Homomorphic Encrypted Text Multiplication via Quotient–Remainder Decomposition

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Solution Overview

Problem

Homomorphic multiplication operations in existing encryption methods consume excessive modulus resources, leading to reduced plain text space and inefficiencies, which can result in the need for frequent bootstrapping operations that are time-consuming.

Innovation Solution

The method involves decomposing homomorphic ciphertexts into quotient and remainder data, performing operations on these components to generate a homomorphic multiplication result, and then reassembling the result while minimizing modulus consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If homomorphic multiplication operation is performed using existing encryption methods, then the operation can be executed on encrypted data, but the modulus consumption is excessive leading to reduced plain text space

Engineering Contradiction:
Improvehomomorphic multiplication operationVSAvoidmodulus consumption
Core Design Contradiction:
Ease of operationVSQuantity of substance

Solution Approach 1:

The patent divides the homomorphic multiplication operation into two independent parts: a first homomorphic multiplication operation and a second homomorphic multiplication operation. Each operation uses a portion of the modulus, thereby reducing the total modulus consumption while maintaining the ability to perform homomorphic multiplication on encrypted data.

Inventive Principle:
Principle #1Segmentation

2Quantity of substance

If modulus consumption is reduced through operation decomposition, then plain text space is extended, but the operation complexity increases

Engineering Contradiction:
Improvemodulus consumptionVSAvoidoperation complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The homomorphic multiplication is segmented into two operations that can be executed in parallel or sequentially. This segmentation reduces modulus consumption and extends plain text space, while the overall process remains manageable through structured decomposition into defined operational steps.

Inventive Principle:
Principle #1Segmentation

3Reliability

If bootstrapping operations are performed frequently to extend plain text space, then the encryption can maintain security, but the processing time increases significantly

Engineering Contradiction:
Improveencryption securityVSAvoidbootstrapping operation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary decomposition of the homomorphic multiplication operation into two separate operations before execution. This preliminary structuring allows the system to achieve secure encryption with extended plain text space without requiring frequent bootstrapping operations, thereby reducing processing time while maintaining security.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4641967A1Method and electronic device for processing homomorphic encrypted text
Publication Date: 2025.10.29 CRYPTO LAB INC
  • EP4641967A1 patent drawingFigure 1
  • EP4641967A1 patent drawingFigure 2
  • EP4641967A1 patent drawingFigure 3

AI summary

An electronic apparatus of the present disclosure comprises: a memory for storing a plurality of homomorphic ciphertexts; and a processor for performing homomorphic multiplication operations on the plurality of homomorphic ciphertexts, wherein the processor uses the plurality of homomorphic ciphertexts decomposed into quotient data divided by a preset modulus and remainder data, so as to generate a plurality of intermediate operation results using quotient operation data using quotient data of each of the plurality of homomorphic ciphertexts, quotient data of one text among the plurality of homomorphic ciphertexts, and the remainder data of the remaining homomorphic ciphertexts, and uses the quotient operation data and the plurality of intermediate operation results so as to generate a homomorphic ciphertext according to the result of the homomorphic multiplication operations.