One-way Key Fob Pairing Using Device IDs and ECC
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Solution Overview
Problem
Conventional key fob and vehicle control unit pairing methods are vulnerable to security breaches and require unnecessary communication and human involvement, as they rely on secret keys that need to be managed by multiple parties, increasing costs and complexity.
Innovation Solution
The use of device identifiers assigned by manufacturers for entity authentication and trust transfer, combined with elliptical curve cryptography and public key cryptography, allows for secure one-way key fob pairing, reducing vulnerabilities and communication requirements, while preventing unauthorized access by ensuring the key fob can only transmit and not receive, thus minimizing human intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional secret key pairing methods are used, then key fob and vehicle control unit can be paired, but security vulnerabilities increase and communication complexity increases
Solution Approach 1:
The patent extracts the secret key management complexity from the pairing process by using public key infrastructure. Instead of sharing secret keys between multiple parties (vehicle manufacturer, dealer, control unit, key fob), each party has their own public key that can be freely distributed. The actual secret keys never leave their respective devices, eliminating the need for secure key distribution channels and reducing communication complexity while maintaining security.
Solution Approach 2:
The patent introduces public keys as intermediaries in the pairing process. Rather than directly exchanging secret keys between parties, the pairing is achieved through public key authentication and cryptographic challenge-response protocols. This intermediary mechanism allows secure pairing without requiring trusted intermediaries to distribute secret keys, simplifying the overall system architecture.
2Ease of operation
If secret keys are managed by multiple parties, then pairing can be achieved, but operational costs increase
Solution Approach 1:
The patent enables each device (vehicle control unit and key fob) to autonomously generate and manage its own cryptographic key pairs. The control unit generates its public key and stores it locally, while the key fob similarly generates and stores its public key. During pairing, these public keys are exchanged and used for authentication without requiring external key distribution services, eliminating key management overhead for dealers and manufacturers.
3Adaptability or versatility
If key fob can transmit and receive, then bidirectional communication is achieved, but security vulnerabilities increase
Solution Approach 1:
The patent applies asymmetric cryptography where the key fob and control unit have different communication capabilities and key usage patterns. The key fob holds the private key and can initiate authentication by proving possession of this key through cryptographic challenges. The control unit holds the public key and verifies authentication requests. This asymmetric relationship allows the key fob to be simpler (transmit-only or limited receive) while maintaining strong security, as the critical secret never leaves the key fob.
Data Source
AI summary
Key fob and vehicle control unit identifiers (IDs) are used for entity authentication or trust transfer to achieve a secured initial pairing. The key fob is capable of transmitting only (not receiving) and is paired with a control unit in a vehicle or with any other control device. Use of the key fob and control unit IDs prevents unauthorized pairing and access to the operation key (OpKey) that is later used for communications between the devices. Elliptical curve cryptography (ECC) is used for strong security and efficient implementation. In the pairing process, device IDs are used for entity authentication and public key cryptography is used for easy key management. Symmetric encryption is used for fast normal operation and to accommodate key fob addition or revocation after key fob loss.