ZETH: On Integrating Zerocash on Ethereum
This addresses privacy issues for users of Ethereum and similar account-based blockchains, offering a practical solution for private transactions in public and permissioned chains, though it is incremental as it builds on existing Zerocash work.
The authors tackled the problem of transaction privacy on Ethereum by adapting Zerocash to create ZETH, enabling private transfers of Ether and other digital assets without modifying Ethereum's base layer, with analysis showing controlled information leakages.
Transaction privacy is a hard problem on an account-based blockchain such as Ethereum. While Ben-Sasson et al. presented the Zerocash protocol [BCG+14] as a decentralized anonymous payment (DAP) scheme standing on top of Bitcoin, no study about the integration of such DAP on top of a ledger defined in the account model was provided. In this paper we aim to fill this gap and propose ZETH, an adaptation of Zerocash that can be deployed on top of Ethereum without making any change to the base layer. Our study shows that not only ZETH could be used to transfer Ether, the base currency of Ethereum, but it could also be used to transfer other types of smart contract-based digital assets. We propose an analysis of ZETH's privacy promises and argue that information leakages intrinsic to the use of this protocol are controlled and well-defined, which makes it a viable solution to support private transactions in the context of public and permissioned chains.