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diff --git a/contracts/exchange/contracts/examples/Whitelist.sol b/contracts/exchange/contracts/examples/Whitelist.sol
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+++ b/contracts/exchange/contracts/examples/Whitelist.sol
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+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../src/interfaces/IExchange.sol";
+import "@0x/contracts-exchange-libs/contracts/src/LibOrder.sol";
+import "@0x/contracts-utils/contracts/src/Ownable.sol";
+
+
+contract Whitelist is
+    Ownable
+{
+
+    // Mapping of address => whitelist status.
+    mapping (address => bool) public isWhitelisted;
+
+    // Exchange contract.
+    // solhint-disable var-name-mixedcase
+    IExchange internal EXCHANGE;
+    bytes internal TX_ORIGIN_SIGNATURE;
+    // solhint-enable var-name-mixedcase
+
+    byte constant internal VALIDATOR_SIGNATURE_BYTE = "\x05";
+
+    constructor (address _exchange)
+        public
+    {
+        EXCHANGE = IExchange(_exchange);
+        TX_ORIGIN_SIGNATURE = abi.encodePacked(address(this), VALIDATOR_SIGNATURE_BYTE);
+    }
+
+    /// @dev Adds or removes an address from the whitelist.
+    /// @param target Address to add or remove from whitelist.
+    /// @param isApproved Whitelist status to assign to address.
+    function updateWhitelistStatus(
+        address target,
+        bool isApproved
+    )
+        external
+        onlyOwner
+    {
+        isWhitelisted[target] = isApproved;
+    }
+
+    /// @dev Verifies signer is same as signer of current Ethereum transaction.
+    ///      NOTE: This function can currently be used to validate signatures coming from outside of this contract.
+    ///      Extra safety checks can be added for a production contract.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof of signing.
+    /// @return Validity of order signature.
+    // solhint-disable no-unused-vars
+    function isValidSignature(
+        bytes32 hash,
+        address signerAddress,
+        bytes signature
+    )
+        external
+        view
+        returns (bool isValid)
+    {
+        // solhint-disable-next-line avoid-tx-origin
+        return signerAddress == tx.origin;
+    }
+    // solhint-enable no-unused-vars
+
+    /// @dev Fills an order using `msg.sender` as the taker.
+    ///      The transaction will revert if both the maker and taker are not whitelisted.
+    ///      Orders should specify this contract as the `senderAddress` in order to gaurantee
+    ///      that both maker and taker have been whitelisted.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param salt Arbitrary value to gaurantee uniqueness of 0x transaction hash.
+    /// @param orderSignature Proof that order has been created by maker.
+    function fillOrderIfWhitelisted(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        uint256 salt,
+        bytes memory orderSignature
+    )
+        public
+    {
+        address takerAddress = msg.sender;
+
+        // This contract must be the entry point for the transaction.
+        require(
+            // solhint-disable-next-line avoid-tx-origin
+            takerAddress == tx.origin,
+            "INVALID_SENDER"
+        );
+
+        // Check if maker is on the whitelist.
+        require(
+            isWhitelisted[order.makerAddress],
+            "MAKER_NOT_WHITELISTED"
+        );
+
+        // Check if taker is on the whitelist.
+        require(
+            isWhitelisted[takerAddress],
+            "TAKER_NOT_WHITELISTED"
+        );
+
+        // Encode arguments into byte array.
+        bytes memory data = abi.encodeWithSelector(
+            EXCHANGE.fillOrder.selector,
+            order,
+            takerAssetFillAmount,
+            orderSignature
+        );
+
+        // Call `fillOrder` via `executeTransaction`.
+        EXCHANGE.executeTransaction(
+            salt,
+            takerAddress,
+            data,
+            TX_ORIGIN_SIGNATURE
+        );
+    }
+}