Add Validator signature type

packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol

@@ -20,6 +20,7 @@ pragma solidity ^0.4.24;
 
 import "./mixins/MSignatureValidator.sol";
 import "./interfaces/ISigner.sol";
+import "./interfaces/IValidator.sol";
 import "./libs/LibExchangeErrors.sol";
 import "../../utils/LibBytes/LibBytes.sol";
 
@@ -169,9 +170,38 @@ contract MixinSignatureValidator is
             isValid = signer == recovered;
             return isValid;
 
-        // Signature verified by signer contract
+        // Signature verified by signer contract.
+        // If used with an order, the maker of the order is the signer contract.
         } else if (signatureType == SignatureType.Contract) {
-            isValid = ISigner(signer).isValidSignature(hash, signature);
+            // Pass in signature without signature type.
+            bytes memory signatureWithoutType = deepCopyBytes(
+                signature,
+                1,
+                signature.length - 1
+            );
+            isValid = ISigner(signer).isValidSignature(hash, signatureWithoutType);
+            return isValid;
+
+        // Signature verified by validator contract.
+        // If used with an order, the maker of the order can still be an EOA.
+        // A signature using this type should be encoded as:
+        // | Offset | Length | Contents                        |
+        // | 0x00   | 1      | Signature type is always "\x07" |
+        // | 0x01   | 20     | Address of validator contract   |
+        // | 0x15   | **     | Signature to validate           |
+        } else if (signatureType == SignatureType.Validator) {
+            address validator = readAddress(signature, 1);
+            // Pass in signature without type or validator address.
+            bytes memory signatureWithoutTypeOrAddress = deepCopyBytes(
+                signature,
+                21,
+                signature.length - 21
+            );
+            isValid = IValidator(validator).isValidSignature(
+                hash,
+                signer,
+                signatureWithoutTypeOrAddress
+            );
             return isValid;
 
         // Signer signed hash previously using the preSign function

packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IValidator.sol

@@ -0,0 +1,35 @@
+/*
+
+  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 ^0.4.23;
+
+contract IValidator {
+
+    /// @dev Verifies that a signature is valid.
+    /// @param hash Message hash that is signed.
+    /// @param signer Address that should have signed the given hash.
+    /// @param signature Proof of signing.
+    /// @return Validity of order signature.
+    function isValidSignature(
+        bytes32 hash,
+        address signer,
+        bytes signature)
+        external
+        view
+        returns (bool isValid);
+}

packages/contracts/src/contracts/current/protocol/Exchange/mixins/MSignatureValidator.sol

@@ -32,6 +32,7 @@ contract MSignatureValidator is
         EIP712,
         Trezor,
         Contract,
+        Validator,
         PreSigned
     }
 

packages/contracts/test/libraries/lib_bytes.ts

@@ -60,7 +60,7 @@ describe('LibBytes', () => {
         await blockchainLifecycle.revertAsync();
     });
 
-    describe.only('deepCopyBytes', () => {
+    describe('deepCopyBytes', () => {
         const byteArrayLongerThan32BytesLen = (byteArrayLongerThan32Bytes.length - 2) / 2;
         it('should throw if length of copy is 0', async () => {
             const index = new BigNumber(0);