Wallet Key Share Transfer for Loss-Resistant Secure Access
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Solution Overview
Problem
Existing cryptographic systems face challenges in securely establishing a common secret symmetric key across unsecure networks, and the storage of private keys in digital wallets is vulnerable to loss or unauthorized access, whether stored client-side or server-side.
Innovation Solution
A method involving Shamir's Secret Sharing Scheme is used to split a cryptographic key into shares, stored across multiple independent locations, with a common secret generated independently at each node for secure transmission using asymmetric cryptography, ensuring the key can be reconstructed securely even if one location is compromised.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the private key is stored only at the client side, then security is improved, but the key can be lost through theft, loss or damage caused to the user's hardware
Solution Approach 1:
The private key is divided into multiple shares using Shamir's Secret Sharing Scheme. Each share is stored in different locations (client device, server, hardware security module). No single location contains the complete private key, so even if one location is compromised or lost, the private key can be reconstructed from sufficient shares.
2Ease of operation
If the private key is stored by a wallet service provider (server side), then access continuity is improved, but security breaches at the server side become a significant risk
Solution Approach 1:
The private key shares are distributed across multiple independent storage locations including client devices and server systems. The wallet service provider stores only a portion of shares, not the complete private key, reducing the security risk while maintaining access continuity through coordinated share retrieval.
Solution Approach 2:
A threshold mechanism acts as an intermediary between client-side and server-side storage. The system requires a predetermined number of shares from multiple sources to reconstruct the private key, creating a balanced access control mechanism that prevents any single party from having full control while ensuring availability.
3Device complexity
If symmetric-key algorithms are used for secure communication, then encryption simplicity is improved, but the symmetric-key must be transmitted securely which creates a catastrophic vulnerability
Solution Approach 1:
Asymmetric key pairs are generated in advance before secure communication begins. The public key is made available beforehand, allowing the symmetric key to be securely derived during communication without requiring pre-transmission of secret materials over the network.
Solution Approach 2:
Asymmetric cryptography serves as an intermediary mechanism to enable secure symmetric key establishment. The asymmetric key exchange protocol mediates the secure creation and sharing of symmetric keys without requiring direct transmission of the symmetric key itself, eliminating the catastrophic vulnerability.
Data Source
AI summary
A solution for controlling access to a resource such as a digital wallet implemented using a blockchain. Use of the invention during set-up of the wallet can enable subsequent operations to be handled in a secure manner over an insecure channel. An example method comprises splitting a verification element into multiple shares; determining a common secret at multiple nodes in a network; and using the common secret to transmit a share of the verification element between nodes. The shares can be split such that no share is sufficient to determine the verification element and can be stored at separate locations. Upon share unavailability, the share can be retrieved a location accessibility. For safe transmission of the share(s), the common secret is generated at two different nodes independently and used to generate an encryption key for encrypting at least one share of the verification element to be transmitted securely.