Cryptocurrency Key Splitting via Shamir Secret Sharing
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Solution Overview
Problem
Current cryptocurrency key management systems face security threats due to the risk of private keys being stolen during key generation, backup, and restore operations, particularly in software-based Transaction Signing Servers (TSS) where memory attacks can occur, and hierarchical deterministic wallets rely on secure seed storage that is vulnerable to theft and unauthorized access.
Innovation Solution
The Seed Splitting and Firmware Extension for Secure Cryptocurrency Key Backup, Restore, and Transaction Signing Platform (SFTSP) employs a deterministic key derivation method using Shamir's Secret Sharing to split master private keys into shares stored on FIPS 140-2 certified Hardware Security Modules (HSMs), enforcing M-of-N authentication policies to protect keys from physical and software theft, and utilizing secure firmware transaction signing components to ensure tamper-proof storage and authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If private keys are stored in software-based Transaction Signing Servers for key generation and backup operations, then key management functionality is improved, but security is worsened due to vulnerability to memory attacks and unauthorized access
Solution Approach 1:
The patent segments the master private key into multiple key shares using Shamir's Secret Sharing scheme. These key shares are then distributed and stored in separate Hardware Security Modules (HSMs) rather than keeping the complete key in one location. This segmentation prevents any single point of failure or attack from compromising the entire key, directly resolving the security vulnerability of software-based storage while maintaining key management functionality.
Solution Approach 2:
The patent introduces HSMs as intermediary devices between the key management system and external access points. These HSMs provide a secure hardware layer that mediates all key operations, preventing direct software-based access that is vulnerable to memory attacks. The HSMs act as trusted intermediaries that enforce security policies while enabling key generation, backup, and restoration operations.
2Reliability
If master private keys are split into shares and stored on multiple HSMs using Shamir's Secret Sharing, then security against theft is improved, but system complexity is worsened
Solution Approach 1:
The patent implements a universal key management system that handles multiple operations (key generation, backup, restoration, transaction signing) through a single standardized interface. The key management server coordinates all operations across multiple HSMs using unified protocols, making the complex distributed system appear as a simple, unified service. This multi-functionality approach manages system complexity while maintaining enhanced security through key sharing.
3Reliability
If M-of-N authentication policies are enforced on HSMs, then protection from unauthorized access is improved, but operational overhead is worsened
Solution Approach 1:
The patent implements preliminary authentication setup where M-of-N policies are pre-configured on HSMs during system initialization. Authentication credentials for multiple users are pre-provisioned, and the threshold parameters (M-of-N) are established in advance. When key operations need to be performed, the pre-configured authentication mechanisms are already in place, reducing the time and overhead during actual operations compared to setting up authentication dynamically.
Data Source
AI summary
The Seed Splitting and Firmware Extension for Secure Cryptocurrency Key Backup, Restore, and Transaction Signing Platform Apparatuses, Methods and Systems (“SFTSP”) transforms transaction signing request, key backup request, key recovery request inputs via SFTSP components into transaction signing response, key backup response, key recovery response outputs. An offline transaction signing request message for a transaction is received by a first cold HSM and includes an encrypted second master key share from a second cold HSM and an encrypted third master key share from a hot HSM. A first master key share is retrieved. The encrypted master key shares are decrypted and, along with the first master key share, used to recover a master private key. A keychain path is determined. A signing private key for the keychain path is generated using the master private key. The transaction is signed using the signing private key, and the generated signature is returned.