Address Details

contract

pragma solidity ^0.5.3;


library SafeMath {
    
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");

        return c;
    }

    
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        return sub(a, b, "SafeMath: subtraction overflow");
    }

    
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        uint256 c = a - b;

        return c;
    }

    
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        
        
        
        if (a == 0) {
            return 0;
        }

        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");

        return c;
    }

    
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        return div(a, b, "SafeMath: division by zero");
    }

    
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        
        require(b > 0, errorMessage);
        uint256 c = a / b;
        

        return c;
    }

    
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        return mod(a, b, "SafeMath: modulo by zero");
    }

    
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b != 0, errorMessage);
        return a % b;
    }
}

contract Context {
    
    
    constructor () internal { }
    

    function _msgSender() internal view returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view returns (bytes memory) {
        this; 
        return msg.data;
    }
}

contract Ownable is Context {
    address private _owner;

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    
    constructor () internal {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    
    function owner() public view returns (address) {
        return _owner;
    }

    
    modifier onlyOwner() {
        require(isOwner(), "Ownable: caller is not the owner");
        _;
    }

    
    function isOwner() public view returns (bool) {
        return _msgSender() == _owner;
    }

    
    function renounceOwnership() public onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    
    function transferOwnership(address newOwner) public onlyOwner {
        _transferOwnership(newOwner);
    }

    
    function _transferOwnership(address newOwner) internal {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}

interface IERC20 {
    
    function totalSupply() external view returns (uint256);

    
    function balanceOf(address account) external view returns (uint256);

    
    function transfer(address recipient, uint256 amount) external returns (bool);

    
    function allowance(address owner, address spender) external view returns (uint256);

    
    function approve(address spender, uint256 amount) external returns (bool);

    
    function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);

    
    event Transfer(address indexed from, address indexed to, uint256 value);

    
    event Approval(address indexed owner, address indexed spender, uint256 value);
}

contract ERC20 is Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    
    function totalSupply() public view returns (uint256) {
        return _totalSupply;
    }

    
    function balanceOf(address account) public view returns (uint256) {
        return _balances[account];
    }

    
    function transfer(address recipient, uint256 amount) public returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    
    function allowance(address owner, address spender) public view returns (uint256) {
        return _allowances[owner][spender];
    }

    
    function approve(address spender, uint256 amount) public returns (bool) {
        _approve(_msgSender(), spender, amount);
        return true;
    }

    
    function transferFrom(address sender, address recipient, uint256 amount) public returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        return true;
    }

    
    function increaseAllowance(address spender, uint256 addedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(addedValue));
        return true;
    }

    
    function decreaseAllowance(address spender, uint256 subtractedValue) public returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        return true;
    }

    
    function _transfer(address sender, address recipient, uint256 amount) internal {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(amount);
        emit Transfer(sender, recipient, amount);
    }

    
    function _mint(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: mint to the zero address");

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(amount);
        emit Transfer(address(0), account, amount);
    }

    
    function _burn(address account, uint256 amount) internal {
        require(account != address(0), "ERC20: burn from the zero address");

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(amount);
        emit Transfer(account, address(0), amount);
    }

    
    function _approve(address owner, address spender, uint256 amount) internal {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

        _allowances[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }

    
    function _burnFrom(address account, uint256 amount) internal {
        _burn(account, amount);
        _approve(account, _msgSender(), _allowances[account][_msgSender()].sub(amount, "ERC20: burn amount exceeds allowance"));
    }
}

interface IAttestations {
  function setAttestationRequestFee(address, uint256) external;
  function request(bytes32, uint256, address) external;
  function selectIssuers(bytes32) external;
  function complete(bytes32, uint8, bytes32, bytes32) external;
  function revoke(bytes32, uint256) external;
  function withdraw(address) external;

  function setAttestationExpiryBlocks(uint256) external;

  function getMaxAttestations() external view returns (uint256);

  function getUnselectedRequest(bytes32, address) external view returns (uint32, uint32, address);
  function getAttestationRequestFee(address) external view returns (uint256);

  function lookupAccountsForIdentifier(bytes32) external view returns (address[] memory);

  function getAttestationStats(bytes32, address) external view returns (uint32, uint32);

  function getAttestationState(bytes32, address, address)
    external
    view
    returns (uint8, uint32, address);
  function getCompletableAttestations(bytes32, address)
    external
    view
    returns (uint32[] memory, address[] memory, uint256[] memory, bytes memory);
}

interface IEscrow {
  function transfer(
    bytes32 identifier,
    address token,
    uint256 value,
    uint256 expirySeconds,
    address paymentId,
    uint256 minAttestations
  ) external returns (bool);

  function withdraw(address paymentID, uint8 v, bytes32 r, bytes32 s) external returns (bool);

  function revoke(address paymentID) external returns (bool);

  function getReceivedPaymentIds(bytes32 identifier) external view returns (address[] memory);

  function getSentPaymentIds(address sender) external view returns (address[] memory);
}

contract Initializable {
  bool public initialized;

  modifier initializer() {
    require(!initialized, "contract already initialized");
    initialized = true;
    _;
  }
}

interface IAccounts {
  function isAccount(address) external view returns (bool);
  function voteSignerToAccount(address) external view returns (address);
  function validatorSignerToAccount(address) external view returns (address);
  function attestationSignerToAccount(address) external view returns (address);
  function signerToAccount(address) external view returns (address);
  function getAttestationSigner(address) external view returns (address);
  function getValidatorSigner(address) external view returns (address);
  function getVoteSigner(address) external view returns (address);
  function hasAuthorizedVoteSigner(address) external view returns (bool);
  function hasAuthorizedValidatorSigner(address) external view returns (bool);
  function hasAuthorizedAttestationSigner(address) external view returns (bool);

  function setAccountDataEncryptionKey(bytes calldata) external;
  function setMetadataURL(string calldata) external;
  function setName(string calldata) external;
  function setWalletAddress(address, uint8, bytes32, bytes32) external;
  function setAccount(string calldata, bytes calldata, address, uint8, bytes32, bytes32) external;

  function getDataEncryptionKey(address) external view returns (bytes memory);
  function getWalletAddress(address) external view returns (address);
  function getMetadataURL(address) external view returns (string memory);
  function batchGetMetadataURL(address[] calldata)
    external
    view
    returns (uint256[] memory, bytes memory);
  function getName(address) external view returns (string memory);

  function authorizeVoteSigner(address, uint8, bytes32, bytes32) external;
  function authorizeValidatorSigner(address, uint8, bytes32, bytes32) external;
  function authorizeValidatorSignerWithPublicKey(address, uint8, bytes32, bytes32, bytes calldata)
    external;
  function authorizeValidatorSignerWithKeys(
    address,
    uint8,
    bytes32,
    bytes32,
    bytes calldata,
    bytes calldata,
    bytes calldata
  ) external;
  function authorizeAttestationSigner(address, uint8, bytes32, bytes32) external;
  function createAccount() external returns (bool);
}

interface IFeeCurrencyWhitelist {
  function addToken(address) external;
  function getWhitelist() external view returns (address[] memory);
}

interface IFreezer {
  function isFrozen(address) external view returns (bool);
}

interface IRegistry {
  function setAddressFor(string calldata, address) external;
  function getAddressForOrDie(bytes32) external view returns (address);
  function getAddressFor(bytes32) external view returns (address);
  function isOneOf(bytes32[] calldata, address) external view returns (bool);
}

interface IElection {
  function getTotalVotes() external view returns (uint256);
  function getActiveVotes() external view returns (uint256);
  function getTotalVotesByAccount(address) external view returns (uint256);
  function markGroupIneligible(address) external;
  function markGroupEligible(address, address, address) external;
  function electValidatorSigners() external view returns (address[] memory);
  function vote(address, uint256, address, address) external returns (bool);
  function activate(address) external returns (bool);
  function revokeActive(address, uint256, address, address, uint256) external returns (bool);
  function revokeAllActive(address, address, address, uint256) external returns (bool);
  function revokePending(address, uint256, address, address, uint256) external returns (bool);
  function forceDecrementVotes(
    address,
    uint256,
    address[] calldata,
    address[] calldata,
    uint256[] calldata
  ) external returns (uint256);
}

interface IGovernance {
  function isVoting(address) external view returns (bool);
}

interface ILockedGold {
  function incrementNonvotingAccountBalance(address, uint256) external;
  function decrementNonvotingAccountBalance(address, uint256) external;
  function getAccountTotalLockedGold(address) external view returns (uint256);
  function getTotalLockedGold() external view returns (uint256);
  function getPendingWithdrawals(address)
    external
    view
    returns (uint256[] memory, uint256[] memory);
  function getTotalPendingWithdrawals(address) external view returns (uint256);
  function lock() external payable;
  function unlock(uint256) external;
  function relock(uint256, uint256) external;
  function withdraw(uint256) external;
  function slash(
    address account,
    uint256 penalty,
    address reporter,
    uint256 reward,
    address[] calldata lessers,
    address[] calldata greaters,
    uint256[] calldata indices
  ) external;
  function isSlasher(address) external view returns (bool);
}

interface IValidators {
  function getAccountLockedGoldRequirement(address) external view returns (uint256);
  function meetsAccountLockedGoldRequirements(address) external view returns (bool);
  function getGroupNumMembers(address) external view returns (uint256);
  function getGroupsNumMembers(address[] calldata) external view returns (uint256[] memory);
  function getNumRegisteredValidators() external view returns (uint256);
  function getTopGroupValidators(address, uint256) external view returns (address[] memory);
  function updateEcdsaPublicKey(address, address, bytes calldata) external returns (bool);
  function updatePublicKeys(address, address, bytes calldata, bytes calldata, bytes calldata)
    external
    returns (bool);
  function isValidator(address) external view returns (bool);
  function isValidatorGroup(address) external view returns (bool);
  function calculateGroupEpochScore(uint256[] calldata uptimes) external view returns (uint256);
  function groupMembershipInEpoch(address account, uint256 epochNumber, uint256 index)
    external
    view
    returns (address);
  function halveSlashingMultiplier(address group) external;
  function forceDeaffiliateIfValidator(address validator) external;
  function getValidatorGroupSlashingMultiplier(address) external view returns (uint256);
  function affiliate(address group) external returns (bool);
}

interface IRandom {
  function revealAndCommit(bytes32, bytes32, address) external;
  function randomnessBlockRetentionWindow() external view returns (uint256);
  function random() external view returns (bytes32);
  function getBlockRandomness(uint256) external view returns (bytes32);
}

interface IExchange {
  function exchange(uint256, uint256, bool) external returns (uint256);
  function setUpdateFrequency(uint256) external;
  function getBuyTokenAmount(uint256, bool) external view returns (uint256);
  function getSellTokenAmount(uint256, bool) external view returns (uint256);
  function getBuyAndSellBuckets(bool) external view returns (uint256, uint256);
}

interface IReserve {
  function setTobinTaxStalenessThreshold(uint256) external;
  function addToken(address) external returns (bool);
  function removeToken(address, uint256) external returns (bool);
  function transferGold(address payable, uint256) external returns (bool);
  function transferExchangeGold(address payable, uint256) external returns (bool);
  function getReserveGoldBalance() external view returns (uint256);
  function getUnfrozenReserveGoldBalance() external view returns (uint256);
  function getOrComputeTobinTax() external returns (uint256, uint256);
  function getTokens() external view returns (address[] memory);
  function getReserveRatio() external view returns (uint256);
}

interface ISortedOracles {
  function addOracle(address, address) external;
  function removeOracle(address, address, uint256) external;
  function report(address, uint256, address, address) external;
  function removeExpiredReports(address, uint256) external;
  function isOldestReportExpired(address token) external view returns (bool, address);
  function numRates(address) external view returns (uint256);
  function medianRate(address) external view returns (uint256, uint256);
  function numTimestamps(address) external view returns (uint256);
  function medianTimestamp(address) external view returns (uint256);
}

interface IStableToken {
  function mint(address, uint256) external returns (bool);
  function burn(uint256) external returns (bool);
  function setInflationParameters(uint256, uint256) external;
  function valueToUnits(uint256) external view returns (uint256);
  function unitsToValue(uint256) external view returns (uint256);
  function getInflationParameters() external view returns (uint256, uint256, uint256, uint256);

  
  function balanceOf(address) external view returns (uint256);
}

contract UsingRegistry is Ownable {
  event RegistrySet(address indexed registryAddress);

  
  bytes32 constant ACCOUNTS_REGISTRY_ID = keccak256(abi.encodePacked("Accounts"));
  bytes32 constant ATTESTATIONS_REGISTRY_ID = keccak256(abi.encodePacked("Attestations"));
  bytes32 constant DOWNTIME_SLASHER_REGISTRY_ID = keccak256(abi.encodePacked("DowntimeSlasher"));
  bytes32 constant DOUBLE_SIGNING_SLASHER_REGISTRY_ID = keccak256(
    abi.encodePacked("DoubleSigningSlasher")
  );
  bytes32 constant ELECTION_REGISTRY_ID = keccak256(abi.encodePacked("Election"));
  bytes32 constant EXCHANGE_REGISTRY_ID = keccak256(abi.encodePacked("Exchange"));
  bytes32 constant FEE_CURRENCY_WHITELIST_REGISTRY_ID = keccak256(
    abi.encodePacked("FeeCurrencyWhitelist")
  );
  bytes32 constant FREEZER_REGISTRY_ID = keccak256(abi.encodePacked("Freezer"));
  bytes32 constant GOLD_TOKEN_REGISTRY_ID = keccak256(abi.encodePacked("GoldToken"));
  bytes32 constant GOVERNANCE_REGISTRY_ID = keccak256(abi.encodePacked("Governance"));
  bytes32 constant GOVERNANCE_SLASHER_REGISTRY_ID = keccak256(
    abi.encodePacked("GovernanceSlasher")
  );
  bytes32 constant LOCKED_GOLD_REGISTRY_ID = keccak256(abi.encodePacked("LockedGold"));
  bytes32 constant RESERVE_REGISTRY_ID = keccak256(abi.encodePacked("Reserve"));
  bytes32 constant RANDOM_REGISTRY_ID = keccak256(abi.encodePacked("Random"));
  bytes32 constant SORTED_ORACLES_REGISTRY_ID = keccak256(abi.encodePacked("SortedOracles"));
  bytes32 constant STABLE_TOKEN_REGISTRY_ID = keccak256(abi.encodePacked("StableToken"));
  bytes32 constant VALIDATORS_REGISTRY_ID = keccak256(abi.encodePacked("Validators"));
  

  IRegistry public registry;

  modifier onlyRegisteredContract(bytes32 identifierHash) {
    require(registry.getAddressForOrDie(identifierHash) == msg.sender, "only registered contract");
    _;
  }

  modifier onlyRegisteredContracts(bytes32[] memory identifierHashes) {
    require(registry.isOneOf(identifierHashes, msg.sender), "only registered contracts");
    _;
  }

  
  function setRegistry(address registryAddress) public onlyOwner {
    require(registryAddress != address(0), "Cannot register the null address");
    registry = IRegistry(registryAddress);
    emit RegistrySet(registryAddress);
  }

  function getAccounts() internal view returns (IAccounts) {
    return IAccounts(registry.getAddressForOrDie(ACCOUNTS_REGISTRY_ID));
  }

  function getAttestations() internal view returns (IAttestations) {
    return IAttestations(registry.getAddressForOrDie(ATTESTATIONS_REGISTRY_ID));
  }

  function getElection() internal view returns (IElection) {
    return IElection(registry.getAddressForOrDie(ELECTION_REGISTRY_ID));
  }

  function getExchange() internal view returns (IExchange) {
    return IExchange(registry.getAddressForOrDie(EXCHANGE_REGISTRY_ID));
  }

  function getFeeCurrencyWhitelistRegistry() internal view returns (IFeeCurrencyWhitelist) {
    return IFeeCurrencyWhitelist(registry.getAddressForOrDie(FEE_CURRENCY_WHITELIST_REGISTRY_ID));
  }

  function getFreezer() internal view returns (IFreezer) {
    return IFreezer(registry.getAddressForOrDie(FREEZER_REGISTRY_ID));
  }

  function getGoldToken() internal view returns (IERC20) {
    return IERC20(registry.getAddressForOrDie(GOLD_TOKEN_REGISTRY_ID));
  }

  function getGovernance() internal view returns (IGovernance) {
    return IGovernance(registry.getAddressForOrDie(GOVERNANCE_REGISTRY_ID));
  }

  function getLockedGold() internal view returns (ILockedGold) {
    return ILockedGold(registry.getAddressForOrDie(LOCKED_GOLD_REGISTRY_ID));
  }

  function getRandom() internal view returns (IRandom) {
    return IRandom(registry.getAddressForOrDie(RANDOM_REGISTRY_ID));
  }

  function getReserve() internal view returns (IReserve) {
    return IReserve(registry.getAddressForOrDie(RESERVE_REGISTRY_ID));
  }

  function getSortedOracles() internal view returns (ISortedOracles) {
    return ISortedOracles(registry.getAddressForOrDie(SORTED_ORACLES_REGISTRY_ID));
  }

  function getStableToken() internal view returns (IStableToken) {
    return IStableToken(registry.getAddressForOrDie(STABLE_TOKEN_REGISTRY_ID));
  }

  function getValidators() internal view returns (IValidators) {
    return IValidators(registry.getAddressForOrDie(VALIDATORS_REGISTRY_ID));
  }
}

library ECDSA {
    
    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
        
        if (signature.length != 65) {
            return (address(0));
        }

        
        bytes32 r;
        bytes32 s;
        uint8 v;

        
        
        
        assembly {
            r := mload(add(signature, 0x20))
            s := mload(add(signature, 0x40))
            v := byte(0, mload(add(signature, 0x60)))
        }

        
        
        
        
        
        
        
        
        
        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
            return address(0);
        }

        if (v != 27 && v != 28) {
            return address(0);
        }

        
        return ecrecover(hash, v, r, s);
    }

    
    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
        
        
        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
    }
}

library Signatures {
  
  function getSignerOfAddress(address message, uint8 v, bytes32 r, bytes32 s)
    public
    pure
    returns (address)
  {
    bytes32 hash = keccak256(abi.encodePacked(message));
    return getSignerOfMessageHash(hash, v, r, s);
  }

  
  function getSignerOfMessageHash(bytes32 messageHash, uint8 v, bytes32 r, bytes32 s)
    public
    pure
    returns (address)
  {
    bytes memory signature = new bytes(65);
    
    assembly {
      mstore(add(signature, 32), r)
      mstore(add(signature, 64), s)
      mstore8(add(signature, 96), v)
    }
    bytes32 prefixedHash = ECDSA.toEthSignedMessageHash(messageHash);
    return ECDSA.recover(prefixedHash, signature);
  }
}

contract ReentrancyGuard {
  
  uint256 private _guardCounter;

  constructor() internal {
    
    
    _guardCounter = 1;
  }

  
  modifier nonReentrant() {
    _guardCounter += 1;
    uint256 localCounter = _guardCounter;
    _;
    require(localCounter == _guardCounter, "reentrant call");
  }
}

contract Escrow is IEscrow, ReentrancyGuard, Ownable, Initializable, UsingRegistry {
  using SafeMath for uint256;

  event Transfer(
    address indexed from,
    bytes32 indexed identifier,
    address indexed token,
    uint256 value,
    address paymentId,
    uint256 minAttestations
  );

  event Withdrawal(
    bytes32 indexed identifier,
    address indexed to,
    address indexed token,
    uint256 value,
    address paymentId
  );

  event Revocation(
    bytes32 indexed identifier,
    address indexed by,
    address indexed token,
    uint256 value,
    address paymentId
  );

  struct EscrowedPayment {
    bytes32 recipientIdentifier;
    address sender;
    address token;
    uint256 value;
    uint256 sentIndex; 
    uint256 receivedIndex; 
    uint256 timestamp;
    uint256 expirySeconds;
    uint256 minAttestations;
  }

  
  
  mapping(address => EscrowedPayment) public escrowedPayments;

  
  mapping(bytes32 => address[]) public receivedPaymentIds;

  
  mapping(address => address[]) public sentPaymentIds;

  
  function initialize(address registryAddress) external initializer {
    _transferOwnership(msg.sender);
    setRegistry(registryAddress);
  }

  
  
  function transfer(
    bytes32 identifier,
    address token,
    uint256 value,
    uint256 expirySeconds,
    address paymentId,
    uint256 minAttestations
  ) external nonReentrant returns (bool) {
    require(token != address(0) && value > 0 && expirySeconds > 0, "Invalid transfer inputs.");
    require(
      !(identifier.length <= 0 && !(minAttestations == 0)),
      "Invalid privacy inputs: Can't require attestations if no identifier"
    );

    IAttestations attestations = IAttestations(registry.getAddressFor(ATTESTATIONS_REGISTRY_ID));
    require(
      minAttestations <= attestations.getMaxAttestations(),
      "minAttestations larger than limit"
    );

    uint256 sentIndex = sentPaymentIds[msg.sender].push(paymentId).sub(1);
    uint256 receivedIndex = receivedPaymentIds[identifier].push(paymentId).sub(1);

    EscrowedPayment storage newPayment = escrowedPayments[paymentId];
    require(newPayment.timestamp == 0, "paymentId already used");
    newPayment.recipientIdentifier = identifier;
    newPayment.sender = msg.sender;
    newPayment.token = token;
    newPayment.value = value;
    newPayment.sentIndex = sentIndex;
    newPayment.receivedIndex = receivedIndex;
    
    newPayment.timestamp = now;
    newPayment.expirySeconds = expirySeconds;
    newPayment.minAttestations = minAttestations;

    require(ERC20(token).transferFrom(msg.sender, address(this), value), "Transfer unsuccessful.");
    emit Transfer(msg.sender, identifier, token, value, paymentId, minAttestations);
    return true;
  }

  
  function withdraw(address paymentId, uint8 v, bytes32 r, bytes32 s)
    external
    nonReentrant
    returns (bool)
  {
    address signer = Signatures.getSignerOfAddress(msg.sender, v, r, s);
    require(signer == paymentId, "Failed to prove ownership of the withdraw key");
    EscrowedPayment memory payment = escrowedPayments[paymentId];
    require(payment.token != address(0) && payment.value > 0, "Invalid withdraw value.");

    if (payment.recipientIdentifier.length > 0) {
      IAttestations attestations = IAttestations(registry.getAddressFor(ATTESTATIONS_REGISTRY_ID));
      (uint64 completedAttestations, ) = attestations.getAttestationStats(
        payment.recipientIdentifier,
        msg.sender
      );
      require(
        uint256(completedAttestations) >= payment.minAttestations,
        "This account does not have enough attestations to withdraw this payment."
      );
    }

    deletePayment(paymentId);

    require(ERC20(payment.token).transfer(msg.sender, payment.value), "Transfer not successful.");

    emit Withdrawal(
      payment.recipientIdentifier,
      payment.sender,
      payment.token,
      payment.value,
      paymentId
    );

    return true;
  }

  
  function revoke(address paymentId) external nonReentrant returns (bool) {
    EscrowedPayment memory payment = escrowedPayments[paymentId];
    require(payment.sender == msg.sender, "Only sender of payment can attempt to revoke payment.");
    require(
      
      now >= (payment.timestamp.add(payment.expirySeconds)),
      "Transaction not redeemable for sender yet."
    );

    deletePayment(paymentId);

    require(ERC20(payment.token).transfer(msg.sender, payment.value), "Transfer not successful.");

    emit Revocation(
      payment.recipientIdentifier,
      payment.sender,
      payment.token,
      payment.value,
      paymentId
    );

    return true;

  }

  
  function getReceivedPaymentIds(bytes32 identifier) external view returns (address[] memory) {
    return receivedPaymentIds[identifier];
  }

  
  function getSentPaymentIds(address sender) external view returns (address[] memory) {
    return sentPaymentIds[sender];
  }

  
  function deletePayment(address paymentId) private {
    EscrowedPayment storage payment = escrowedPayments[paymentId];
    address[] storage received = receivedPaymentIds[payment.recipientIdentifier];
    address[] storage sent = sentPaymentIds[payment.sender];

    escrowedPayments[received[received.length - 1]].receivedIndex = payment.receivedIndex;
    received[payment.receivedIndex] = received[received.length - 1];
    received.length = received.length.sub(1);

    escrowedPayments[sent[sent.length - 1]].sentIndex = payment.sentIndex;
    sent[payment.sentIndex] = sent[sent.length - 1];
    sent.length = sent.length.sub(1);

    delete escrowedPayments[paymentId];
  }
}