Hardware Security Module Memory Write Protection
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Solution Overview
Problem
Existing methods for updating control units in machines and vehicles lack robust protection against unauthorized changes, as they rely solely on password-based write protection, which can be compromised without additional verification.
Innovation Solution
Implementing a hardware security module (HSM) that blocks memory write protection until authorization is confirmed by a separate, external confirmation unit, using challenge-response authentication to ensure only authorized updates can proceed, thereby enhancing the security of the application software.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If password-based write protection is used for memory, then protection against unauthorized changes is provided, but the protection can be compromised without additional verification
Solution Approach 1:
A confirmation unit is introduced as an intermediary between the caller and the HSM. This external unit verifies the caller's authorization credentials and communicates the verification result to the HSM, adding an additional layer of security without requiring complex changes to the existing HSM architecture
Solution Approach 2:
The authorization verification process is segmented into separate functions: the HSM manages write protection and password storage, while the external confirmation unit handles authorization credential verification. This separation allows each component to specialize in its function and improves overall system security
2Reliability
If authorization check by external confirmation unit is implemented, then enhanced protection against manipulations is achieved, but communication and coordination overhead increases
Solution Approach 1:
The confirmation unit verifies authorization credentials before the HSM releases write protection, performing the verification action in advance. This ensures that only authorized callers can proceed with memory rewriting operations, preventing unauthorized access before it can occur
3Adaptability or versatility
If write protection is blocked for memory rewriting, then updates can be performed, but protection against unauthorized changes is reduced
Solution Approach 1:
The write protection state is made dynamic rather than static. The HSM can switch between blocking and unblocking write access based on the authorization verification result from the confirmation unit, allowing the system to adapt its security level according to the current operation's authorization status
Data Source
AI summary
A method for securely updating a control unit. The control unit includes a host configured to execute an update program and at least one application program, a memory, which contains the programs and data, and a hardware security module (HSM) which is configured to block and to unblock a write access to the memory. The method includes starting the host and the HSM; blocking the write access by the HSM; starting the update program; determining by the update program whether a request of a caller to carry out an update is present; if a request is present, checking an authorization of the caller by the HSM to carry out an update, the authorization of the caller being confirmed by a confirmation unit differing from the control unit; and if the caller is authorized, unblocking the write access and rewriting at least a portion of the memory by the update program.