hideyour.cash

Zero Knowledge based solution to perform anonymous transactions on NEAR blockchain with compliance features.

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Who we are:

We are hack-a-chain, a software development company from Brazil, specializing on web 3.0. Currently, we focus on developing in the NEAR blockchain.

Inspiration:

Hack-a-Chain (the software company behind hideyour.cash project) that likes to study and implementing cutting edge web 3 technologies. Zero Knowledge has called our attention for its huge potential to create privacy enhancing protocols on top of blockchains and, while studying how Tornado.cash worked, we realized that this kind of technology wasn't available on NEAR yet, and that inspired us to create it.

What it does:

hideyour.cash is a private transaction protocol on top of NEAR. The protocol works through a technology called zkSNARKS which is a type of zero-knowledge cryptographic proof. Any user can deposit to the smart contract by sending over a commitment (think of it as the hash of a private key), later any other account can withdraw the amount deposited by submitting a zero-knowledge proof that they know the secret key that generated one of the deposits. What happens is, since multiple people are depositing and withdrawing from the protocol at the same time, there is no way to tell which withdrawing account belongs to each initial depositor, thus your withdrawing account becomes private, no one can tell who originally deposited to it.

How we built it:

we studied cryptography and ZK for months before getting into the hackathon, so during that 48 hours we focused on building the ZK infrastructure on NEAR. We have created ZK Validator with groth algorithm, implemented a MIMC hash and created a library for big number arithmetic on NEAR, which are all open source on our github. Later, we built the Smart Contract for the protocol and integrated it with a basic front-end to deposit, withdraw and register to whitelist.

Challenges we ran into:

no native implementation of ZK on Rust and NEAR; integrations between rust, JS, TS and WASM code; difficult of finding end users on the conference (we have interviewed over 20 people).

Accomplishments that we're proud of:

first open source ZK solution on NEAR, development of ZK tooling for anyone to use on NEAR, first compliant focused private transactions protocol.

What we learned:

implementing groth 16 algorithm on Rust/NEAR; average blockchain users value privacy but are unware of how it might be compromised onchain; privacy is something you have to provide to people regardless they're shown interest (in a conversation with Illia, he quoted Brave's example). We also learned that ZK is a enabling technology that can power a whole set of privacy solutions. We sure want to keep deepening our knowledge regarding this matter to leverage our knowledge on ZK to enhance blockchain privacy.

What's next for hideyour.cash:

we want to bring the MVP to mainnet to start interacting to users, getting feedback and improving the project. Our vision is to create privacy enhancing tools for NEAR and we're not stick to a private transactions platform; we are going deep into this market to understand where privacy is needed the most so we can design specialized solutions for this problems.

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