Deposit any ERC-20, and receive corresponding zkERC20 tokens. These can be transferred to any user and bridged to any chain — without revealing the token type, amount, or receiver.
Dependencies:
To install and run tests, in the cloned directory, simply run:
make testIMPORTANT DISCLAIMER: This project is intended to be a proof of concept and is not production ready. Not all features are necessarily fully implemented or tested, and the code has not been audited.
The protocol consists of a contract on each supported ecosystem, which utilizes zero knowledge proofs (ZKPs) to regulate user balances in a vector commitment. These contracts interact through messages on LayerZero, allowing users to send and bridge assets completely privately and anonymously. In fact, outside observers cannot even determine exactly how a token's supply is spread across the chains.
The zero knowledge (ZK) circuits powering this functionality are designed to be friendly towards potential privacy-focused DeFi protocols, including escrow contracts, anonymous perps/leverage protocols, and dark pools (private orderbooks/DEX). Of course, users can at any time withdraw their zkERC20. On the original chain, this leaves them with the corresponding ERC-20; on others, they receive a wrapped variant economically pegged 1:1.
For more information about the privacy guarantees of the protocol, see docs/MOTIVATIONS.md.
Our protocol uses completely custom ZK circuits in Circom, which allows for the privacy-preserving guarantees without being dependent on specialized ecosystem features. This allows the application to be trivially expanded across EVM-compatible chains, and even to be supported on others like Aptos.
Users interact with the protocol by providing proofs of certain invariants that are produced off-chain. There are a number of options: these can be computed directly in the browser using WebAssembly, or even using a self-hosted server implementation.
The bridging mechanism allows assets to be transferred with very concise messages. We choose to implement a higher level abstraction that allows the protocol to be composed with any bridge. This expands the number of chains and possible trust configurations.