Title: Blockchain-based criminal smart contract for symmetric key selling using ZK-SNARKs

Authors: G. Pavithra; Kunwar Singh

Addresses: Computer Science and Engineering, National Institute of Technology Tiruchirappalli, Tanjore Main Road, NH67, Near BHEL, Tiruchirappalli, Tamil Nadu – 620015, India ' Computer Science and Engineering, National Institute of Technology Tiruchirappalli, Tanjore Main Road, NH67, Near BHEL, Tiruchirappalli, Tamil Nadu – 620015, India

Abstract: Blockchain-based systems - Bitcoin, Ethereum, etc. - are very famous for various applications but, due to their properties like pseudo-anonymity, no central authority, they can pave way for criminal applications which are difficult to detect. We have proposed one such criminal application (which we call criminal smart contract) that can happen: on the blockchain, how a perpetrator can sell the symmetric key of a specific user to a contractor (who specifies his/her target user of interest) using ZK-SNARKs. We consider that the perpetrator has somehow already stolen/gotten to know the key of the user as specified by the contractor. Through this, we want to emphasise on the point that we have to devise methods to prevent the occurrence of various types of crimes in order to fully leverage the benefits of the blockchain. On this line, we have also provided few counter measures to avoid such cases of privacy and security issues.

Keywords: ZK-SNARKs; zero knowledge proofs; cryptography; criminal smart contract; CSC; blockchain; bitcoin; smart contract; Ethereum; public key cryptosystems; security; circom; ciminion.

DOI: 10.1504/IJBC.2023.135006

International Journal of Blockchains and Cryptocurrencies, 2023 Vol.4 No.3, pp.257 - 272

Received: 06 Aug 2023
Accepted: 01 Oct 2023
Published online: 24 Nov 2023 *

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