LSAG Signature Key-Image Mechanism for Blockchain Privacy
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Solution Overview
Problem
Blockchain transactions lack privacy protection, as asset management using ring signatures can lead to 'double-spending' issues due to hidden signer identities, and maintaining multiple public-private key pairs for each asset is costly and inefficient.
Innovation Solution
The implementation of Linkable Spontaneous Anonymous Group (LSAG) signatures, which generate key-images related to private keys and asset identifiers, allowing for anonymous transactions without exposing public keys, thus alleviating 'double-spending' and reducing key pair maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If ring signatures are used to hide signer identities for privacy protection, then transaction privacy is improved, but double-spending issues arise due to hidden identities
Solution Approach 1:
The patent introduces key-images as an intermediary element that bridges the signer's private key and the public verification system. Each key-image is derived from the private key and asset identifier, serving as a unique fingerprint that can be verified without revealing the signer's identity. This intermediary allows the system to track spent assets while maintaining anonymity, resolving the contradiction between privacy and double-spending prevention.
Solution Approach 2:
The patent segments the identification process into two independent parts: the signer's identity (hidden) and the asset identifier (visible). By separating these components and using key-images to link them, the system can verify asset uniqueness without exposing the signer. This segmentation allows privacy protection while maintaining reliable tracking of asset movements to prevent double-spending.
2Measurement precision
If multiple public-private key pairs are maintained for each asset, then asset identification accuracy is improved, but system complexity and maintenance cost increase
Solution Approach 1:
The patent makes the key-image generation process universal by deriving key-images from a single private key combined with asset identifiers. Instead of requiring separate key pairs for each asset, the same private key can generate key-images for multiple different assets by combining it with their respective identifiers. This multi-functionality reduces key pair maintenance complexity while maintaining accurate asset identification through the unique combination of key-image and asset identifier.
Solution Approach 2:
The patent creates a copy of the identification function through key-images. Rather than maintaining multiple original key pairs, the system generates key-image copies that carry the identification information. These key-images serve as substitutes that preserve the ability to uniquely identify assets without requiring the full complexity of multiple private key pairs, thus reducing system maintenance overhead.
3Productivity
If public keys are exposed in transactions, then verification efficiency is improved, but privacy protection is compromised
Solution Approach 1:
The patent uses key-images as an intermediary that enables verification without direct public key exposure. The key-images are derived from private keys but can be verified through the ring signature mechanism without revealing the underlying public keys. This intermediary allows the verification process to proceed efficiently while maintaining signer anonymity, as the key-images themselves do not directly expose the signer's identity.
Solution Approach 2:
The patent shifts the verification dimension from direct public key comparison to key-image fingerprint matching. Instead of verifying through exposed public keys in the traditional sense, the system verifies by matching key-images against a historical set. This dimensional change allows verification to occur in a privacy-preserving manner, as the key-images serve as obfuscated representations that can be verified without revealing the original public keys.
Data Source
AI summary
This disclosure relates to anonymous transactions based on ring signatures. In one aspect, a method includes receiving a remittance transaction. The remittance transaction is generated by a client device of a remitter by assembling unspent assets in an account corresponding to the remitter and masked assets in an account corresponding to a masked participant. Key images are obtained from a linkable spontaneous anonymous group (LSAG) signature of the remittance transaction. Values of the key-images are based on a private key, a public key, and unspent assets of the remitter. The LSAG signature is verified. The LSAG signature is generated by the client device of the remitter based on the private key and the public key of the remitter, and a second public key of the masked participant. The remittance transaction is executed when a transaction execution condition is met.