Offline Access Revocation via Local Blacklist Storage

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Solution Overview

Problem

Existing device access revocation protocols are not suitable for resource-constrained environments and may not function effectively under limited or unreliable network connectivity, as they require complex client-server architectures and significant memory and storage resources to prevent security breaches.

Innovation Solution

An access control system utilizing a blacklist stored at the resource device, which allows for immediate revocation of access by adding entries for users, roles, or permission levels, even when valid access tokens are presented, enabling denial of access independent of network connectivity and prior authorization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If complex client-server architectures with consistent network connectivity are used for device access revocation, then security against replay attacks is improved, but device complexity and resource requirements increase significantly

Engineering Contradiction:
Improvesecurity against replay attacksVSAvoidclient-server architecture complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the revocation list from the server and stores it locally in the device's non-transitory storage medium. This allows the device to independently check token validity against the revocation list without requiring continuous server connectivity, thereby reducing architectural complexity while maintaining security

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system segments the access control functionality by separating token validation from revocation list updates. The device can validate tokens using locally stored revocation lists, enabling offline security operations, while periodically synchronizing with the server when connectivity is available

Inventive Principle:
Principle #1Segmentation

2Reliability

If complex client-server architectures with high memory and storage requirements are used for device access revocation, then security against breaches is improved, but resource consumption increases making it unsuitable for resource-constrained environments

Engineering Contradiction:
Improvesecurity against breachesVSAvoidmemory and storage resources
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent implements a streamlined revocation list structure with fixed fields (token identifier, issuance time, expiration time) that can be efficiently stored and processed. The list is updated periodically rather than maintaining complex real-time synchronization, reducing overall resource requirements while maintaining security effectiveness

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

Solution Approach 2:

The revocation list is pre-populated and stored in the device's non-transitory storage medium before token validation occurs. This preliminary storage eliminates the need for complex runtime queries to external servers, reducing both memory requirements and processing overhead during critical validation operations

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If access tokens are allowed to expire naturally for revocation, then system simplicity is maintained, but revocation speed is insufficient for immediate access restriction

Engineering Contradiction:
Improvesystem architecture simplicityVSAvoidrevocation time delay
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The system pre-populates the revocation list with tokens that need to be revoked, with their validity periods explicitly defined. When a token is added to the revocation list, the device can immediately check against this list during validation, enabling instant revocation effect without waiting for token expiration

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The device continuously checks the revocation list during token validation operations. When the revocation list is updated with new entries, the validation process immediately reflects these changes by checking against the updated list, providing real-time feedback on token validity and enabling prompt access restriction

Inventive Principle:
Principle #23Feedback

4Extent of automation

If continuous network connectivity is required for access revocation, then centralized control is maintained, but system reliability decreases in environments with limited or unreliable network connectivity

Engineering Contradiction:
Improvecentralized access controlVSAvoidoperation under limited network connectivity
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The system segments access control into independent offline validation operations and periodic online synchronization operations. The device can validate tokens against locally stored revocation lists without network connectivity, maintaining operational reliability, while periodically updating the revocation list from the server when connectivity is available

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The revocation list is pre-stored in the device's non-transitory storage medium, enabling offline validation. The device is prepared in advance with the necessary revocation data, eliminating the need for continuous network connectivity during critical token validation operations

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3345370B1Device access revocation
Publication Date: 2019.03.13 GOOGLE LLC
  • EP3345370B1 patent drawingFigure 1
  • EP3345370B1 patent drawingFigure 2A
  • EP3345370B1 patent drawingFigure 2B

AI summary

In some implementations, after one or more users have each been granted a respective access token allowing access to a resource device, revocation data is received by the resource device. The revocation data indicates that the previously granted access to the resource device should be revoked. For example, the revocation data may indicate (i) a user, role, or permission level for which access is revoked and (ii) a duration that access to the resource device was allowed. After receiving the revocation data, the resource device receives token data derived from an access token that allows access to the resource device. The resource device determines that the access token relies on authorization of the user, role, or permission level indicated by the revocation data, and in response, the resource device denies access.