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/**
*Submitted for verification at Etherscan.io on 2017-11-28
*/

pragma solidity ^0.4.17;

/**

• @title SafeMath

• @dev Math operations with safety checks that throw on error
  */
  library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
  if (a == 0) {
  return 0;
  }
  uint256 c = a * b;
  assert(c / a == b);
  return c;
  }

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
  // assert(b > 0); // Solidity automatically throws when dividing by 0
  uint256 c = a / b;
  // assert(a == b * c + a % b); // There is no case in which this doesn't hold
  return c;
  }

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
  assert(b <= a);
  return a - b;
  }

  function add(uint256 a, uint256 b) internal pure returns (uint256) {
  uint256 c = a + b;
  assert(c >= a);
  return c;
  }
  }

/**

• @title Ownable

• @dev The Ownable contract has an owner address, and provides basic authorization control

• functions, this simplifies the implementation of "user permissions".
  */
  contract Ownable {
  address public owner;

  /**

  • @dev The Ownable constructor sets the original owner of the contract to the sender
  • account.
    */
    function Ownable() public {
    owner = msg.sender;
    }

  /**

  • @dev Throws if called by any account other than the owner.
    */
    modifier onlyOwner() {
    require(msg.sender == 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) public onlyOwner {
    if (newOwner != address(0)) {
    owner = newOwner;
    }
    }

}

/**

• @title ERC20Basic
• @dev Simpler version of ERC20 interface
• @dev see ethereum/EIPs#20
  */
  contract ERC20Basic {
  uint public _totalSupply;
  function totalSupply() public constant returns (uint);
  function balanceOf(address who) public constant returns (uint);
  function transfer(address to, uint value) public;
  event Transfer(address indexed from, address indexed to, uint value);
  }

/**

• @title ERC20 interface
• @dev see ethereum/EIPs#20
  */
  contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) public constant returns (uint);
  function transferFrom(address from, address to, uint value) public;
  function approve(address spender, uint value) public;
  event Approval(address indexed owner, address indexed spender, uint value);
  }

/**

• @title Basic token

• @dev Basic version of StandardToken, with no allowances.
  */
  contract BasicToken is Ownable, ERC20Basic {
  using SafeMath for uint;

  mapping(address => uint) public balances;

  // additional variables for use if transaction fees ever became necessary
  uint public basisPointsRate = 0;
  uint public maximumFee = 0;

  /**

  • @dev Fix for the ERC20 short address attack.
    */
    modifier onlyPayloadSize(uint size) {
    require(!(msg.data.length < size + 4));
    _;
    }

  /**

  • @dev transfer token for a specified address
  • @param _to The address to transfer to.
  • @param _value The amount to be transferred.
    */
    function transfer(address _to, uint _value) public onlyPayloadSize(2 * 32) {
    uint fee = (_value.mul(basisPointsRate)).div(10000);
    if (fee > maximumFee) {
    fee = maximumFee;
    }
    uint sendAmount = _value.sub(fee);
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(sendAmount);
    if (fee > 0) {
    balances[owner] = balances[owner].add(fee);
    Transfer(msg.sender, owner, fee);
    }
    Transfer(msg.sender, _to, sendAmount);
    }

  /**

  • @dev Gets the balance of the specified address.
  • @param _owner The address to query the the balance of.
  • @return An uint representing the amount owned by the passed address.
    */
    function balanceOf(address _owner) public constant returns (uint balance) {
    return balances[_owner];
    }

}

/**

• @title Standard ERC20 token

• @dev Implementation of the basic standard token.

• @dev ethereum/EIPs#20

• @dev Based oncode by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
  */
  contract StandardToken is BasicToken, ERC20 {

  mapping (address => mapping (address => uint)) public allowed;

  uint public constant MAX_UINT = 2**256 - 1;

  /**

  • @dev Transfer tokens from one address to another

  • @param _from address The address which you want to send tokens from

  • @param _to address The address which you want to transfer to

  • @param _value uint the amount of tokens to be transferred
    */
    function transferFrom(address _from, address _to, uint _value) public onlyPayloadSize(3 * 32) {
    var _allowance = allowed[_from][msg.sender];

    // Check is not needed because sub(_allowance, _value) will already throw if this condition is not met
    // if (_value > _allowance) throw;

    uint fee = (_value.mul(basisPointsRate)).div(10000);
    if (fee > maximumFee) {
    fee = maximumFee;
    }
    if (_allowance < MAX_UINT) {
    allowed[_from][msg.sender] = _allowance.sub(_value);
    }
    uint sendAmount = _value.sub(fee);
    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(sendAmount);
    if (fee > 0) {
    balances[owner] = balances[owner].add(fee);
    Transfer(_from, owner, fee);
    }
    Transfer(_from, _to, sendAmount);
    }

  /**

  • @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.

  • @param _spender The address which will spend the funds.

  • @param _value The amount of tokens to be spent.
    */
    function approve(address _spender, uint _value) public onlyPayloadSize(2 * 32) {

    // To change the approve amount you first have to reduce the addresses// allowance to zero by callingapprove(_spender, 0)` if it is not
    // already 0 to mitigate the race condition described here:
    // ethereum/EIPs#20 (comment)
    require(!((_value != 0) && (allowed[msg.sender][_spender] != 0)));

    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
    }

  /**

  • @dev Function to check the amount of tokens than an owner allowed to a spender.
  • @param _owner address The address which owns the funds.
  • @param _spender address The address which will spend the funds.
  • @return A uint specifying the amount of tokens still available for the spender.
    */
    function allowance(address _owner, address _spender) public constant returns (uint remaining) {
    return allowed[_owner][_spender];
    }

}

/**

• @title Pausable
• @dev Base contract which allows children to implement an emergency stop mechanism.
  */
  contract Pausable is Ownable {
  event Pause();
  event Unpause();

bool public paused = false;

/**

• @dev Modifier to make a function callable only when the contract is not paused.
  */
  modifier whenNotPaused() {
  require(!paused);
  _;
  }

/**

• @dev Modifier to make a function callable only when the contract is paused.
  */
  modifier whenPaused() {
  require(paused);
  _;
  }

/**

• @dev called by the owner to pause, triggers stopped state
  */
  function pause() onlyOwner whenNotPaused public {
  paused = true;
  Pause();
  }

/**

• @dev called by the owner to unpause, returns to normal state
  */
  function unpause() onlyOwner whenPaused public {
  paused = false;
  Unpause();
  }
  }

contract BlackList is Ownable, BasicToken {

/////// Getters to allow the same blacklist to be used also by other contracts (including upgraded Tether) ///////
function getBlackListStatus(address _maker) external constant returns (bool) {
    return isBlackListed[_maker];
}

function getOwner() external constant returns (address) {
    return owner;
}

mapping (address => bool) public isBlackListed;

function addBlackList (address _evilUser) public onlyOwner {
    isBlackListed[_evilUser] = true;
    AddedBlackList(_evilUser);
}

function removeBlackList (address _clearedUser) public onlyOwner {
    isBlackListed[_clearedUser] = false;
    RemovedBlackList(_clearedUser);
}

function destroyBlackFunds (address _blackListedUser) public onlyOwner {
    require(isBlackListed[_blackListedUser]);
    uint dirtyFunds = balanceOf(_blackListedUser);
    balances[_blackListedUser] = 0;
    _totalSupply -= dirtyFunds;
    DestroyedBlackFunds(_blackListedUser, dirtyFunds);
}

event DestroyedBlackFunds(address _blackListedUser, uint _balance);

event AddedBlackList(address _user);

event RemovedBlackList(address _user);

}

contract UpgradedStandardToken is StandardToken{
// those methods are called by the legacy contract
// and they must ensure msg.sender to be the contract address
function transferByLegacy(address from, address to, uint value) public;
function transferFromByLegacy(address sender, address from, address spender, uint value) public;
function approveByLegacy(address from, address spender, uint value) public;
}

contract TetherToken is Pausable, StandardToken, BlackList {

string public name;
string public symbol;
uint public decimals;
address public upgradedAddress;
bool public deprecated;

//  The contract can be initialized with a number of tokens
//  All the tokens are deposited to the owner address
//
// @param _balance Initial supply of the contract
// @param _name Token Name
// @param _symbol Token symbol
// @param _decimals Token decimals
function TetherToken(uint _initialSupply, string _name, string _symbol, uint _decimals) public {
    _totalSupply = _initialSupply;
    name = _name;
    symbol = _symbol;
    decimals = _decimals;
    balances[owner] = _initialSupply;
    deprecated = false;
}

// Forward ERC20 methods to upgraded contract if this one is deprecated
function transfer(address _to, uint _value) public whenNotPaused {
    require(!isBlackListed[msg.sender]);
    if (deprecated) {
        return UpgradedStandardToken(upgradedAddress).transferByLegacy(msg.sender, _to, _value);
    } else {
        return super.transfer(_to, _value);
    }
}

// Forward ERC20 methods to upgraded contract if this one is deprecated
function transferFrom(address _from, address _to, uint _value) public whenNotPaused {
    require(!isBlackListed[_from]);
    if (deprecated) {
        return UpgradedStandardToken(upgradedAddress).transferFromByLegacy(msg.sender, _from, _to, _value);
    } else {
        return super.transferFrom(_from, _to, _value);
    }
}

// Forward ERC20 methods to upgraded contract if this one is deprecated
function balanceOf(address who) public constant returns (uint) {
    if (deprecated) {
        return UpgradedStandardToken(upgradedAddress).balanceOf(who);
    } else {
        return super.balanceOf(who);
    }
}

// Forward ERC20 methods to upgraded contract if this one is deprecated
function approve(address _spender, uint _value) public onlyPayloadSize(2 * 32) {
    if (deprecated) {
        return UpgradedStandardToken(upgradedAddress).approveByLegacy(msg.sender, _spender, _value);
    } else {
        return super.approve(_spender, _value);
    }
}

// Forward ERC20 methods to upgraded contract if this one is deprecated
function allowance(address _owner, address _spender) public constant returns (uint remaining) {
    if (deprecated) {
        return StandardToken(upgradedAddress).allowance(_owner, _spender);
    } else {
        return super.allowance(_owner, _spender);
    }
}

// deprecate current contract in favour of a new one
function deprecate(address _upgradedAddress) public onlyOwner {
    deprecated = true;
    upgradedAddress = _upgradedAddress;
    Deprecate(_upgradedAddress);
}

// deprecate current contract if favour of a new one
function totalSupply() public constant returns (uint) {
    if (deprecated) {
        return StandardToken(upgradedAddress).totalSupply();
    } else {
        return _totalSupply;
    }
}

// Issue a new amount of tokens
// these tokens are deposited into the owner address
//
// @param _amount Number of tokens to be issued
function issue(uint amount) public onlyOwner {
    require(_totalSupply + amount > _totalSupply);
    require(balances[owner] + amount > balances[owner]);

    balances[owner] += amount;
    _totalSupply += amount;
    Issue(amount);
}

// Redeem tokens.
// These tokens are withdrawn from the owner address
// if the balance must be enough to cover the redeem
// or the call will fail.
// @param _amount Number of tokens to be issued
function redeem(uint amount) public onlyOwner {
    require(_totalSupply >= amount);
    require(balances[owner] >= amount);

    _totalSupply -= amount;
    balances[owner] -= amount;
    Redeem(amount);
}

function setParams(uint newBasisPoints, uint newMaxFee) public onlyOwner {
    // Ensure transparency by hardcoding limit beyond which fees can never be added
    require(newBasisPoints < 20);
    require(newMaxFee < 50);

    basisPointsRate = newBasisPoints;
    maximumFee = newMaxFee.mul(10**decimals);

    Params(basisPointsRate, maximumFee);
}

// Called when new token are issued
event Issue(uint amount);

// Called when tokens are redeemed
event Redeem(uint amount);

// Called when contract is deprecated
event Deprecate(address newAddress);

// Called if contract ever adds fees
event Params(uint feeBasisPoints, uint maxFee);

}

纯属好奇，
名气这么大的ERC-20代币项目怎么会没有^-^