ECU Public-Key Unlocking for Secure Debug Access
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hardware debug interfaces in electronic control units are vulnerable to attacks due to the potential exposure of secret keys and critical data, and the storage and management of these keys by suppliers pose security risks and inefficiencies.
Innovation Solution
A cryptographic key exchange mechanism using a modified Diffie-Hellman protocol where the private key is generated on-device and the public key is displayed on the control unit, allowing the OEM to recreate the shared secret without storing it, ensuring secure access and eliminating the need for a backend database.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If secret keys are stored in a supplier's database or transmitted to the OEM, then debug access can be provided, but security risks increase due to potential breaches and unauthorized access
Solution Approach 1:
The secret key is extracted from the supplier's database and removed from external storage. Instead of storing the key in a vulnerable database, only the public key is transmitted to the OEM, while the secret key remains exclusively within the electronic control unit's secure element, eliminating the security vulnerability of centralized key storage
Solution Approach 2:
A public key infrastructure acts as an intermediary between the supplier and the OEM. The public key serves as a safe mediator that allows the OEM to provision debug access without exposing the secret key. The OEM can verify the ECU's identity and provision access using the public key, while the secret key never leaves the ECU
2Reliability
If secret keys are stored securely with mandatory security mechanisms, then access control is maintained, but device complexity and storage requirements increase
Solution Approach 1:
The complex key management burden is extracted from the OEM's infrastructure. Instead of requiring the OEM to implement and maintain secure key storage systems with mandatory security mechanisms, only the lightweight public key is stored at the OEM, which can be safely stored in simple non-volatile memory without special security protections
Solution Approach 2:
The secret key is effectively copied only to the secure element within the ECU, while the OEM receives only a copy of the public key. This copying strategy allows the OEM to have access control capability without bearing the complexity of secure key management infrastructure
3Adaptability or versatility
If a backend system is implemented to store and manage secret keys, then key management is centralized, but system complexity and maintenance requirements increase
Solution Approach 1:
The backend key management system is extracted and replaced by a decentralized approach. The secret key is taken out of any centralized backend system and embedded directly in the ECU's secure element. The OEM's key management capability is maintained through possession of the public key, eliminating the need for complex backend infrastructure
Solution Approach 2:
The ECU performs self-service for key management by generating its own key pair and securely storing the secret key within its own secure element. The ECU independently verifies debug access requests using its private key and public key, without requiring external backend systems for key management operations
4Ease of operation
If the main processor is inactive due to an internal error state, then the system is non-functional, but debug access is needed for troubleshooting
Solution Approach 1:
The debug access functionality is segmented from the main processor and implemented as an independent verification path. The secure element and debug interface can operate independently of the main processor state, allowing debug access verification to proceed even when the main processor is inactive or in an error state
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
Examples relate to an electronic control unit, a method and a computer program for an electronic control unit, and to an apparatus, method and computer program for performing control operations on an electronic control unit. A public key of the electronic control unit is shown in machine-readable form on the electronic control unit. The electronic control unit comprises processing circuitry configured to determine first cryptographic information based on a private key of the electronic control unit and based on a public key of a second entity. The processing circuitry is configured to obtain second cryptographic information via an interface, with the second cryptographic information being based on the public key of the electronic control unit. The processing circuitry is configured to compare the first cryptographic information and the second cryptographic information. The processing circuitry is configured to unlock a control access to the electronic control unit if the first cryptographic information and the second cryptographic information match.