Hybrid Segment Reference Filters for Compromised-Key File Reads
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Solution Overview
Problem
Current key-based encryption systems fail to identify and prevent reads on files encrypted with compromised encryption keys, posing a security risk in deduplicated storage systems.
Innovation Solution
Implement a cryptographic key management system that uses a segment reference filter to efficiently identify and disallow reads on files impacted by compromised keys, ensuring secure re-encryption of affected data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a key-based encryption system is used to encrypt data at rest, then data security is improved, but the system cannot identify and prevent reads on files encrypted with compromised keys
Solution Approach 1:
The system divides the encryption key management into separate segments: a key manager that handles key operations and a file system that uses key identifiers in metadata. This segmentation allows the file system to track which files use which keys without managing the actual key material, enabling identification of files encrypted with compromised keys through metadata analysis rather than requiring full system re-scanning.
Solution Approach 2:
The patent introduces a key identifier as an intermediary element between the encryption key and the file data. This key identifier is stored in the file metadata and acts as a reference point that the file system can query to determine which files are encrypted with specific keys, including compromised ones, without directly handling the key material or requiring complex key-to-file mapping operations.
2Reliability
If the system scans all files to identify those encrypted with compromised keys, then complete identification is achieved, but the process is time-consuming and impacts system performance
Solution Approach 1:
The system performs preliminary action by pre-storing key identifiers in the file metadata during the normal file creation and encryption process. This preliminary setup eliminates the need for time-consuming full-file-scanning operations later. When a key compromise is detected, the system can immediately query the metadata using the key identifier to rapidly identify all affected files without scanning their actual content or performing exhaustive searches.
Solution Approach 2:
The patent uses a copy of the key identifier in the metadata rather than storing the actual key material in the file system. This metadata copy acts as a reference that can be quickly queried and compared, enabling fast identification of files associated with compromised keys without requiring the system to process or scan the actual encrypted data or manage complex key-to-file mappings.
3Reliability
If the system prevents all reads on files with compromised keys, then data protection is improved, but legitimate access to unaffected files may be blocked
Solution Approach 1:
The system applies local quality by making the read prevention decision at the individual file level based on its specific key identifier in the metadata, rather than applying a blanket restriction to all files. When a key compromise is detected, the file system queries the key identifier to determine which specific files are affected and applies read prevention only to those files, while allowing normal access to files encrypted with unaffected keys. This targeted approach maintains ease of operation for legitimate files while ensuring data protection for compromised files.
Data Source
AI summary
A method of blocking access to files encrypted with a compromised key by mapping keys and ranges of containers encrypted by the keys. Upon notification that a key is compromised, containers impacted by the compromised key are identified. The identified containers are masked to prevent new file duplication to the segments from the compromised containers and a list of existing files referring to segments from the impacted containers is compiled. Metadata segments are processed using a deterministic segment reference filter and data segments are processed using a probabilistic reference filter to iterate through the directory levels of a filesystem managing the files to mark the impacted files as unreadable.