Concealed Modulus Conversion for Secret Sharing Without Quotient Transfer

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Solution Overview

Problem

Existing modulus transformation methods for secure computation are inefficient when the condition of quotient transfer is not satisfied.

Innovation Solution

A secure modulus conversion system and method that utilizes n distributed processing apparatuses, each equipped with first and second secret sharing conversion units, bit decomposition units, addition units, and sure computation units, to convert (k,n)-secret-sharing shares into (k,k)-additive-secret-sharing shares, perform bit decomposition and modulus conversion, and calculate the quotient, enabling efficient modulus conversion even without quotient transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the prior art modulus conversion method is used, then the modulus conversion can be performed efficiently, but it cannot be used when the condition of quotient transfer is not satisfied

Engineering Contradiction:
Improvemodulus conversion efficiencyVSAvoidapplicability when quotient transfer condition is not satisfied
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent changes the parameters of the modulus conversion process by introducing a new method that does not rely on the quotient transfer condition. Instead of using the traditional method that requires quotient transfer, the patent uses a different approach with modified parameters (different conversion steps and conditions) that works regardless of whether quotient transfer is satisfied, thus achieving both efficiency and versatility

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a universal modulus conversion method that can handle multiple scenarios - both when quotient transfer condition is satisfied and when it is not. The conversion process is designed to be multi-functional, adapting to different input conditions and producing correct results in all cases, thereby eliminating the limitation of the prior art

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If traditional modulus conversion is performed without quotient transfer, then versatility is improved, but communication and computation overhead increases

Engineering Contradiction:
Improveapplicability without quotient transfer conditionVSAvoidcommunication and computation overhead
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent segments the modulus conversion process into distinct phases: bit decomposition, modulus conversion, and quotient calculation. By breaking down the complex conversion into manageable segments, the system can optimize each phase independently and reduce overall overhead while maintaining versatility across different input conditions

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary bit decomposition and prepares conversion tables in advance. This preliminary action reduces the computational burden during the actual modulus conversion, thereby reducing communication and computation overhead while maintaining the ability to handle cases where quotient transfer condition is not satisfied

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4213134B1Concealed modulus conversion system, distributed processing device, concealed modulus conversion method, and program
Publication Date: 2025.12.10 NT T INC
  • EP4213134B1 patent drawingFigure 1
  • EP4213134B1 patent drawingFigure 2
  • EP4213134B1 patent drawingFigure 3

AI summary

(k,n)-secret-sharing share [[a]]p is converted into (k,k)-additive-secret-sharing share p, each bit of a'0 is (k,n)-secret-sharing to obtain a share [[a'0]]2^|p|; each bit of the share p1 is (k,n)-secret-shared to obtain a share [[a1]]2^|p|; a bit representation share [[a'0+a1]]2^(|p|+1) of a'0+a1 is obtained; it is assumed that the most significant bit of the share [[a'0+a1]]2^(|p|+1) is a share [[q]]2, a share [[q]]Q is obtained from the share [[q]]2; p0 mod Q, p1 mod Q are obtained from p0, p1 and are set as a share <a'>Q; the share <a'>Q is converted in (k,n)-secret-sharing to obtain (k,n)-secret-sharing share [[a']]Q; [[a]]Q is calculated from the share [[a']]Q and the share [[q]]Q.