tonic-cash / tonic-core

🥃 Core smart contracts of Tonic, implementing private token transfers in Klaytn & WEMIX

Tonic Core

Privacy Transactions for Everyone, Powered by zk-SNARK Technology.

This repository contains core smart contracts for Tonic(토닉), a decentralized privacy protocol that implements private token transfers on an EVM-based blockchain, making it harder to track them. Currently, it supports Klaytn and WEMIX as the first-ever crypto mixer.

• ✈️ App: tonic.cash
• ✈️ Docs: docs.tonic.cash
• 🛫 Twitter: @tonic_cash
• 🛫 Telegram (Channel): @tonic_cash

🌊 Protocol Flow

This is how Tonic works under the hood. (v2023.04)

🛡️ Security

🔒 Trusted Setup (Tornado Cash)

Zero-knowledge proofs are cryptographic techniques that enable one party to prove knowledge of specific information without revealing the actual data. In the context of Tonic, they are essential for ensuring privacy in transactions.

Tonic takes advantage of Tornado Cash's Trusted Setup, which has received contributions from over 1,100 participants, making it one of the most extensive and secure setups available. The extensive participation in the Trusted Setup ensures the generation of robust and secure parameters, which are vital for creating zero-knowledge proofs.

By leveraging the proven open-source keys from Tornado Cash's Trusted Setup, Tonic enhances its censorship resistance and transparency. This, in turn, significantly improves the platform's overall security and reliability, providing users with a dependable and privacy-preserving solution for transactions.

The keys generated in their Trusted Setup Ceremony can be found here: Unstoppable Tornado Cash

🌪️ Audits (Tornado Cash)

Tonic is a project forked from Tornado Cash. Tornado Cash received security audits for cryptographic technology, smart contracts, and ZK-SNARK circuits through ABDK Consulting in November 2019. You can find their reports under here, under our audit/tornado-cash folder.

Given the minor changes made in this fork, which do not affect the fundamental aspects of the original project, it is not necessary to undergo another security audit. Relying on the robust security evaluations conducted for Tornado Cash is reasonable, as the core functionality remains largely unaltered.

⚒️ Modifications

In the interest of transparency, we would like to outline the modifications made in the fork:

1. Implements IKIP7Receiver for compatibility with KIP7 (Klaytn's own fungible token standard):

The IKIP7Receiver interface introduces the onKIP7Received function, which handles the receipt of KIP-7 tokens. KIP-7 smart contracts call this function on the recipient after a safeTransfer. Returning any value other than the magic value(0x9d188c22) will result in the transaction being reverted.

interface IKIP7Receiver {
  function onKIP7Received(
    address _operator,
    address _from,
    uint256 _amount,
    bytes memory _data
  ) external returns (bytes4);
}

Tonic Instances(ETHTonic and ERC20Tonic), implements the onKIP7Received function as follows:

function onKIP7Received(
  address _operator,
  address _from,
  uint256 _amount,
  bytes memory _data
) external pure returns (bytes4) {
  return 0x9d188c22;
}

2. Make it possible for the owner to withdraw unrelated tokens(airdrops) from the contract:

The fork incorporates the Ownable functionality, allowing the owner of the contract to withdraw unrelated tokens, such as tokens received through airdrops (this is why we implemented IKIP7Receiver for ETHTonic as well).

This feature provides more control and flexibility for the contract owner in managing unexpected token transfers to the contract.

// ETHTonic (Tonic Instance for Native Tokens)
...

// Only contract-based tokens, just in case for airdrops!
receive() external payable {}

function transfer(address _recipient, address _token, uint256 _amount) external onlyOwner {
    IToken token = IToken(_token);
    token.transfer(_recipient, _amount);
}

// ERC20Tonic (Tonic instance of ERC20/KIP7)
...

// Only 1) native token and 2) contract-based tokens that is not deposit token, just in case for airdrops!
receive() external payable {}

function transfer(address _recipient, uint256 _amount) external onlyOwner {
    payable(_recipient).transfer(_amount);
}

function transfer(address _recipient, address _tokenAddr, uint256 _amount) external onlyOwner {
    require(_tokenAddr != address(token), "token address should not be the same as deposit token");
    IToken transferableToken = IToken(_tokenAddr);
    transferableToken.transfer(_recipient, _amount);
}

3. Added state variables to keep track of stats, enabling queries in our frontend app:

The fork introduces two new state variables, numberOfDeposits and numberOfWithdrawals, to maintain statistics on the number of deposits and withdrawals. This allows users to access these statistics through the frontend app using multicall.

// values to keep track of stats
uint256 public numberOfDeposits;
uint256 public numberOfWithdrawals;

4. Implemented TonicFeePolicyManager to manage the policy of withdrawal fees:

Tonic employs the newly-added TonicFeePolicyManager contract to manage withdrawal fee policies. You can view the code here. Our contracts have the feePolicyManager state (which is set by the initial constructor and cannot be changed afterward) and include three internal view functions: _feeNumerator(), _feeDenominator(), and _treasury(). These functions return the fee numerator, fee denominator, and treasury address, respectively, querying the TonicFeePolicyManager with each call.

In the _processWithdraw function within the Tonic instances, the treasuryFee is calculated, and the recipientAmount is determined by subtracting the treasuryFee and _relayerFee from the denomination.

// Tonic instances
uint256 treasuryFee = (denomination * _feeNumerator()) / _feeDenominator();
uint256 recipientAmount = denomination - treasuryFee - _relayerFee;

For ETHTonic (Tonic Instance for Native Tokens), the treasuryFee is transferred to the treasury address.

// ETHTonic (Tonic Instance for Native Tokens)
if (treasuryFee > 0) {
    (bool feeSuccess, ) = _treasury().call{ value: treasuryFee }("");
    require(feeSuccess, "payment to treasury did not go thru");
}

For ERC20Tonic (Tonic instance of ERC20/KIP7), the treasuryFee is safely transferred to the treasury address using the safeTransfer function.

// ERC20Tonic (Tonic instance of ERC20/KIP7)
if (treasuryFee > 0) {
    token.safeTransfer(_treasury(), treasuryFee);
}

📃 Deployed Contracts

🟠 Klaytn Mainnet (Cypress)

Tonic Instances

Name	Contract Address
KLAY 100	0x033237b3d6ABCb7d48C5A40Ec3038A53aEc1b77e
KLAY 1000	0x7b853e8387FC6bcFCAa9BDab8d0479E6c9E6782b
KLAY 10000	0x457Caf470fB1031530E8cdD06703da7B1BbCCe04
KLAY 100000	0x9694ea20de96D5E46C8FE1E7975D7a2C7C79Bf2c
oUSDT 100	0x528AE79DAe416bf9623B94fA6Baef0FC3dd12ef8
oUSDT 1000	0xc69C9bBabEDE59562Cd8a6F92Fa50aFf10D8310e
oUSDT 10000	0x503d6D4E14A2A4f78f4c3E51c94F1F53C6bd6D96
oUSDT 100000	0x804aA592f7bF0B7EB98db08825D1106eC4822fb3
oETH 0.1	0x70D8D865d556f7D03c463e296ac706CE11B73d4B
oETH 1	0x402f2297f15b6fc9415D6F193ae882a3879b5F09
oETH 10	0xCFa2494dddB338c2fd15224B4Eb9668a5C4de695
oETH 100	0xD10aaD96548CAa7874e435Db0d9676b64554092b

Periphery

Name	Contract Address
MulticallV2	0x5f5f0d1b9ff8b3dcace308e39b13b203354906e9
TonicFeePolicyManager	0x5199e8b9d54786EB7d261FE09f51FcA64b61e9fD

🟣 WEMIX Mainnet

Tonic Instances

Name	Contract Address
WEMIX 100	0x033237b3d6ABCb7d48C5A40Ec3038A53aEc1b77e
WEMIX 1000	0x7b853e8387FC6bcFCAa9BDab8d0479E6c9E6782b
WEMIX 10000	0x457Caf470fB1031530E8cdD06703da7B1BbCCe04
WEMIX 100000	0x9694ea20de96D5E46C8FE1E7975D7a2C7C79Bf2c
WEMIX$ 100	0x144120Ef18d4223Ab3f4695653a5755C23FBF469
WEMIX$ 1000	0xc978f195C838d3344f74DDBA84235130B3091847
WEMIX$ 10000	0xeD4a38cC990a6E5D817C9d89677c886994803d38
WEMIX$ 100000	0xAc04FDbADd7CF8d4BaD0F957d37e3fd0c093A9B6
ETH 0.1	0x2D3bAeBa85D78D202887D34f5618380e90F3c272
ETH 1	0xD2510D275dbca0fe333dAff8Eb51b9105f6aC212
ETH 10	0xE1d1c5094d5eEF16E0207834b2E5FDf634278217
ETH 100	0xfF30E4d7ec19a45710049033d1E51C1a6848E1FA

Periphery

Name	Contract Address
MulticallV2	0x528AE79DAe416bf9623B94fA6Baef0FC3dd12ef8
TonicFeePolicyManager	0x5199e8b9d54786EB7d261FE09f51FcA64b61e9fD