Post-quantum Key Rotation in Storage Devices
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Solution Overview
Problem
Existing data storage devices face challenges in securely rotating encryption keys without compromising data security, as adversaries can access old keys, and existing solutions require decryption and involve complex client operations.
Innovation Solution
An updatable encryption scheme is employed, where a client generates an update token using a ciphertext header and a new key, allowing the data storage device to re-encrypt data without accessing plaintext, ensuring secure key rotation and compatibility with industry standards like AES and quantum-safe algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional key rotation methods are used, then data security can be maintained, but the system requires decryption and involves complex client operations
Solution Approach 1:
The storage device performs self-service by autonomously re-encrypting data with new keys using update tokens, without requiring client intervention for decryption or key management operations. The device independently generates ciphertext headers, manages key rotation, and updates encrypted data blocks, eliminating complex client-side cryptographic operations while maintaining security through server-side automated key rotation.
Solution Approach 2:
The invention extracts the decryption and re-encryption operations from the client system and relocates them to the storage device. By separating the ciphertext header management and key rotation functions from the client, the system eliminates complex client operations while the storage device handles all cryptographic transformations locally using update tokens and re-encryption algorithms.
2Reliability
If encryption keys are rotated frequently, then security against adversaries is improved, but client workload increases
Solution Approach 1:
The storage device autonomously performs frequent key rotation operations using update tokens, eliminating the need for client involvement in each rotation event. The device independently manages ciphertext header updates, re-encrypts data blocks with new keys, and maintains security against adversaries through automated frequent key changes without increasing client workload.
Solution Approach 2:
The system performs preliminary preparation by generating update tokens that encapsulate key rotation information. These tokens are pre-computed and sent to the storage device, which then autonomously executes the re-encryption process. This preliminary action allows frequent key rotation to occur without requiring real-time client participation, maintaining security while minimizing client workload.
3Ease of operation
If client computers perform decryption operations, then data access is flexible, but security risks increase when devices are compromised
Solution Approach 1:
The invention extracts decryption operations from the client system and relocates them entirely to the storage device. The client never possesses decryption keys or performs decryption, eliminating security risks associated with compromised client devices. The storage device independently decrypts data using stored keys, re-encrypts with new keys using update tokens, and returns only ciphertext to the client, ensuring that even if the client is compromised, no decryption capability exists outside the secured storage environment.
Solution Approach 2:
The storage device acts as an intermediary that mediates all decryption and re-encryption operations. Rather than the client directly decrypting data, the storage device receives encrypted data, performs decryption using its secured key management system, applies update tokens for re-encryption, and returns the updated ciphertext. This intermediary role isolates decryption capabilities within the trusted storage boundary, preventing security risks from propagating to compromised client systems.
Data Source
AI summary
A method includes receiving, in a data storage device, a request from a client computer for a portion of ciphertext stored in the data storage device, and providing, by a controller of the data storage device, the portion of the ciphertext to the client computer. The method also includes receiving, in the data storage device, an update token generated by the client computer from the portion of the ciphertext. The method further includes performing, by the controller of the data storage device, re-encryption of the ciphertext using the update token.