Threshold Key Sharding for Assured Deletion of Encrypted Data
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Solution Overview
Problem
Existing encryption methods for personal data are vulnerable to single points of failure and attacks, leading to potential data loss or unauthorized data recovery, as they rely on storing encryption keys in a centralized manner without adequate fault tolerance.
Innovation Solution
The method involves classifying information by sensitivity levels, generating encryption keys and key shards based on thresholds, distributing these keys across multiple servers, and using multi-party collaboration to ensure secure recovery and deletion, including polynomial-based key sharding and XOR/Hash operations to manage keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If encryption keys are stored in a centralized manner, then key management is simple, but the system is vulnerable to single point failures and attacks
Solution Approach 1:
The patent divides the encryption key into multiple key shards using secret sharing schemes (e.g., Shamir's Secret Sharing). Each key shard is stored in a separate node, so that no single node possesses the complete key. This segmentation eliminates the single point of failure while maintaining manageable key distribution through automated threshold-based reconstruction.
2Reliability
If key copies are distributed across multiple nodes, then fault tolerance is improved, but the system remains vulnerable to attacks on individual nodes
Solution Approach 1:
The patent introduces a trusted execution environment (TEE) as an intermediary layer between the key shards and the nodes storing them. The TEE provides hardware-based security boundaries that protect key shards from extraction even if nodes are compromised. This intermediary mechanism allows wide distribution of key shards for fault tolerance while mitigating the attack surface through cryptographic isolation.
3Productivity
If a single key is used for encryption, then decryption is efficient, but data loss occurs when the key is lost
Solution Approach 1:
The patent implements dynamic key management where the system can adaptively reconstruct keys from key shards based on threshold conditions. Multiple key shards are maintained in an active state, allowing flexible reconstruction if some nodes fail. The system dynamically adjusts key availability based on the number of available nodes, ensuring data restorability while maintaining decryption efficiency through pre-computed key shards.
4Reliability
If all key shards are deleted to ensure data non-restorability, then security is enhanced, but key recovery becomes impossible even for legitimate users
Solution Approach 1:
The patent implements a feedback-based key management system with multiple operational states. The system continuously monitors the state of key shards and nodes, and automatically transitions between states (e.g., from recoverable to non-recoverable) based on security policies and operational conditions. This feedback mechanism ensures that key deletion operations are reversible for legitimate recovery scenarios while providing irreversible deletion when security requirements demand, thus resolving the contradiction between non-restorability and recovery capability.
Data Source
AI summary
A method and system for encryption and assured deletion of information is provided, the method at least includes: sorting fields of the information into at least two sensitivity levels by sensitivity; generating encryption keys and key shards thereof based on predetermined thresholds, and creating mapping between targets and the key shards, based on the encryption keys for the sensitivity levels, encrypting the information fields of the corresponding sensitivity levels and deleting the original information and encryption keys; and in response to reception of a recover request, recovering the encryption keys based on the key shards and performing decryption, so as to recover the original information. The present disclosure aims at the problem that information is difficult to be safely stored and assuredly deleted, and realizes multi-party security key deletion of encrypted personal information.