Blockchain Privacy via Non-Interactive Multi-Party Computation
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Solution Overview
Problem
Blockchains face challenges in maintaining data privacy, as each node stores a complete copy of the ledger, making it difficult to allow a party to observe only their own computation output without exposing all inputs.
Innovation Solution
A method involving receiving a secret key and correlated randomness from trusted authorities, generating a randomized mask, and using non-interactive multi-party computation (NIMPC) to encrypt inputs, which are then submitted to a blockchain, ensuring only the party can observe their output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each node stores a complete copy of the ledger, then data availability and consistency are improved, but data privacy deteriorates
Solution Approach 1:
The patent segments the ledger data by introducing temporal segments and party-specific views. Instead of each node storing the complete ledger, the system divides the ledger into time-based segments and assigns specific segments to specific parties based on their participation rights. This segmentation allows nodes to store only relevant portions of the ledger while maintaining consistency for authorized parties.
Solution Approach 2:
The patent introduces a privacy-preserving intermediary layer between the complete ledger and individual nodes. This intermediary uses encryption and selective disclosure mechanisms to allow nodes to access only the specific ledger segments they are authorized to view, while the complete ledger remains available to trusted authorities. The intermediary protects privacy without compromising overall data consistency.
2Ease of operation
If all inputs are exposed in blockchain computations, then computation transparency is improved, but information privacy deteriorates
Solution Approach 1:
The patent applies local quality by providing different levels of information access to different parties. Each party can access and verify computations related to their own inputs and temporal segments, while other parties' inputs remain hidden. This creates a localized transparent view for each party without requiring global transparency, thus preserving input privacy while maintaining operational transparency for authorized operations.
3Loss of information
If selective privacy is implemented, then information privacy is improved, but system complexity increases
Solution Approach 1:
The patent employs preliminary action by pre-establishing temporal segments, party authorization lists, and encryption keys before computations occur. The system pre-divides the ledger into time-based segments and pre-assigns access rights to parties. This preliminary configuration enables selective privacy to be enforced automatically during computations without requiring complex real-time decision-making, thus reducing operational complexity while maintaining information privacy.
Data Source
AI summary
A method may include receiving, from a first trusted authority, a secret key specific to a party for use in posting to a blockchain. The method may also include receiving, from a second trusted authority, a correlated randomness component specific to the party and associated with a given temporal segment. The method may additionally include generating a party-generated randomized mask, and computing, using an input from the party, the correlated randomness component, and the party-generated randomized mask in a non-interactive multi-party computation (NIMPC), an NIMPC-encrypted input associated with the party for the given temporal segment. The method may also include encrypting the NIMPC-encrypted input according to a blockchain encryption algorithm to yield a ciphertext, and submitting the ciphertext to a block associated with the given temporal segment in a blockchain.