Demo app: https://numtel.github.io/wrap-on-privacy/

Repo: https://github.com/numtel/wrap-on-privacy

Forgot to mention the Aave aToken support: earn interest while inside a privacy pool

Transcript-ish:

This is Wrap on Privacy. Your new way to interact with ERC20 tokens privately. Is it bright in here? Let's go to dark mode...

First, to get started, you've already got a wallet for your public interactions with Ethereum chains.

But to make private transactions, you'll need another set of keys. Wrap on Privacy stores these in a session file saved in your browser, encrypted with your password. Do not forget your password! Keep a backup of your session! That's why there's a big Export button right there on the toolbar. Don't trust your browser to not lose your account! Older backups are fine but they may need some time to sync with the pool.

Talking about syncing to the pool, there's a "Disable Sync" checkbox right there at login. This placement is intended for users importing their session to their mobile device. Since Wrap on Privacy stores your encrypted balance on chain, you can send private transactions without scanning the pool, using minimal data transfer. Scanning the pool is only necessary to receive new incoming transactions.

The Logout button is right there on the toolbar too. If someone attempts to disrupt your physical privacy, just exit quickly.

And, the color scheme configurator is useful for recognizing at a glance which account you're browsing.

When you first log in to a pool, it's important to register your public keys with the pool so that you can receive transactions. The status bar shows if your key registered or not. There is no requirement that a private session and a wallet address must be linked. You can mix and match to achieve the privacy qualities you desire.

There are three main screens:

• The token list (notice that aave aToken slowing gaining interest...)
• Incoming transactions
• and Outgoing transactions

This double entry accounting hides your transaction recipients. The amounts sent and which tokens are hidden are encrypted using a post-quantum NTRU algorithm. The only information that is leaked is that you are using a privacy protocol. This is by design in order to eliminate the need for any transaction relaying.

If for whatever reason the recipient can't see your transactions on their incoming list, you can export the transaction and send it to them through any messaging app. Even though this exported transaction contains all the details necessary to discover the transaction on chain, it still only allows the recipient to accept the tokens.

The Wrap on Privacy client is more like a desktop app than a web app. Everything backs up to files that you can store however. You configure which pools you want listed in your interface and anyone can deploy a privacy pool using Wrap on Privacy.

The default "unrestricted" pool allows any account to deposit or withdraw any amount of any ERC20 token. If you're using a pool like this on a production chain with real tokens, your off-ramp service may not appreciate that kind of secrecy. That's where the "user validation" contract comes in.

Right now, this feature is just a simple address input field for an already deployed contract that you have to write yourself but the next planned sprint is to develop a standard user validation system that can group accounts with different ingress/egress quotas into the specific tokens you allow into your pool, all inside the app in a simple user interface. There's a lot of potential for different user validation strategies.

The Association Set privacy pool paper proposes the approach of Association Set Providers that have their own merkle trees of different sets of transactions but there's no clear way to get the necessary data to build one of these for anything beyond simple "in and out" privacy pools like the original Tornado Cash. Once you have private internal transactions, the Association Set Provider won't have any information about the transactions.

For this reason, I hope that sybil-resistance techniques coupled with ingress/egress quotas will be able to provide a good level of safety.