Hardened MPC Key Derivation With Refresh-Preserving Offsets
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Solution Overview
Problem
Current methods for hardened key derivation in multi-party computation (MPC) settings fail to maintain key refresh properties, making them non-hardened and vulnerable to reverse engineering.
Innovation Solution
Implement a method using a second random generator G′ in elliptic curve cryptography to derive child private key shares, ensuring that the sum of parent and child private key shares remains invariant, and using an offset defined by hash((sum of all parent private key shares)*G′ to maintain key refresh properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hardened derivation is implemented in multi-party computation using current methods, then security against reverse engineering is improved, but key refresh properties are lost
Solution Approach 1:
The private key is segmented into multiple shares distributed among different parties. Each party holds a share and can independently derive child key shares without revealing the parent key shares to others. This segmentation enables both hardened derivation security (parent keys remain protected) and key refresh capability (each party can refresh their own share independently).
Solution Approach 2:
A secret sharing scheme acts as an intermediary mechanism between the need for hardened derivation and key refresh. The scheme allows parties to compute derived keys collectively without any single party having access to the full parent key, thereby maintaining security while enabling flexible key management operations including refresh.
2Adaptability or versatility
If non-hardened derivation is used in multi-party computation, then key refresh properties are maintained, but security against reverse engineering is compromised
Solution Approach 1:
By segmenting the parent key into multiple secret shares distributed among parties, the system achieves hardened derivation security. Each party's share alone is insufficient to reconstruct the parent key or derive child keys without collaboration, preventing reverse engineering while maintaining key refresh capabilities through independent share management.
3Reliability
If parent private key shares are distributed among multiple parties, then security is improved through key fragmentation, but complexity of key derivation process increases
Solution Approach 1:
Each party independently performs key derivation operations on their own share using the secret sharing scheme. The protocol enables parties to self-serve by computing their own child key shares without requiring complex coordination or centralized management, thereby reducing overall system complexity while maintaining security through fragmentation.
Data Source
AI summary
Systems and methods for hardened key derivation in multi-party computation. The method includes deriving child private key shares from parent private key shares using hardened multiparty computation while maintaining key refresh properties. The method includes selecting a random number generator G and a second random number generator G′. Child private key shares are derived by computing an offset using G′.