Transient File System Installation via Cryptographic Signature Validation
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Solution Overview
Problem
Deployed computing devices face risks of file system compromise, where system files can be corrupted or modified, and extraneous software or firmware can be added by unauthorized individuals, leading to potential system malfunctions.
Innovation Solution
The file system is abstracted into encrypted and cryptographically signed components, with a non-persistent RAM-based file system created during boot time. The operating system, software, and firmware are unencrypted and validated, ensuring only authorized components are installed in the transient storage, thus mitigating tampering risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a persistent file system is used to store operating system and firmware, then data persistence is improved, but security against unauthorized modification deteriorates
Solution Approach 1:
The file system is segmented into persistent storage (for configuration and state) and transient storage (for operating system and firmware). The transient file system is created in volatile memory during boot, separated from the persistent file system on non-volatile storage. This segmentation allows the system to maintain persistence where needed while ensuring security for critical components by storing them in a transient, replaceable environment.
2Reliability
If cryptographic validation is performed on all file system components, then security is improved, but boot time and system initialization speed deteriorates
Solution Approach 1:
Cryptographic validation is performed preliminarily during the boot process before the operating system becomes fully operational. The boot loader validates the digital signatures of the operating system and firmware components during system initialization. This preliminary validation ensures security is established early, allowing the rest of the system to operate without continuous validation overhead, thus balancing security with performance.
3Reliability
If a non-persistent RAM-based file system is used, then security against tampering is improved, but data retention between reboots deteriorates
Solution Approach 1:
The operating system and firmware are extracted from the persistent file system and loaded into a transient RAM-based file system during boot. This extraction places critical components in a controlled, volatile environment that cannot be tampered with while the system is running. Configuration files and state information are separately managed in the persistent file system, allowing data retention for necessary settings while maintaining security for executable components through their transient storage.
Data Source
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AI summary
Certain aspects of the disclosure are directed toward validation and installation of a file system. A method for mitigating security breach for a circuit platform subject to compromise by unauthorized changes to a file system includes abstracting the file system into an encrypted file with cryptographically signed components. The file system may have instruction code or other data for an operating system and may be stored by or on behalf of the circuit platform. During boot time of the operating system, an unencrypted version of the operating system and the encrypted file may be accessed and used by validating a signature associated with the file system. In response to validating the signature, the file system is installed into a transient, non-persistent storage circuit. As such, the operating system executes instruction code via a central processing unit (CPU) circuit under authorization based on the validated signature.