Tamper-proof Data Processing Device with Microcontroller Authentication
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Solution Overview
Problem
Mobile data processing devices face significant security challenges due to easy physical access and widespread malware, making it difficult to protect them against tampering and hacker attacks, especially in security-critical applications.
Innovation Solution
A data processing device with a microcontroller acting as a security gateway, using a public/private key pair for authentication of an externally connectable memory module to control hardware switches and power supply, ensuring only authenticated modules can activate hardware components, and incorporating a tampering sensor and power failure detector for enhanced security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical access barriers and software firewalls are used to protect mobile data processing devices, then security against tampering and hacker attacks is improved, but device complexity increases
Solution Approach 1:
The authentication system is segmented into separate functional components: a microcontroller for authentication logic, a persistent key memory for storing public keys, controllable switches for hardware component control, and an interface for memory module communication. This segmentation isolates security-critical functions from the main processor, reducing the attack surface while maintaining security functionality.
Solution Approach 2:
A dedicated microcontroller acts as an intermediary between the external memory module and the hardware components. This intermediary handles all authentication operations, verifying signatures from memory modules and controlling switch states based on authentication results. This mediator approach protects the main processor from direct exposure to authentication protocols and potential attacks.
2Reliability
If authentication of externally connectable memory modules is implemented using public/private key pairs, then security against unauthorized access is improved, but device complexity increases
Solution Approach 1:
The private key is extracted from the device and stored exclusively in the external memory module, while only the public key is stored in the device's persistent key memory. This extraction eliminates the need to protect private keys within the device hardware, simplifying the security model. The authentication process uses only the public key for signature verification, avoiding complex key management within the device.
Solution Approach 2:
Public keys are pre-stored in the persistent key memory during device initialization or manufacturing. This preliminary action prepares the authentication system in advance, allowing rapid signature verification during operation without requiring complex key generation or exchange protocols during the authentication process itself.
3Reliability
If hardware components are controlled via controllable switches to prevent unauthorized operation, then security against tampering is improved, but device complexity increases
Solution Approach 1:
Different hardware components have different switch control states based on their security requirements. The microcontroller selectively activates or deactivates specific switches for specific hardware components based on authentication results. This local quality approach allows fine-grained control over hardware access, enabling security-critical components to be protected while allowing non-critical components to remain accessible.
Data Source
AI summary
A data processing device having a housing in which are arranged a processor, a program memory connected to the processor and at least one hardware component connected to the processor via a data line and supplied with power via a power supply line, comprises a microcontroller arranged in the housing and having an interface and a persistent key memory in which the public key of a first public/private key pair is stored, wherein a switch controlled by the microcontroller is interposed in the data line, and wherein the microcontroller is configured to receive a signature, generated using the private key of the first key pair, of a memory module detachably connected to the interface via the interface, to verify the signature using the public key of the first key pair, and to switch on the switch in the case of verification.