Partial Modular Exponentiation for Secure Computation

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Solution Overview

Problem

Current secure computation methods for modular exponentiation are inefficient in terms of communication amount and number of communications, particularly when keeping the exponent secret, as they require large communication volumes and frequencies.

Innovation Solution

An information processing apparatus and method that performs partial modular exponentiation calculations using shared exponents, allowing for efficient calculation of modular exponentiation results without revealing the shared exponents, utilizing a (2,3) RSS scheme to minimize communication and maintain secrecy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional secure computation methods are used for modular exponentiation, then security is maintained, but communication amount and number of communications become large

Engineering Contradiction:
ImprovesecurityVSAvoidcommunication amount
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The exponent a is divided into multiple shares a1, a2, a3 such that a = a1 + a2 + a3 mod p. Each share is distributed to different apparatuses, allowing modular exponentiation to be performed through local calculations without requiring large communication volumes while maintaining security through the secret sharing mechanism

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a modulus p as an intermediary element that enables efficient computation. By performing calculations in the modular field defined by p, the system achieves both security and computational efficiency, reducing communication requirements compared to conventional methods

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If conventional secure computation methods are used for modular exponentiation, then security is maintained, but number of communications increases

Engineering Contradiction:
ImprovesecurityVSAvoidnumber of communications
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The computation is segmented into local operations at each apparatus. Each apparatus performs modular exponentiation on its own share independently, eliminating the need for multiple sequential communications and reducing the number of communication rounds while maintaining security through the distributed share structure

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The shares a1, a2, a3 are prepared and distributed in advance before the modular exponentiation computation. This preliminary distribution allows the actual computation to proceed with minimal communication, as each apparatus already holds the necessary share information to perform local calculations

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS11895230B2Information processing apparatus, secure computation method, and program
Publication Date: 2024.02.06 NEC CORP
  • US11895230B2 patent drawing
  • US11895230B2 patent drawing
  • US11895230B2 patent drawing

AI summary

An information processing apparatus comprises a partial modular exponentiation calculating part and a partial modular exponentiation synthesizing part. The partial modular exponentiation calculating part is given a base in plaintext and a modulo in plaintext and shared exponents and calculates a partial modular exponentiation that equals a set of shared values according to a modular exponentiation of the base raised by the shared exponent. The partial modular exponentiation synthesizing part calculates shared values of the modular exponentiation from the partial modular exponentiation that equals shared values relating to the modular exponentiation of a sum of shared exponents.