Merge pull request #698 from 0xProject/fix/contracts/using-libbytes

Fixes and refactoring regarding LibBytes

25 files changed, 947 insertions, 700 deletions

diff --git a/packages/contracts/compiler.json b/packages/contracts/compiler.json
index 38580f4dc..6b7b69caa 100644
--- a/packages/contracts/compiler.json
+++ b/packages/contracts/compiler.json
@@ -30,10 +30,10 @@
         "MixinAuthorizable",
         "MultiSigWallet",
         "MultiSigWalletWithTimeLock",
+        "TestAssetProxyOwner",
         "TestAssetDataDecoders",
         "TestAssetProxyDispatcher",
         "TestLibBytes",
-        "TestLibMem",
         "TestLibs",
         "TestSignatureValidator",
         "TestValidator",
diff --git a/packages/contracts/package.json b/packages/contracts/package.json
index 3bb66067d..8249b9e0c 100644
--- a/packages/contracts/package.json
+++ b/packages/contracts/package.json
@@ -34,7 +34,7 @@
     },
     "config": {
         "abis":
-            "../migrations/artifacts/2.0.0/@(AssetProxyOwner|DummyERC20Token|DummyERC721Receiver|DummyERC721Token|ERC20Proxy|ERC721Proxy|Exchange|ExchangeWrapper|MixinAuthorizable|MultiSigWallet|MultiSigWalletWithTimeLock|TestAssetDataDecoders|TestAssetProxyDispatcher|TestLibBytes|TestLibMem|TestLibs|TestSignatureValidator|TestValidator|TestWallet|TokenRegistry|Whitelist|WETH9|ZRXToken).json"
+            "../migrations/artifacts/2.0.0/@(AssetProxyOwner|DummyERC20Token|DummyERC721Receiver|DummyERC721Token|ERC20Proxy|ERC721Proxy|Exchange|ExchangeWrapper|MixinAuthorizable|MultiSigWallet|MultiSigWalletWithTimeLock|TestAssetProxyOwner|TestAssetDataDecoders|TestAssetProxyDispatcher|TestLibBytes|TestLibs|TestSignatureValidator|TestValidator|TestWallet|TokenRegistry|Whitelist|WETH9|ZRXToken).json"
     },
     "repository": {
         "type": "git",
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol
index 8cb4254c5..37c12f861 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol
@@ -69,7 +69,7 @@ contract MixinAuthorizable is
         );
 
         delete authorized[target];
-        for (uint i = 0; i < authorities.length; i++) {
+        for (uint256 i = 0; i < authorities.length; i++) {
             if (authorities[i] == target) {
                 authorities[i] = authorities[authorities.length - 1];
                 authorities.length -= 1;
@@ -87,8 +87,13 @@ contract MixinAuthorizable is
         uint256 index
     )
         external
+        onlyOwner
     {
         require(
+            authorized[target],
+            TARGET_NOT_AUTHORIZED
+        );
+        require(
             index < authorities.length,
             INDEX_OUT_OF_BOUNDS
         );
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC20Transfer.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC20Transfer.sol
index 4af39a00b..0e7f3fc89 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC20Transfer.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC20Transfer.sol
@@ -24,9 +24,10 @@ import "../../tokens/ERC20Token/IERC20Token.sol";
 import "./libs/LibTransferErrors.sol";
 
 contract MixinERC20Transfer is
-    LibBytes,
     LibTransferErrors
 {
+    using LibBytes for bytes;
+
     /// @dev Internal version of `transferFrom`.
     /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
@@ -41,7 +42,7 @@ contract MixinERC20Transfer is
         internal
     {
         // Decode asset data.
-        address token = readAddress(assetData, 0);
+        address token = assetData.readAddress(0);
 
         // Transfer tokens.
         // We do a raw call so we can check the success separate
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol
index 6e3156e8a..944068bbb 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinERC721Transfer.sol
@@ -24,9 +24,10 @@ import "../../tokens/ERC721Token/ERC721Token.sol";
 import "./libs/LibTransferErrors.sol";
 
 contract MixinERC721Transfer is
-    LibBytes,
     LibTransferErrors
 {
+    using LibBytes for bytes;
+    
     /// @dev Internal version of `transferFrom`.
     /// @param assetData Encoded byte array.
     /// @param from Address to transfer asset from.
@@ -78,10 +79,10 @@ contract MixinERC721Transfer is
         )
     {
         // Decode asset data.
-        token = readAddress(assetData, 0);
-        tokenId = readUint256(assetData, 20);
+        token = assetData.readAddress(0);
+        tokenId = assetData.readUint256(20);
         if (assetData.length > 52) {
-            receiverData = readBytes(assetData, 52);
+            receiverData = assetData.readBytesWithLength(52);
         }
 
         return (
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxyOwner/AssetProxyOwner.sol b/packages/contracts/src/contracts/current/protocol/AssetProxyOwner/AssetProxyOwner.sol
index 7f5f056b5..eb58b3374 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxyOwner/AssetProxyOwner.sol
+++ b/packages/contracts/src/contracts/current/protocol/AssetProxyOwner/AssetProxyOwner.sol
@@ -22,24 +22,24 @@ import "../../multisig/MultiSigWalletWithTimeLock.sol";
 import "../../utils/LibBytes/LibBytes.sol";
 
 contract AssetProxyOwner is
-    LibBytes,
     MultiSigWalletWithTimeLock
 {
+    using LibBytes for bytes;
 
     event AssetProxyRegistration(address assetProxyContract, bool isRegistered);
 
     // Mapping of AssetProxy contract address =>
-    // if this contract is allowed to call the AssetProxy's removeAuthorizedAddress method without a time lock.
+    // if this contract is allowed to call the AssetProxy's `removeAuthorizedAddressAtIndex` method without a time lock.
     mapping (address => bool) public isAssetProxyRegistered;
 
-    bytes4 constant REMOVE_AUTHORIZED_ADDRESS_SELECTOR = bytes4(keccak256("removeAuthorizedAddress(address)"));
+    bytes4 constant REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR = bytes4(keccak256("removeAuthorizedAddressAtIndex(address,uint256)"));
 
-    /// @dev Function will revert if the transaction does not call `removeAuthorizedAddress`
+    /// @dev Function will revert if the transaction does not call `removeAuthorizedAddressAtIndex`
     ///      on an approved AssetProxy contract.
-    modifier validRemoveAuthorizedAddressTx(uint256 transactionId) {
+    modifier validRemoveAuthorizedAddressAtIndexTx(uint256 transactionId) {
         Transaction storage tx = transactions[transactionId];
         require(isAssetProxyRegistered[tx.destination]);
-        require(isFunctionRemoveAuthorizedAddress(tx.data));
+        require(tx.data.readBytes4(0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR);
         _;
     }
 
@@ -66,7 +66,7 @@ contract AssetProxyOwner is
     }
 
     /// @dev Registers or deregisters an AssetProxy to be able to execute
-    ///      removeAuthorizedAddress without a timelock.
+    ///      `removeAuthorizedAddressAtIndex` without a timelock.
     /// @param assetProxyContract Address of AssetProxy contract.
     /// @param isRegistered Status of approval for AssetProxy contract.
     function registerAssetProxy(address assetProxyContract, bool isRegistered)
@@ -78,13 +78,13 @@ contract AssetProxyOwner is
         AssetProxyRegistration(assetProxyContract, isRegistered);
     }
 
-    /// @dev Allows execution of removeAuthorizedAddress without time lock.
+    /// @dev Allows execution of `removeAuthorizedAddressAtIndex` without time lock.
     /// @param transactionId Transaction ID.
-    function executeRemoveAuthorizedAddress(uint256 transactionId)
+    function executeRemoveAuthorizedAddressAtIndex(uint256 transactionId)
         public
         notExecuted(transactionId)
         fullyConfirmed(transactionId)
-        validRemoveAuthorizedAddressTx(transactionId)
+        validRemoveAuthorizedAddressAtIndexTx(transactionId)
     {
         Transaction storage tx = transactions[transactionId];
         tx.executed = true;
@@ -95,17 +95,4 @@ contract AssetProxyOwner is
             tx.executed = false;
         }
     }
-
-    /// @dev Compares first 4 bytes of byte array to removeAuthorizedAddress function selector.
-    /// @param data Transaction data.
-    /// @return Successful if data is a call to removeAuthorizedAddress.
-    function isFunctionRemoveAuthorizedAddress(bytes memory data)
-        public
-        pure
-        returns (bool)
-    {
-        bytes4 first4Bytes = readFirst4(data);
-        require(REMOVE_AUTHORIZED_ADDRESS_SELECTOR == first4Bytes);
-        return true;
-    }
 }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
index f85019012..b8d6c0722 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
@@ -19,14 +19,12 @@
 pragma solidity ^0.4.24;
 
 import "../../utils/Ownable/Ownable.sol";
-import "../../utils/LibBytes/LibBytes.sol";
 import "./libs/LibExchangeErrors.sol";
 import "./mixins/MAssetProxyDispatcher.sol";
 import "../AssetProxy/interfaces/IAssetProxy.sol";
 
 contract MixinAssetProxyDispatcher is
     Ownable,
-    LibBytes,
     LibExchangeErrors,
     MAssetProxyDispatcher
 {
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
index c227d210f..b207b3e57 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
@@ -32,7 +32,6 @@ import "./mixins/MAssetProxyDispatcher.sol";
 
 contract MixinExchangeCore is
     LibConstants,
-    LibBytes,
     LibMath,
     LibOrder,
     LibFillResults,
@@ -42,6 +41,8 @@ contract MixinExchangeCore is
     MSignatureValidator,
     MTransactions
 {
+    using LibBytes for bytes;
+    
     // Mapping of orderHash => amount of takerAsset already bought by maker
     mapping (bytes32 => uint256) public filled;
 
@@ -411,8 +412,8 @@ contract MixinExchangeCore is
     )
         private
     {
-        uint8 makerAssetProxyId = uint8(popLastByte(order.makerAssetData));
-        uint8 takerAssetProxyId = uint8(popLastByte(order.takerAssetData));
+        uint8 makerAssetProxyId = uint8(order.makerAssetData.popLastByte());
+        uint8 takerAssetProxyId = uint8(order.takerAssetData.popLastByte());
         bytes memory zrxAssetData = ZRX_ASSET_DATA;
         dispatchTransferFrom(
             order.makerAssetData,
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
index 82325a29f..e36fcc2c5 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
@@ -27,7 +27,6 @@ import "./mixins/MAssetProxyDispatcher.sol";
 
 contract MixinMatchOrders is
     LibConstants,
-    LibBytes,
     LibMath,
     LibExchangeErrors,
     MAssetProxyDispatcher,
@@ -35,6 +34,7 @@ contract MixinMatchOrders is
     MMatchOrders,
     MTransactions
 {
+    using LibBytes for bytes;
 
     /// @dev Match two complementary orders that have a profitable spread.
     ///      Each order is filled at their respective price point. However, the calculations are
@@ -242,8 +242,8 @@ contract MixinMatchOrders is
     )
         private
     {
-        uint8 leftMakerAssetProxyId = uint8(popLastByte(leftOrder.makerAssetData));
-        uint8 rightMakerAssetProxyId = uint8(popLastByte(rightOrder.makerAssetData));
+        uint8 leftMakerAssetProxyId = uint8(leftOrder.makerAssetData.popLastByte());
+        uint8 rightMakerAssetProxyId = uint8(rightOrder.makerAssetData.popLastByte());
         bytes memory zrxAssetData = ZRX_ASSET_DATA;
         // Order makers and taker
         dispatchTransferFrom(
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
index 881d6e7b3..cbb55bfce 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
+++ b/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
@@ -26,11 +26,12 @@ import "./interfaces/IWallet.sol";
 import "./interfaces/IValidator.sol";
 
 contract MixinSignatureValidator is
-    LibBytes,
     LibExchangeErrors,
     MSignatureValidator,
     MTransactions
 {
+    using LibBytes for bytes;
+    
     // Personal message headers
     string constant ETH_PERSONAL_MESSAGE = "\x19Ethereum Signed Message:\n32";
     string constant TREZOR_PERSONAL_MESSAGE = "\x19Ethereum Signed Message:\n\x20";
@@ -102,7 +103,7 @@ contract MixinSignatureValidator is
         );
 
         // Ensure signature is supported
-        uint8 signatureTypeRaw = uint8(popLastByte(signature));
+        uint8 signatureTypeRaw = uint8(signature.popLastByte());
         require(
             signatureTypeRaw < uint8(SignatureType.NSignatureTypes),
             SIGNATURE_UNSUPPORTED
@@ -144,8 +145,8 @@ contract MixinSignatureValidator is
                 LENGTH_65_REQUIRED
             );
             v = uint8(signature[0]);
-            r = readBytes32(signature, 1);
-            s = readBytes32(signature, 33);
+            r = signature.readBytes32(1);
+            s = signature.readBytes32(33);
             recovered = ecrecover(hash, v, r, s);
             isValid = signerAddress == recovered;
             return isValid;
@@ -157,8 +158,8 @@ contract MixinSignatureValidator is
                 LENGTH_65_REQUIRED
             );
             v = uint8(signature[0]);
-            r = readBytes32(signature, 1);
-            s = readBytes32(signature, 33);
+            r = signature.readBytes32(1);
+            s = signature.readBytes32(33);
             recovered = ecrecover(
                 keccak256(abi.encodePacked(ETH_PERSONAL_MESSAGE, hash)),
                 v,
@@ -199,7 +200,9 @@ contract MixinSignatureValidator is
         // | 0x14 + x | 1      | Signature type is always "\x06" |
         } else if (signatureType == SignatureType.Validator) {
             // Pop last 20 bytes off of signature byte array.
-            address validatorAddress = popLast20Bytes(signature);
+
+            address validatorAddress = signature.popLast20Bytes();
+            
             // Ensure signer has approved validator.
             if (!allowedValidators[signerAddress][validatorAddress]) {
                 return false;
@@ -230,8 +233,8 @@ contract MixinSignatureValidator is
                 LENGTH_65_REQUIRED
             );
             v = uint8(signature[0]);
-            r = readBytes32(signature, 1);
-            s = readBytes32(signature, 33);
+            r = signature.readBytes32(1);
+            s = signature.readBytes32(33);
             recovered = ecrecover(
                 keccak256(abi.encodePacked(TREZOR_PERSONAL_MESSAGE, hash)),
                 v,
diff --git a/packages/contracts/src/contracts/current/test/TestAssetProxyOwner/TestAssetProxyOwner.sol b/packages/contracts/src/contracts/current/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
new file mode 100644
index 000000000..2abcd17a0
--- /dev/null
+++ b/packages/contracts/src/contracts/current/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
@@ -0,0 +1,56 @@
+/*
+
+  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;
+
+import "../../protocol/AssetProxyOwner/AssetProxyOwner.sol";
+
+contract TestAssetProxyOwner is
+    AssetProxyOwner
+{
+    constructor(
+        address[] memory _owners,
+        address[] memory _assetProxyContracts,
+        uint256 _required,
+        uint256 _secondsTimeLocked
+    )
+        public
+        AssetProxyOwner(_owners, _assetProxyContracts, _required, _secondsTimeLocked)
+    {
+    }
+    
+    function testValidRemoveAuthorizedAddressAtIndexTx(uint256 id)
+        public
+        validRemoveAuthorizedAddressAtIndexTx(id)
+        returns (bool)
+    {
+        // Do nothing. We expect reverts through the modifier
+        return true;
+    }
+    
+    /// @dev Compares first 4 bytes of byte array to `removeAuthorizedAddressAtIndex` function selector.
+    /// @param data Transaction data.
+    /// @return Successful if data is a call to `removeAuthorizedAddressAtIndex`.
+    function isFunctionRemoveAuthorizedAddressAtIndex(bytes memory data)
+        public
+        pure
+        returns (bool)
+    {
+        return data.readBytes4(0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR;
+    }
+}
diff --git a/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol b/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
index 6f1898acd..f45faaf36 100644
--- a/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
+++ b/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
@@ -21,9 +21,9 @@ pragma experimental ABIEncoderV2;
 
 import "../../utils/LibBytes/LibBytes.sol";
 
-contract TestLibBytes is
-    LibBytes
-{
+contract TestLibBytes {
+    
+    using LibBytes for bytes;
 
     /// @dev Pops the last byte off of a byte array by modifying its length.
     /// @param b Byte array that will be modified.
@@ -33,7 +33,7 @@ contract TestLibBytes is
         pure
         returns (bytes memory, bytes1 result)
     {
-        result = popLastByte(b);
+        result = b.popLastByte();
         return (b, result);
     }
 
@@ -45,7 +45,7 @@ contract TestLibBytes is
         pure
         returns (bytes memory, address result)
     {
-        result = popLast20Bytes(b);
+        result = b.popLast20Bytes();
         return (b, result);
     }
 
@@ -53,12 +53,23 @@ contract TestLibBytes is
     /// @param lhs First byte array to compare.
     /// @param rhs Second byte array to compare.
     /// @return True if arrays are the same. False otherwise.
-    function publicAreBytesEqual(bytes memory lhs, bytes memory rhs)
+    function publicEquals(bytes memory lhs, bytes memory rhs)
         public
         pure
         returns (bool equal)
     {
-        equal = areBytesEqual(lhs, rhs);
+        equal = lhs.equals(rhs);
+        return equal;
+    }
+    
+    function publicEqualsPop1(bytes memory lhs, bytes memory rhs)
+        public
+        pure
+        returns (bool equal)
+    {
+        lhs.popLastByte();
+        rhs.popLastByte();
+        equal = lhs.equals(rhs);
         return equal;
     }
 
@@ -73,7 +84,7 @@ contract TestLibBytes is
         pure
         returns (bytes memory)
     {
-        deepCopyBytes(dest, source);
+        LibBytes.deepCopyBytes(dest, source);
         return dest;
     }
 
@@ -89,7 +100,7 @@ contract TestLibBytes is
         pure
         returns (address result)
     {
-        result = readAddress(b, index);
+        result = b.readAddress(index);
         return result;
     }
 
@@ -106,7 +117,7 @@ contract TestLibBytes is
         pure
         returns (bytes memory)
     {
-        writeAddress(b, index, input);
+        b.writeAddress(index, input);
         return b;
     }
 
@@ -122,7 +133,7 @@ contract TestLibBytes is
         pure
         returns (bytes32 result)
     {
-        result = readBytes32(b, index);
+        result = b.readBytes32(index);
         return result;
     }
 
@@ -139,7 +150,7 @@ contract TestLibBytes is
         pure
         returns (bytes memory)
     {
-        writeBytes32(b, index, input);
+        b.writeBytes32(index, input);
         return b;
     }
 
@@ -155,7 +166,7 @@ contract TestLibBytes is
         pure
         returns (uint256 result)
     {
-        result = readUint256(b, index);
+        result = b.readUint256(index);
         return result;
     }
 
@@ -172,19 +183,23 @@ contract TestLibBytes is
         pure
         returns (bytes memory)
     {
-        writeUint256(b, index, input);
+        b.writeUint256(index, input);
         return b;
     }
 
-    /// @dev Reads the first 4 bytes from a byte array of arbitrary length.
-    /// @param b Byte array to read first 4 bytes from.
-    /// @return First 4 bytes of data.
-    function publicReadFirst4(bytes memory b)
+    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
+    /// @param b Byte array containing a bytes4 value.
+    /// @param index Index in byte array of bytes4 value.
+    /// @return bytes4 value from byte array.
+    function publicReadBytes4(
+        bytes memory b,
+        uint256 index
+    )
         public
         pure
         returns (bytes4 result)
     {
-        result = readFirst4(b);
+        result = b.readBytes4(index);
         return result;
     }
 
@@ -192,7 +207,7 @@ contract TestLibBytes is
     /// @param b Byte array containing nested bytes.
     /// @param index Index of nested bytes.
     /// @return result Nested bytes.
-    function publicReadBytes(
+    function publicReadBytesWithLength(
         bytes memory b,
         uint256 index
     )
@@ -200,7 +215,7 @@ contract TestLibBytes is
         pure
         returns (bytes memory result)
     {
-        result = readBytes(b, index);
+        result = b.readBytesWithLength(index);
         return result;
     }
 
@@ -209,7 +224,7 @@ contract TestLibBytes is
     /// @param index Index in byte array of <input>.
     /// @param input bytes to insert.
     /// @return b Updated input byte array
-    function publicWriteBytes(
+    function publicWriteBytesWithLength(
         bytes memory b,
         uint256 index,
         bytes memory input
@@ -218,7 +233,37 @@ contract TestLibBytes is
         pure
         returns (bytes memory)
     {
-        writeBytes(b, index, input);
+        b.writeBytesWithLength(index, input);
         return b;
     }
+    
+    /// @dev Copies a block of memory from one location to another.
+    /// @param mem Memory contents we want to apply memCopy to
+    /// @param dest Destination offset into <mem>.
+    /// @param source Source offset into <mem>.
+    /// @param length Length of bytes to copy from <source> to <dest>
+    /// @return mem Memory contents after calling memCopy.
+    function testMemcpy(
+        bytes mem,
+        uint256 dest,
+        uint256 source,
+        uint256 length
+    )
+        public // not external, we need input in memory
+        pure
+        returns (bytes)
+    {
+        // Sanity check. Overflows are not checked.
+        require(source + length <= mem.length);
+        require(dest + length <= mem.length);
+
+        // Get pointer to memory contents
+        uint256 offset = mem.contentAddress();
+
+        // Execute memCopy adjusted for memory array location
+        LibBytes.memCopy(offset + dest, offset + source, length);
+
+        // Return modified memory contents
+        return mem;
+    }
 }
diff --git a/packages/contracts/src/contracts/current/test/TestLibMem/TestLibMem.sol b/packages/contracts/src/contracts/current/test/TestLibMem/TestLibMem.sol
deleted file mode 100644
index b7e2e06b8..000000000
--- a/packages/contracts/src/contracts/current/test/TestLibMem/TestLibMem.sol
+++ /dev/null
@@ -1,56 +0,0 @@
-/*
-
-  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;
-
-import "../../utils/LibMem/LibMem.sol";
-
-contract TestLibMem is
-    LibMem
-{
-
-    /// @dev Copies a block of memory from one location to another.
-    /// @param mem Memory contents we want to apply memCopy to
-    /// @param dest Destination offset into <mem>.
-    /// @param source Source offset into <mem>.
-    /// @param length Length of bytes to copy from <source> to <dest>
-    /// @return mem Memory contents after calling memCopy.
-    function testMemcpy(
-        bytes mem,
-        uint256 dest,
-        uint256 source,
-        uint256 length
-    )
-        public // not external, we need input in memory
-        pure
-        returns (bytes)
-    {
-        // Sanity check. Overflows are not checked.
-        require(source + length <= mem.length);
-        require(dest + length <= mem.length);
-
-        // Get pointer to memory contents
-        uint256 offset = getMemAddress(mem) + 32;
-
-        // Execute memCopy adjusted for memory array location
-        memCopy(offset + dest, offset + source, length);
-
-        // Return modified memory contents
-        return mem;
-    }
-}
diff --git a/packages/contracts/src/contracts/current/test/TestWallet/TestWallet.sol b/packages/contracts/src/contracts/current/test/TestWallet/TestWallet.sol
index aca74b409..17dee9e9c 100644
--- a/packages/contracts/src/contracts/current/test/TestWallet/TestWallet.sol
+++ b/packages/contracts/src/contracts/current/test/TestWallet/TestWallet.sol
@@ -22,9 +22,9 @@ import "../../protocol/Exchange/interfaces/IWallet.sol";
 import "../../utils/LibBytes/LibBytes.sol";
 
 contract TestWallet is 
-    IWallet,
-    LibBytes
+    IWallet
 {
+    using LibBytes for bytes;
 
     string constant LENGTH_65_REQUIRED = "LENGTH_65_REQUIRED";
 
@@ -56,8 +56,8 @@ contract TestWallet is
         );
 
         uint8 v = uint8(eip712Signature[0]);
-        bytes32 r = readBytes32(eip712Signature, 1);
-        bytes32 s = readBytes32(eip712Signature, 33);
+        bytes32 r = eip712Signature.readBytes32(1);
+        bytes32 s = eip712Signature.readBytes32(33);
         address recoveredAddress = ecrecover(hash, v, r, s);
         isValid = WALLET_OWNER == recoveredAddress;
         return isValid;
diff --git a/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol b/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
index 10d7ce41a..e4cbf318b 100644
--- a/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
+++ b/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
@@ -18,11 +18,8 @@
 
 pragma solidity ^0.4.24;
 
-import "../LibMem/LibMem.sol";
-
-contract LibBytes is
-    LibMem
-{
+library LibBytes {
+    using LibBytes for bytes;
 
     // Revert reasons
     string constant GREATER_THAN_ZERO_LENGTH_REQUIRED = "GREATER_THAN_ZERO_LENGTH_REQUIRED";
@@ -31,6 +28,187 @@ contract LibBytes is
     string constant GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED";
     string constant GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED";
     string constant GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED";
+    string constant FROM_LESS_THAN_TO_REQUIRED = "FROM_LESS_THAN_TO_REQUIRED";
+    string constant TO_LESS_THAN_LENGTH_REQUIRED = "TO_LESS_THAN_LENGTH_REQUIRED";
+
+    /// @dev Gets the memory address for a byte array.
+    /// @param input Byte array to lookup.
+    /// @return memoryAddress Memory address of byte array. This
+    ///         points to the header of the byte array which contains
+    ///         the length.
+    function rawAddress(bytes memory input)
+        internal
+        pure
+        returns (uint256 memoryAddress)
+    {
+        assembly {
+            memoryAddress := input
+        }
+        return memoryAddress;
+    }
+    
+    /// @dev Gets the memory address for the contents of a byte array.
+    /// @param input Byte array to lookup.
+    /// @return memoryAddress Memory address of the contents of the byte array.
+    function contentAddress(bytes memory input)
+        internal
+        pure
+        returns (uint256 memoryAddress)
+    {
+        assembly {
+            memoryAddress := add(input, 32)
+        }
+        return memoryAddress;
+    }
+
+    /// @dev Copies `length` bytes from memory location `source` to `dest`.
+    /// @param dest memory address to copy bytes to.
+    /// @param source memory address to copy bytes from.
+    /// @param length number of bytes to copy.
+    function memCopy(
+        uint256 dest,
+        uint256 source,
+        uint256 length
+    )
+        internal
+        pure
+    {
+        if (length < 32) {
+            // Handle a partial word by reading destination and masking
+            // off the bits we are interested in.
+            // This correctly handles overlap, zero lengths and source == dest
+            assembly {
+                let mask := sub(exp(256, sub(32, length)), 1)
+                let s := and(mload(source), not(mask))
+                let d := and(mload(dest), mask)
+                mstore(dest, or(s, d))
+            }
+        } else {
+            // Skip the O(length) loop when source == dest.
+            if (source == dest) {
+                return;
+            }
+
+            // For large copies we copy whole words at a time. The final
+            // word is aligned to the end of the range (instead of after the
+            // previous) to handle partial words. So a copy will look like this:
+            //
+            //  ####
+            //      ####
+            //          ####
+            //            ####
+            //
+            // We handle overlap in the source and destination range by
+            // changing the copying direction. This prevents us from
+            // overwriting parts of source that we still need to copy.
+            //
+            // This correctly handles source == dest
+            //
+            if (source > dest) {
+                assembly {
+                    // We subtract 32 from `sEnd` and `dEnd` because it
+                    // is easier to compare with in the loop, and these
+                    // are also the addresses we need for copying the
+                    // last bytes.
+                    length := sub(length, 32)
+                    let sEnd := add(source, length)
+                    let dEnd := add(dest, length)
+
+                    // Remember the last 32 bytes of source
+                    // This needs to be done here and not after the loop
+                    // because we may have overwritten the last bytes in
+                    // source already due to overlap.
+                    let last := mload(sEnd)
+
+                    // Copy whole words front to back
+                    // Note: the first check is always true,
+                    // this could have been a do-while loop.
+                    for {} lt(source, sEnd) {} {
+                        mstore(dest, mload(source))
+                        source := add(source, 32)
+                        dest := add(dest, 32)
+                    }
+                    
+                    // Write the last 32 bytes
+                    mstore(dEnd, last)
+                }
+            } else {
+                assembly {
+                    // We subtract 32 from `sEnd` and `dEnd` because those
+                    // are the starting points when copying a word at the end.
+                    length := sub(length, 32)
+                    let sEnd := add(source, length)
+                    let dEnd := add(dest, length)
+
+                    // Remember the first 32 bytes of source
+                    // This needs to be done here and not after the loop
+                    // because we may have overwritten the first bytes in
+                    // source already due to overlap.
+                    let first := mload(source)
+
+                    // Copy whole words back to front
+                    // We use a signed comparisson here to allow dEnd to become
+                    // negative (happens when source and dest < 32). Valid
+                    // addresses in local memory will never be larger than
+                    // 2**255, so they can be safely re-interpreted as signed.
+                    // Note: the first check is always true,
+                    // this could have been a do-while loop.
+                    for {} slt(dest, dEnd) {} {
+                        mstore(dEnd, mload(sEnd))
+                        sEnd := sub(sEnd, 32)
+                        dEnd := sub(dEnd, 32)
+                    }
+                    
+                    // Write the first 32 bytes
+                    mstore(dest, first)
+                }
+            }
+        }
+    }
+    
+    /// @dev Returns a slices from a byte array.
+    /// @param b The byte array to take a slice from.
+    /// @param from The starting index for the slice (inclusive).
+    /// @param to The final index for the slice (exclusive).
+    /// @return result The slice containing bytes at indices [from, to)
+    function slice(bytes memory b, uint256 from, uint256 to)
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        require(from <= to, FROM_LESS_THAN_TO_REQUIRED);
+        require(to < b.length, TO_LESS_THAN_LENGTH_REQUIRED);
+        
+        // Create a new bytes structure and copy contents
+        result = new bytes(to - from);
+        memCopy(
+            result.contentAddress(),
+            b.contentAddress() + from,
+            result.length);
+        return result;
+    }
+    
+    /// @dev Returns a slice from a byte array without preserving the input.
+    /// @param b The byte array to take a slice from. Will be destroyed in the process.
+    /// @param from The starting index for the slice (inclusive).
+    /// @param to The final index for the slice (exclusive).
+    /// @return result The slice containing bytes at indices [from, to)
+    /// @dev When `from == 0`, the original array will match the slice. In other cases its state will be corrupted.
+    function sliceDestructive(bytes memory b, uint256 from, uint256 to)
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        require(from <= to, FROM_LESS_THAN_TO_REQUIRED);
+        require(to < b.length, TO_LESS_THAN_LENGTH_REQUIRED);
+        
+        // Create a new bytes structure around [from, to) in-place.
+        assembly {
+            result := add(b, from)
+            mstore(result, sub(to, from))
+        }
+        return result;
+    }
 
     /// @dev Pops the last byte off of a byte array by modifying its length.
     /// @param b Byte array that will be modified.
@@ -80,6 +258,24 @@ contract LibBytes is
         return result;
     }
 
+    /// @dev Tests equality of two byte arrays.
+    /// @param lhs First byte array to compare.
+    /// @param rhs Second byte array to compare.
+    /// @return True if arrays are the same. False otherwise.
+    function equals(
+        bytes memory lhs,
+        bytes memory rhs
+    )
+        internal
+        pure
+        returns (bool equal)
+    {
+        // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
+        // We early exit on unequal lengths, but keccak would also correctly
+        // handle this.
+        return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
+    }
+
     /// @dev Reads an address from a position in a byte array.
     /// @param b Byte array containing an address.
     /// @param index Index in byte array of address.
@@ -145,6 +341,10 @@ contract LibBytes is
             // 2. Load 32-byte word from memory
             // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
             let neighbors := and(mload(add(b, index)), 0xffffffffffffffffffffffff0000000000000000000000000000000000000000)
+            
+            // Make sure input address is clean.
+            // (Solidity does not guarantee this)
+            input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
 
             // Store the neighbors and address into memory
             mstore(add(b, index), xor(input, neighbors))
@@ -234,20 +434,26 @@ contract LibBytes is
         writeBytes32(b, index, bytes32(input));
     }
 
-    /// @dev Reads the first 4 bytes from a byte array of arbitrary length.
-    /// @param b Byte array to read first 4 bytes from.
-    /// @return First 4 bytes of data.
-    function readFirst4(bytes memory b)
+    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
+    /// @param b Byte array containing a bytes4 value.
+    /// @param index Index in byte array of bytes4 value.
+    /// @return bytes4 value from byte array.
+    function readBytes4(
+        bytes memory b,
+        uint256 index)
         internal
         pure
         returns (bytes4 result)
     {
         require(
-            b.length >= 4,
+            b.length >= index + 4,
             GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED
         );
         assembly {
             result := mload(add(b, 32))
+            // Solidity does not require us to clean the trailing bytes.
+            // We do it anyway
+            result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
         }
         return result;
     }
@@ -256,7 +462,7 @@ contract LibBytes is
     /// @param b Byte array containing nested bytes.
     /// @param index Index of nested bytes.
     /// @return result Nested bytes.
-    function readBytes(
+    function readBytesWithLength(
         bytes memory b,
         uint256 index
     )
@@ -278,8 +484,8 @@ contract LibBytes is
         // Allocate memory and copy value to result
         result = new bytes(nestedBytesLength);
         memCopy(
-            getMemAddress(result) + 32, // +32 skips array length
-            getMemAddress(b) + index + 32,
+            result.contentAddress(),
+            b.contentAddress() + index,
             nestedBytesLength
         );
 
@@ -290,7 +496,7 @@ contract LibBytes is
     /// @param b Byte array to insert <input> into.
     /// @param index Index in byte array of <input>.
     /// @param input bytes to insert.
-    function writeBytes(
+    function writeBytesWithLength(
         bytes memory b,
         uint256 index,
         bytes memory input
@@ -307,47 +513,12 @@ contract LibBytes is
 
         // Copy <input> into <b>
         memCopy(
-            getMemAddress(b) + 32 + index,  // +32 to skip length of <b>
-            getMemAddress(input),           // includes length of <input>
-            input.length + 32               // +32 bytes to store <input> length
+            b.contentAddress() + index,
+            input.rawAddress(), // includes length of <input>
+            input.length + 32   // +32 bytes to store <input> length
         );
     }
 
-    /// @dev Tests equality of two byte arrays.
-    /// @param lhs First byte array to compare.
-    /// @param rhs Second byte array to compare.
-    /// @return True if arrays are the same. False otherwise.
-    function areBytesEqual(
-        bytes memory lhs,
-        bytes memory rhs
-    )
-        internal
-        pure
-        returns (bool equal)
-    {
-        assembly {
-            // Get the number of words occupied by <lhs>
-            let lenFullWords := div(add(mload(lhs), 0x1F), 0x20)
-
-            // Add 1 to the number of words, to account for the length field
-            lenFullWords := add(lenFullWords, 0x1)
-
-            // Test equality word-by-word.
-            // Terminates early if there is a mismatch.
-            for {let i := 0} lt(i, lenFullWords) {i := add(i, 1)} {
-                let lhsWord := mload(add(lhs, mul(i, 0x20)))
-                let rhsWord := mload(add(rhs, mul(i, 0x20)))
-                equal := eq(lhsWord, rhsWord)
-                if eq(equal, 0) {
-                    // Break
-                    i := lenFullWords
-                }
-            }
-       }
-
-       return equal;
-    }
-
     /// @dev Performs a deep copy of a byte array onto another byte array of greater than or equal length.
     /// @param dest Byte array that will be overwritten with source bytes.
     /// @param source Byte array to copy onto dest bytes.
@@ -365,8 +536,8 @@ contract LibBytes is
             GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED
         );
         memCopy(
-            getMemAddress(dest) + 32,    // +32 to skip length of <dest>
-            getMemAddress(source) + 32,  // +32 to skip length of <source>
+            dest.contentAddress(),
+            source.contentAddress(),
             sourceLen
         );
     }
diff --git a/packages/contracts/src/contracts/current/utils/LibMem/LibMem.sol b/packages/contracts/src/contracts/current/utils/LibMem/LibMem.sol
deleted file mode 100644
index 97fb5fb0f..000000000
--- a/packages/contracts/src/contracts/current/utils/LibMem/LibMem.sol
+++ /dev/null
@@ -1,142 +0,0 @@
-/*
-
-  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;
-
-contract LibMem
-{
-
-    /// @dev Gets the memory address for a byte array.
-    /// @param input Byte array to lookup.
-    /// @return memoryAddress Memory address of byte array.
-    function getMemAddress(bytes memory input)
-        internal
-        pure
-        returns (uint256 memoryAddress)
-    {
-        assembly {
-            memoryAddress := input
-        }
-        return memoryAddress;
-    }
-
-    /// @dev Copies `length` bytes from memory location `source` to `dest`.
-    /// @param dest memory address to copy bytes to.
-    /// @param source memory address to copy bytes from.
-    /// @param length number of bytes to copy.
-    function memCopy(
-        uint256 dest,
-        uint256 source,
-        uint256 length
-    )
-        internal
-        pure
-    {
-        if (length < 32) {
-            // Handle a partial word by reading destination and masking
-            // off the bits we are interested in.
-            // This correctly handles overlap, zero lengths and source == dest
-            assembly {
-                let mask := sub(exp(256, sub(32, length)), 1)
-                let s := and(mload(source), not(mask))
-                let d := and(mload(dest), mask)
-                mstore(dest, or(s, d))
-            }
-        } else {
-            // Skip the O(length) loop when source == dest.
-            if (source == dest) {
-                return;
-            }
-
-            // For large copies we copy whole words at a time. The final
-            // word is aligned to the end of the range (instead of after the
-            // previous) to handle partial words. So a copy will look like this:
-            //
-            //  ####
-            //      ####
-            //          ####
-            //            ####
-            //
-            // We handle overlap in the source and destination range by
-            // changing the copying direction. This prevents us from
-            // overwriting parts of source that we still need to copy.
-            //
-            // This correctly handles source == dest
-            //
-            if (source > dest) {
-                assembly {
-                    // We subtract 32 from `sEnd` and `dEnd` because it
-                    // is easier to compare with in the loop, and these
-                    // are also the addresses we need for copying the
-                    // last bytes.
-                    length := sub(length, 32)
-                    let sEnd := add(source, length)
-                    let dEnd := add(dest, length)
-
-                    // Remember the last 32 bytes of source
-                    // This needs to be done here and not after the loop
-                    // because we may have overwritten the last bytes in
-                    // source already due to overlap.
-                    let last := mload(sEnd)
-
-                    // Copy whole words front to back
-                    // Note: the first check is always true,
-                    // this could have been a do-while loop.
-                    for {} lt(source, sEnd) {} {
-                        mstore(dest, mload(source))
-                        source := add(source, 32)
-                        dest := add(dest, 32)
-                    }
-                    
-                    // Write the last 32 bytes
-                    mstore(dEnd, last)
-                }
-            } else {
-                assembly {
-                    // We subtract 32 from `sEnd` and `dEnd` because those
-                    // are the starting points when copying a word at the end.
-                    length := sub(length, 32)
-                    let sEnd := add(source, length)
-                    let dEnd := add(dest, length)
-
-                    // Remember the first 32 bytes of source
-                    // This needs to be done here and not after the loop
-                    // because we may have overwritten the first bytes in
-                    // source already due to overlap.
-                    let first := mload(source)
-
-                    // Copy whole words back to front
-                    // We use a signed comparisson here to allow dEnd to become
-                    // negative (happens when source and dest < 32). Valid
-                    // addresses in local memory will never be larger than
-                    // 2**255, so they can be safely re-interpreted as signed.
-                    // Note: the first check is always true,
-                    // this could have been a do-while loop.
-                    for {} slt(dest, dEnd) {} {
-                        mstore(dEnd, mload(sEnd))
-                        sEnd := sub(sEnd, 32)
-                        dEnd := sub(dEnd, 32)
-                    }
-                    
-                    // Write the first 32 bytes
-                    mstore(dest, first)
-                }
-            }
-        }
-    }
-}
diff --git a/packages/contracts/src/contracts/current/utils/Ownable/Ownable.sol b/packages/contracts/src/contracts/current/utils/Ownable/Ownable.sol
index 296c6c856..99b93d0d2 100644
--- a/packages/contracts/src/contracts/current/utils/Ownable/Ownable.sol
+++ b/packages/contracts/src/contracts/current/utils/Ownable/Ownable.sol
@@ -13,6 +13,9 @@ import "./IOwnable.sol";
 contract Ownable is IOwnable {
     address public owner;
 
+    // Revert reasons
+    string constant ONLY_CONTRACT_OWNER = "ONLY_CONTRACT_OWNER";
+
     constructor ()
         public
     {
@@ -22,7 +25,7 @@ contract Ownable is IOwnable {
     modifier onlyOwner() {
         require(
             msg.sender == owner,
-            "Only contract owner is allowed to call this method."
+            ONLY_CONTRACT_OWNER
         );
         _;
     }
diff --git a/packages/contracts/src/utils/artifacts.ts b/packages/contracts/src/utils/artifacts.ts
index 4375d87c6..a46bab9ae 100644
--- a/packages/contracts/src/utils/artifacts.ts
+++ b/packages/contracts/src/utils/artifacts.ts
@@ -13,8 +13,8 @@ import * as MultiSigWallet from '../artifacts/MultiSigWallet.json';
 import * as MultiSigWalletWithTimeLock from '../artifacts/MultiSigWalletWithTimeLock.json';
 import * as TestAssetDataDecoders from '../artifacts/TestAssetDataDecoders.json';
 import * as TestAssetProxyDispatcher from '../artifacts/TestAssetProxyDispatcher.json';
+import * as TestAssetProxyOwner from '../artifacts/TestAssetProxyOwner.json';
 import * as TestLibBytes from '../artifacts/TestLibBytes.json';
-import * as TestLibMem from '../artifacts/TestLibMem.json';
 import * as TestLibs from '../artifacts/TestLibs.json';
 import * as TestSignatureValidator from '../artifacts/TestSignatureValidator.json';
 import * as TestValidator from '../artifacts/TestValidator.json';
@@ -37,10 +37,10 @@ export const artifacts = {
     MixinAuthorizable: (MixinAuthorizable as any) as ContractArtifact,
     MultiSigWallet: (MultiSigWallet as any) as ContractArtifact,
     MultiSigWalletWithTimeLock: (MultiSigWalletWithTimeLock as any) as ContractArtifact,
+    TestAssetProxyOwner: (TestAssetProxyOwner as any) as ContractArtifact,
     TestAssetProxyDispatcher: (TestAssetProxyDispatcher as any) as ContractArtifact,
     TestAssetDataDecoders: (TestAssetDataDecoders as any) as ContractArtifact,
     TestLibBytes: (TestLibBytes as any) as ContractArtifact,
-    TestLibMem: (TestLibMem as any) as ContractArtifact,
     TestLibs: (TestLibs as any) as ContractArtifact,
     TestSignatureValidator: (TestSignatureValidator as any) as ContractArtifact,
     TestValidator: (TestValidator as any) as ContractArtifact,
diff --git a/packages/contracts/src/utils/multi_sig_wrapper.ts b/packages/contracts/src/utils/multi_sig_wrapper.ts
index f0098bd5e..b0d4fa8ab 100644
--- a/packages/contracts/src/utils/multi_sig_wrapper.ts
+++ b/packages/contracts/src/utils/multi_sig_wrapper.ts
@@ -40,13 +40,15 @@ export class MultiSigWrapper {
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
     }
-    public async executeRemoveAuthorizedAddressAsync(
+    public async executeRemoveAuthorizedAddressAtIndexAsync(
         txId: BigNumber,
         from: string,
     ): Promise<TransactionReceiptWithDecodedLogs> {
         // tslint:disable-next-line:no-unnecessary-type-assertion
         const txHash = await (this
-            ._multiSig as AssetProxyOwnerContract).executeRemoveAuthorizedAddress.sendTransactionAsync(txId, { from });
+            ._multiSig as AssetProxyOwnerContract).executeRemoveAuthorizedAddressAtIndex.sendTransactionAsync(txId, {
+            from,
+        });
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
     }
diff --git a/packages/contracts/src/utils/types.ts b/packages/contracts/src/utils/types.ts
index 7a1f92afd..5dfac64fc 100644
--- a/packages/contracts/src/utils/types.ts
+++ b/packages/contracts/src/utils/types.ts
@@ -92,7 +92,6 @@ export enum ContractName {
     Arbitrage = 'Arbitrage',
     TestAssetDataDecoders = 'TestAssetDataDecoders',
     TestAssetProxyDispatcher = 'TestAssetProxyDispatcher',
-    TestLibMem = 'TestLibMem',
     TestLibs = 'TestLibs',
     TestSignatureValidator = 'TestSignatureValidator',
     ERC20Proxy = 'ERC20Proxy',
diff --git a/packages/contracts/test/asset_proxy/authorizable.ts b/packages/contracts/test/asset_proxy/authorizable.ts
index ed582b63e..c35dc7882 100644
--- a/packages/contracts/test/asset_proxy/authorizable.ts
+++ b/packages/contracts/test/asset_proxy/authorizable.ts
@@ -1,4 +1,5 @@
 import { BlockchainLifecycle } from '@0xproject/dev-utils';
+import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 
 import { MixinAuthorizableContract } from '../../src/generated_contract_wrappers/mixin_authorizable';
@@ -102,6 +103,74 @@ describe('Authorizable', () => {
         });
     });
 
+    describe('removeAuthorizedAddressAtIndex', () => {
+        it('should throw if not called by owner', async () => {
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await authorizable.addAuthorizedAddress.sendTransactionAsync(address, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const index = new BigNumber(0);
+            return expectRevertOrAlwaysFailingTransactionAsync(
+                authorizable.removeAuthorizedAddressAtIndex.sendTransactionAsync(address, index, {
+                    from: notOwner,
+                }),
+            );
+        });
+        it('should throw if index is >= authorities.length', async () => {
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await authorizable.addAuthorizedAddress.sendTransactionAsync(address, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const index = new BigNumber(1);
+            return expectRevertOrAlwaysFailingTransactionAsync(
+                authorizable.removeAuthorizedAddressAtIndex.sendTransactionAsync(address, index, {
+                    from: owner,
+                }),
+            );
+        });
+        it('should throw if owner attempts to remove an address that is not authorized', async () => {
+            const index = new BigNumber(0);
+            return expectRevertOrAlwaysFailingTransactionAsync(
+                authorizable.removeAuthorizedAddressAtIndex.sendTransactionAsync(address, index, {
+                    from: owner,
+                }),
+            );
+        });
+        it('should throw if address at index does not match target', async () => {
+            const address1 = address;
+            const address2 = notOwner;
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await authorizable.addAuthorizedAddress.sendTransactionAsync(address1, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await authorizable.addAuthorizedAddress.sendTransactionAsync(address2, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const address1Index = new BigNumber(0);
+            return expectRevertOrAlwaysFailingTransactionAsync(
+                authorizable.removeAuthorizedAddressAtIndex.sendTransactionAsync(address2, address1Index, {
+                    from: owner,
+                }),
+            );
+        });
+        it('should allow owner to remove an authorized address', async () => {
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await authorizable.addAuthorizedAddress.sendTransactionAsync(address, { from: owner }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const index = new BigNumber(0);
+            await web3Wrapper.awaitTransactionSuccessAsync(
+                await authorizable.removeAuthorizedAddressAtIndex.sendTransactionAsync(address, index, {
+                    from: owner,
+                }),
+                constants.AWAIT_TRANSACTION_MINED_MS,
+            );
+            const isAuthorized = await authorizable.authorized.callAsync(address);
+            expect(isAuthorized).to.be.false();
+        });
+    });
+
     describe('getAuthorizedAddresses', () => {
         it('should return all authorized addresses', async () => {
             const initial = await authorizable.getAuthorizedAddresses.callAsync();
diff --git a/packages/contracts/test/asset_proxy/decoder.ts b/packages/contracts/test/asset_proxy/decoder.ts
index 875d55daa..98d18aa38 100644
--- a/packages/contracts/test/asset_proxy/decoder.ts
+++ b/packages/contracts/test/asset_proxy/decoder.ts
@@ -27,7 +27,6 @@ describe('TestAssetDataDecoders', () => {
         // Setup accounts & addresses
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
         testAddress = accounts[0];
-        // Deploy TestLibMem
         testAssetProxyDecoder = await TestAssetDataDecodersContract.deployFrom0xArtifactAsync(
             artifacts.TestAssetDataDecoders,
             provider,
diff --git a/packages/contracts/test/asset_proxy_owner.ts b/packages/contracts/test/asset_proxy_owner.ts
index aa4999e95..188cba5a3 100644
--- a/packages/contracts/test/asset_proxy_owner.ts
+++ b/packages/contracts/test/asset_proxy_owner.ts
@@ -11,6 +11,7 @@ import {
     SubmissionContractEventArgs,
 } from '../src/generated_contract_wrappers/asset_proxy_owner';
 import { MixinAuthorizableContract } from '../src/generated_contract_wrappers/mixin_authorizable';
+import { TestAssetProxyOwnerContract } from '../src/generated_contract_wrappers/test_asset_proxy_owner';
 import { artifacts } from '../src/utils/artifacts';
 import {
     expectRevertOrAlwaysFailingTransactionAsync,
@@ -34,7 +35,7 @@ describe('AssetProxyOwner', () => {
 
     let erc20Proxy: MixinAuthorizableContract;
     let erc721Proxy: MixinAuthorizableContract;
-    let multiSig: AssetProxyOwnerContract;
+    let testAssetProxyOwner: TestAssetProxyOwnerContract;
     let multiSigWrapper: MultiSigWrapper;
 
     before(async () => {
@@ -58,8 +59,8 @@ describe('AssetProxyOwner', () => {
             txDefaults,
         );
         const defaultAssetProxyContractAddresses: string[] = [];
-        multiSig = await AssetProxyOwnerContract.deployFrom0xArtifactAsync(
-            artifacts.AssetProxyOwner,
+        testAssetProxyOwner = await TestAssetProxyOwnerContract.deployFrom0xArtifactAsync(
+            artifacts.TestAssetProxyOwner,
             provider,
             txDefaults,
             owners,
@@ -67,13 +68,17 @@ describe('AssetProxyOwner', () => {
             REQUIRED_APPROVALS,
             SECONDS_TIME_LOCKED,
         );
-        multiSigWrapper = new MultiSigWrapper(multiSig, provider);
+        multiSigWrapper = new MultiSigWrapper(testAssetProxyOwner, provider);
         await web3Wrapper.awaitTransactionSuccessAsync(
-            await erc20Proxy.transferOwnership.sendTransactionAsync(multiSig.address, { from: initialOwner }),
+            await erc20Proxy.transferOwnership.sendTransactionAsync(testAssetProxyOwner.address, {
+                from: initialOwner,
+            }),
             constants.AWAIT_TRANSACTION_MINED_MS,
         );
         await web3Wrapper.awaitTransactionSuccessAsync(
-            await erc721Proxy.transferOwnership.sendTransactionAsync(multiSig.address, { from: initialOwner }),
+            await erc721Proxy.transferOwnership.sendTransactionAsync(testAssetProxyOwner.address, {
+                from: initialOwner,
+            }),
             constants.AWAIT_TRANSACTION_MINED_MS,
         );
     });
@@ -117,24 +122,28 @@ describe('AssetProxyOwner', () => {
         });
     });
 
-    describe('isFunctionRemoveAuthorizedAddress', () => {
-        it('should throw if data is not for removeAuthorizedAddress', async () => {
+    describe('isFunctionRemoveAuthorizedAddressAtIndex', () => {
+        it('should return false if data is not for removeAuthorizedAddressAtIndex', async () => {
             const notRemoveAuthorizedAddressData = erc20Proxy.addAuthorizedAddress.getABIEncodedTransactionData(
                 owners[0],
             );
-            return expectRevertOrContractCallFailedAsync(
-                multiSig.isFunctionRemoveAuthorizedAddress.callAsync(notRemoveAuthorizedAddressData),
+
+            const isFunctionRemoveAuthorizedAddressAtIndex = await testAssetProxyOwner.isFunctionRemoveAuthorizedAddressAtIndex.callAsync(
+                notRemoveAuthorizedAddressData,
             );
+            expect(isFunctionRemoveAuthorizedAddressAtIndex).to.be.false();
         });
 
-        it('should return true if data is for removeAuthorizedAddress', async () => {
-            const removeAuthorizedAddressData = erc20Proxy.removeAuthorizedAddress.getABIEncodedTransactionData(
+        it('should return true if data is for removeAuthorizedAddressAtIndex', async () => {
+            const index = new BigNumber(0);
+            const removeAuthorizedAddressAtIndexData = erc20Proxy.removeAuthorizedAddressAtIndex.getABIEncodedTransactionData(
                 owners[0],
+                index,
             );
-            const isFunctionRemoveAuthorizedAddress = await multiSig.isFunctionRemoveAuthorizedAddress.callAsync(
-                removeAuthorizedAddressData,
+            const isFunctionRemoveAuthorizedAddressAtIndex = await testAssetProxyOwner.isFunctionRemoveAuthorizedAddressAtIndex.callAsync(
+                removeAuthorizedAddressAtIndexData,
             );
-            expect(isFunctionRemoveAuthorizedAddress).to.be.true();
+            expect(isFunctionRemoveAuthorizedAddressAtIndex).to.be.true();
         });
     });
 
@@ -142,19 +151,21 @@ describe('AssetProxyOwner', () => {
         it('should throw if not called by multisig', async () => {
             const isRegistered = true;
             return expectRevertOrAlwaysFailingTransactionAsync(
-                multiSig.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, isRegistered, { from: owners[0] }),
+                testAssetProxyOwner.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, isRegistered, {
+                    from: owners[0],
+                }),
             );
         });
 
         it('should register an address if called by multisig after timelock', async () => {
             const addressToRegister = erc20Proxy.address;
             const isRegistered = true;
-            const registerAssetProxyData = multiSig.registerAssetProxy.getABIEncodedTransactionData(
+            const registerAssetProxyData = testAssetProxyOwner.registerAssetProxy.getABIEncodedTransactionData(
                 addressToRegister,
                 isRegistered,
             );
             const submitTxRes = await multiSigWrapper.submitTransactionAsync(
-                multiSig.address,
+                testAssetProxyOwner.address,
                 registerAssetProxyData,
                 owners[0],
             );
@@ -170,19 +181,21 @@ describe('AssetProxyOwner', () => {
             expect(registerLog.args.assetProxyContract).to.equal(addressToRegister);
             expect(registerLog.args.isRegistered).to.equal(isRegistered);
 
-            const isAssetProxyRegistered = await multiSig.isAssetProxyRegistered.callAsync(addressToRegister);
+            const isAssetProxyRegistered = await testAssetProxyOwner.isAssetProxyRegistered.callAsync(
+                addressToRegister,
+            );
             expect(isAssetProxyRegistered).to.equal(isRegistered);
         });
 
         it('should fail if registering a null address', async () => {
             const addressToRegister = constants.NULL_ADDRESS;
             const isRegistered = true;
-            const registerAssetProxyData = multiSig.registerAssetProxy.getABIEncodedTransactionData(
+            const registerAssetProxyData = testAssetProxyOwner.registerAssetProxy.getABIEncodedTransactionData(
                 addressToRegister,
                 isRegistered,
             );
             const submitTxRes = await multiSigWrapper.submitTransactionAsync(
-                multiSig.address,
+                testAssetProxyOwner.address,
                 registerAssetProxyData,
                 owners[0],
             );
@@ -196,22 +209,26 @@ describe('AssetProxyOwner', () => {
             const failureLog = executeTxRes.logs[0] as LogWithDecodedArgs<ExecutionFailureContractEventArgs>;
             expect(failureLog.args.transactionId).to.be.bignumber.equal(txId);
 
-            const isAssetProxyRegistered = await multiSig.isAssetProxyRegistered.callAsync(addressToRegister);
+            const isAssetProxyRegistered = await testAssetProxyOwner.isAssetProxyRegistered.callAsync(
+                addressToRegister,
+            );
             expect(isAssetProxyRegistered).to.equal(false);
         });
     });
 
-    describe('executeRemoveAuthorizedAddress', () => {
+    describe('Calling removeAuthorizedAddressAtIndex', () => {
+        const erc20Index = new BigNumber(0);
+        const erc721Index = new BigNumber(1);
         before('authorize both proxies and register erc20 proxy', async () => {
             // Only register ERC20 proxy
             const addressToRegister = erc20Proxy.address;
             const isRegistered = true;
-            const registerAssetProxyData = multiSig.registerAssetProxy.getABIEncodedTransactionData(
+            const registerAssetProxyData = testAssetProxyOwner.registerAssetProxy.getABIEncodedTransactionData(
                 addressToRegister,
                 isRegistered,
             );
             const registerAssetProxySubmitRes = await multiSigWrapper.submitTransactionAsync(
-                multiSig.address,
+                testAssetProxyOwner.address,
                 registerAssetProxyData,
                 owners[0],
             );
@@ -248,113 +265,180 @@ describe('AssetProxyOwner', () => {
             await multiSigWrapper.executeTransactionAsync(erc721AddAuthorizedAddressTxId, owners[0]);
         });
 
-        it('should throw without the required confirmations', async () => {
-            const removeAuthorizedAddressData = erc20Proxy.removeAuthorizedAddress.getABIEncodedTransactionData(
-                authorized,
-            );
-            const res = await multiSigWrapper.submitTransactionAsync(
-                erc20Proxy.address,
-                removeAuthorizedAddressData,
-                owners[0],
-            );
-            const log = res.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
-            const txId = log.args.transactionId;
-
-            return expectRevertOrAlwaysFailingTransactionAsync(
-                multiSig.executeRemoveAuthorizedAddress.sendTransactionAsync(txId, { from: owners[1] }),
-            );
-        });
-
-        it('should throw if tx destination is not registered', async () => {
-            const removeAuthorizedAddressData = erc721Proxy.removeAuthorizedAddress.getABIEncodedTransactionData(
-                authorized,
-            );
-            const res = await multiSigWrapper.submitTransactionAsync(
-                erc721Proxy.address,
-                removeAuthorizedAddressData,
-                owners[0],
-            );
-            const log = res.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
-            const txId = log.args.transactionId;
-
-            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
-
-            return expectRevertOrAlwaysFailingTransactionAsync(
-                multiSig.executeRemoveAuthorizedAddress.sendTransactionAsync(txId, { from: owners[1] }),
-            );
-        });
-
-        it('should throw if tx data is not for removeAuthorizedAddress', async () => {
-            const newAuthorized = owners[1];
-            const addAuthorizedAddressData = erc20Proxy.addAuthorizedAddress.getABIEncodedTransactionData(
-                newAuthorized,
-            );
-            const res = await multiSigWrapper.submitTransactionAsync(
-                erc20Proxy.address,
-                addAuthorizedAddressData,
-                owners[0],
-            );
-            const log = res.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
-            const txId = log.args.transactionId;
-
-            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
-
-            return expectRevertOrAlwaysFailingTransactionAsync(
-                multiSig.executeRemoveAuthorizedAddress.sendTransactionAsync(txId, { from: owners[1] }),
-            );
-        });
-
-        it('should execute removeAuthorizedAddress for registered address if fully confirmed', async () => {
-            const removeAuthorizedAddressData = erc20Proxy.removeAuthorizedAddress.getABIEncodedTransactionData(
-                authorized,
-            );
-            const submitRes = await multiSigWrapper.submitTransactionAsync(
-                erc20Proxy.address,
-                removeAuthorizedAddressData,
-                owners[0],
-            );
-            const submitLog = submitRes.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
-            const txId = submitLog.args.transactionId;
-
-            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
-
-            const execRes = await multiSigWrapper.executeRemoveAuthorizedAddressAsync(txId, owners[0]);
-            const execLog = execRes.logs[0] as LogWithDecodedArgs<ExecutionContractEventArgs>;
-            expect(execLog.args.transactionId).to.be.bignumber.equal(txId);
-
-            const tx = await multiSig.transactions.callAsync(txId);
-            const isExecuted = tx[3];
-            expect(isExecuted).to.equal(true);
-
-            const isAuthorized = await erc20Proxy.authorized.callAsync(authorized);
-            expect(isAuthorized).to.equal(false);
+        describe('validRemoveAuthorizedAddressAtIndexTx', () => {
+            it('should revert if data is not for removeAuthorizedAddressAtIndex and proxy is registered', async () => {
+                const notRemoveAuthorizedAddressData = erc20Proxy.addAuthorizedAddress.getABIEncodedTransactionData(
+                    authorized,
+                );
+                const submitTxRes = await multiSigWrapper.submitTransactionAsync(
+                    erc20Proxy.address,
+                    notRemoveAuthorizedAddressData,
+                    owners[0],
+                );
+                const log = submitTxRes.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
+                const txId = log.args.transactionId;
+                return expectRevertOrContractCallFailedAsync(
+                    testAssetProxyOwner.testValidRemoveAuthorizedAddressAtIndexTx.callAsync(txId),
+                );
+            });
+
+            it('should return true if data is for removeAuthorizedAddressAtIndex and proxy is registered', async () => {
+                const removeAuthorizedAddressAtIndexData = erc20Proxy.removeAuthorizedAddressAtIndex.getABIEncodedTransactionData(
+                    authorized,
+                    erc20Index,
+                );
+                const submitTxRes = await multiSigWrapper.submitTransactionAsync(
+                    erc20Proxy.address,
+                    removeAuthorizedAddressAtIndexData,
+                    owners[0],
+                );
+                const log = submitTxRes.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
+                const txId = log.args.transactionId;
+                const isValidRemoveAuthorizedAddressAtIndexTx = await testAssetProxyOwner.testValidRemoveAuthorizedAddressAtIndexTx.callAsync(
+                    txId,
+                );
+                expect(isValidRemoveAuthorizedAddressAtIndexTx).to.be.true();
+            });
+
+            it('should revert if data is for removeAuthorizedAddressAtIndex and proxy is not registered', async () => {
+                const removeAuthorizedAddressAtIndexData = erc721Proxy.removeAuthorizedAddressAtIndex.getABIEncodedTransactionData(
+                    authorized,
+                    erc721Index,
+                );
+                const submitTxRes = await multiSigWrapper.submitTransactionAsync(
+                    erc721Proxy.address,
+                    removeAuthorizedAddressAtIndexData,
+                    owners[0],
+                );
+                const log = submitTxRes.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
+                const txId = log.args.transactionId;
+                return expectRevertOrContractCallFailedAsync(
+                    testAssetProxyOwner.testValidRemoveAuthorizedAddressAtIndexTx.callAsync(txId),
+                );
+            });
         });
 
-        it('should throw if already executed', async () => {
-            const removeAuthorizedAddressData = erc20Proxy.removeAuthorizedAddress.getABIEncodedTransactionData(
-                authorized,
-            );
-            const submitRes = await multiSigWrapper.submitTransactionAsync(
-                erc20Proxy.address,
-                removeAuthorizedAddressData,
-                owners[0],
-            );
-            const submitLog = submitRes.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
-            const txId = submitLog.args.transactionId;
-
-            await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
-
-            const execRes = await multiSigWrapper.executeRemoveAuthorizedAddressAsync(txId, owners[0]);
-            const execLog = execRes.logs[0] as LogWithDecodedArgs<ExecutionContractEventArgs>;
-            expect(execLog.args.transactionId).to.be.bignumber.equal(txId);
-
-            const tx = await multiSig.transactions.callAsync(txId);
-            const isExecuted = tx[3];
-            expect(isExecuted).to.equal(true);
-
-            return expectRevertOrAlwaysFailingTransactionAsync(
-                multiSig.executeRemoveAuthorizedAddress.sendTransactionAsync(txId, { from: owners[1] }),
-            );
+        describe('executeRemoveAuthorizedAddressAtIndex', () => {
+            it('should throw without the required confirmations', async () => {
+                const removeAuthorizedAddressAtIndexData = erc20Proxy.removeAuthorizedAddressAtIndex.getABIEncodedTransactionData(
+                    authorized,
+                    erc20Index,
+                );
+                const res = await multiSigWrapper.submitTransactionAsync(
+                    erc20Proxy.address,
+                    removeAuthorizedAddressAtIndexData,
+                    owners[0],
+                );
+                const log = res.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
+                const txId = log.args.transactionId;
+
+                return expectRevertOrAlwaysFailingTransactionAsync(
+                    testAssetProxyOwner.executeRemoveAuthorizedAddressAtIndex.sendTransactionAsync(txId, {
+                        from: owners[1],
+                    }),
+                );
+            });
+
+            it('should throw if tx destination is not registered', async () => {
+                const removeAuthorizedAddressAtIndexData = erc721Proxy.removeAuthorizedAddressAtIndex.getABIEncodedTransactionData(
+                    authorized,
+                    erc721Index,
+                );
+                const res = await multiSigWrapper.submitTransactionAsync(
+                    erc721Proxy.address,
+                    removeAuthorizedAddressAtIndexData,
+                    owners[0],
+                );
+                const log = res.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
+                const txId = log.args.transactionId;
+
+                await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+
+                return expectRevertOrAlwaysFailingTransactionAsync(
+                    testAssetProxyOwner.executeRemoveAuthorizedAddressAtIndex.sendTransactionAsync(txId, {
+                        from: owners[1],
+                    }),
+                );
+            });
+
+            it('should throw if tx data is not for removeAuthorizedAddressAtIndex', async () => {
+                const newAuthorized = owners[1];
+                const addAuthorizedAddressData = erc20Proxy.addAuthorizedAddress.getABIEncodedTransactionData(
+                    newAuthorized,
+                );
+                const res = await multiSigWrapper.submitTransactionAsync(
+                    erc20Proxy.address,
+                    addAuthorizedAddressData,
+                    owners[0],
+                );
+                const log = res.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
+                const txId = log.args.transactionId;
+
+                await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+
+                return expectRevertOrAlwaysFailingTransactionAsync(
+                    testAssetProxyOwner.executeRemoveAuthorizedAddressAtIndex.sendTransactionAsync(txId, {
+                        from: owners[1],
+                    }),
+                );
+            });
+
+            it('should execute removeAuthorizedAddressAtIndex for registered address if fully confirmed', async () => {
+                const removeAuthorizedAddressAtIndexData = erc20Proxy.removeAuthorizedAddressAtIndex.getABIEncodedTransactionData(
+                    authorized,
+                    erc20Index,
+                );
+                const submitRes = await multiSigWrapper.submitTransactionAsync(
+                    erc20Proxy.address,
+                    removeAuthorizedAddressAtIndexData,
+                    owners[0],
+                );
+                const submitLog = submitRes.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
+                const txId = submitLog.args.transactionId;
+
+                await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+
+                const execRes = await multiSigWrapper.executeRemoveAuthorizedAddressAtIndexAsync(txId, owners[0]);
+                const execLog = execRes.logs[0] as LogWithDecodedArgs<ExecutionContractEventArgs>;
+                expect(execLog.args.transactionId).to.be.bignumber.equal(txId);
+
+                const tx = await testAssetProxyOwner.transactions.callAsync(txId);
+                const isExecuted = tx[3];
+                expect(isExecuted).to.equal(true);
+
+                const isAuthorized = await erc20Proxy.authorized.callAsync(authorized);
+                expect(isAuthorized).to.equal(false);
+            });
+
+            it('should throw if already executed', async () => {
+                const removeAuthorizedAddressAtIndexData = erc20Proxy.removeAuthorizedAddressAtIndex.getABIEncodedTransactionData(
+                    authorized,
+                    erc20Index,
+                );
+                const submitRes = await multiSigWrapper.submitTransactionAsync(
+                    erc20Proxy.address,
+                    removeAuthorizedAddressAtIndexData,
+                    owners[0],
+                );
+                const submitLog = submitRes.logs[0] as LogWithDecodedArgs<SubmissionContractEventArgs>;
+                const txId = submitLog.args.transactionId;
+
+                await multiSigWrapper.confirmTransactionAsync(txId, owners[1]);
+
+                const execRes = await multiSigWrapper.executeRemoveAuthorizedAddressAtIndexAsync(txId, owners[0]);
+                const execLog = execRes.logs[0] as LogWithDecodedArgs<ExecutionContractEventArgs>;
+                expect(execLog.args.transactionId).to.be.bignumber.equal(txId);
+
+                const tx = await testAssetProxyOwner.transactions.callAsync(txId);
+                const isExecuted = tx[3];
+                expect(isExecuted).to.equal(true);
+
+                return expectRevertOrAlwaysFailingTransactionAsync(
+                    testAssetProxyOwner.executeRemoveAuthorizedAddressAtIndex.sendTransactionAsync(txId, {
+                        from: owners[1],
+                    }),
+                );
+            });
         });
     });
 });
diff --git a/packages/contracts/test/libraries/lib_bytes.ts b/packages/contracts/test/libraries/lib_bytes.ts
index a31a4789c..56f1dc2bc 100644
--- a/packages/contracts/test/libraries/lib_bytes.ts
+++ b/packages/contracts/test/libraries/lib_bytes.ts
@@ -17,6 +17,12 @@ chaiSetup.configure();
 const expect = chai.expect;
 const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
 
+// BUG: Ideally we would use Buffer.from(memory).toString('hex')
+// https://github.com/Microsoft/TypeScript/issues/23155
+const toHex = (buf: Uint8Array): string => buf.reduce((a, v) => a + ('00' + v.toString(16)).slice(-2), '0x');
+
+const fromHex = (str: string): Uint8Array => Uint8Array.from(Buffer.from(str.slice(2), 'hex'));
+
 describe('LibBytes', () => {
     let libBytes: TestLibBytesContract;
     const byteArrayShorterThan32Bytes = '0x012345';
@@ -123,48 +129,55 @@ describe('LibBytes', () => {
         });
     });
 
-    describe('areBytesEqual', () => {
+    describe('equals', () => {
         it('should return true if byte arrays are equal (both arrays < 32 bytes)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayShorterThan32Bytes,
                 byteArrayShorterThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.true();
+            return expect(isEqual).to.be.true();
         });
         it('should return true if byte arrays are equal (both arrays > 32 bytes)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayLongerThan32Bytes,
                 byteArrayLongerThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.true();
+            return expect(isEqual).to.be.true();
         });
         it('should return false if byte arrays are not equal (first array < 32 bytes, second array > 32 bytes)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayShorterThan32Bytes,
                 byteArrayLongerThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.false();
+            return expect(isEqual).to.be.false();
         });
         it('should return false if byte arrays are not equal (first array > 32 bytes, second array < 32 bytes)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayLongerThan32Bytes,
                 byteArrayShorterThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.false();
+            return expect(isEqual).to.be.false();
         });
         it('should return false if byte arrays are not equal (same length, but a byte in first word differs)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayLongerThan32BytesFirstBytesSwapped,
                 byteArrayLongerThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.false();
+            return expect(isEqual).to.be.false();
         });
         it('should return false if byte arrays are not equal (same length, but a byte in last word differs)', async () => {
-            const areBytesEqual = await libBytes.publicAreBytesEqual.callAsync(
+            const isEqual = await libBytes.publicEquals.callAsync(
                 byteArrayLongerThan32BytesLastBytesSwapped,
                 byteArrayLongerThan32Bytes,
             );
-            return expect(areBytesEqual).to.be.false();
+            return expect(isEqual).to.be.false();
+        });
+
+        describe('should ignore trailing data', () => {
+            it('should return true when both < 32 bytes', async () => {
+                const isEqual = await libBytes.publicEqualsPop1.callAsync('0x0102', '0x0103');
+                return expect(isEqual).to.be.true();
+            });
         });
     });
 
@@ -443,26 +456,26 @@ describe('LibBytes', () => {
         });
     });
 
-    describe('readFirst4', () => {
+    describe('readBytes4', () => {
         // AssertionError: expected promise to be rejected with an error including 'revert' but it was fulfilled with '0x08c379a0'
         it('should revert if byte array has a length < 4', async () => {
             const byteArrayLessThan4Bytes = '0x010101';
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadFirst4.callAsync(byteArrayLessThan4Bytes),
+                libBytes.publicReadBytes4.callAsync(byteArrayLessThan4Bytes, new BigNumber(0)),
                 constants.LIB_BYTES_GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED,
             );
         });
         it('should return the first 4 bytes of a byte array of arbitrary length', async () => {
-            const first4Bytes = await libBytes.publicReadFirst4.callAsync(byteArrayLongerThan32Bytes);
+            const first4Bytes = await libBytes.publicReadBytes4.callAsync(byteArrayLongerThan32Bytes, new BigNumber(0));
             const expectedFirst4Bytes = byteArrayLongerThan32Bytes.slice(0, 10);
             expect(first4Bytes).to.equal(expectedFirst4Bytes);
         });
     });
 
-    describe('readBytes', () => {
+    describe('readBytesWithLength', () => {
         it('should successfully read short, nested array of bytes when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
-            const bytes = await libBytes.publicReadBytes.callAsync(shortTestBytes, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(shortTestBytes, testBytesOffset);
             return expect(bytes).to.be.equal(shortData);
         });
         it('should successfully read short, nested array of bytes when it is offset in the array', async () => {
@@ -470,12 +483,12 @@ describe('LibBytes', () => {
             const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, shortTestBytesAsBuffer]);
             const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
             const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
-            const bytes = await libBytes.publicReadBytes.callAsync(combinedByteArray, testUint256Offset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(combinedByteArray, testUint256Offset);
             return expect(bytes).to.be.equal(shortData);
         });
         it('should successfully read a nested array of bytes - one word in length - when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
-            const bytes = await libBytes.publicReadBytes.callAsync(wordOfTestBytes, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(wordOfTestBytes, testBytesOffset);
             return expect(bytes).to.be.equal(wordOfData);
         });
         it('should successfully read a nested array of bytes - one word in length - when it is offset in the array', async () => {
@@ -483,12 +496,12 @@ describe('LibBytes', () => {
             const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, wordOfTestBytesAsBuffer]);
             const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
             const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
-            const bytes = await libBytes.publicReadBytes.callAsync(combinedByteArray, testUint256Offset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(combinedByteArray, testUint256Offset);
             return expect(bytes).to.be.equal(wordOfData);
         });
         it('should successfully read long, nested array of bytes when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
-            const bytes = await libBytes.publicReadBytes.callAsync(longTestBytes, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(longTestBytes, testBytesOffset);
             return expect(bytes).to.be.equal(longData);
         });
         it('should successfully read long, nested array of bytes when it is offset in the array', async () => {
@@ -496,46 +509,50 @@ describe('LibBytes', () => {
             const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, longTestBytesAsBuffer]);
             const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
             const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
-            const bytes = await libBytes.publicReadBytes.callAsync(combinedByteArray, testUint256Offset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(combinedByteArray, testUint256Offset);
             return expect(bytes).to.be.equal(longData);
         });
         it('should fail if the byte array is too short to hold the length of a nested byte array', async () => {
             // The length of the nested array is 32 bytes. By storing less than 32 bytes, a length cannot be read.
             const offset = new BigNumber(0);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadBytes.callAsync(byteArrayShorterThan32Bytes, offset),
+                libBytes.publicReadBytesWithLength.callAsync(byteArrayShorterThan32Bytes, offset),
                 constants.LIB_BYTES_GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED,
             );
         });
         it('should fail if we store a nested byte array length, without a nested byte array', async () => {
             const offset = new BigNumber(0);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadBytes.callAsync(testBytes32, offset),
+                libBytes.publicReadBytesWithLength.callAsync(testBytes32, offset),
                 constants.LIB_BYTES_GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED,
             );
         });
         it('should fail if the length between the offset and end of the byte array is too short to hold the length of a nested byte array', async () => {
             const badOffset = new BigNumber(ethUtil.toBuffer(byteArrayShorterThan32Bytes).byteLength);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadBytes.callAsync(byteArrayShorterThan32Bytes, badOffset),
+                libBytes.publicReadBytesWithLength.callAsync(byteArrayShorterThan32Bytes, badOffset),
                 constants.LIB_BYTES_GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED,
             );
         });
         it('should fail if the length between the offset and end of the byte array is too short to hold the nested byte array', async () => {
             const badOffset = new BigNumber(ethUtil.toBuffer(testBytes32).byteLength);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicReadBytes.callAsync(testBytes32, badOffset),
+                libBytes.publicReadBytesWithLength.callAsync(testBytes32, badOffset),
                 constants.LIB_BYTES_GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED,
             );
         });
     });
 
-    describe('writeBytes', () => {
+    describe('writeBytesWithLength', () => {
         it('should successfully write short, nested array of bytes when it takes up the whole array)', async () => {
             const testBytesOffset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(shortTestBytesAsBuffer.byteLength));
-            const bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, testBytesOffset, shortData);
-            const bytesRead = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                testBytesOffset,
+                shortData,
+            );
+            const bytesRead = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytesRead).to.be.equal(shortData);
         });
         it('should successfully write short, nested array of bytes when it is offset in the array', async () => {
@@ -546,19 +563,31 @@ describe('LibBytes', () => {
             const emptyByteArray = ethUtil.bufferToHex(
                 new Buffer(prefixDataAsBuffer.byteLength + shortTestBytesAsBuffer.byteLength),
             );
-            let bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, prefixOffset, prefixData);
+            let bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                prefixOffset,
+                prefixData,
+            );
             // Write data after prefix
             const testBytesOffset = new BigNumber(prefixDataAsBuffer.byteLength);
-            bytesWritten = await libBytes.publicWriteBytes.callAsync(bytesWritten, testBytesOffset, shortData);
+            bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                bytesWritten,
+                testBytesOffset,
+                shortData,
+            );
             // Read data after prefix and validate
-            const bytes = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytes).to.be.equal(shortData);
         });
         it('should successfully write a nested array of bytes - one word in length - when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(wordOfTestBytesAsBuffer.byteLength));
-            const bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, testBytesOffset, wordOfData);
-            const bytesRead = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                testBytesOffset,
+                wordOfData,
+            );
+            const bytesRead = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytesRead).to.be.equal(wordOfData);
         });
         it('should successfully write a nested array of bytes - one word in length - when it is offset in the array', async () => {
@@ -569,19 +598,31 @@ describe('LibBytes', () => {
             const emptyByteArray = ethUtil.bufferToHex(
                 new Buffer(prefixDataAsBuffer.byteLength + wordOfTestBytesAsBuffer.byteLength),
             );
-            let bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, prefixOffset, prefixData);
+            let bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                prefixOffset,
+                prefixData,
+            );
             // Write data after prefix
             const testBytesOffset = new BigNumber(prefixDataAsBuffer.byteLength);
-            bytesWritten = await libBytes.publicWriteBytes.callAsync(bytesWritten, testBytesOffset, wordOfData);
+            bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                bytesWritten,
+                testBytesOffset,
+                wordOfData,
+            );
             // Read data after prefix and validate
-            const bytes = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytes).to.be.equal(wordOfData);
         });
         it('should successfully write a long, nested bytes when it takes up the whole array', async () => {
             const testBytesOffset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(longTestBytesAsBuffer.byteLength));
-            const bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, testBytesOffset, longData);
-            const bytesRead = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                testBytesOffset,
+                longData,
+            );
+            const bytesRead = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytesRead).to.be.equal(longData);
         });
         it('should successfully write long, nested array of bytes when it is offset in the array', async () => {
@@ -592,19 +633,23 @@ describe('LibBytes', () => {
             const emptyByteArray = ethUtil.bufferToHex(
                 new Buffer(prefixDataAsBuffer.byteLength + longTestBytesAsBuffer.byteLength),
             );
-            let bytesWritten = await libBytes.publicWriteBytes.callAsync(emptyByteArray, prefixOffset, prefixData);
+            let bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                prefixOffset,
+                prefixData,
+            );
             // Write data after prefix
             const testBytesOffset = new BigNumber(prefixDataAsBuffer.byteLength);
-            bytesWritten = await libBytes.publicWriteBytes.callAsync(bytesWritten, testBytesOffset, longData);
+            bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(bytesWritten, testBytesOffset, longData);
             // Read data after prefix and validate
-            const bytes = await libBytes.publicReadBytes.callAsync(bytesWritten, testBytesOffset);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
             return expect(bytes).to.be.equal(longData);
         });
         it('should fail if the byte array is too short to hold the length of a nested byte array', async () => {
             const offset = new BigNumber(0);
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(1));
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicWriteBytes.callAsync(emptyByteArray, offset, longData),
+                libBytes.publicWriteBytesWithLength.callAsync(emptyByteArray, offset, longData),
                 constants.LIB_BYTES_GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED,
             );
         });
@@ -612,10 +657,176 @@ describe('LibBytes', () => {
             const emptyByteArray = ethUtil.bufferToHex(new Buffer(shortTestBytesAsBuffer.byteLength));
             const badOffset = new BigNumber(ethUtil.toBuffer(shortTestBytesAsBuffer).byteLength);
             return expectRevertOrOtherErrorAsync(
-                libBytes.publicWriteBytes.callAsync(emptyByteArray, badOffset, shortData),
+                libBytes.publicWriteBytesWithLength.callAsync(emptyByteArray, badOffset, shortData),
                 constants.LIB_BYTES_GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED,
             );
         });
     });
+
+    describe('memCopy', () => {
+        // Create memory 0x000102...FF
+        const memSize = 256;
+        // tslint:disable:no-shadowed-variable
+        const memory = new Uint8Array(memSize).map((_, i) => i);
+        const memHex = toHex(memory);
+
+        // Reference implementation to test against
+        const refMemcpy = (mem: Uint8Array, dest: number, source: number, length: number): Uint8Array =>
+            Uint8Array.from(mem).copyWithin(dest, source, source + length);
+
+        // Test vectors: destination, source, length, job description
+        type Tests = Array<[number, number, number, string]>;
+
+        const test = (tests: Tests) =>
+            tests.forEach(([dest, source, length, job]) =>
+                it(job, async () => {
+                    const expected = refMemcpy(memory, dest, source, length);
+                    const resultStr = await libBytes.testMemcpy.callAsync(
+                        memHex,
+                        new BigNumber(dest),
+                        new BigNumber(source),
+                        new BigNumber(length),
+                    );
+                    const result = fromHex(resultStr);
+                    expect(result).to.deep.equal(expected);
+                }),
+            );
+
+        test([[0, 0, 0, 'copies zero bytes with overlap']]);
+
+        describe('copies forward', () =>
+            test([
+                [128, 0, 0, 'zero bytes'],
+                [128, 0, 1, 'one byte'],
+                [128, 0, 11, 'eleven bytes'],
+                [128, 0, 31, 'thirty-one bytes'],
+                [128, 0, 32, 'one word'],
+                [128, 0, 64, 'two words'],
+                [128, 0, 96, 'three words'],
+                [128, 0, 33, 'one word and one byte'],
+                [128, 0, 72, 'two words and eight bytes'],
+                [128, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward within one word', () =>
+            test([
+                [16, 0, 0, 'zero bytes'],
+                [16, 0, 1, 'one byte'],
+                [16, 0, 11, 'eleven bytes'],
+                [16, 0, 16, 'sixteen bytes'],
+            ]));
+
+        describe('copies forward with one byte overlap', () =>
+            test([
+                [0, 0, 1, 'one byte'],
+                [10, 0, 11, 'eleven bytes'],
+                [30, 0, 31, 'thirty-one bytes'],
+                [31, 0, 32, 'one word'],
+                [32, 0, 33, 'one word and one byte'],
+                [71, 0, 72, 'two words and eight bytes'],
+                [99, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with thirty-one bytes overlap', () =>
+            test([
+                [0, 0, 31, 'thirty-one bytes'],
+                [1, 0, 32, 'one word'],
+                [2, 0, 33, 'one word and one byte'],
+                [41, 0, 72, 'two words and eight bytes'],
+                [69, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with one word overlap', () =>
+            test([
+                [0, 0, 32, 'one word'],
+                [1, 0, 33, 'one word and one byte'],
+                [41, 0, 72, 'two words and eight bytes'],
+                [69, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with one word and one byte overlap', () =>
+            test([
+                [0, 0, 33, 'one word and one byte'],
+                [40, 0, 72, 'two words and eight bytes'],
+                [68, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with two words overlap', () =>
+            test([
+                [0, 0, 64, 'two words'],
+                [8, 0, 72, 'two words and eight bytes'],
+                [36, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward within one word and one byte overlap', () =>
+            test([[0, 0, 1, 'one byte'], [10, 0, 11, 'eleven bytes'], [15, 0, 16, 'sixteen bytes']]));
+
+        describe('copies backward', () =>
+            test([
+                [0, 128, 0, 'zero bytes'],
+                [0, 128, 1, 'one byte'],
+                [0, 128, 11, 'eleven bytes'],
+                [0, 128, 31, 'thirty-one bytes'],
+                [0, 128, 32, 'one word'],
+                [0, 128, 64, 'two words'],
+                [0, 128, 96, 'three words'],
+                [0, 128, 33, 'one word and one byte'],
+                [0, 128, 72, 'two words and eight bytes'],
+                [0, 128, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward within one word', () =>
+            test([
+                [0, 16, 0, 'zero bytes'],
+                [0, 16, 1, 'one byte'],
+                [0, 16, 11, 'eleven bytes'],
+                [0, 16, 16, 'sixteen bytes'],
+            ]));
+
+        describe('copies backward with one byte overlap', () =>
+            test([
+                [0, 0, 1, 'one byte'],
+                [0, 10, 11, 'eleven bytes'],
+                [0, 30, 31, 'thirty-one bytes'],
+                [0, 31, 32, 'one word'],
+                [0, 32, 33, 'one word and one byte'],
+                [0, 71, 72, 'two words and eight bytes'],
+                [0, 99, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with thirty-one bytes overlap', () =>
+            test([
+                [0, 0, 31, 'thirty-one bytes'],
+                [0, 1, 32, 'one word'],
+                [0, 2, 33, 'one word and one byte'],
+                [0, 41, 72, 'two words and eight bytes'],
+                [0, 69, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with one word overlap', () =>
+            test([
+                [0, 0, 32, 'one word'],
+                [0, 1, 33, 'one word and one byte'],
+                [0, 41, 72, 'two words and eight bytes'],
+                [0, 69, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with one word and one byte overlap', () =>
+            test([
+                [0, 0, 33, 'one word and one byte'],
+                [0, 40, 72, 'two words and eight bytes'],
+                [0, 68, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with two words overlap', () =>
+            test([
+                [0, 0, 64, 'two words'],
+                [0, 8, 72, 'two words and eight bytes'],
+                [0, 36, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward within one word and one byte overlap', () =>
+            test([[0, 0, 1, 'one byte'], [0, 10, 11, 'eleven bytes'], [0, 15, 16, 'sixteen bytes']]));
+    });
 });
 // tslint:disable:max-file-line-count
diff --git a/packages/contracts/test/libraries/lib_mem.ts b/packages/contracts/test/libraries/lib_mem.ts
deleted file mode 100644
index 00f7c4d8b..000000000
--- a/packages/contracts/test/libraries/lib_mem.ts
+++ /dev/null
@@ -1,190 +0,0 @@
-import { BigNumber } from '@0xproject/utils';
-import * as chai from 'chai';
-
-import { TestLibMemContract } from '../../src/generated_contract_wrappers/test_lib_mem';
-import { artifacts } from '../../src/utils/artifacts';
-import { chaiSetup } from '../../src/utils/chai_setup';
-import { provider, txDefaults } from '../../src/utils/web3_wrapper';
-
-chaiSetup.configure();
-const expect = chai.expect;
-
-// BUG: Ideally we would use Buffer.from(memory).toString('hex')
-// https://github.com/Microsoft/TypeScript/issues/23155
-const toHex = (buf: Uint8Array): string => buf.reduce((a, v) => a + ('00' + v.toString(16)).slice(-2), '0x');
-
-const fromHex = (str: string): Uint8Array => Uint8Array.from(Buffer.from(str.slice(2), 'hex'));
-
-describe('LibMem', () => {
-    let testLibMem: TestLibMemContract;
-
-    before(async () => {
-        // Deploy TestLibMem
-        testLibMem = await TestLibMemContract.deployFrom0xArtifactAsync(artifacts.TestLibMem, provider, txDefaults);
-    });
-
-    describe('memCopy', () => {
-        // Create memory 0x000102...FF
-        const memSize = 256;
-        const memory = new Uint8Array(memSize).map((_, i) => i);
-        const memHex = toHex(memory);
-
-        // Reference implementation to test against
-        const refMemcpy = (_mem: Uint8Array, dest: number, source: number, length: number): Uint8Array =>
-            Uint8Array.from(memory).copyWithin(dest, source, source + length);
-
-        // Test vectors: destination, source, length, job description
-        type Tests = Array<[number, number, number, string]>;
-
-        const test = (tests: Tests) =>
-            tests.forEach(([dest, source, length, job]) =>
-                it(job, async () => {
-                    const expected = refMemcpy(memory, dest, source, length);
-                    const resultStr = await testLibMem.testMemcpy.callAsync(
-                        memHex,
-                        new BigNumber(dest),
-                        new BigNumber(source),
-                        new BigNumber(length),
-                    );
-                    const result = fromHex(resultStr);
-                    expect(result).to.deep.equal(expected);
-                }),
-            );
-
-        test([[0, 0, 0, 'copies zero bytes with overlap']]);
-
-        describe('copies forward', () =>
-            test([
-                [128, 0, 0, 'zero bytes'],
-                [128, 0, 1, 'one byte'],
-                [128, 0, 11, 'eleven bytes'],
-                [128, 0, 31, 'thirty-one bytes'],
-                [128, 0, 32, 'one word'],
-                [128, 0, 64, 'two words'],
-                [128, 0, 96, 'three words'],
-                [128, 0, 33, 'one word and one byte'],
-                [128, 0, 72, 'two words and eight bytes'],
-                [128, 0, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies forward within one word', () =>
-            test([
-                [16, 0, 0, 'zero bytes'],
-                [16, 0, 1, 'one byte'],
-                [16, 0, 11, 'eleven bytes'],
-                [16, 0, 16, 'sixteen bytes'],
-            ]));
-
-        describe('copies forward with one byte overlap', () =>
-            test([
-                [0, 0, 1, 'one byte'],
-                [10, 0, 11, 'eleven bytes'],
-                [30, 0, 31, 'thirty-one bytes'],
-                [31, 0, 32, 'one word'],
-                [32, 0, 33, 'one word and one byte'],
-                [71, 0, 72, 'two words and eight bytes'],
-                [99, 0, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies forward with thirty-one bytes overlap', () =>
-            test([
-                [0, 0, 31, 'thirty-one bytes'],
-                [1, 0, 32, 'one word'],
-                [2, 0, 33, 'one word and one byte'],
-                [41, 0, 72, 'two words and eight bytes'],
-                [69, 0, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies forward with one word overlap', () =>
-            test([
-                [0, 0, 32, 'one word'],
-                [1, 0, 33, 'one word and one byte'],
-                [41, 0, 72, 'two words and eight bytes'],
-                [69, 0, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies forward with one word and one byte overlap', () =>
-            test([
-                [0, 0, 33, 'one word and one byte'],
-                [40, 0, 72, 'two words and eight bytes'],
-                [68, 0, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies forward with two words overlap', () =>
-            test([
-                [0, 0, 64, 'two words'],
-                [8, 0, 72, 'two words and eight bytes'],
-                [36, 0, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies forward within one word and one byte overlap', () =>
-            test([[0, 0, 1, 'one byte'], [10, 0, 11, 'eleven bytes'], [15, 0, 16, 'sixteen bytes']]));
-
-        describe('copies backward', () =>
-            test([
-                [0, 128, 0, 'zero bytes'],
-                [0, 128, 1, 'one byte'],
-                [0, 128, 11, 'eleven bytes'],
-                [0, 128, 31, 'thirty-one bytes'],
-                [0, 128, 32, 'one word'],
-                [0, 128, 64, 'two words'],
-                [0, 128, 96, 'three words'],
-                [0, 128, 33, 'one word and one byte'],
-                [0, 128, 72, 'two words and eight bytes'],
-                [0, 128, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies backward within one word', () =>
-            test([
-                [0, 16, 0, 'zero bytes'],
-                [0, 16, 1, 'one byte'],
-                [0, 16, 11, 'eleven bytes'],
-                [0, 16, 16, 'sixteen bytes'],
-            ]));
-
-        describe('copies backward with one byte overlap', () =>
-            test([
-                [0, 0, 1, 'one byte'],
-                [0, 10, 11, 'eleven bytes'],
-                [0, 30, 31, 'thirty-one bytes'],
-                [0, 31, 32, 'one word'],
-                [0, 32, 33, 'one word and one byte'],
-                [0, 71, 72, 'two words and eight bytes'],
-                [0, 99, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies backward with thirty-one bytes overlap', () =>
-            test([
-                [0, 0, 31, 'thirty-one bytes'],
-                [0, 1, 32, 'one word'],
-                [0, 2, 33, 'one word and one byte'],
-                [0, 41, 72, 'two words and eight bytes'],
-                [0, 69, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies backward with one word overlap', () =>
-            test([
-                [0, 0, 32, 'one word'],
-                [0, 1, 33, 'one word and one byte'],
-                [0, 41, 72, 'two words and eight bytes'],
-                [0, 69, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies backward with one word and one byte overlap', () =>
-            test([
-                [0, 0, 33, 'one word and one byte'],
-                [0, 40, 72, 'two words and eight bytes'],
-                [0, 68, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies backward with two words overlap', () =>
-            test([
-                [0, 0, 64, 'two words'],
-                [0, 8, 72, 'two words and eight bytes'],
-                [0, 36, 100, 'three words and four bytes'],
-            ]));
-
-        describe('copies forward within one word and one byte overlap', () =>
-            test([[0, 0, 1, 'one byte'], [0, 10, 11, 'eleven bytes'], [0, 15, 16, 'sixteen bytes']]));
-    });
-});