Privacy preservation for transaction initiators: stronger key image ring signature and smart contract-based framework

Abstract

Recently, blockchain technology has garnered a great deal of suport, however, an attenuating factor to its global adoption in certain use cases is privacypreservation (owing to its inherent transparency). A widely explored cryptographic option to address this challenge has been a ring signature that, aside from its privacy guarantee, must be double-spending resistant. In this paper, we identify and prove a catastrophic flaw for double-spending attacks in a lightweight ring signature scheme and proceed to construct a new fortified commitment scheme that uses a signer’s entire private key. Subsequently, we compute a stronger key image to yield a double-spending-resistant signature scheme that is solidly backed by formal proof. Inherent in our solution is a novel, zero-knowledge-based, secure, and cost-effective smart contract for public key aggregation. We test our solution on a private blockchain as well as a Kovan testnet along with a performance analysis that attests to its efficiency and usability – and, we make the code publicly available on GitHub.