Secret Key Share Auditing for MPC Blockchain Signatures
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Solution Overview
Problem
Existing multi-party computation (MPC) technology for crypto-asset transactions may generate electronic signatures without involving the wallet user, leading to potential misuse or theft of secret key distribution pieces.
Innovation Solution
An information processing device that controls and verifies the distribution of secret key pieces among selected distribution destinations, generates electronic signatures using a subset of these pieces, and audits which piece was used for each transaction, ensuring user involvement and security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MPC technology is used to distribute secret key pieces among multiple destinations, then security in managing the secret key is improved, but flexibility in operation decreases because all distribution pieces must be collected for signature generation
Solution Approach 1:
The secret key is segmented into multiple distribution pieces that are stored at different distribution destinations. This segmentation enables the system to achieve both security through distribution and flexibility through selective access - the key is broken into manageable parts that can be operated on independently while maintaining overall security.
Solution Approach 2:
The system dynamically adjusts the threshold number of distribution pieces required for signature generation based on operational needs. This dynamic configuration allows the system to adapt between high-security modes (requiring more pieces) and high-flexibility modes (requiring fewer pieces), resolving the contradiction between security and ease of operation.
2Ease of operation
If the threshold for collecting distribution pieces is reduced to improve flexibility, then ease of operation is improved, but security decreases because fewer pieces are needed for signature generation
Solution Approach 1:
The system changes the threshold parameter for collecting distribution pieces based on the operational context. By adjusting this parameter dynamically, the system can optimize the balance between security and flexibility for different scenarios, allowing reduced thresholds for flexibility when appropriate while maintaining higher thresholds for security-critical operations.
3Reliability
If distribution pieces are managed in a distributed manner to improve security, then reliability is improved, but difficulty of detecting misuse increases because it becomes harder to track which piece was used
Solution Approach 1:
The system implements feedback mechanisms that track and report which distribution piece was used for each signature generation operation. This feedback enables continuous monitoring and detection of misuse, allowing the system to maintain the benefits of distributed management while solving the detection difficulty through systematic tracking and reporting.
4Reliability
If all distribution pieces must be collected for signature generation to maximize security, then reliability is improved, but loss of time increases due to the time required to collect all pieces
Solution Approach 1:
The system allows signature generation to proceed with a partial set of distribution pieces rather than requiring all pieces to be collected. This partial action approach reduces the time required for signature generation while maintaining adequate security through the use of threshold-based verification that ensures sufficient pieces are collected to validate the operation.
Data Source
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AI summary
[Problem] To verify which one of the distribution pieces of a secret key has been used to generate an electronic signature generated by the secret key. [Solution] An information processing device including: a distribution destination control unit that controls a plurality of distribution destinations for respectively storing a plurality of distribution pieces obtained by secretly distributing a secret key, on the basis of a selection by a user; a signature generation unit that generates an electronic signature by the secret key, by using part of the plurality of distribution pieces stored in the plurality of distribution destinations; a transaction issuance unit that issues a transaction, which is attached with the electronic signature, to a blockchain; and an audit unit that verifies which one of the plurality of distribution pieces has been used to generate the electronic signature attached to the transaction on the blockchain.