The distributed ledgers ensuring privacy-preserving transactions

• Main Author: Sergey V. Zapechnikov
• Format: Article
• Language: English
• Published: Moscow Engineering Physics Institute 2020-12-01
• Series: Bezopasnostʹ Informacionnyh Tehnologij
• Subjects: distributed ledger, blockchain technologies, cryptocurrency, consensus, state machine replication, confidentiality.
• Online Access: https://bit.mephi.ru/index.php/bit/article/view/1310

The paper is devoted to the actual problem of ensuring privacy during performing transactions in distributed ledgers. We discuss various aspects of transaction privacy, as well as the specifics of setting the problem for distributed ledgers with two main models for representing participants' balances: the UTXO-model and the account model. Based on these results, we outline definitions and consider security properties of the main cryptographic primitives used for preserving the privacy of transactions: mixers, ring signatures, homomorphic encryption, and zero-knowledge proofs. We analyze well-known solutions for distributed ledgers based on the UTXO-model, such as Zcash, Monero, Zcoin, Dash, CoinShuffle, Verge, Grin, and others, as well as for systems based on the account model: DSC, Zether, Zeth, BlockMaze. Based on the comparison of advantages, disadvantages, and limitations for existing solutions, conclusions are drawn about the future development of distributed ledgers that ensure the privacy of transactions, and new research tasks are outlined.