Device-Specific Version-Aware Encryption Keys for Mutable Partitions
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Solution Overview
Problem
Existing secure boot methodologies for unmanned aerial vehicles (UAVs) fail to adequately secure writable partitions, allowing attackers to modify system storage and persist malicious data across software updates, especially in cases where device software has been exploited.
Innovation Solution
Implement a software version-aware encryption key derived from a device-specific secret key and a unique software version identifier, ensuring that the encryption key changes with software updates, making it impractical for attackers to persist malicious data across versions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a static encryption key is used for writable partitions, then ease of operation is improved, but security deteriorates because attackers can persist malicious data across software updates
Solution Approach 1:
The patent applies dynamics by transitioning from a static encryption key to a dynamic encryption key that changes with each software version. The encryption key is now derived from both the device-specific secret key and the software version identifier, making the key dynamic and version-dependent. This resolves the security vulnerability where static keys allowed persistent malicious data across updates.
Solution Approach 2:
The patent changes the parameters of the encryption key by incorporating the software version identifier as an additional parameter in the key derivation process. This parameter change ensures that the encryption key is unique to each software version, preventing attackers from using the same key across different versions to persist malicious data.
2Ease of manufacture
If encryption key is derived only from device-specific secret key, then ease of manufacture is improved, but security deteriorates because cloned devices can access the same encryption key
Solution Approach 1:
The patent applies local quality by making the encryption key unique to each specific device-software version combination. While the device-specific secret key provides a base level of uniqueness, adding the software version identifier creates a locally unique key for each device at each software version, preventing cloned devices from accessing the same encryption key even if they have the same device secret key.
3Ease of operation
If writable partition is integrated with filesystem structure, then ease of operation is improved, but security deteriorates because modified data can be persisted across updates
Solution Approach 1:
The patent applies preliminary anti-action by proactively invalidating data in the writable partition when the software version changes. The system detects the version change and automatically clears or invalidates the writable partition content before the new software version executes, preventing malicious data from being persisted across updates while maintaining the integrated filesystem structure for ease of operation.
Data Source
AI summary
Described herein are systems for software version-aware encryption key for secure mutable partitions. For example, some methods include verifying a digital signature of a header for an application image, wherein the header includes a hash of the application image; generating an encryption key based on the hash; encrypting, using the encryption key, data to be written to a writable partition that is mounted with a filesystem of the application image; and decrypting, using the encryption key, data read from the writable partition.