Bilinear Map Accumulators for Privacy-Preserving Blockchain Authorization
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Solution Overview
Problem
Current blockchain systems lack efficient and secure methods to authorize digital asset transfers based on group membership, particularly in scenarios where membership is dynamic and privacy preservation is essential, as they often require revealing excessive information during transaction validation.
Innovation Solution
The implementation of a computer-implemented method using accumulation trees and bilinear map accumulators to generate and verify membership proofs, allowing for secure and privacy-preserving authorization of digital asset transfers by leveraging elliptic curve cryptography and distributed data structures like blockchains, such as Bitcoin, to embed group membership requirements into locking scripts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional blockchain authorization methods are used, then security is maintained through cryptographic verification, but excessive information about group membership must be disclosed during transaction validation
Solution Approach 1:
The patent extracts only the essential authorization information (proof of group membership) from the complete group membership data structure. By using cryptographic accumulators, the system proves membership without exposing the actual group composition or individual member identities, thus maintaining security while preserving privacy.
Solution Approach 2:
The patent transforms the authorization problem from a dimensional space requiring full membership disclosure to a cryptographic space where only verification bits are exchanged. By mapping group membership verification to a different dimensional representation (cryptographic proofs rather than direct data exposure), the system achieves both security and privacy.
2Ease of operation
If detailed group membership information is disclosed for authorization, then transaction validation is simplified, but privacy and security are compromised
Solution Approach 1:
The patent introduces cryptographic accumulators as an intermediary mechanism between group membership management and transaction validation. This intermediary structure allows validation to proceed without direct exposure of sensitive membership information, as the accumulator serves as a mediator that verifies membership without revealing the underlying data.
Solution Approach 2:
The patent creates cryptographic copies (proofs) of group membership rather than using the actual membership data. These cryptographic copies contain all necessary validation information while being mathematically designed to prevent reconstruction of the original sensitive data, thus enabling easy validation without privacy loss.
3Loss of information
If cryptographic proofs of group membership are implemented, then privacy is preserved, but computational complexity increases
Solution Approach 1:
The patent performs preliminary actions by pre-computing and storing cryptographic accumulators that encapsulate group membership information. This preliminary computation allows subsequent transaction validations to use these pre-prepared cryptographic structures, reducing the computational burden during actual authorization operations while maintaining strong privacy guarantees.
4Ease of manufacture
If traditional authorization scripts are used in blockchain, then implementation is straightforward, but they cannot efficiently handle dynamic group membership
Solution Approach 1:
The patent implements dynamic group membership handling by using cryptographic accumulators that can be efficiently updated as members are added or removed from groups. The accumulator structure allows dynamic modification of group composition while maintaining the ability to verify current membership, providing both adaptability and continued ease of implementation through standardized cryptographic operations.
Data Source
AI summary
The invention relates to distributed ledger technologies such as consensus-based blockchains. Computer-implemented methods for locking and unlocking transaction inputs and outputs are described. The invention is implemented using a blockchain network, which may be, for example, a Bitcoin blockchain. A group of entities form a group in with membership may be proven using an accumulation tree. A variety of methods are described for generating the accumulation tree, including methods that use a central authority and methods that use a decentralized protocol in place of the central authority. In various implementations, parties are able to unlock transaction outputs that are based on group membership without revealing their identity generally.