Split-Key Master Encryption Key Management in Distributed Systems
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Solution Overview
Problem
Existing systems for managing master encryption keys in distributed computing environments are insecure, as unauthorized access to a single device can compromise the entire system, and require administrator passwords for device startup, which is cumbersome, especially in large-scale environments.
Innovation Solution
A split-key based system using a key splitting server that generates a master encryption key and splits it into shares, requiring at least three shares to reconstruct, with shares distributed to a remote management server, managed devices, and the key splitting server, ensuring secure storage and unattended startup without administrator intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the master encryption key is stored on a single device for easy access during startup, then device startup is simplified, but security is compromised as attackers can access the key by compromising that single device
Solution Approach 1:
The master encryption key is segmented into multiple key shares distributed across different devices. No single device contains the complete key, so compromising one device does not expose the full key. The key is split such that a threshold number of shares are required to reconstruct it, enabling secure distributed storage while maintaining startup functionality.
2Reliability
If administrator passwords are required for device startup to protect the master encryption key, then security is improved, but ease of operation deteriorates due to the cumbersome process in large-scale environments
Solution Approach 1:
The system enables unattended device startup by having devices automatically retrieve and use their assigned key shares without requiring administrator intervention. The distributed key share architecture allows devices to autonomously participate in key reconstruction, eliminating the need for manual password entry while maintaining security through the threshold mechanism.
3Reliability
If the master encryption key is distributed to multiple devices, then security is improved by requiring multiple compromises, but device complexity increases due to key management overhead
Solution Approach 1:
A key management server acts as an intermediary to handle the complexity of key share distribution, storage, and reconstruction. This centralized coordinator manages the polynomial-based secret sharing scheme, distributes appropriate key shares to devices, and facilitates key reconstruction when needed, thereby reducing the operational complexity at the device level while maintaining the security benefits of distributed key storage.
Data Source
AI summary
A master encryption key is split at a key splitting server such that three key shares are required to reconstruct it, and is then destroyed. The key shares are distributed such that an encrypted remote management server key share is stored at a remote management server, an encrypted managed device key share is stored at a managed device, and a key splitting server key share is stored on the key splitting server. Incoming communications to the key splitting server from managed devices are prevented, and outgoing communications from the key splitting server are only allowed to managed devices. The managed device obtains the master encryption key at startup by sending its managed device key share to the remote management server, which sends the managed device key share and the remote management server key share to the key splitting server. The key splitting server reconstructs the master encryption key, encrypts it using a public key of the managed device, and sends it to the managed device.