ECU Security Access via Unique Key Challenge Response
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Solution Overview
Problem
Existing challenge/response mechanisms for securing access to vehicle electronic control units (ECUs) are either vulnerable to unauthorized access once the response is known or rely on a secret algorithm that compromises overall security if exposed.
Innovation Solution
A system where each ECU has a unique identification value and security key, stored on a remote secure server, which generates a response to a challenge, ensuring each ECU uses a different algorithm and maintaining security even if one ECU's algorithm is reverse-engineered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed challenge/response mechanism is used where the ECU stores the challenge and response, then the implementation is simple and does not require computation capability in the ECU, but the security is limited because the same response unlocks the ECU forever once known
Solution Approach 1:
The patent transforms the static fixed challenge/response mechanism into a dynamic system where the challenge changes with each access attempt. The ECU generates a new random challenge value for each unlock request, preventing replay attacks and ensuring that each response is valid only for its specific challenge instance, thereby resolving the security limitation while maintaining implementation simplicity.
Solution Approach 2:
The patent changes the parameter of the challenge from fixed to variable by introducing random challenge generation in the ECU. This parameter change ensures that the challenge value differs with each access attempt, making the system secure against replay attacks while keeping the ECU implementation relatively simple through the use of basic random number generation.
2Reliability
If a variable response mechanism is used where the ECU computes a response to a given challenge using a secret algorithm, then the security is improved by preventing response reuse, but the overall security is compromised if the algorithm is exposed since all devices use the same algorithm
Solution Approach 1:
The patent segments the secret algorithm into two parts: a public challenge generation function and a private key stored in the ECU. Each ECU has its own unique key, so even if the algorithm structure is known, the security of each individual ECU depends on its secret key. This segmentation prevents the vulnerability of having a single shared secret algorithm that, if exposed, compromises all devices.
Solution Approach 2:
The patent applies local quality by giving each ECU its own unique secret key rather than using a common algorithm for all devices. This means that the security properties are localized to each individual ECU, so compromising one ECU's key does not affect the security of other ECUs, thereby resolving the vulnerability to algorithm exposure.
3Ease of operation
If the same secret algorithm is embedded in every ECU to enable variable responses, then the implementation is consistent across devices, but the security of the system is reduced because exposure of the algorithm compromises all ECUs
Solution Approach 1:
The patent segments the authentication mechanism so that while the overall protocol structure remains consistent across devices (maintaining ease of operation), each ECU has its own unique secret key. This segmentation ensures that the system benefits from both implementation consistency and enhanced security, as each device's security is independent of others.
Solution Approach 2:
The patent implements preliminary action by pre-provisioning each ECU with a unique secret key during manufacturing. This preliminary setup allows the ECU to participate in the challenge/response protocol with its own individual credentials, maintaining implementation consistency while ensuring that each device's security is independent and not vulnerable to algorithm exposure.
Data Source
AI summary
A system and method for employing a mechanism for unlocking a vehicle ECU. The ECU stores a unique ECU identification value that identifies the particular ECU and a secure server stores the ECU identification value and a unique ECU security key value, where the identification value identifies the security key value in the server, and where the secure server stores the unique ECU identification value and the unique security key value for many ECUs. A service tool that wants to gain access to the ECU for software reprogramming or service requests the ECU identification value and a challenge from the ECU and sends them to the secure server, which then identifies the security key value associated with that ECU identification value and the response for the challenge. The secure server then sends the response to the service tool, which provides it to the ECU to unlock it for programming.