Self-Signed Root Certificate for Changing Identity Devices

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Solution Overview

Problem

Existing certificate authority-based systems become burdensome and inefficient when devices with changing identities frequently need to establish secure connections, as they require repeated communication with an external trusted third party, leading to delays and potential overload on the certificate authority.

Innovation Solution

Devices act as their own certificate authorities by issuing self-signed root certificates and creating derived certificates for short-term identities, allowing peer-to-peer mutual authentication without external involvement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If devices use traditional certificate authority-based authentication, then secure connections can be established, but repeated communication with external certificate authority causes delays and overload

Engineering Contradiction:
Improveauthentication securityVSAvoidcertificate request delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

Each device acts as its own certificate authority by issuing self-signed root certificates and creating derived certificates for short-term identities. This self-service approach eliminates the need to communicate with external certificate authorities, resolving the contradiction by maintaining authentication security through cryptographic verification while removing the time delays associated with external CA communication.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The authentication system is segmented into hierarchical certificate levels: root certificates for long-term identity and derived certificates for short-term identities. This segmentation allows devices to use pre-established root certificates for authentication without needing to contact external CAs, thus maintaining security while eliminating delays.

Inventive Principle:
Principle #1Segmentation

2Adaptability or versatility

If devices frequently request new certificates from certificate authority, then updated certificates are obtained, but certificate authority becomes overloaded

Engineering Contradiction:
Improveidentity change capabilityVSAvoidcertificate creation efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

Devices autonomously generate derived certificates for short-term identities using their own long-term private keys, eliminating the need to contact external certificate authorities. This resolves the contradiction by enabling frequent identity changes without impacting certificate authority productivity, as the self-service mechanism handles all certificate generation locally.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

Devices perform preliminary actions by pre-generating root certificates and establishing trust relationships before needing short-term certificates. When identity changes occur, devices can immediately create derived certificates without external intervention, thus maintaining adaptability while preventing certificate authority overload.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If external certificate authority is used for each identity change, then proper authentication is ensured, but system complexity increases

Engineering Contradiction:
Improveauthentication trustVSAvoidsystem architecture complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system replaces the complex external certificate authority infrastructure with a self-service model where each device independently manages its own certificate hierarchy. Trust is maintained through cryptographic verification of self-signed root certificates and derived certificates, resolving the contradiction by simplifying system architecture while preserving authentication reliability.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The certificate authority function is extracted from external systems and embedded within each device itself. Each device contains its own certificate generation and verification capabilities, eliminating the need for complex external CA infrastructure and reducing overall system complexity while maintaining trust through local cryptographic operations.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP2600647B1Derived certificate based on changing identity
Publication Date: 2015.03.18 BLACKBERRY LTD
  • EP2600647B1 patent drawingFigure 1
  • EP2600647B1 patent drawingFigure 2
  • EP2600647B1 patent drawingFigure 3

AI summary

A first device (102,200,500) with a changing identity establishes a secure connection with a second device (104,106,250,600) in a network (100) by acting as its own certificate authority. The first device issues itself a self-signed root certificate (112,206,518) that binds an identity of the first device to a long-term public key (204,516) of the first device. The root certificate is digitally signed using a long-term private key (202,514), where the long-term public key and the long-term private key form a public/private key pair. The first device provides its root certificate to the second device in any trusted manner. The first device can then create a certificate (130,220,534) for one or more short-term identities (132) acquired by the first device and sign the newly-created certificate using the long-term private key. The first device can authenticate itself to the second device by sending the newly-created certificate to the second device.