Secure Computation Device Authentication Integrity

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Solution Overview

Problem

Existing secure computation techniques are vulnerable to spoofing attacks, where unauthorized concealed verification values can be computed, leading to false successful authentication even when w-ω ≠ 0, making it difficult to detect unauthorized authentication information.

Innovation Solution

A secure computation device and system that uses secret sharing values for authentication information and random numbers, generating concealed verification values through secure computation, and employing Shamir's secret sharing scheme to ensure authentication integrity, preventing unauthorized verification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If simple secure computation method is used to compute concealed verification value, then authentication processing can be performed while keeping authentication information secret, but security level against spoofing attacks becomes low

Engineering Contradiction:
Improveauthentication securityVSAvoidspoofing vulnerability
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by dividing the concealed verification value computation into multiple stages using Shamir's secret sharing scheme. Instead of computing a single concealed verification value directly, the system segments the authentication information into multiple shares and performs verification through polynomial interpolation, making it difficult for attackers to obtain unauthorized verification values even if they compromise individual shares.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter representation by working in extended finite fields (Fε) rather than simple finite fields. This parameter transformation allows the system to compute verification values with higher security margins, where the verification value y = (y0, y1, ..., yε-1) provides multiple layers of verification that increase resistance against spoofing attacks.

Inventive Principle:
Principle #35Parameter changes

2Loss of information

If authentication information is kept secret using simple concealment, then privacy is protected, but detection of unauthorized verification values becomes difficult

Engineering Contradiction:
Improveauthentication information secrecyVSAvoidunauthorized verification detection
Core Design Contradiction:
Loss of informationVSDifficulty of detecting and measuring

Solution Approach 1:

The patent implements feedback mechanisms through verification value computation that provides detectable signals of unauthorized access. By computing verification values based on polynomial shares and comparing them against expected results, the system can detect when unauthorized verification values are attempted, providing feedback that reveals spoofing attempts without exposing the underlying authentication information.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs preliminary actions by pre-computing and storing shares of authentication information using Shamir's secret sharing before actual verification is needed. This preliminary segmentation of authentication data into cryptographic shares allows the system to quickly detect unauthorized verification attempts during the verification phase without having to reveal or reconstruct the original authentication information.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3757976B1Secret calculation device, secret calculation authentication system, secret calculation method, and program
Publication Date: 2023.10.11 NIPPON TELEGRAPH & TELEPHONE CORP
  • EP3757976B1 patent drawingFigure 1
  • EP3757976B1 patent drawingFigure 2
  • EP3757976B1 patent drawingFigure 3A~3B

AI summary

A secure computation device obtains a first concealed verification value [z]i = [w-ω]i with secure computation by using concealed authentication information [w]i which is preliminarily stored and concealed authentication information [ω]i which is inputted, obtains a concealed extension field random number [rm]i∈[Fε] which is a secret sharing value of an extension field random number rm, obtains a second concealed verification value [ym]i in which ym is concealed with secure computation by using the first concealed verification value [z]i, and obtains a third concealed verification value [rmym]i with secure computation by using the concealed extension field random number [rm]i and the second concealed verification value [ym]i and outputs the third concealed verification value [rmym]i.