// File: SignatureUtils.sol

pragma solidity ^0.4.24;

/// @title A library of utilities for (multi)signatures
/// @author Alexander Kern <alex@cleargraph.com>
/// @dev This library can be linked to another Solidity contract to expose signature manipulation functions.
contract SignatureUtils {

    /// @notice Converts a bytes32 to an signed message hash.
    /// @param _msg The bytes32 message (i.e. keccak256 result) to encrypt
    function toEthBytes32SignedMessageHash(
        bytes32 _msg
    )
        pure
        public
        returns (bytes32 signHash)
    {
        signHash = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", _msg));
    }

    /// @notice Converts a byte array to a personal signed message hash (result of `web3.personal.sign(...)`) by concatenating its length.
    /// @param _msg The bytes array to encrypt
    function toEthPersonalSignedMessageHash(
        bytes _msg
    )
        pure
        public
        returns (bytes32 signHash)
    {
        signHash = keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n", uintToString(_msg.length), _msg));
    }

    /// @notice Converts a uint to its decimal string representation.
    /// @param v The uint to convert
    function uintToString(
        uint v
    )
        pure
        public
        returns (string)
    {
        uint w = v;
        bytes32 x;
        if (v == 0) {
            x = "0";
        } else {
            while (w > 0) {
                x = bytes32(uint(x) / (2 ** 8));
                x |= bytes32(((w % 10) + 48) * 2 ** (8 * 31));
                w /= 10;
            }
        }

        bytes memory bytesString = new bytes(32);
        uint charCount = 0;
        for (uint j = 0; j < 32; j++) {
            byte char = byte(bytes32(uint(x) * 2 ** (8 * j)));
            if (char != 0) {
                bytesString[charCount] = char;
                charCount++;
            }
        }
        bytes memory resultBytes = new bytes(charCount);
        for (j = 0; j < charCount; j++) {
            resultBytes[j] = bytesString[j];
        }

        return string(resultBytes);
    }

    /// @notice Extracts the r, s, and v parameters to `ecrecover(...)` from the signature at position `_pos` in a densely packed signatures bytes array.
    /// @dev Based on [OpenZeppelin's ECRecovery](https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/ECRecovery.sol)
    /// @param _signatures The signatures bytes array
    /// @param _pos The position of the signature in the bytes array (0 indexed)
    function parseSignature(
        bytes _signatures,
        uint _pos
    )
        pure
        public
        returns (uint8 v, bytes32 r, bytes32 s)
    {
        uint offset = _pos * 65;
        // The signature format is a compact form of:
        //   {bytes32 r}{bytes32 s}{uint8 v}
        // Compact means, uint8 is not padded to 32 bytes.
        assembly { // solium-disable-line security/no-inline-assembly
            r := mload(add(_signatures, add(32, offset)))
            s := mload(add(_signatures, add(64, offset)))
            // Here we are loading the last 32 bytes, including 31 bytes
            // of 's'. There is no 'mload8' to do this.
            //
            // 'byte' is not working due to the Solidity parser, so lets
            // use the second best option, 'and'
            v := and(mload(add(_signatures, add(65, offset))), 0xff)
        }

        if (v < 27) v += 27;

        require(v == 27 || v == 28);
    }

    /// @notice Counts the number of signatures in a signatures bytes array. Returns 0 if the length is invalid.
    /// @param _signatures The signatures bytes array
    /// @dev Signatures are 65 bytes long and are densely packed.
    function countSignatures(
        bytes _signatures
    )
        pure
        public
        returns (uint)
    {
        return _signatures.length % 65 == 0 ? _signatures.length / 65 : 0;
    }

    /// @notice Recovers an address using a message hash and a signature in a bytes array.
    /// @param _hash The signed message hash
    /// @param _signatures The signatures bytes array
    /// @param _pos The signature's position in the bytes array (0 indexed)
    function recoverAddress(
        bytes32 _hash,
        bytes _signatures,
        uint _pos
    )
        pure
        public
        returns (address)
    {
        uint8 v;
        bytes32 r;
        bytes32 s;
        (v, r, s) = parseSignature(_signatures, _pos);
        return ecrecover(_hash, v, r, s);
    }

    /// @notice Recovers an array of addresses using a message hash and a signatures bytes array.
    /// @param _hash The signed message hash
    /// @param _signatures The signatures bytes array
    function recoverAddresses(
        bytes32 _hash,
        bytes _signatures
    )
        pure
        public
        returns (address[] addresses)
    {
        uint8 v;
        bytes32 r;
        bytes32 s;
        uint count = countSignatures(_signatures);
        addresses = new address[](count);
        for (uint i = 0; i < count; i++) {
            (v, r, s) = parseSignature(_signatures, i);
            addresses[i] = ecrecover(_hash, v, r, s);
        }
    }

}

// File: ERC20.sol

pragma solidity ^0.4.24;

/**
 * @title ERC20 interface
 * @dev see https://github.com/ethereum/EIPs/issues/20
 */
interface IERC20 {
  function totalSupply() external view returns (uint256);

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

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

  function transfer(address to, uint256 value) external returns (bool);

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

  function transferFrom(address from, address to, uint256 value)
    external returns (bool);

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

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


/**
 * @title SafeMath
 * @dev Math operations with safety checks that revert on error
 */
library SafeMath {

  /**
  * @dev Multiplies two numbers, reverts on 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-solidity/pull/522
    if (a == 0) {
      return 0;
    }

    uint256 c = a * b;
    require(c / a == b);

    return c;
  }

  /**
  * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
  */
  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b > 0); // Solidity only automatically asserts 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;
  }

  /**
  * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
  */
  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b <= a);
    uint256 c = a - b;

    return c;
  }

  /**
  * @dev Adds two numbers, reverts on overflow.
  */
  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    require(c >= a);

    return c;
  }

  /**
  * @dev Divides two numbers and returns the remainder (unsigned integer modulo),
  * reverts when dividing by zero.
  */
  function mod(uint256 a, uint256 b) internal pure returns (uint256) {
    require(b != 0);
    return a % b;
  }
}

/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md
 * Originally based on code by FirstBlood: https://github.com/Firstbloodio/token/blob/master/smart_contract/FirstBloodToken.sol
 */
contract ERC20 is IERC20 {
  using SafeMath for uint256;

  mapping (address => uint256) private _balances;

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

  uint256 private _totalSupply;

  /**
  * @dev Total number of tokens in existence
  */
  function totalSupply() public view returns (uint256) {
    return _totalSupply;
  }

  /**
  * @dev Gets the balance of the specified address.
  * @param owner The address to query the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  */
  function balanceOf(address owner) public view returns (uint256) {
    return _balances[owner];
  }

  /**
   * @dev Function to check the amount of tokens that 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 uint256 specifying the amount of tokens still available for the spender.
   */
  function allowance(
    address owner,
    address spender
   )
    public
    view
    returns (uint256)
  {
    return _allowed[owner][spender];
  }

  /**
  * @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, uint256 value) public returns (bool) {
    _transfer(msg.sender, to, value);
    return true;
  }

  /**
   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   * 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
   * @param spender The address which will spend the funds.
   * @param value The amount of tokens to be spent.
   */
  function approve(address spender, uint256 value) public returns (bool) {
    require(spender != address(0));

    _allowed[msg.sender][spender] = value;
    emit Approval(msg.sender, spender, value);
    return true;
  }

  /**
   * @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 uint256 the amount of tokens to be transferred
   */
  function transferFrom(
    address from,
    address to,
    uint256 value
  )
    public
    returns (bool)
  {
    require(value <= _allowed[from][msg.sender]);

    _allowed[from][msg.sender] = _allowed[from][msg.sender].sub(value);
    _transfer(from, to, value);
    return true;
  }

  /**
   * @dev Increase the amount of tokens that an owner allowed to a spender.
   * approve should be called when allowed_[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param spender The address which will spend the funds.
   * @param addedValue The amount of tokens to increase the allowance by.
   */
  function increaseAllowance(
    address spender,
    uint256 addedValue
  )
    public
    returns (bool)
  {
    require(spender != address(0));

    _allowed[msg.sender][spender] = (
      _allowed[msg.sender][spender].add(addedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  /**
   * @dev Decrease the amount of tokens that an owner allowed to a spender.
   * approve should be called when allowed_[_spender] == 0. To decrement
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
   * @param spender The address which will spend the funds.
   * @param subtractedValue The amount of tokens to decrease the allowance by.
   */
  function decreaseAllowance(
    address spender,
    uint256 subtractedValue
  )
    public
    returns (bool)
  {
    require(spender != address(0));

    _allowed[msg.sender][spender] = (
      _allowed[msg.sender][spender].sub(subtractedValue));
    emit Approval(msg.sender, spender, _allowed[msg.sender][spender]);
    return true;
  }

  /**
  * @dev Transfer token for a specified addresses
  * @param from The address to transfer from.
  * @param to The address to transfer to.
  * @param value The amount to be transferred.
  */
  function _transfer(address from, address to, uint256 value) internal {
    require(value <= _balances[from]);
    require(to != address(0));

    _balances[from] = _balances[from].sub(value);
    _balances[to] = _balances[to].add(value);
    emit Transfer(from, to, value);
  }

  /**
   * @dev Internal function that mints an amount of the token and assigns it to
   * an account. This encapsulates the modification of balances such that the
   * proper events are emitted.
   * @param account The account that will receive the created tokens.
   * @param value The amount that will be created.
   */
  function _mint(address account, uint256 value) internal {
    require(account != 0);
    _totalSupply = _totalSupply.add(value);
    _balances[account] = _balances[account].add(value);
    emit Transfer(address(0), account, value);
  }

  /**
   * @dev Internal function that burns an amount of the token of a given
   * account.
   * @param account The account whose tokens will be burnt.
   * @param value The amount that will be burnt.
   */
  function _burn(address account, uint256 value) internal {
    require(account != 0);
    require(value <= _balances[account]);

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

  /**
   * @dev Internal function that burns an amount of the token of a given
   * account, deducting from the sender's allowance for said account. Uses the
   * internal burn function.
   * @param account The account whose tokens will be burnt.
   * @param value The amount that will be burnt.
   */
  function _burnFrom(address account, uint256 value) internal {
    require(value <= _allowed[account][msg.sender]);

    // Should https://github.com/OpenZeppelin/zeppelin-solidity/issues/707 be accepted,
    // this function needs to emit an event with the updated approval.
    _allowed[account][msg.sender] = _allowed[account][msg.sender].sub(
      value);
    _burn(account, value);
  }
}
// File: Bridgeable.sol

pragma solidity ^0.4.24;


/**
 * @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;

  function Ownable() {
    owner = msg.sender;
  }

  modifier onlyOwner() {
    if (msg.sender != owner) {
      throw;
    }
    _;
  }

  function transferOwnership(address newOwner) onlyOwner {
    if (newOwner != address(0)) {
      owner = newOwner;
    }
  }
}


contract Bridgeable is ERC20, SignatureUtils, Ownable {
	address[] public validators;
	address public foreignContract;
	mapping (bytes32 => bool) foreignTransactions;

	event EnterBridgeEvent(address indexed from, uint256 amount);
  event ExitBridgeEvent(address indexed sender, uint256 amount);
  event Mint(address indexed to, uint256 amount);
	event Burn(address indexed burner, uint256 value);

    function addValidator(address _validator) public onlyOwner {
        validators.push(_validator);
    }

    function pair(address _foreignContract) public onlyOwner {
    	foreignContract = _foreignContract;
    }
        
    function enter(uint256 _amount) public {
        emit EnterBridgeEvent(msg.sender, _amount);
        burn(_amount);
    }
    
    function exit(bytes32 _txnHash, address _foreignContract, uint256 _amount, bytes _signatures) public {
    	require(contains(_txnHash) == false, 'Foreign transaction has already been processed');
        bytes32 hash = toEthBytes32SignedMessageHash(entranceHash(_txnHash,_foreignContract, _amount));
        address[] memory recovered = recoverAddresses(hash, _signatures);
        require(verifyValidators(recovered), "Validator verification failed.");
        require(_foreignContract == foreignContract, "Invalid contract target.");
        mint(msg.sender, _amount);
        foreignTransactions[_txnHash] = true;
        emit ExitBridgeEvent(msg.sender, _amount);      
    }

    function contains(bytes32 _txnHash) internal view returns (bool){
        return foreignTransactions[_txnHash];
    }

    function verifyValidators(address[] recovered) internal view returns (bool) {
        require(recovered.length == validators.length, "Invalid number of signatures");
        for(uint i = 0 ; i < validators.length; i++) {
            if(validators[i] != recovered[i]) {
                return false;
            }
        }
        return true;
    }

    function mint( address _to, uint256 _amount )
	    internal returns (bool) {
      _mint(_to, _amount);
	    // emit Mint(_to, _amount);
	    return true;
	  }

    /**
    * @dev Burns a specific amount of tokens.
    * @param _value The amount of token to be burned.
    */
    function burn(uint256 _value) internal {
      _burn(msg.sender, _value);
    }
	    
    /**
     * @notice Hash (keccak256) of the payload used by deposit
     * @param _contractAddress the target ERC20 address
     * @param _amount the original minter
     */
    function entranceHash(bytes32 txnHash, address _contractAddress, uint256 _amount) public view returns (bytes32) {
        // "0x8177cf3c": entranceHash(bytes32, address,uint256)
        return keccak256(abi.encode( bytes4(0x8177cf3c), msg.sender, txnHash, _contractAddress, _amount));
    }

}
// File: bECH.sol

pragma solidity ^0.4.25;


contract BridgedEchelon is Bridgeable {
    string public name = "Bridged Echelon"; 
    string public symbol = "bECH";
    uint public decimals = 18;

    constructor() public {
        // totalSupply = INITIAL_SUPPLY / 2;
        // balanceOf[msg.sender] = totalSupply;
    }
}

{
  "compilationTarget": {
    "BridgedEchelon.sol": "BridgedEchelon"
  },
  "evmVersion": "byzantium",
  "libraries": {},
  "optimizer": {
    "enabled": true,
    "runs": 200
  },
  "remappings": []
}