Time-Controlled Data Encryption Key Management

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Solution Overview

Problem

Current data management systems fail to ensure the inaccessibility of data with a limited lifespan, especially when backed up, as erasing data from backups is complex and often not fully implemented, and restoring backups can inadvertently restore deleted data.

Innovation Solution

A data management system employs an indexed list of encryption keys with predefined validity periods, where data is encrypted with keys that expire, ensuring data becomes inaccessible when the encryption key is replaced and erased, and access requests are authenticated using periodic updates of the current index.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If data is erased from the database after the retention period, then data confidentiality is improved, but data accessibility during the retention period deteriorates due to backup restoration risks

Engineering Contradiction:
Improvedata confidentialityVSAvoiddata accessibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The encryption key is segmented into multiple parts: a first part stored in the database and a second part stored securely elsewhere. This segmentation allows the data to remain encrypted and inaccessible even when restored from backups, while still being accessible during the retention period through key reconstruction.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The data is encrypted with a key that is preliminarily split and stored in separate locations before the retention period ends. This preliminary action ensures that when the data is restored from backup, the encryption key cannot be reconstructed, automatically preventing access without requiring post-restoration intervention.

Inventive Principle:
Principle #10Preliminary action

2Ease of operation

If backups are restored to ensure data availability, then data accessibility is improved, but data confidentiality deteriorates as deleted data may be restored

Engineering Contradiction:
Improvedata accessibilityVSAvoiddata confidentiality
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The critical part of the encryption key (the second part) is extracted from the database and stored in a separate secure location. This extraction ensures that backup restoration alone cannot provide access to the data, as the extracted key component is not present in the restored backup.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A secure key management system acts as an intermediary between the stored encryption key part and the data decryption process. This intermediary controls and verifies key usage, ensuring that even if backup data is restored, unauthorized decryption attempts are blocked by the intermediary's security checks.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If physical destruction of backups is used to guarantee data inaccessibility, then data confidentiality is improved, but the principle of backup is violated and data accessibility deteriorates

Engineering Contradiction:
Improvedata confidentialityVSAvoidbackup utility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

Different quality requirements are applied to different parts of the encryption key: the first part can be stored in standard backups, while the second part requires enhanced security measures. This local quality differentiation allows backups to remain useful while ensuring that critical security elements are protected.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts key management based on the retention period. During the retention period, both key parts are available for data access. After the retention period expires, the second key part is securely deleted or invalidated, dynamically transitioning the system from an accessible state to an inaccessible state without physical destruction of backups.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3543890B1Methods and system for managing data allowing time control of the data
Publication Date: 2021.06.09 SAGEMCOM ENERGY & TELECOM SAS
  • EP3543890B1 patent drawingFigure 1~2
  • EP3543890B1 patent drawingFigure 3A~3C
  • EP3543890B1 patent drawingFigure 4~5

AI summary

A data recording method for time-based access control of data in a data management system, the method being executed by a server comprising an indexed list of encryption keys, a current index being initially predetermined, the method comprising the steps of receiving data to be recorded and a desired retention period, determining, based on the retention period, the validity period of an encryption key, the current index and the size of the list, an index, encrypting the data using the encryption key associated with said index, determining, based on the received data and the encryption key, an authentication code and recording said encrypted data in association with the index and the authentication code.The current index is updated periodically, with the update including a replacement of the encryption key associated with the current index with a new encryption key and an increment of the current index.