Privacy on the Blockchain: Unique Ring Signatures

TL;DR

This paper introduces a novel unique ring signature scheme compatible with blockchain systems, enhancing user privacy and anonymity, and provides an implementation suitable for Ethereum smart contracts.

Contribution

It presents the first implementation of a unique ring signature scheme using secp256k1 for blockchain privacy, enabling practical deployment in Ethereum smart contracts.

Findings

Scheme offers strong privacy and security properties

Implementation is compatible with existing blockchain libraries

Efficiency compares favorably with other privacy approaches

Abstract

Ring signatures are cryptographic protocols designed to allow any member of a group to produce a signature on behalf of the group, without revealing the individual signer's identity. This offers group members a level of anonymity not attainable through generic digital signature schemes. We call this property 'plausible deniability', or anonymity with respect to an anonymity set. We concentrate in particular on implementing privacy on the blockchain, introducing a unique ring signature scheme that works with existing blockchain systems. We implement a unique ring signature (URS) scheme using secp256k1, creating the first implementation compatible with blockchain libraries in this way, so as for easy implementation as an Ethereum smart contract. We review the privacy and security properties offered by the scheme we have constructed, and compare its efficiency with other commonly suggested approaches to privacy on the blockchain.