tornado-core/contracts/Mixer.sol
2019-09-10 16:31:34 +03:00

112 lines
4.7 KiB
Solidity

// https://tornado.cash
/*
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*/
pragma solidity ^0.5.8;
import "./MerkleTreeWithHistory.sol";
contract IVerifier {
function verifyProof(uint256[2] memory a, uint256[2][2] memory b, uint256[2] memory c, uint256[5] memory input) public returns(bool);
}
contract Mixer is MerkleTreeWithHistory {
bool public isDepositsEnabled = true;
// operator can disable new deposits in case of emergency
// it also receives a relayer fee
address payable public operator;
mapping(uint256 => bool) public nullifierHashes;
// we store all commitments just to prevent accidental deposits with the same commitment
mapping(uint256 => bool) public commitments;
IVerifier public verifier;
uint256 public mixDenomination;
event Deposit(uint256 indexed commitment, uint256 leafIndex, uint256 timestamp);
event Withdraw(address to, uint256 nullifierHash, address indexed relayer, uint256 fee);
/**
@dev The constructor
@param _verifier the address of SNARK verifier for this contract
@param _merkleTreeHeight the height of deposits' Merkle Tree
@param _emptyElement default element of the deposits' Merkle Tree
@param _operator operator address (see operator above)
*/
constructor(
address _verifier,
uint256 _mixDenomination,
uint8 _merkleTreeHeight,
uint256 _emptyElement,
address payable _operator
) MerkleTreeWithHistory(_merkleTreeHeight, _emptyElement) public {
verifier = IVerifier(_verifier);
operator = _operator;
mixDenomination = _mixDenomination;
}
/**
@dev Deposit funds into mixer. The caller must send value equal to `mixDenomination` of this mixer.
@param commitment the note commitment, which is PedersenHash(nullifier + secret)
*/
/**
@dev Deposit funds into the mixer. The caller must send ETH value equal to `userEther` of this mixer.
The caller also has to have at least `mixDenomination` amount approved for the mixer.
@param commitment the note commitment, which is PedersenHash(nullifier + secret)
*/
function deposit(uint256 commitment) public payable {
require(isDepositsEnabled, "deposits disabled");
require(!commitments[commitment], "The commitment has been submitted");
_processDeposit();
_insert(commitment);
commitments[commitment] = true;
emit Deposit(commitment, next_index - 1, block.timestamp);
}
/**
@dev Withdraw deposit from the mixer. `a`, `b`, and `c` are zkSNARK proof data, and input is an array of circuit public inputs
`input` array consists of:
- merkle root of all deposits in the mixer
- hash of unique deposit nullifier to prevent double spends
- the receiver of funds
- optional fee that goes to the transaction sender (usually a relay)
*/
function withdraw(uint256[2] memory a, uint256[2][2] memory b, uint256[2] memory c, uint256[5] memory input) public {
uint256 root = input[0];
uint256 nullifierHash = input[1];
address payable receiver = address(input[2]);
address payable relayer = address(input[3]);
uint256 fee = input[4];
require(fee < mixDenomination, "Fee exceeds transfer value");
require(!nullifierHashes[nullifierHash], "The note has been already spent");
require(isKnownRoot(root), "Cannot find your merkle root"); // Make sure to use a recent one
require(verifier.verifyProof(a, b, c, input), "Invalid withdraw proof");
nullifierHashes[nullifierHash] = true;
_processWithdraw(receiver, relayer, fee);
emit Withdraw(receiver, nullifierHash, relayer, fee);
}
function toggleDeposits() external {
require(msg.sender == operator, "unauthorized");
isDepositsEnabled = !isDepositsEnabled;
}
function changeOperator(address payable _newAccount) external {
require(msg.sender == operator, "unauthorized");
operator = _newAccount;
}
function isSpent(uint256 nullifier) public view returns(bool) {
return nullifierHashes[nullifier];
}
function _processDeposit() internal {}
function _processWithdraw(address payable _receiver, address payable _relayer, uint256 _fee) internal {}
}