I wrote the core ZK circuits and contracts for private stargate finance last weekend at the web3privacy now hackathon. The goal of this hackathon was to build a nice UI for the protocol that is entirely decentralised, running on ipfs (at https://privatestargatefinance.eth.limo) and only requiring an ETH RPC to get all data that the user needs to transact.

The existing core functionality of the circuits and contracts are:

• deposit (move from standard ERC20 to encrypted ERC20)
• transfer (encrypted transfer)
• warp (cross chain private transfer)
• withdraw (move from encrypted ERC20 -> standard ERC20)

However, as part of this UI integration, I had to build:

• note sharing (ensuring that users can share notes via encrypted onchain calldata)
• multiple chain merkle tree state management
• build the account model out, and into the browser (I use passkey to store an encrypted mnemonic)

The thing that I was not expecting to be as difficult as what it is was the UTXO arithmetic required to make transfers and warps compatible with a nice user interface. This combined with the retrieval of emitted Events on the contract programmatically and cleanly has been quite a pain.