Threshold Keyshare Refresh for Efficient MPC Decryption
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Solution Overview
Problem
Existing key share refresh operations in multi-party computation (MPC) schemes are complex and inefficient, especially when dealing with large quantities of key shares and multiple parties, and require high computational effort for periodic refreshes.
Innovation Solution
Implementing a key share refresh mechanism using a public threshold encryption key to encrypt and decrypt key shares, allowing parties to perform MPC operations efficiently by combining partial decryption results and periodically refreshing key shares using a public threshold encryption key.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional key share refresh operations are used in MPC schemes, then key share refreshment is achieved, but computational complexity and operational efficiency deteriorate significantly
Solution Approach 1:
The key share refresh operation is segmented into two distinct phases: a setup phase where a public threshold encryption key is established, and a computation phase where only threshold decryption operations are performed. This segmentation allows the complex encryption setup to be done once while keeping subsequent operations simple and efficient.
Solution Approach 2:
The public threshold encryption key is generated in advance during the setup phase, before the actual key share refresh computation begins. This preliminary action eliminates the need for complex encryption operations during the main computation, significantly reducing computational complexity while maintaining security.
2Reliability
If periodic key share refresh operations are implemented, then security is improved, but productivity and computational effort deteriorate
Solution Approach 1:
The system implements periodic key share refresh operations using the threshold decryption mechanism. By leveraging the pre-generated public threshold encryption key, the system can perform efficient periodic refreshes without requiring complex computational operations during each refresh cycle, thus maintaining both security and productivity.
3Reliability
If key shares are encrypted using public threshold encryption key, then security and proactive security are enhanced, but ease of operation deteriorates
Solution Approach 1:
The public threshold encryption key acts as an intermediary that enables secure encryption of key shares without requiring direct manipulation of complex cryptographic operations. Parties can simply perform threshold decryption operations on this intermediary key to obtain key shares, simplifying the operational process while maintaining strong security.
Data Source
AI summary
Methods, systems, and devices for key management are described. A party having a key share of multiple key shares of a cryptographic key may encrypt a key share via a public threshold encryption key. The party may transmit, in accordance with a multi-party computation (MPC) operation, requests to multiple parties having private key shares of a private threshold decryption key corresponding to the public threshold encryption key. The party may receive multiple partial decryption results from a subset of the parties having the private key shares of the private threshold decryption key. The party may combine the partial decryption results to generate the key share and execute a portion of the MPC operation using the generated key share. Executing the portion of the MPC operation may cause a key share refresh operation for the key share of the cryptographic key.