ETH Price: $3,139.24 (+3.36%)
Gas: 4 Gwei

Transaction Decoder

Block:
16542857 at Feb-02-2023 06:18:59 PM +UTC
Transaction Fee:
0.003424432514195175 ETH $10.75
Gas Used:
48,525 Gas / 70.570479427 Gwei

Emitted Events:

133 FiatTokenProxy.0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef( 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef, 0x0000000000000000000000002db1d8cdf1abe8c70b531a790cdf2ff38aecf652, 0x00000000000000000000000050bf638886db4c82a04cd87c5ff0746027bde50e, 0000000000000000000000000000000000000000000000000000000031d818ca )

Account State Difference:

  Address   Before After State Difference Code
0x2Db1D8Cd...38aecF652
(Newton)
340.289893215062798707 Eth
Nonce: 162079
340.286468782548603532 Eth
Nonce: 162080
0.003424432514195175
(beaverbuild)
85.304588960222432259 Eth85.304661796247432259 Eth0.000072836025
0xA0b86991...E3606eB48

Execution Trace

FiatTokenProxy.a9059cbb( )
  • FiatTokenV2_1.transfer( to=0x50bf638886DB4C82A04Cd87c5FF0746027bde50E, value=836245706 ) => ( True )
    File 1 of 2: FiatTokenProxy
    pragma solidity ^0.4.24;
    
    // File: zos-lib/contracts/upgradeability/Proxy.sol
    
    /**
     * @title Proxy
     * @dev Implements delegation of calls to other contracts, with proper
     * forwarding of return values and bubbling of failures.
     * It defines a fallback function that delegates all calls to the address
     * returned by the abstract _implementation() internal function.
     */
    contract Proxy {
      /**
       * @dev Fallback function.
       * Implemented entirely in `_fallback`.
       */
      function () payable external {
        _fallback();
      }
    
      /**
       * @return The Address of the implementation.
       */
      function _implementation() internal view returns (address);
    
      /**
       * @dev Delegates execution to an implementation contract.
       * This is a low level function that doesn't return to its internal call site.
       * It will return to the external caller whatever the implementation returns.
       * @param implementation Address to delegate.
       */
      function _delegate(address implementation) internal {
        assembly {
          // Copy msg.data. We take full control of memory in this inline assembly
          // block because it will not return to Solidity code. We overwrite the
          // Solidity scratch pad at memory position 0.
          calldatacopy(0, 0, calldatasize)
    
          // Call the implementation.
          // out and outsize are 0 because we don't know the size yet.
          let result := delegatecall(gas, implementation, 0, calldatasize, 0, 0)
    
          // Copy the returned data.
          returndatacopy(0, 0, returndatasize)
    
          switch result
          // delegatecall returns 0 on error.
          case 0 { revert(0, returndatasize) }
          default { return(0, returndatasize) }
        }
      }
    
      /**
       * @dev Function that is run as the first thing in the fallback function.
       * Can be redefined in derived contracts to add functionality.
       * Redefinitions must call super._willFallback().
       */
      function _willFallback() internal {
      }
    
      /**
       * @dev fallback implementation.
       * Extracted to enable manual triggering.
       */
      function _fallback() internal {
        _willFallback();
        _delegate(_implementation());
      }
    }
    
    // File: openzeppelin-solidity/contracts/AddressUtils.sol
    
    /**
     * Utility library of inline functions on addresses
     */
    library AddressUtils {
    
      /**
       * Returns whether the target address is a contract
       * @dev This function will return false if invoked during the constructor of a contract,
       * as the code is not actually created until after the constructor finishes.
       * @param addr address to check
       * @return whether the target address is a contract
       */
      function isContract(address addr) internal view returns (bool) {
        uint256 size;
        // XXX Currently there is no better way to check if there is a contract in an address
        // than to check the size of the code at that address.
        // See https://ethereum.stackexchange.com/a/14016/36603
        // for more details about how this works.
        // TODO Check this again before the Serenity release, because all addresses will be
        // contracts then.
        // solium-disable-next-line security/no-inline-assembly
        assembly { size := extcodesize(addr) }
        return size > 0;
      }
    
    }
    
    // File: zos-lib/contracts/upgradeability/UpgradeabilityProxy.sol
    
    /**
     * @title UpgradeabilityProxy
     * @dev This contract implements a proxy that allows to change the
     * implementation address to which it will delegate.
     * Such a change is called an implementation upgrade.
     */
    contract UpgradeabilityProxy is Proxy {
      /**
       * @dev Emitted when the implementation is upgraded.
       * @param implementation Address of the new implementation.
       */
      event Upgraded(address implementation);
    
      /**
       * @dev Storage slot with the address of the current implementation.
       * This is the keccak-256 hash of "org.zeppelinos.proxy.implementation", and is
       * validated in the constructor.
       */
      bytes32 private constant IMPLEMENTATION_SLOT = 0x7050c9e0f4ca769c69bd3a8ef740bc37934f8e2c036e5a723fd8ee048ed3f8c3;
    
      /**
       * @dev Contract constructor.
       * @param _implementation Address of the initial implementation.
       */
      constructor(address _implementation) public {
        assert(IMPLEMENTATION_SLOT == keccak256("org.zeppelinos.proxy.implementation"));
    
        _setImplementation(_implementation);
      }
    
      /**
       * @dev Returns the current implementation.
       * @return Address of the current implementation
       */
      function _implementation() internal view returns (address impl) {
        bytes32 slot = IMPLEMENTATION_SLOT;
        assembly {
          impl := sload(slot)
        }
      }
    
      /**
       * @dev Upgrades the proxy to a new implementation.
       * @param newImplementation Address of the new implementation.
       */
      function _upgradeTo(address newImplementation) internal {
        _setImplementation(newImplementation);
        emit Upgraded(newImplementation);
      }
    
      /**
       * @dev Sets the implementation address of the proxy.
       * @param newImplementation Address of the new implementation.
       */
      function _setImplementation(address newImplementation) private {
        require(AddressUtils.isContract(newImplementation), "Cannot set a proxy implementation to a non-contract address");
    
        bytes32 slot = IMPLEMENTATION_SLOT;
    
        assembly {
          sstore(slot, newImplementation)
        }
      }
    }
    
    // File: zos-lib/contracts/upgradeability/AdminUpgradeabilityProxy.sol
    
    /**
     * @title AdminUpgradeabilityProxy
     * @dev This contract combines an upgradeability proxy with an authorization
     * mechanism for administrative tasks.
     * All external functions in this contract must be guarded by the
     * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
     * feature proposal that would enable this to be done automatically.
     */
    contract AdminUpgradeabilityProxy is UpgradeabilityProxy {
      /**
       * @dev Emitted when the administration has been transferred.
       * @param previousAdmin Address of the previous admin.
       * @param newAdmin Address of the new admin.
       */
      event AdminChanged(address previousAdmin, address newAdmin);
    
      /**
       * @dev Storage slot with the admin of the contract.
       * This is the keccak-256 hash of "org.zeppelinos.proxy.admin", and is
       * validated in the constructor.
       */
      bytes32 private constant ADMIN_SLOT = 0x10d6a54a4754c8869d6886b5f5d7fbfa5b4522237ea5c60d11bc4e7a1ff9390b;
    
      /**
       * @dev Modifier to check whether the `msg.sender` is the admin.
       * If it is, it will run the function. Otherwise, it will delegate the call
       * to the implementation.
       */
      modifier ifAdmin() {
        if (msg.sender == _admin()) {
          _;
        } else {
          _fallback();
        }
      }
    
      /**
       * Contract constructor.
       * It sets the `msg.sender` as the proxy administrator.
       * @param _implementation address of the initial implementation.
       */
      constructor(address _implementation) UpgradeabilityProxy(_implementation) public {
        assert(ADMIN_SLOT == keccak256("org.zeppelinos.proxy.admin"));
    
        _setAdmin(msg.sender);
      }
    
      /**
       * @return The address of the proxy admin.
       */
      function admin() external view ifAdmin returns (address) {
        return _admin();
      }
    
      /**
       * @return The address of the implementation.
       */
      function implementation() external view ifAdmin returns (address) {
        return _implementation();
      }
    
      /**
       * @dev Changes the admin of the proxy.
       * Only the current admin can call this function.
       * @param newAdmin Address to transfer proxy administration to.
       */
      function changeAdmin(address newAdmin) external ifAdmin {
        require(newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");
        emit AdminChanged(_admin(), newAdmin);
        _setAdmin(newAdmin);
      }
    
      /**
       * @dev Upgrade the backing implementation of the proxy.
       * Only the admin can call this function.
       * @param newImplementation Address of the new implementation.
       */
      function upgradeTo(address newImplementation) external ifAdmin {
        _upgradeTo(newImplementation);
      }
    
      /**
       * @dev Upgrade the backing implementation of the proxy and call a function
       * on the new implementation.
       * This is useful to initialize the proxied contract.
       * @param newImplementation Address of the new implementation.
       * @param data Data to send as msg.data in the low level call.
       * It should include the signature and the parameters of the function to be
       * called, as described in
       * https://solidity.readthedocs.io/en/develop/abi-spec.html#function-selector-and-argument-encoding.
       */
      function upgradeToAndCall(address newImplementation, bytes data) payable external ifAdmin {
        _upgradeTo(newImplementation);
        require(address(this).call.value(msg.value)(data));
      }
    
      /**
       * @return The admin slot.
       */
      function _admin() internal view returns (address adm) {
        bytes32 slot = ADMIN_SLOT;
        assembly {
          adm := sload(slot)
        }
      }
    
      /**
       * @dev Sets the address of the proxy admin.
       * @param newAdmin Address of the new proxy admin.
       */
      function _setAdmin(address newAdmin) internal {
        bytes32 slot = ADMIN_SLOT;
    
        assembly {
          sstore(slot, newAdmin)
        }
      }
    
      /**
       * @dev Only fall back when the sender is not the admin.
       */
      function _willFallback() internal {
        require(msg.sender != _admin(), "Cannot call fallback function from the proxy admin");
        super._willFallback();
      }
    }
    
    // File: contracts/FiatTokenProxy.sol
    
    /**
    * Copyright CENTRE SECZ 2018
    *
    * Permission is hereby granted, free of charge, to any person obtaining a copy 
    * of this software and associated documentation files (the "Software"), to deal 
    * in the Software without restriction, including without limitation the rights 
    * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
    * copies of the Software, and to permit persons to whom the Software is furnished to 
    * do so, subject to the following conditions:
    *
    * The above copyright notice and this permission notice shall be included in all 
    * copies or substantial portions of the Software.
    *
    * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
    * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
    * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
    * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
    * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
    * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    */
    
    pragma solidity ^0.4.24;
    
    
    /**
     * @title FiatTokenProxy
     * @dev This contract proxies FiatToken calls and enables FiatToken upgrades
    */ 
    contract FiatTokenProxy is AdminUpgradeabilityProxy {
        constructor(address _implementation) public AdminUpgradeabilityProxy(_implementation) {
        }
    }

    File 2 of 2: FiatTokenV2_1
    // File: @openzeppelin/contracts/math/SafeMath.sol
    
    // SPDX-License-Identifier: MIT
    
    pragma solidity ^0.6.0;
    
    /**
     * @dev Wrappers over Solidity's arithmetic operations with added overflow
     * checks.
     *
     * Arithmetic operations in Solidity wrap on overflow. This can easily result
     * in bugs, because programmers usually assume that an overflow raises an
     * error, which is the standard behavior in high level programming languages.
     * `SafeMath` restores this intuition by reverting the transaction when an
     * operation overflows.
     *
     * Using this library instead of the unchecked operations eliminates an entire
     * class of bugs, so it's recommended to use it always.
     */
    library SafeMath {
        /**
         * @dev Returns the addition of two unsigned integers, reverting on
         * overflow.
         *
         * Counterpart to Solidity's `+` operator.
         *
         * Requirements:
         *
         * - Addition cannot overflow.
         */
        function add(uint256 a, uint256 b) internal pure returns (uint256) {
            uint256 c = a + b;
            require(c >= a, "SafeMath: addition overflow");
    
            return c;
        }
    
        /**
         * @dev Returns the subtraction of two unsigned integers, reverting on
         * overflow (when the result is negative).
         *
         * Counterpart to Solidity's `-` operator.
         *
         * Requirements:
         *
         * - Subtraction cannot overflow.
         */
        function sub(uint256 a, uint256 b) internal pure returns (uint256) {
            return sub(a, b, "SafeMath: subtraction overflow");
        }
    
        /**
         * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
         * overflow (when the result is negative).
         *
         * Counterpart to Solidity's `-` operator.
         *
         * Requirements:
         *
         * - Subtraction cannot overflow.
         */
        function sub(
            uint256 a,
            uint256 b,
            string memory errorMessage
        ) internal pure returns (uint256) {
            require(b <= a, errorMessage);
            uint256 c = a - b;
    
            return c;
        }
    
        /**
         * @dev Returns the multiplication of two unsigned integers, reverting on
         * overflow.
         *
         * Counterpart to Solidity's `*` operator.
         *
         * Requirements:
         *
         * - Multiplication cannot overflow.
         */
        function mul(uint256 a, uint256 b) internal pure returns (uint256) {
            // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
            // benefit is lost if 'b' is also tested.
            // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
            if (a == 0) {
                return 0;
            }
    
            uint256 c = a * b;
            require(c / a == b, "SafeMath: multiplication overflow");
    
            return c;
        }
    
        /**
         * @dev Returns the integer division of two unsigned integers. Reverts on
         * division by zero. The result is rounded towards zero.
         *
         * Counterpart to Solidity's `/` operator. Note: this function uses a
         * `revert` opcode (which leaves remaining gas untouched) while Solidity
         * uses an invalid opcode to revert (consuming all remaining gas).
         *
         * Requirements:
         *
         * - The divisor cannot be zero.
         */
        function div(uint256 a, uint256 b) internal pure returns (uint256) {
            return div(a, b, "SafeMath: division by zero");
        }
    
        /**
         * @dev Returns the integer division of two unsigned integers. Reverts with custom message on
         * division by zero. The result is rounded towards zero.
         *
         * Counterpart to Solidity's `/` operator. Note: this function uses a
         * `revert` opcode (which leaves remaining gas untouched) while Solidity
         * uses an invalid opcode to revert (consuming all remaining gas).
         *
         * Requirements:
         *
         * - The divisor cannot be zero.
         */
        function div(
            uint256 a,
            uint256 b,
            string memory errorMessage
        ) internal pure returns (uint256) {
            require(b > 0, errorMessage);
            uint256 c = a / b;
            // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    
            return c;
        }
    
        /**
         * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
         * Reverts when dividing by zero.
         *
         * Counterpart to Solidity's `%` operator. This function uses a `revert`
         * opcode (which leaves remaining gas untouched) while Solidity uses an
         * invalid opcode to revert (consuming all remaining gas).
         *
         * Requirements:
         *
         * - The divisor cannot be zero.
         */
        function mod(uint256 a, uint256 b) internal pure returns (uint256) {
            return mod(a, b, "SafeMath: modulo by zero");
        }
    
        /**
         * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
         * Reverts with custom message when dividing by zero.
         *
         * Counterpart to Solidity's `%` operator. This function uses a `revert`
         * opcode (which leaves remaining gas untouched) while Solidity uses an
         * invalid opcode to revert (consuming all remaining gas).
         *
         * Requirements:
         *
         * - The divisor cannot be zero.
         */
        function mod(
            uint256 a,
            uint256 b,
            string memory errorMessage
        ) internal pure returns (uint256) {
            require(b != 0, errorMessage);
            return a % b;
        }
    }
    
    // File: @openzeppelin/contracts/token/ERC20/IERC20.sol
    
    pragma solidity ^0.6.0;
    
    /**
     * @dev Interface of the ERC20 standard as defined in the EIP.
     */
    interface IERC20 {
        /**
         * @dev Returns the amount of tokens in existence.
         */
        function totalSupply() external view returns (uint256);
    
        /**
         * @dev Returns the amount of tokens owned by `account`.
         */
        function balanceOf(address account) external view returns (uint256);
    
        /**
         * @dev Moves `amount` tokens from the caller's account to `recipient`.
         *
         * Returns a boolean value indicating whether the operation succeeded.
         *
         * Emits a {Transfer} event.
         */
        function transfer(address recipient, uint256 amount)
            external
            returns (bool);
    
        /**
         * @dev Returns the remaining number of tokens that `spender` will be
         * allowed to spend on behalf of `owner` through {transferFrom}. This is
         * zero by default.
         *
         * This value changes when {approve} or {transferFrom} are called.
         */
        function allowance(address owner, address spender)
            external
            view
            returns (uint256);
    
        /**
         * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
         *
         * Returns a boolean value indicating whether the operation succeeded.
         *
         * IMPORTANT: Beware that changing an allowance with this method brings the risk
         * that someone may use both the old and the new allowance by unfortunate
         * transaction ordering. One possible solution to mitigate this race
         * condition is to first reduce the spender's allowance to 0 and set the
         * desired value afterwards:
         * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
         *
         * Emits an {Approval} event.
         */
        function approve(address spender, uint256 amount) external returns (bool);
    
        /**
         * @dev Moves `amount` tokens from `sender` to `recipient` using the
         * allowance mechanism. `amount` is then deducted from the caller's
         * allowance.
         *
         * Returns a boolean value indicating whether the operation succeeded.
         *
         * Emits a {Transfer} event.
         */
        function transferFrom(
            address sender,
            address recipient,
            uint256 amount
        ) external returns (bool);
    
        /**
         * @dev Emitted when `value` tokens are moved from one account (`from`) to
         * another (`to`).
         *
         * Note that `value` may be zero.
         */
        event Transfer(address indexed from, address indexed to, uint256 value);
    
        /**
         * @dev Emitted when the allowance of a `spender` for an `owner` is set by
         * a call to {approve}. `value` is the new allowance.
         */
        event Approval(
            address indexed owner,
            address indexed spender,
            uint256 value
        );
    }
    
    // File: contracts/v1/AbstractFiatTokenV1.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    abstract contract AbstractFiatTokenV1 is IERC20 {
        function _approve(
            address owner,
            address spender,
            uint256 value
        ) internal virtual;
    
        function _transfer(
            address from,
            address to,
            uint256 value
        ) internal virtual;
    }
    
    // File: contracts/v1/Ownable.sol
    
    /**
     * Copyright (c) 2018 zOS Global Limited.
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    pragma solidity 0.6.12;
    
    /**
     * @notice The Ownable contract has an owner address, and provides basic
     * authorization control functions
     * @dev Forked from https://github.com/OpenZeppelin/openzeppelin-labs/blob/3887ab77b8adafba4a26ace002f3a684c1a3388b/upgradeability_ownership/contracts/ownership/Ownable.sol
     * Modifications:
     * 1. Consolidate OwnableStorage into this contract (7/13/18)
     * 2. Reformat, conform to Solidity 0.6 syntax, and add error messages (5/13/20)
     * 3. Make public functions external (5/27/20)
     */
    contract Ownable {
        // Owner of the contract
        address private _owner;
    
        /**
         * @dev Event to show ownership has been transferred
         * @param previousOwner representing the address of the previous owner
         * @param newOwner representing the address of the new owner
         */
        event OwnershipTransferred(address previousOwner, address newOwner);
    
        /**
         * @dev The constructor sets the original owner of the contract to the sender account.
         */
        constructor() public {
            setOwner(msg.sender);
        }
    
        /**
         * @dev Tells the address of the owner
         * @return the address of the owner
         */
        function owner() external view returns (address) {
            return _owner;
        }
    
        /**
         * @dev Sets a new owner address
         */
        function setOwner(address newOwner) internal {
            _owner = newOwner;
        }
    
        /**
         * @dev Throws if called by any account other than the owner.
         */
        modifier onlyOwner() {
            require(msg.sender == _owner, "Ownable: caller is not the owner");
            _;
        }
    
        /**
         * @dev Allows the current owner to transfer control of the contract to a newOwner.
         * @param newOwner The address to transfer ownership to.
         */
        function transferOwnership(address newOwner) external onlyOwner {
            require(
                newOwner != address(0),
                "Ownable: new owner is the zero address"
            );
            emit OwnershipTransferred(_owner, newOwner);
            setOwner(newOwner);
        }
    }
    
    // File: contracts/v1/Pausable.sol
    
    /**
     * Copyright (c) 2016 Smart Contract Solutions, Inc.
     * Copyright (c) 2018-2020 CENTRE SECZ0
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @notice Base contract which allows children to implement an emergency stop
     * mechanism
     * @dev Forked from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/feb665136c0dae9912e08397c1a21c4af3651ef3/contracts/lifecycle/Pausable.sol
     * Modifications:
     * 1. Added pauser role, switched pause/unpause to be onlyPauser (6/14/2018)
     * 2. Removed whenNotPause/whenPaused from pause/unpause (6/14/2018)
     * 3. Removed whenPaused (6/14/2018)
     * 4. Switches ownable library to use ZeppelinOS (7/12/18)
     * 5. Remove constructor (7/13/18)
     * 6. Reformat, conform to Solidity 0.6 syntax and add error messages (5/13/20)
     * 7. Make public functions external (5/27/20)
     */
    contract Pausable is Ownable {
        event Pause();
        event Unpause();
        event PauserChanged(address indexed newAddress);
    
        address public pauser;
        bool public paused = false;
    
        /**
         * @dev Modifier to make a function callable only when the contract is not paused.
         */
        modifier whenNotPaused() {
            require(!paused, "Pausable: paused");
            _;
        }
    
        /**
         * @dev throws if called by any account other than the pauser
         */
        modifier onlyPauser() {
            require(msg.sender == pauser, "Pausable: caller is not the pauser");
            _;
        }
    
        /**
         * @dev called by the owner to pause, triggers stopped state
         */
        function pause() external onlyPauser {
            paused = true;
            emit Pause();
        }
    
        /**
         * @dev called by the owner to unpause, returns to normal state
         */
        function unpause() external onlyPauser {
            paused = false;
            emit Unpause();
        }
    
        /**
         * @dev update the pauser role
         */
        function updatePauser(address _newPauser) external onlyOwner {
            require(
                _newPauser != address(0),
                "Pausable: new pauser is the zero address"
            );
            pauser = _newPauser;
            emit PauserChanged(pauser);
        }
    }
    
    // File: contracts/v1/Blacklistable.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @title Blacklistable Token
     * @dev Allows accounts to be blacklisted by a "blacklister" role
     */
    contract Blacklistable is Ownable {
        address public blacklister;
        mapping(address => bool) internal blacklisted;
    
        event Blacklisted(address indexed _account);
        event UnBlacklisted(address indexed _account);
        event BlacklisterChanged(address indexed newBlacklister);
    
        /**
         * @dev Throws if called by any account other than the blacklister
         */
        modifier onlyBlacklister() {
            require(
                msg.sender == blacklister,
                "Blacklistable: caller is not the blacklister"
            );
            _;
        }
    
        /**
         * @dev Throws if argument account is blacklisted
         * @param _account The address to check
         */
        modifier notBlacklisted(address _account) {
            require(
                !blacklisted[_account],
                "Blacklistable: account is blacklisted"
            );
            _;
        }
    
        /**
         * @dev Checks if account is blacklisted
         * @param _account The address to check
         */
        function isBlacklisted(address _account) external view returns (bool) {
            return blacklisted[_account];
        }
    
        /**
         * @dev Adds account to blacklist
         * @param _account The address to blacklist
         */
        function blacklist(address _account) external onlyBlacklister {
            blacklisted[_account] = true;
            emit Blacklisted(_account);
        }
    
        /**
         * @dev Removes account from blacklist
         * @param _account The address to remove from the blacklist
         */
        function unBlacklist(address _account) external onlyBlacklister {
            blacklisted[_account] = false;
            emit UnBlacklisted(_account);
        }
    
        function updateBlacklister(address _newBlacklister) external onlyOwner {
            require(
                _newBlacklister != address(0),
                "Blacklistable: new blacklister is the zero address"
            );
            blacklister = _newBlacklister;
            emit BlacklisterChanged(blacklister);
        }
    }
    
    // File: contracts/v1/FiatTokenV1.sol
    
    /**
     *
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @title FiatToken
     * @dev ERC20 Token backed by fiat reserves
     */
    contract FiatTokenV1 is AbstractFiatTokenV1, Ownable, Pausable, Blacklistable {
        using SafeMath for uint256;
    
        string public name;
        string public symbol;
        uint8 public decimals;
        string public currency;
        address public masterMinter;
        bool internal initialized;
    
        mapping(address => uint256) internal balances;
        mapping(address => mapping(address => uint256)) internal allowed;
        uint256 internal totalSupply_ = 0;
        mapping(address => bool) internal minters;
        mapping(address => uint256) internal minterAllowed;
    
        event Mint(address indexed minter, address indexed to, uint256 amount);
        event Burn(address indexed burner, uint256 amount);
        event MinterConfigured(address indexed minter, uint256 minterAllowedAmount);
        event MinterRemoved(address indexed oldMinter);
        event MasterMinterChanged(address indexed newMasterMinter);
    
        function initialize(
            string memory tokenName,
            string memory tokenSymbol,
            string memory tokenCurrency,
            uint8 tokenDecimals,
            address newMasterMinter,
            address newPauser,
            address newBlacklister,
            address newOwner
        ) public {
            require(!initialized, "FiatToken: contract is already initialized");
            require(
                newMasterMinter != address(0),
                "FiatToken: new masterMinter is the zero address"
            );
            require(
                newPauser != address(0),
                "FiatToken: new pauser is the zero address"
            );
            require(
                newBlacklister != address(0),
                "FiatToken: new blacklister is the zero address"
            );
            require(
                newOwner != address(0),
                "FiatToken: new owner is the zero address"
            );
    
            name = tokenName;
            symbol = tokenSymbol;
            currency = tokenCurrency;
            decimals = tokenDecimals;
            masterMinter = newMasterMinter;
            pauser = newPauser;
            blacklister = newBlacklister;
            setOwner(newOwner);
            initialized = true;
        }
    
        /**
         * @dev Throws if called by any account other than a minter
         */
        modifier onlyMinters() {
            require(minters[msg.sender], "FiatToken: caller is not a minter");
            _;
        }
    
        /**
         * @dev Function to mint tokens
         * @param _to The address that will receive the minted tokens.
         * @param _amount The amount of tokens to mint. Must be less than or equal
         * to the minterAllowance of the caller.
         * @return A boolean that indicates if the operation was successful.
         */
        function mint(address _to, uint256 _amount)
            external
            whenNotPaused
            onlyMinters
            notBlacklisted(msg.sender)
            notBlacklisted(_to)
            returns (bool)
        {
            require(_to != address(0), "FiatToken: mint to the zero address");
            require(_amount > 0, "FiatToken: mint amount not greater than 0");
    
            uint256 mintingAllowedAmount = minterAllowed[msg.sender];
            require(
                _amount <= mintingAllowedAmount,
                "FiatToken: mint amount exceeds minterAllowance"
            );
    
            totalSupply_ = totalSupply_.add(_amount);
            balances[_to] = balances[_to].add(_amount);
            minterAllowed[msg.sender] = mintingAllowedAmount.sub(_amount);
            emit Mint(msg.sender, _to, _amount);
            emit Transfer(address(0), _to, _amount);
            return true;
        }
    
        /**
         * @dev Throws if called by any account other than the masterMinter
         */
        modifier onlyMasterMinter() {
            require(
                msg.sender == masterMinter,
                "FiatToken: caller is not the masterMinter"
            );
            _;
        }
    
        /**
         * @dev Get minter allowance for an account
         * @param minter The address of the minter
         */
        function minterAllowance(address minter) external view returns (uint256) {
            return minterAllowed[minter];
        }
    
        /**
         * @dev Checks if account is a minter
         * @param account The address to check
         */
        function isMinter(address account) external view returns (bool) {
            return minters[account];
        }
    
        /**
         * @notice Amount of remaining tokens spender is allowed to transfer on
         * behalf of the token owner
         * @param owner     Token owner's address
         * @param spender   Spender's address
         * @return Allowance amount
         */
        function allowance(address owner, address spender)
            external
            override
            view
            returns (uint256)
        {
            return allowed[owner][spender];
        }
    
        /**
         * @dev Get totalSupply of token
         */
        function totalSupply() external override view returns (uint256) {
            return totalSupply_;
        }
    
        /**
         * @dev Get token balance of an account
         * @param account address The account
         */
        function balanceOf(address account)
            external
            override
            view
            returns (uint256)
        {
            return balances[account];
        }
    
        /**
         * @notice Set spender's allowance over the caller's tokens to be a given
         * value.
         * @param spender   Spender's address
         * @param value     Allowance amount
         * @return True if successful
         */
        function approve(address spender, uint256 value)
            external
            override
            whenNotPaused
            notBlacklisted(msg.sender)
            notBlacklisted(spender)
            returns (bool)
        {
            _approve(msg.sender, spender, value);
            return true;
        }
    
        /**
         * @dev Internal function to set allowance
         * @param owner     Token owner's address
         * @param spender   Spender's address
         * @param value     Allowance amount
         */
        function _approve(
            address owner,
            address spender,
            uint256 value
        ) internal override {
            require(owner != address(0), "ERC20: approve from the zero address");
            require(spender != address(0), "ERC20: approve to the zero address");
            allowed[owner][spender] = value;
            emit Approval(owner, spender, value);
        }
    
        /**
         * @notice Transfer tokens by spending allowance
         * @param from  Payer's address
         * @param to    Payee's address
         * @param value Transfer amount
         * @return True if successful
         */
        function transferFrom(
            address from,
            address to,
            uint256 value
        )
            external
            override
            whenNotPaused
            notBlacklisted(msg.sender)
            notBlacklisted(from)
            notBlacklisted(to)
            returns (bool)
        {
            require(
                value <= allowed[from][msg.sender],
                "ERC20: transfer amount exceeds allowance"
            );
            _transfer(from, to, value);
            allowed[from][msg.sender] = allowed[from][msg.sender].sub(value);
            return true;
        }
    
        /**
         * @notice Transfer tokens from the caller
         * @param to    Payee's address
         * @param value Transfer amount
         * @return True if successful
         */
        function transfer(address to, uint256 value)
            external
            override
            whenNotPaused
            notBlacklisted(msg.sender)
            notBlacklisted(to)
            returns (bool)
        {
            _transfer(msg.sender, to, value);
            return true;
        }
    
        /**
         * @notice Internal function to process transfers
         * @param from  Payer's address
         * @param to    Payee's address
         * @param value Transfer amount
         */
        function _transfer(
            address from,
            address to,
            uint256 value
        ) internal override {
            require(from != address(0), "ERC20: transfer from the zero address");
            require(to != address(0), "ERC20: transfer to the zero address");
            require(
                value <= balances[from],
                "ERC20: transfer amount exceeds balance"
            );
    
            balances[from] = balances[from].sub(value);
            balances[to] = balances[to].add(value);
            emit Transfer(from, to, value);
        }
    
        /**
         * @dev Function to add/update a new minter
         * @param minter The address of the minter
         * @param minterAllowedAmount The minting amount allowed for the minter
         * @return True if the operation was successful.
         */
        function configureMinter(address minter, uint256 minterAllowedAmount)
            external
            whenNotPaused
            onlyMasterMinter
            returns (bool)
        {
            minters[minter] = true;
            minterAllowed[minter] = minterAllowedAmount;
            emit MinterConfigured(minter, minterAllowedAmount);
            return true;
        }
    
        /**
         * @dev Function to remove a minter
         * @param minter The address of the minter to remove
         * @return True if the operation was successful.
         */
        function removeMinter(address minter)
            external
            onlyMasterMinter
            returns (bool)
        {
            minters[minter] = false;
            minterAllowed[minter] = 0;
            emit MinterRemoved(minter);
            return true;
        }
    
        /**
         * @dev allows a minter to burn some of its own tokens
         * Validates that caller is a minter and that sender is not blacklisted
         * amount is less than or equal to the minter's account balance
         * @param _amount uint256 the amount of tokens to be burned
         */
        function burn(uint256 _amount)
            external
            whenNotPaused
            onlyMinters
            notBlacklisted(msg.sender)
        {
            uint256 balance = balances[msg.sender];
            require(_amount > 0, "FiatToken: burn amount not greater than 0");
            require(balance >= _amount, "FiatToken: burn amount exceeds balance");
    
            totalSupply_ = totalSupply_.sub(_amount);
            balances[msg.sender] = balance.sub(_amount);
            emit Burn(msg.sender, _amount);
            emit Transfer(msg.sender, address(0), _amount);
        }
    
        function updateMasterMinter(address _newMasterMinter) external onlyOwner {
            require(
                _newMasterMinter != address(0),
                "FiatToken: new masterMinter is the zero address"
            );
            masterMinter = _newMasterMinter;
            emit MasterMinterChanged(masterMinter);
        }
    }
    
    // File: @openzeppelin/contracts/utils/Address.sol
    
    pragma solidity ^0.6.2;
    
    /**
     * @dev Collection of functions related to the address type
     */
    library Address {
        /**
         * @dev Returns true if `account` is a contract.
         *
         * [IMPORTANT]
         * ====
         * It is unsafe to assume that an address for which this function returns
         * false is an externally-owned account (EOA) and not a contract.
         *
         * Among others, `isContract` will return false for the following
         * types of addresses:
         *
         *  - an externally-owned account
         *  - a contract in construction
         *  - an address where a contract will be created
         *  - an address where a contract lived, but was destroyed
         * ====
         */
        function isContract(address account) internal view returns (bool) {
            // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
            // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
            // for accounts without code, i.e. `keccak256('')`
            bytes32 codehash;
    
                bytes32 accountHash
             = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
            // solhint-disable-next-line no-inline-assembly
            assembly {
                codehash := extcodehash(account)
            }
            return (codehash != accountHash && codehash != 0x0);
        }
    
        /**
         * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
         * `recipient`, forwarding all available gas and reverting on errors.
         *
         * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
         * of certain opcodes, possibly making contracts go over the 2300 gas limit
         * imposed by `transfer`, making them unable to receive funds via
         * `transfer`. {sendValue} removes this limitation.
         *
         * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
         *
         * IMPORTANT: because control is transferred to `recipient`, care must be
         * taken to not create reentrancy vulnerabilities. Consider using
         * {ReentrancyGuard} or the
         * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
         */
        function sendValue(address payable recipient, uint256 amount) internal {
            require(
                address(this).balance >= amount,
                "Address: insufficient balance"
            );
    
            // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
            (bool success, ) = recipient.call{ value: amount }("");
            require(
                success,
                "Address: unable to send value, recipient may have reverted"
            );
        }
    
        /**
         * @dev Performs a Solidity function call using a low level `call`. A
         * plain`call` is an unsafe replacement for a function call: use this
         * function instead.
         *
         * If `target` reverts with a revert reason, it is bubbled up by this
         * function (like regular Solidity function calls).
         *
         * Returns the raw returned data. To convert to the expected return value,
         * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
         *
         * Requirements:
         *
         * - `target` must be a contract.
         * - calling `target` with `data` must not revert.
         *
         * _Available since v3.1._
         */
        function functionCall(address target, bytes memory data)
            internal
            returns (bytes memory)
        {
            return functionCall(target, data, "Address: low-level call failed");
        }
    
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
         * `errorMessage` as a fallback revert reason when `target` reverts.
         *
         * _Available since v3.1._
         */
        function functionCall(
            address target,
            bytes memory data,
            string memory errorMessage
        ) internal returns (bytes memory) {
            return _functionCallWithValue(target, data, 0, errorMessage);
        }
    
        /**
         * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
         * but also transferring `value` wei to `target`.
         *
         * Requirements:
         *
         * - the calling contract must have an ETH balance of at least `value`.
         * - the called Solidity function must be `payable`.
         *
         * _Available since v3.1._
         */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value
        ) internal returns (bytes memory) {
            return
                functionCallWithValue(
                    target,
                    data,
                    value,
                    "Address: low-level call with value failed"
                );
        }
    
        /**
         * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
         * with `errorMessage` as a fallback revert reason when `target` reverts.
         *
         * _Available since v3.1._
         */
        function functionCallWithValue(
            address target,
            bytes memory data,
            uint256 value,
            string memory errorMessage
        ) internal returns (bytes memory) {
            require(
                address(this).balance >= value,
                "Address: insufficient balance for call"
            );
            return _functionCallWithValue(target, data, value, errorMessage);
        }
    
        function _functionCallWithValue(
            address target,
            bytes memory data,
            uint256 weiValue,
            string memory errorMessage
        ) private returns (bytes memory) {
            require(isContract(target), "Address: call to non-contract");
    
            // solhint-disable-next-line avoid-low-level-calls
            (bool success, bytes memory returndata) = target.call{
                value: weiValue
            }(data);
            if (success) {
                return returndata;
            } else {
                // Look for revert reason and bubble it up if present
                if (returndata.length > 0) {
                    // The easiest way to bubble the revert reason is using memory via assembly
    
                    // solhint-disable-next-line no-inline-assembly
                    assembly {
                        let returndata_size := mload(returndata)
                        revert(add(32, returndata), returndata_size)
                    }
                } else {
                    revert(errorMessage);
                }
            }
        }
    }
    
    // File: @openzeppelin/contracts/token/ERC20/SafeERC20.sol
    
    pragma solidity ^0.6.0;
    
    /**
     * @title SafeERC20
     * @dev Wrappers around ERC20 operations that throw on failure (when the token
     * contract returns false). Tokens that return no value (and instead revert or
     * throw on failure) are also supported, non-reverting calls are assumed to be
     * successful.
     * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
     * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
     */
    library SafeERC20 {
        using SafeMath for uint256;
        using Address for address;
    
        function safeTransfer(
            IERC20 token,
            address to,
            uint256 value
        ) internal {
            _callOptionalReturn(
                token,
                abi.encodeWithSelector(token.transfer.selector, to, value)
            );
        }
    
        function safeTransferFrom(
            IERC20 token,
            address from,
            address to,
            uint256 value
        ) internal {
            _callOptionalReturn(
                token,
                abi.encodeWithSelector(token.transferFrom.selector, from, to, value)
            );
        }
    
        /**
         * @dev Deprecated. This function has issues similar to the ones found in
         * {IERC20-approve}, and its usage is discouraged.
         *
         * Whenever possible, use {safeIncreaseAllowance} and
         * {safeDecreaseAllowance} instead.
         */
        function safeApprove(
            IERC20 token,
            address spender,
            uint256 value
        ) internal {
            // safeApprove should only be called when setting an initial allowance,
            // or when resetting it to zero. To increase and decrease it, use
            // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
            // solhint-disable-next-line max-line-length
            require(
                (value == 0) || (token.allowance(address(this), spender) == 0),
                "SafeERC20: approve from non-zero to non-zero allowance"
            );
            _callOptionalReturn(
                token,
                abi.encodeWithSelector(token.approve.selector, spender, value)
            );
        }
    
        function safeIncreaseAllowance(
            IERC20 token,
            address spender,
            uint256 value
        ) internal {
            uint256 newAllowance = token.allowance(address(this), spender).add(
                value
            );
            _callOptionalReturn(
                token,
                abi.encodeWithSelector(
                    token.approve.selector,
                    spender,
                    newAllowance
                )
            );
        }
    
        function safeDecreaseAllowance(
            IERC20 token,
            address spender,
            uint256 value
        ) internal {
            uint256 newAllowance = token.allowance(address(this), spender).sub(
                value,
                "SafeERC20: decreased allowance below zero"
            );
            _callOptionalReturn(
                token,
                abi.encodeWithSelector(
                    token.approve.selector,
                    spender,
                    newAllowance
                )
            );
        }
    
        /**
         * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
         * on the return value: the return value is optional (but if data is returned, it must not be false).
         * @param token The token targeted by the call.
         * @param data The call data (encoded using abi.encode or one of its variants).
         */
        function _callOptionalReturn(IERC20 token, bytes memory data) private {
            // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
            // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
            // the target address contains contract code and also asserts for success in the low-level call.
    
            bytes memory returndata = address(token).functionCall(
                data,
                "SafeERC20: low-level call failed"
            );
            if (returndata.length > 0) {
                // Return data is optional
                // solhint-disable-next-line max-line-length
                require(
                    abi.decode(returndata, (bool)),
                    "SafeERC20: ERC20 operation did not succeed"
                );
            }
        }
    }
    
    // File: contracts/v1.1/Rescuable.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    contract Rescuable is Ownable {
        using SafeERC20 for IERC20;
    
        address private _rescuer;
    
        event RescuerChanged(address indexed newRescuer);
    
        /**
         * @notice Returns current rescuer
         * @return Rescuer's address
         */
        function rescuer() external view returns (address) {
            return _rescuer;
        }
    
        /**
         * @notice Revert if called by any account other than the rescuer.
         */
        modifier onlyRescuer() {
            require(msg.sender == _rescuer, "Rescuable: caller is not the rescuer");
            _;
        }
    
        /**
         * @notice Rescue ERC20 tokens locked up in this contract.
         * @param tokenContract ERC20 token contract address
         * @param to        Recipient address
         * @param amount    Amount to withdraw
         */
        function rescueERC20(
            IERC20 tokenContract,
            address to,
            uint256 amount
        ) external onlyRescuer {
            tokenContract.safeTransfer(to, amount);
        }
    
        /**
         * @notice Assign the rescuer role to a given address.
         * @param newRescuer New rescuer's address
         */
        function updateRescuer(address newRescuer) external onlyOwner {
            require(
                newRescuer != address(0),
                "Rescuable: new rescuer is the zero address"
            );
            _rescuer = newRescuer;
            emit RescuerChanged(newRescuer);
        }
    }
    
    // File: contracts/v1.1/FiatTokenV1_1.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @title FiatTokenV1_1
     * @dev ERC20 Token backed by fiat reserves
     */
    contract FiatTokenV1_1 is FiatTokenV1, Rescuable {
    
    }
    
    // File: contracts/v2/AbstractFiatTokenV2.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    abstract contract AbstractFiatTokenV2 is AbstractFiatTokenV1 {
        function _increaseAllowance(
            address owner,
            address spender,
            uint256 increment
        ) internal virtual;
    
        function _decreaseAllowance(
            address owner,
            address spender,
            uint256 decrement
        ) internal virtual;
    }
    
    // File: contracts/util/ECRecover.sol
    
    /**
     * Copyright (c) 2016-2019 zOS Global Limited
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @title ECRecover
     * @notice A library that provides a safe ECDSA recovery function
     */
    library ECRecover {
        /**
         * @notice Recover signer's address from a signed message
         * @dev Adapted from: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/65e4ffde586ec89af3b7e9140bdc9235d1254853/contracts/cryptography/ECDSA.sol
         * Modifications: Accept v, r, and s as separate arguments
         * @param digest    Keccak-256 hash digest of the signed message
         * @param v         v of the signature
         * @param r         r of the signature
         * @param s         s of the signature
         * @return Signer address
         */
        function recover(
            bytes32 digest,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal pure returns (address) {
            // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
            // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
            // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
            // signatures from current libraries generate a unique signature with an s-value in the lower half order.
            //
            // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
            // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
            // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
            // these malleable signatures as well.
            if (
                uint256(s) >
                0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0
            ) {
                revert("ECRecover: invalid signature 's' value");
            }
    
            if (v != 27 && v != 28) {
                revert("ECRecover: invalid signature 'v' value");
            }
    
            // If the signature is valid (and not malleable), return the signer address
            address signer = ecrecover(digest, v, r, s);
            require(signer != address(0), "ECRecover: invalid signature");
    
            return signer;
        }
    }
    
    // File: contracts/util/EIP712.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @title EIP712
     * @notice A library that provides EIP712 helper functions
     */
    library EIP712 {
        /**
         * @notice Make EIP712 domain separator
         * @param name      Contract name
         * @param version   Contract version
         * @return Domain separator
         */
        function makeDomainSeparator(string memory name, string memory version)
            internal
            view
            returns (bytes32)
        {
            uint256 chainId;
            assembly {
                chainId := chainid()
            }
            return
                keccak256(
                    abi.encode(
                        // keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)")
                        0x8b73c3c69bb8fe3d512ecc4cf759cc79239f7b179b0ffacaa9a75d522b39400f,
                        keccak256(bytes(name)),
                        keccak256(bytes(version)),
                        chainId,
                        address(this)
                    )
                );
        }
    
        /**
         * @notice Recover signer's address from a EIP712 signature
         * @param domainSeparator   Domain separator
         * @param v                 v of the signature
         * @param r                 r of the signature
         * @param s                 s of the signature
         * @param typeHashAndData   Type hash concatenated with data
         * @return Signer's address
         */
        function recover(
            bytes32 domainSeparator,
            uint8 v,
            bytes32 r,
            bytes32 s,
            bytes memory typeHashAndData
        ) internal pure returns (address) {
            bytes32 digest = keccak256(
                abi.encodePacked(
                    "\x19\x01",
                    domainSeparator,
                    keccak256(typeHashAndData)
                )
            );
            return ECRecover.recover(digest, v, r, s);
        }
    }
    
    // File: contracts/v2/EIP712Domain.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @title EIP712 Domain
     */
    contract EIP712Domain {
        /**
         * @dev EIP712 Domain Separator
         */
        bytes32 public DOMAIN_SEPARATOR;
    }
    
    // File: contracts/v2/EIP3009.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @title EIP-3009
     * @notice Provide internal implementation for gas-abstracted transfers
     * @dev Contracts that inherit from this must wrap these with publicly
     * accessible functions, optionally adding modifiers where necessary
     */
    abstract contract EIP3009 is AbstractFiatTokenV2, EIP712Domain {
        // keccak256("TransferWithAuthorization(address from,address to,uint256 value,uint256 validAfter,uint256 validBefore,bytes32 nonce)")
        bytes32
            public constant TRANSFER_WITH_AUTHORIZATION_TYPEHASH = 0x7c7c6cdb67a18743f49ec6fa9b35f50d52ed05cbed4cc592e13b44501c1a2267;
    
        // keccak256("ReceiveWithAuthorization(address from,address to,uint256 value,uint256 validAfter,uint256 validBefore,bytes32 nonce)")
        bytes32
            public constant RECEIVE_WITH_AUTHORIZATION_TYPEHASH = 0xd099cc98ef71107a616c4f0f941f04c322d8e254fe26b3c6668db87aae413de8;
    
        // keccak256("CancelAuthorization(address authorizer,bytes32 nonce)")
        bytes32
            public constant CANCEL_AUTHORIZATION_TYPEHASH = 0x158b0a9edf7a828aad02f63cd515c68ef2f50ba807396f6d12842833a1597429;
    
        /**
         * @dev authorizer address => nonce => bool (true if nonce is used)
         */
        mapping(address => mapping(bytes32 => bool)) private _authorizationStates;
    
        event AuthorizationUsed(address indexed authorizer, bytes32 indexed nonce);
        event AuthorizationCanceled(
            address indexed authorizer,
            bytes32 indexed nonce
        );
    
        /**
         * @notice Returns the state of an authorization
         * @dev Nonces are randomly generated 32-byte data unique to the
         * authorizer's address
         * @param authorizer    Authorizer's address
         * @param nonce         Nonce of the authorization
         * @return True if the nonce is used
         */
        function authorizationState(address authorizer, bytes32 nonce)
            external
            view
            returns (bool)
        {
            return _authorizationStates[authorizer][nonce];
        }
    
        /**
         * @notice Execute a transfer with a signed authorization
         * @param from          Payer's address (Authorizer)
         * @param to            Payee's address
         * @param value         Amount to be transferred
         * @param validAfter    The time after which this is valid (unix time)
         * @param validBefore   The time before which this is valid (unix time)
         * @param nonce         Unique nonce
         * @param v             v of the signature
         * @param r             r of the signature
         * @param s             s of the signature
         */
        function _transferWithAuthorization(
            address from,
            address to,
            uint256 value,
            uint256 validAfter,
            uint256 validBefore,
            bytes32 nonce,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal {
            _requireValidAuthorization(from, nonce, validAfter, validBefore);
    
            bytes memory data = abi.encode(
                TRANSFER_WITH_AUTHORIZATION_TYPEHASH,
                from,
                to,
                value,
                validAfter,
                validBefore,
                nonce
            );
            require(
                EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == from,
                "FiatTokenV2: invalid signature"
            );
    
            _markAuthorizationAsUsed(from, nonce);
            _transfer(from, to, value);
        }
    
        /**
         * @notice Receive a transfer with a signed authorization from the payer
         * @dev This has an additional check to ensure that the payee's address
         * matches the caller of this function to prevent front-running attacks.
         * @param from          Payer's address (Authorizer)
         * @param to            Payee's address
         * @param value         Amount to be transferred
         * @param validAfter    The time after which this is valid (unix time)
         * @param validBefore   The time before which this is valid (unix time)
         * @param nonce         Unique nonce
         * @param v             v of the signature
         * @param r             r of the signature
         * @param s             s of the signature
         */
        function _receiveWithAuthorization(
            address from,
            address to,
            uint256 value,
            uint256 validAfter,
            uint256 validBefore,
            bytes32 nonce,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal {
            require(to == msg.sender, "FiatTokenV2: caller must be the payee");
            _requireValidAuthorization(from, nonce, validAfter, validBefore);
    
            bytes memory data = abi.encode(
                RECEIVE_WITH_AUTHORIZATION_TYPEHASH,
                from,
                to,
                value,
                validAfter,
                validBefore,
                nonce
            );
            require(
                EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == from,
                "FiatTokenV2: invalid signature"
            );
    
            _markAuthorizationAsUsed(from, nonce);
            _transfer(from, to, value);
        }
    
        /**
         * @notice Attempt to cancel an authorization
         * @param authorizer    Authorizer's address
         * @param nonce         Nonce of the authorization
         * @param v             v of the signature
         * @param r             r of the signature
         * @param s             s of the signature
         */
        function _cancelAuthorization(
            address authorizer,
            bytes32 nonce,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal {
            _requireUnusedAuthorization(authorizer, nonce);
    
            bytes memory data = abi.encode(
                CANCEL_AUTHORIZATION_TYPEHASH,
                authorizer,
                nonce
            );
            require(
                EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == authorizer,
                "FiatTokenV2: invalid signature"
            );
    
            _authorizationStates[authorizer][nonce] = true;
            emit AuthorizationCanceled(authorizer, nonce);
        }
    
        /**
         * @notice Check that an authorization is unused
         * @param authorizer    Authorizer's address
         * @param nonce         Nonce of the authorization
         */
        function _requireUnusedAuthorization(address authorizer, bytes32 nonce)
            private
            view
        {
            require(
                !_authorizationStates[authorizer][nonce],
                "FiatTokenV2: authorization is used or canceled"
            );
        }
    
        /**
         * @notice Check that authorization is valid
         * @param authorizer    Authorizer's address
         * @param nonce         Nonce of the authorization
         * @param validAfter    The time after which this is valid (unix time)
         * @param validBefore   The time before which this is valid (unix time)
         */
        function _requireValidAuthorization(
            address authorizer,
            bytes32 nonce,
            uint256 validAfter,
            uint256 validBefore
        ) private view {
            require(
                now > validAfter,
                "FiatTokenV2: authorization is not yet valid"
            );
            require(now < validBefore, "FiatTokenV2: authorization is expired");
            _requireUnusedAuthorization(authorizer, nonce);
        }
    
        /**
         * @notice Mark an authorization as used
         * @param authorizer    Authorizer's address
         * @param nonce         Nonce of the authorization
         */
        function _markAuthorizationAsUsed(address authorizer, bytes32 nonce)
            private
        {
            _authorizationStates[authorizer][nonce] = true;
            emit AuthorizationUsed(authorizer, nonce);
        }
    }
    
    // File: contracts/v2/EIP2612.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @title EIP-2612
     * @notice Provide internal implementation for gas-abstracted approvals
     */
    abstract contract EIP2612 is AbstractFiatTokenV2, EIP712Domain {
        // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)")
        bytes32
            public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
    
        mapping(address => uint256) private _permitNonces;
    
        /**
         * @notice Nonces for permit
         * @param owner Token owner's address (Authorizer)
         * @return Next nonce
         */
        function nonces(address owner) external view returns (uint256) {
            return _permitNonces[owner];
        }
    
        /**
         * @notice Verify a signed approval permit and execute if valid
         * @param owner     Token owner's address (Authorizer)
         * @param spender   Spender's address
         * @param value     Amount of allowance
         * @param deadline  The time at which this expires (unix time)
         * @param v         v of the signature
         * @param r         r of the signature
         * @param s         s of the signature
         */
        function _permit(
            address owner,
            address spender,
            uint256 value,
            uint256 deadline,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) internal {
            require(deadline >= now, "FiatTokenV2: permit is expired");
    
            bytes memory data = abi.encode(
                PERMIT_TYPEHASH,
                owner,
                spender,
                value,
                _permitNonces[owner]++,
                deadline
            );
            require(
                EIP712.recover(DOMAIN_SEPARATOR, v, r, s, data) == owner,
                "EIP2612: invalid signature"
            );
    
            _approve(owner, spender, value);
        }
    }
    
    // File: contracts/v2/FiatTokenV2.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    /**
     * @title FiatToken V2
     * @notice ERC20 Token backed by fiat reserves, version 2
     */
    contract FiatTokenV2 is FiatTokenV1_1, EIP3009, EIP2612 {
        uint8 internal _initializedVersion;
    
        /**
         * @notice Initialize v2
         * @param newName   New token name
         */
        function initializeV2(string calldata newName) external {
            // solhint-disable-next-line reason-string
            require(initialized && _initializedVersion == 0);
            name = newName;
            DOMAIN_SEPARATOR = EIP712.makeDomainSeparator(newName, "2");
            _initializedVersion = 1;
        }
    
        /**
         * @notice Increase the allowance by a given increment
         * @param spender   Spender's address
         * @param increment Amount of increase in allowance
         * @return True if successful
         */
        function increaseAllowance(address spender, uint256 increment)
            external
            whenNotPaused
            notBlacklisted(msg.sender)
            notBlacklisted(spender)
            returns (bool)
        {
            _increaseAllowance(msg.sender, spender, increment);
            return true;
        }
    
        /**
         * @notice Decrease the allowance by a given decrement
         * @param spender   Spender's address
         * @param decrement Amount of decrease in allowance
         * @return True if successful
         */
        function decreaseAllowance(address spender, uint256 decrement)
            external
            whenNotPaused
            notBlacklisted(msg.sender)
            notBlacklisted(spender)
            returns (bool)
        {
            _decreaseAllowance(msg.sender, spender, decrement);
            return true;
        }
    
        /**
         * @notice Execute a transfer with a signed authorization
         * @param from          Payer's address (Authorizer)
         * @param to            Payee's address
         * @param value         Amount to be transferred
         * @param validAfter    The time after which this is valid (unix time)
         * @param validBefore   The time before which this is valid (unix time)
         * @param nonce         Unique nonce
         * @param v             v of the signature
         * @param r             r of the signature
         * @param s             s of the signature
         */
        function transferWithAuthorization(
            address from,
            address to,
            uint256 value,
            uint256 validAfter,
            uint256 validBefore,
            bytes32 nonce,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) external whenNotPaused notBlacklisted(from) notBlacklisted(to) {
            _transferWithAuthorization(
                from,
                to,
                value,
                validAfter,
                validBefore,
                nonce,
                v,
                r,
                s
            );
        }
    
        /**
         * @notice Receive a transfer with a signed authorization from the payer
         * @dev This has an additional check to ensure that the payee's address
         * matches the caller of this function to prevent front-running attacks.
         * @param from          Payer's address (Authorizer)
         * @param to            Payee's address
         * @param value         Amount to be transferred
         * @param validAfter    The time after which this is valid (unix time)
         * @param validBefore   The time before which this is valid (unix time)
         * @param nonce         Unique nonce
         * @param v             v of the signature
         * @param r             r of the signature
         * @param s             s of the signature
         */
        function receiveWithAuthorization(
            address from,
            address to,
            uint256 value,
            uint256 validAfter,
            uint256 validBefore,
            bytes32 nonce,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) external whenNotPaused notBlacklisted(from) notBlacklisted(to) {
            _receiveWithAuthorization(
                from,
                to,
                value,
                validAfter,
                validBefore,
                nonce,
                v,
                r,
                s
            );
        }
    
        /**
         * @notice Attempt to cancel an authorization
         * @dev Works only if the authorization is not yet used.
         * @param authorizer    Authorizer's address
         * @param nonce         Nonce of the authorization
         * @param v             v of the signature
         * @param r             r of the signature
         * @param s             s of the signature
         */
        function cancelAuthorization(
            address authorizer,
            bytes32 nonce,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) external whenNotPaused {
            _cancelAuthorization(authorizer, nonce, v, r, s);
        }
    
        /**
         * @notice Update allowance with a signed permit
         * @param owner       Token owner's address (Authorizer)
         * @param spender     Spender's address
         * @param value       Amount of allowance
         * @param deadline    Expiration time, seconds since the epoch
         * @param v           v of the signature
         * @param r           r of the signature
         * @param s           s of the signature
         */
        function permit(
            address owner,
            address spender,
            uint256 value,
            uint256 deadline,
            uint8 v,
            bytes32 r,
            bytes32 s
        ) external whenNotPaused notBlacklisted(owner) notBlacklisted(spender) {
            _permit(owner, spender, value, deadline, v, r, s);
        }
    
        /**
         * @notice Internal function to increase the allowance by a given increment
         * @param owner     Token owner's address
         * @param spender   Spender's address
         * @param increment Amount of increase
         */
        function _increaseAllowance(
            address owner,
            address spender,
            uint256 increment
        ) internal override {
            _approve(owner, spender, allowed[owner][spender].add(increment));
        }
    
        /**
         * @notice Internal function to decrease the allowance by a given decrement
         * @param owner     Token owner's address
         * @param spender   Spender's address
         * @param decrement Amount of decrease
         */
        function _decreaseAllowance(
            address owner,
            address spender,
            uint256 decrement
        ) internal override {
            _approve(
                owner,
                spender,
                allowed[owner][spender].sub(
                    decrement,
                    "ERC20: decreased allowance below zero"
                )
            );
        }
    }
    
    // File: contracts/v2/FiatTokenV2_1.sol
    
    /**
     * Copyright (c) 2018-2020 CENTRE SECZ
     *
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this software and associated documentation files (the "Software"), to deal
     * in the Software without restriction, including without limitation the rights
     * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     * copies of the Software, and to permit persons to whom the Software is
     * furnished to do so, subject to the following conditions:
     *
     * The above copyright notice and this permission notice shall be included in
     * copies or substantial portions of the Software.
     *
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     * SOFTWARE.
     */
    
    pragma solidity 0.6.12;
    
    // solhint-disable func-name-mixedcase
    
    /**
     * @title FiatToken V2.1
     * @notice ERC20 Token backed by fiat reserves, version 2.1
     */
    contract FiatTokenV2_1 is FiatTokenV2 {
        /**
         * @notice Initialize v2.1
         * @param lostAndFound  The address to which the locked funds are sent
         */
        function initializeV2_1(address lostAndFound) external {
            // solhint-disable-next-line reason-string
            require(_initializedVersion == 1);
    
            uint256 lockedAmount = balances[address(this)];
            if (lockedAmount > 0) {
                _transfer(address(this), lostAndFound, lockedAmount);
            }
            blacklisted[address(this)] = true;
    
            _initializedVersion = 2;
        }
    
        /**
         * @notice Version string for the EIP712 domain separator
         * @return Version string
         */
        function version() external view returns (string memory) {
            return "2";
        }
    }