Secure Full Disk Encryption Key Storage via Block Encoding
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Solution Overview
Problem
Sensitive data, such as encryption keys, cannot be reliably deleted from storage devices like solid-state disks, as overwriting data does not ensure destruction due to the devices' wear-leveling processes, which move data locations, making it difficult to secure highly sensitive information.
Innovation Solution
Data is securely stored by encoding it into multiple blocks that can be recombined, with at least one block overwritten with arbitrary data when destruction is needed, using metadata to track logical locations, ensuring the data remains unrecoverable even if the storage device changes hands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is overwritten on solid-state storage devices, then data deletion is performed, but the wear-leveling process may move data to new locations, making the deletion unreliable
Solution Approach 1:
The data block is divided into multiple encoded blocks that are distributed across different physical locations on the storage device. To destroy the data, at least one of these encoded blocks must be overwritten. This segmentation ensures that even if wear-leveling moves some blocks, overwriting one block prevents reconstruction of the original data, thereby achieving reliable data destruction despite the wear-leveling behavior.
2Reliability
If multiple encoded blocks are used to store data, then data security is improved, but the complexity of data destruction increases
Solution Approach 1:
The metadata is updated in advance to track the current physical locations of the encoded blocks, even before destruction is needed. This preliminary tracking allows the destruction process to simply overwrite blocks at known locations rather than searching for them, significantly simplifying the destruction operation while maintaining the security benefits of multi-block encoding.
3Ease of operation
If encoded blocks are stored at fixed logical locations, then data access is simplified, but the ability to securely destroy data is compromised when physical locations change
Solution Approach 1:
The system dynamically updates the metadata to reflect changes in the physical locations of encoded blocks caused by wear-leveling. This dynamic tracking allows the system to maintain simple logical location mapping for data access while simultaneously tracking the actual physical locations needed for secure destruction, resolving the contradiction between accessibility and destroyability.
Data Source
AI summary
Data is securely stored on a storage device by encoding a data block into multiple encoded blocks, any number of which can be recombined to recover the data block. The encoded blocks are stored at known logical locations corresponding to physical locations on a storage device that change over time. When the data needs to be destroyed, at least one of the encoded blocks is overwritten with arbitrary data. In one aspect, the encoded blocks include at least one random block that is used to encode the data block. In another aspect, the known logical locations are stored in metadata.