Target-Bound Certificates for Granular Resource Authentication

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing systems for implementing differential access to resources on devices rely on correct configuration of multiple trusted-authority root keys, leading to storage and management burdens and vulnerabilities due to incorrect associations between resources and root keys.

Innovation Solution

Extending cryptographic certificates with target-binding information that specifies a particular resource-specific asymmetric keypair, allowing the same trusted-authority root key to be used for multiple keypairs, reducing the need for individual key management and ensuring correct resource access.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple trusted-authority root keys are configured for differential access to resources, then access control granularity is improved, but device complexity and management burden increase

Engineering Contradiction:
Improveaccess control granularityVSAvoidkey management complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the trust verification process by separating the root key storage (single trusted authority) from the resource-specific keypair verification (multiple keypairs with target-binding). Each certificate is segmented to include target-binding information that specifies which particular keypair it binds to, allowing fine-grained access control without requiring multiple root keys.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces certificates with target-binding information as an intermediary between the trusted authority and the resource-specific keypairs. This intermediary carries the binding information that links a public key to a specific resource or target, eliminating the need for multiple root keys while maintaining security.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple trusted-authority root keys are stored for different resources, then security is improved, but storage requirements and management overhead increase

Engineering Contradiction:
ImprovesecurityVSAvoidnumber of root keys
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent makes the single trusted authority root key universal by having it sign multiple certificates that each bind to different resource-specific keypairs. The same root key serves multiple functions by verifying different certificates, each with its own target-binding information specifying a particular keypair. This eliminates the need to store multiple root keys while maintaining security.

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

3Measurement precision

If target-binding information is added to certificates, then authentication precision is improved, but certificate complexity increases

Engineering Contradiction:
Improveauthentication precisionVSAvoidcertificate structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by embedding the target-binding information in the certificate during the certificate issuance process. The trusted authority includes the specific keypair identifier in the certificate before issuance, so that when the certificate is later verified, the binding information is already present and no additional complex verification steps are needed.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4523372B1Systems and methods for extending cryptographic certificates with target-binding information
Publication Date: 2026.04.22 ASSA ABLOY AB
  • EP4523372B1 patent drawingFigure 1
  • EP4523372B1 patent drawingFigure 2
  • EP4523372B1 patent drawingFigure 3

AI summary

A first computing device maintains multiple resource-specific asymmetric keypairs that are each uniquely associated with a different protected resource on the first device, including a first resource-specific asymmetric keypair that is uniquely associated with a first protected resource. The first device engages with a second device in an authentication flow based on the first resource-specific asymmetric keypair. The first device receives, from the second device, a public-key certificate that contains target-binding data that indicates a specified asymmetric keypair. The first device checks whether the specified asymmetric keypair matches the first resource-specific asymmetric keypair. If so, and assuming any other authentication conditions are also met, the first device authenticates the second device to the first resource-specific asymmetric keypair, and grants the second device access to the first protected resource.