Secret Sharing Device Using Matrix Operations

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Solution Overview

Problem

The Shamir (k, n) threshold scheme requires high computational power due to polynomial interpolation, and existing methods like Fujii and Kurihara's schemes are limited to threshold k values of 2 or 3, restricting their applicability.

Innovation Solution

A secret sharing system that uses a generator matrix G of size k(n-1) x n(n-1) to distribute and recover secret information without polynomial interpolation, allowing for any threshold k value between 2 and n, using a recursive process to create recovery matrices from shared information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If polynomial interpolation is used for secret sharing, then the threshold scheme can work for any k value, but the computational complexity increases significantly

Engineering Contradiction:
Improvethreshold value flexibilityVSAvoidcomputational complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent divides the secret information into multiple blocks and processes each block separately through matrix operations. The generator matrix G is constructed in a segmented manner where different blocks can be processed independently, reducing the overall computational complexity while maintaining support for any threshold k value.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent replaces the polynomial interpolation mechanism with a linear algebra-based matrix operation system. Instead of using polynomial fields and interpolation formulas, the invention uses generator matrices and vector spaces over finite fields, substituting a computationally heavier mathematical mechanism with a more efficient linear algebra approach.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If Fujii method or Kurihara method is used, then the computational speed increases, but the threshold k is restricted to 2 or 3

Engineering Contradiction:
Improvecomputational speedVSAvoidthreshold value range
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent creates a universal secret sharing system that can handle any threshold k value (2 ≤ k ≤ n) using the same matrix operation framework. The generator matrix G is designed with a structure that adapts to different k values without requiring fundamentally different algorithms, making the system multi-functional across various threshold requirements.

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

Solution Approach 2:

The patent changes the parameter k (threshold value) by modifying the structure of the generator matrix G rather than changing the underlying algorithm. The matrix dimensions and construction method are parameterized to accommodate different k values, allowing the same computational approach to work universally across different threshold requirements.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If Shamir (k, n) threshold scheme is used, then secret information can be recovered from any k items, but high-speed computer is required

Engineering Contradiction:
Improvesecret recovery capabilityVSAvoidhardware requirement
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses simple XOR operations and basic matrix multiplications that can be implemented with minimal computational resources. Instead of requiring complex polynomial arithmetic that demands high-speed computers, the invention employs operations that can be performed efficiently on low-grade devices, effectively replacing expensive computational resources with simpler, more accessible hardware.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS8074068B2Secret sharing device, method, and program
Publication Date: 2011.12.06 TOSHIBA DIGITAL SOLUTIONS CORP
  • US8074068B2 patent drawing
  • US8074068B2 patent drawing
  • US8074068B2 patent drawing

AI summary

A secret sharing device of (k, n) threshold scheme creates a generator matrix G, first divided secret data, and random number data, calculates shared partial data based on the product of matrices with the random number data, the divided secret data, and the generator matrix G, and delivers the shared information formed by the shared partial data and the header information individually to the storage units. The secret sharing device calculates a recovery matrix and multiplies the shared information by the recovery matrix, hence to recover the secret information.