Void Protocol: a privacy layer for Robinhood Chain

Public blockchains show everything. Every balance, transfer and trade can be traced back to a wallet. For anyone paying, trading or getting paid on-chain, that is a real problem.

Void Protocol set out to make privacy the default on Robinhood Chain, an Arbitrum Orbit layer 2, without asking anyone to hand over their keys. The product had to:

• let people send, buy and sell privately, so amounts and counterparties don't sit on the public ledger
• stay non-custodial, so users keep control of their own funds at all times
• protect wallet metadata at the network layer, not only on-chain
• lock launch liquidity under shared control, so no single key can move it
• hold up under a full security review before launch

We built the whole protocol: the contracts, the zero-knowledge proving pipeline, the off-chain services, the dApp and the website.

Private transactions with zero-knowledge proofs

• Private send, buy and sell built on private notes. Each spend is proven with a zero-knowledge proof instead of being revealed on-chain.
• A dedicated proof service that handles proof generation for the dApp.
• A relayer that submits private transactions on the user's behalf.
• An indexer that tracks notes and protocol events, so the dApp can rebuild a user's private balance quickly.

Smart contracts

• Solidity contracts, written and tested with Foundry.
• A Uniswap v4 hook for the token launch.
• An LP locker that holds launch liquidity under a 2-of-3 Safe multisig.

Privacy at the network layer

• A privacy-preserving RPC proxy between the dApp and the chain, so wallet traffic doesn't leak metadata to public RPC providers.

dApp and website

• A Next.js dApp at app.void-protocol.com for private deposits, sends, buys, sells and withdrawals.
• The public site at void-protocol.com, containerised with Docker and served through nginx.

• Live on Robinhood Chain testnet, with private send, buy and sell working end to end.
• 72 tests passed in our internal security review, with 100% line coverage of the launch contracts.
• Launch liquidity sits in an LP locker controlled by a 2-of-3 Safe, so no single key can move it.

See it at void-protocol.com, try the dApp at app.void-protocol.com and follow @voidprotocolrh on X.