UniStorm: Integrating Tornado Cash with Uniswap v4

Deck: https://gamma.app/docs/UniStorm-t4964wzmw9vl1hp

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Project Overview

UniStorm is a protocol that integrates Tornado Cash with Uniswap v4, utilizing zk-Snarks to facilitate private token swaps.

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Overview

UniStorm extends the functionality of Tornado Cash by incorporating it into Uniswap v4's hook system. Users can deposit tokens and receive their deposits back when they perform a swap, provided they present a valid proof. This integration allows for the separation of deposit and withdrawal addresses, enhancing transaction privacy while utilizing Uniswap v4's liquidity pools.

Architecture

Core Components

1. Privacy Mechanism

   • Implements Tornado Cash's commitment-nullifier scheme
   • Uses a Merkle tree to store deposit commitments
   • Employs zero-knowledge proofs for private withdrawals
   • Maintains denomination pools for standardized amounts

2. Uniswap V4 Integration

   • Implements BaseHook for custom swap logic
   • Manages liquidity through hook-controlled deposits
   • Handles currency settlement and pool state updates
   • Provides both private and public swap paths

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Key Data Structures

struct Deposits {
    uint256 amount;
    bytes32 commitment;
    bool isDeposited;
    Currency token;
    uint256 timestamp;
}

struct SwapState {
    uint256[2] pA;
    uint256[2][2] pB;
    uint256[2] pC;
    bytes32 root;
    bytes32 nullifierHash;
    address recipient;
    address relayer;
    uint256 amountInOutPositive;
}

Flow

Protocol Flow

1. Deposit Process

• User generates random nullifier and secret values.
• Creates a commitment (hash of nullifier and secret).
• Deposits tokens along with the commitment.
• Protocol converts tokens to ETH if necessary.
• Commitment is stored in the Merkle tree.
• Deposit details are recorded with a timestamp.

2. Private Swap Process

• User generates a zero-knowledge proof of deposit ownership.

• Submits proof along with desired swap parameters.

• Protocol verifies:

  • Proof validity
  • Nullifier hasn't been spent
  • Merkle root is valid

• If verification succeeds:

  • Marks nullifier as spent
  • Converts ETH back to tokens
  • Executes swap through Uniswap V4
  • Updates pool state
  • Settles currencies

Security Features Zero-Knowledge Privacy

• Breaks on-chain links between deposits and withdrawals

  • Uses Groth16 proof system Implements nullifier tracking to prevent double-spending Pool Security

  • Enforces hook-controlled liquidity additions Maintains standardized denomination amounts Implements reentrancy protection Verifies all proofs before execution Economic Security

#Key Functions

• deposit(Currency token, uint256 amount, bytes32 commitment)

   Handles initial token deposits
   Converts tokens to ETH if necessary
   Stores commitment in Merkle tree
  

• beforeSwap(address sender, PoolKey key, IPoolManager.SwapParams params, bytes data)

  Routes between private and public swaps Handles proof verification for private swaps Manages currency settlements

• verifyProofAndNullifier(SwapState memory state)

  Validates zero-knowledge proofs Checks nullifier status Verifies Merkle root

Installation & Setup

Clone the Repository

git clone https://github.com/ChinmayGopal931/UniStorm.git

## Installation

Clone this repository

```bash
git clone https://github.com/ChinmayGopal931/UniStorm.git

Install dependencies:

forge install

yarn

Usage

Compiling circom circuits

The main workflow of this repo is:

1. Compile circuits to generate circuit artifacts
2. Perform a powers of tau ceremony
3. Generate proving and verification keys /circuit_artifacts and src/Verifier.sol

These three steps are written as bash commands in the makefile. Run the following to perform these steps:

make all

This will create a /circuit_artifacts folder that contains everything needed to run tests.

Running tests

Run the following command to run tests (after you have generated circuit artifacts):

forge test

Credits

Tornado Cash rebuilt by https://github.com/nkrishang here https://github.com/nkrishang/tornado-cash-rebuilt/