tornado-core/contracts/ETHTornado.sol

// https://tornado.cash
/*
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*    88                                              88             d8'   `88                   88
*    88    .d8888b. 88d888b. 88d888b. .d8888b. .d888b88 .d8888b.    88        .d8888b. .d8888b. 88d888b.
*    88    88'  `88 88'  `88 88'  `88 88'  `88 88'  `88 88'  `88    88        88'  `88 Y8ooooo. 88'  `88
*    88    88.  .88 88       88    88 88.  .88 88.  .88 88.  .88 dP Y8.   .88 88.  .88       88 88    88
*    dP    `88888P' dP       dP    dP `88888P8 `88888P8 `88888P' 88  Y88888P' `88888P8 `88888P' dP    dP
* ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
*/

pragma solidity ^0.5.8;

import "./Tornado.sol";

contract ETHTornado is Tornado {
  constructor(
    IVerifier _verifier,
    uint256 _denomination,
    uint32 _merkleTreeHeight,
    address _operator
  ) Tornado(_verifier, _denomination, _merkleTreeHeight, _operator) public {
  }

  function _processDeposit() internal {
    require(msg.value == denomination, "Please send `mixDenomination` ETH along with transaction");
  }

  function _processWithdraw(address payable _recipient, address payable _relayer, uint256 _fee, uint256 _refund) internal {
    // sanity checks
    require(msg.value == 0, "Message value is supposed to be zero for ETH instance");
    require(_refund == 0, "Refund value is supposed to be zero for ETH instance");

    (bool success, ) = _recipient.call.value(denomination - _fee)("");
    require(success, "payment to _recipient did not go thru");
    if (_fee > 0) {
      (success, ) = _relayer.call.value(_fee)("");
      require(success, "payment to _relayer did not go thru");
    }
  }
}