Kerberized Encrypted File System Access via Key Distribution Center
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Solution Overview
Problem
Existing network file systems lack secure access mechanisms for encrypted files, as they typically operate on unencrypted data, limiting secure sharing and access across machines.
Innovation Solution
A system where a file server determines if a requested file system is encrypted, sends a message to the client, and uses a session ticket with a security protocol to decrypt the encrypted file system, allowing secure access over a secure channel, with optional involvement of a key distribution center for intermediate key management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If network file systems are used to allow access across machines, then ease of operation is improved, but security is worsened because the file systems remain unencrypted
Solution Approach 1:
The patent introduces a key distribution center as an intermediary between the client and file server. The KDC issues session tickets that contain encryption credentials, enabling secure authenticated access without requiring the client to directly handle encryption keys or understand cryptographic protocols. This mediator resolves the contradiction by providing both ease of operation (automatic authentication) and security (encrypted file system access).
Solution Approach 2:
The system dynamically changes the encryption state of the file system based on authentication credentials. When a client presents valid credentials through the key distribution center, the file server transforms the file system from an encrypted state to a decrypted accessible state, and reverses this when access is terminated. This parameter change enables secure remote access while maintaining security when not in use.
2Reliability
If encrypted file systems are stored on a single machine, then security is improved, but adaptability is worsened because users cannot access them from other machines
Solution Approach 1:
The patent makes the encrypted file system universally accessible across multiple machines through the network file system protocol. The file server hosts the encrypted file system and handles decryption requests from any authenticated client machine. The key distribution center provides universal authentication credentials that work across the network, enabling the same encrypted file system to be securely accessed from multiple different machines while maintaining its security properties.
Solution Approach 2:
The key distribution center acts as a universal intermediary that issues credentials valid across the entire network. Instead of requiring separate encryption setups for each machine, the KDC provides a universal authentication mechanism that enables any authorized client to access the encrypted file system on the file server, resolving the contradiction between security and multi-machine adaptability.
3Ease of operation
If the file server decrypts the encrypted file system using the client's private key, then ease of operation is improved for the client, but device complexity is worsened at the file server
Solution Approach 1:
The key distribution center serves as an intermediary that handles the complex key management and authentication protocols. The file server's role is simplified to receiving authenticated requests from clients and performing decryption only after the KDC has validated credentials and established secure channels. This distribution of complexity between the KDC and file server improves client ease of operation while managing the file server's complexity through clear separation of duties.
Solution Approach 2:
The key distribution center performs preliminary authentication and credential verification before the file server performs decryption. By pre-establishing trusted relationships and validating client credentials in advance, the KDC reduces the complexity burden on the file server, which only needs to perform decryption operations for already-authenticated clients rather than implementing full authentication logic itself.
Data Source
AI summary
A file server receives a request from a client to mount an encrypted file system. The file server informs the client that the requested file system is encrypted and, in turn, receives a session ticket from the client that includes a security protocol mounting selection. The file server decrypts the client's user's encrypted private key, and then decrypts the requested encrypted file system using the private key. In turn, the file server sends the decrypted file system to the client over a secure channel, which is based upon the security protocol mounting selection. In one embodiment, a key distribution center server receives a request from the client for the client's user to access the encrypted file system at the file server. The key distribution center server retrieves an intermediate key; includes the intermediate key in a session ticket; and sends the session ticket to the client.