Secret Sharing Method Using XOR and Random Data Combinations

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Solution Overview

Problem

Existing secret sharing methods using XOR operations lack flexibility, allowing third parties to easily reconstruct secret data when they possess more shared data parts than the threshold value, and require significant computational load for polynomial computations.

Innovation Solution

A secret sharing method that allows users to freely incorporate desired algorithms and reduces computational load by creating shared data parts from different combinations of secret and random number data pieces, making it difficult for third parties to reconstruct the secret data even with more shared parts than the threshold value.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polynomial interpolation method is used for secret sharing, then security of secret data is ensured, but computational load increases significantly

Engineering Contradiction:
Improvesecurity of secret dataVSAvoidcomputational load
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The secret data is divided into multiple shared data parts, where each part contains only a portion of the information needed to reconstruct the secret. This segmentation ensures that no single shared data part reveals the complete secret, maintaining security while allowing for simpler individual computations on each segment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of using complex polynomial interpolation to create shares, the invention inverts the approach by using simple XOR operations combined with random number generation. The security is achieved not through computational complexity of the sharing algorithm, but through the information-theoretic security of having insufficient shares below the threshold.

Inventive Principle:
Principle #13The other way round (Inversion)

2Productivity

If XOR operation is used for secret sharing, then computational speed increases, but flexibility decreases and security is compromised when more than threshold shares are obtained

Engineering Contradiction:
Improvecomputational speedVSAvoidsecurity against threshold-exceeding attacks
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

Random number data is generated and incorporated into the shared data parts during the secret sharing process, before any potential reconstruction attempts. This preliminary incorporation of random data ensures that even if an attacker obtains more than the threshold number of shares, they cannot easily reconstruct the secret without the corresponding random number data that was used in the sharing process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention introduces random number data as an intermediary element that mediates between the secret data and the shared data parts. This random number data acts as an additional layer of protection, ensuring that the relationship between shares and secret remains computationally infeasible to reverse, even when the threshold number of shares is exceeded.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If fixed algorithm is used in threshold scheme, then reconstruction is straightforward when threshold shares are obtained, but adaptability to different user requirements decreases

Engineering Contradiction:
Improveease of reconstructionVSAvoidalgorithm flexibility
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The invention makes the secret sharing system dynamic by allowing users to select from multiple different algorithms for creating shared data parts. Instead of a fixed algorithm, the system can adapt to user preferences and requirements by choosing from XOR-based methods, polynomial interpolation, or other custom algorithms, while maintaining the core threshold security properties.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2701337B1Secret sharing method and system
Publication Date: 2018.02.21 PANASONIC HOLDINGS CORP
  • EP2701337B1 patent drawingFigure 1
  • EP2701337B1 patent drawingFigure 2
  • EP2701337B1 patent drawingFigure 3(A)~3(C)

AI summary

In a secret sharing process based on an improved threshold scheme, secret data is shared as shared data parts equal to or greater than a threshold value in number such that the secret data cannot be reconstructed from shared data parts less than the threshold value in number. Each of the shared data pieces is created essentially from a different combination of the secret data pieces and the data pieces for secret sharing computation. The secret sharing process allows an algorithm desired by the user to be freely incorporated, and can prevent the secret data to be easily reconstructed even when more shared data parts than the threshold value are acquired by a third party.