Hourglass Protocol for Cloud File Encryption Verification
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Solution Overview
Problem
Cloud storage providers face challenges in verifying that files are stored in encrypted form, as they manage encryption keys and can deceive clients by sending random strings or encrypting files on demand, making it difficult for clients to ensure compliance with security standards.
Innovation Solution
The hourglass protocol is implemented, which imposes a minimum resource requirement, such as time, on the transformation of files from one format to another, allowing clients to verify that files are stored in an encrypted format by challenging the cloud storage provider to produce proof within a designated time frame, preventing deception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cloud storage provider manages encryption keys and performs encryption/decryption operations, then the provider can furnish plaintext on demand and the client burden is minimized, but the client cannot verify that files are actually stored in encrypted form
Solution Approach 1:
The system performs preliminary encryption of files before storage, creating encrypted versions that are then stored in the cloud. This preliminary action ensures that files are already in encrypted form when stored, eliminating the need for the client to manage keys while maintaining verification capability through the encrypted file format itself
Solution Approach 2:
An intermediary verification mechanism is introduced that allows the client to verify encryption status without accessing the encryption keys. The system uses metadata or verification tokens that serve as intermediaries between the encrypted files and the client, enabling verification while keeping keys secure with the provider
2Reliability
If the cloud storage provider stores files in encrypted form, then security compliance is improved, but the provider could deceive the client by storing files in unencrypted form or sending random strings during verification
Solution Approach 1:
The system uses distinguishable characteristics or markers in the encrypted file format that allow verification of encryption status. These markers act like visual indicators that enable the client to verify encryption without complex analysis, making deception detectable while maintaining security compliance
Solution Approach 2:
A feedback mechanism is implemented where the system provides verification responses to client queries about encryption status. This feedback loop allows continuous verification that files remain in encrypted form, preventing provider deception while maintaining relatively simple verification procedures
3Adaptability or versatility
If the cloud storage provider encrypts files on demand in response to verification requests, then the provider can maintain flexibility, but the client cannot distinguish between pre-stored encrypted files and on-the-fly encrypted files
Solution Approach 1:
Files are encrypted in advance before storage rather than on demand. This preliminary encryption creates a permanent encrypted state with verifiable characteristics, allowing the client to distinguish pre-stored encrypted files from any on-the-fly encryption attempts, thereby maintaining both provider flexibility and verification accuracy
Solution Approach 2:
The system implements periodic verification checks where the client periodically queries the provider to verify encryption status. This periodic action maintains verification accuracy over time while allowing the provider flexibility in between verification periods, preventing on-the-fly encryption deception
Data Source
AI summary
A client device or other processing device comprises a file processing module, with the file processing module being operative to request proof from a file system that a file having a first format is stored by the file system in a second format different than the first format, to receive the proof from the file system, and to verify that the file is stored in the second format using the proof provided by the file system responsive to the request. The proof is based at least in part on application of a function to the file in the second format, and the function imposes a minimum resource requirement on generation of the proof. The file system may comprise one or more servers associated with a cloud storage provider. Advantageously, one or more illustrative embodiments allow a client device to verify that its files are stored by a cloud storage provider in encrypted form or with other appropriate protections.