Tamper-Resistant File System Using Virtual Block Device
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Solution Overview
Problem
Existing data storage solutions, such as public key cryptography and smart cards, face challenges in securing private keys due to system vulnerabilities and management complexities, with smart cards being prone to tampering and loss.
Innovation Solution
A tamper-proof file system is implemented using a virtual block device coupled with a real block device and a private/public key pair, where data is digitally signed with the private key and stored, and the virtual block device is configured to discard the private key after a finite lifespan, providing an acknowledgment with a hash of the public key for verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the private key is stored on a user's computer system, then the security of data protection is compromised due to system vulnerabilities, but storing it externally increases device complexity and management difficulty
Solution Approach 1:
The private key is extracted from the vulnerable computer system environment and stored within a tamper-resistant smart card. The smart card contains a secure element that isolates the private key from external attacks, while the public key remains on the computer system for cryptographic operations. This extraction resolves the security vulnerability by removing the private key from the untrusted environment.
Solution Approach 2:
The smart card acts as an intermediary between the user and the private key. Instead of directly accessing or managing the private key on the computer system, the system communicates with the smart card, which handles key protection, digital signing, and key lifecycle management. This intermediary layer simplifies the overall system architecture by centralizing security functions in a dedicated device.
2Reliability
If smart cards are used for secure key storage, then tamper resistance is improved, but deployment and management become difficult due to fabrication, distribution, and loss risks
Solution Approach 1:
The smart card system performs self-service for key generation, storage, and protection without requiring external intervention. The secure element within the smart card automatically generates cryptographic key pairs, manages the private key lifecycle, and provides tamper detection and response. This self-service capability eliminates the need for complex external key management infrastructure and reduces operational overhead.
Solution Approach 2:
The system implements a lifecycle management approach where smart cards are provisioned with keys, used for their intended purpose, and then securely disposed of or revoked when no longer needed. The secure element can detect tampering attempts and automatically discard compromised keys, and the system can remotely revoke access by discarding cryptographic credentials, eliminating the need for physical recovery or re-provisioning.
3Reliability
If the private key is kept secret for public key cryptography, then cryptographic security is maintained, but the system becomes vulnerable to attacks when the computer system is compromised
Solution Approach 1:
The cryptographic system is segmented into two separate locations: the private key is segmented and stored in the tamper-resistant smart card, while the public key and cryptographic operations are segmented and performed on the computer system. This physical and functional segmentation ensures that even if the computer system is compromised, the private key remains protected in the isolated secure element of the smart card.
Solution Approach 2:
The smart card implements preliminary anti-action by detecting tampering attempts before they can compromise the private key. The secure element monitors for physical attacks, side-channel attacks, and software exploits, and automatically responds by zeroizing the private key or blocking access. This preliminary defense prevents attackers from extracting the private key even if they gain access to the computer system.
Data Source
AI summary
Embodiments of the present invention provide a tamper proof file system. In particular, the present invention utilizes a virtual block device that is coupled with a real block device and a private/public key pair. The virtual block device receives the original data and then digitally signs it with the private key. The virtual block device then passes the digitally signed data to the real block device for storage. In order to retrieve or verify the data, the virtual block device may provide the public key and an acknowledgment. The acknowledgment may include a hash of the public key. The virtual block device is configured to discard the private key and to be removed from the system based on a finite lifespan.