcomputational complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent performs preliminary encoding of the function as a QAP instance before homomorphic evaluation. This preliminary action structures the computation in advance, allowing exact solutions to be obtained during evaluation without requiring complex fault tolerant mechanisms during the actual computation phase, thereby reducing overall computational complexity.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS12256001B2Method of designing one-way computational system in QAP-based homomorphic encryption
Publication Date: 2025.03.18 NATIONAL APPLIED RESEARCH LABORATORIES
  • US12256001B2 patent drawing
  • US12256001B2 patent drawing
  • US12256001B2 patent drawing

AI summary

The present inventive concept discloses a method of designing a one-way computational system in QAP-based homomorphic encryption applied to the n-qubit encode operations of a k-qubit action M for public-key and semi-public-key schemes respectively, n≥k, wherein the method comprises: preparing a tensor-product operator =I2<sup2>n-k</sup2>⊗M=12 and decomposing it into two parts, wherein is composed of elementary gates, and let =1† and 2=; providing a correction operator, =12 for public-key and =I2<sup2>k </sup2>for semi-public-key, and an encoding operator, Qen†V†=W1W2 for public-key and Qp†=W1W2 for semi-public-key, both composed of elementary gates; providing appropriate permutations P, P0 and P1, while P0=P1 for semi-public-key, to obey the nilpotent condition PW1P0=I for the identity operator; through process of merging operators according to sets of identities of gates, including Id-GateELIM, Id-GateEx and Id-GateREP, there obtain the mixed encode for public-key scheme, Uen=PQen†V†=(P1†W1†21W1P1)(P1†P0)(P0†W1†2W1P0) (P0†W2), and that for semi-public key, Uen=PMQp†=(P0†W1†2W1P0)(P0†W2) with n=k, 1=2=I2<sup2>n </sup2>and P0=P1.