Key Storage Apparatus Preventing Service Resumption via One-Way Function

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Solution Overview

Problem

Existing key storage apparatuses fail to prevent service resumption with the same configuration after the arithmetic processing provision period expires, leading to potential information leakage when attackers exploit the secret key.

Innovation Solution

A key storage apparatus that secretly manages a key using a one-way function to generate and store the key before expiration, and outputs it to the user when the period expires, ensuring the key is eliminated from the storage section, thereby preventing attackers from resuming the service.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the secret key is outputted to the user when the arithmetic processing provision period expires, then the user convenience is improved, but the security is worsened because attackers can resume the service with the same configuration

Engineering Contradiction:
Improveuser convenienceVSAvoidsecurity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system performs preliminary elimination of the first information from storage before the key is output to the user. This preliminary action ensures that even if the key is distributed, the attacker cannot resume service because the original secret information is already destroyed. The expiration judging section eliminates the first information and then outputs the key, preventing service resumption while maintaining user convenience.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the secret key is eliminated from the key storage apparatus after the arithmetic processing provision period, then the security is improved, but the user convenience is worsened because users lose means for decrypting ciphertext

Engineering Contradiction:
ImprovesecurityVSAvoiduser convenience
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system eliminates the first information from storage in advance before the user needs the key for decryption. The expiration judging section detects when the provision period expires and immediately eliminates the first information, then outputs the key to the user. This timing ensures security is maintained while the user still receives the necessary key for decrypting ciphertext.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system separates the first information (secret key material) from the output key. The one-way function section generates the key from the first information, allowing the first information to be eliminated while the generated key is already provided to the user. This segmentation allows security enhancement without compromising user convenience.

Inventive Principle:
Principle #1Segmentation

3Reliability

If the first information is eliminated from the storage section after expiration, then the security against service resumption is improved, but the key management complexity increases

Engineering Contradiction:
ImprovesecurityVSAvoidkey management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The expiration judging section automatically detects when the arithmetic processing provision period expires and autonomously eliminates the first information from storage without requiring manual intervention. This self-service mechanism simplifies key management by automating the security-critical elimination process, reducing complexity while maintaining high security standards.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3010173B1Key storage device, key storage method, and program therefor
Publication Date: 2019.01.16 NIPPON TELEGRAPH & TELEPHONE CORP
  • EP3010173B1 patent drawingFigure 1
  • EP3010173B1 patent drawingFigure 2
  • EP3010173B1 patent drawing

AI summary

An object is to provide a key storage apparatus which prevents a service from being resumed with the same configuration as a configuration during an arithmetic processing provision period, a key storage method, and a program therefor. The key storage apparatus is such that it is assumed that, before expiration of a period for providing arithmetic processing using a key, the key is secretly managed, and that the key is outputted when the period expires, and the key storage apparatus comprises: a one-way function section causing a one-way function to act on first information to generate the key; a storage section secretly storing the first information during the period; and an expiration judging section eliminating the first information from the storage section and outputting the key when the period expires.