Merge branch 'v2-prototype' into eth-lightwallet-subprovider-final

36 files changed, 3908 insertions, 0 deletions

diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
new file mode 100644
index 000000000..aed62f54f
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
@@ -0,0 +1,132 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../utils/LibBytes/LibBytes.sol";
+import "./MixinAuthorizable.sol";
+
+contract ERC20Proxy is
+    MixinAuthorizable
+{
+    // Id of this proxy.
+    bytes4 constant PROXY_ID = bytes4(keccak256("ERC20Token(address)"));
+    
+    function () 
+        external
+    {
+        assembly {
+            // The first 4 bytes of calldata holds the function selector
+            let selector := and(calldataload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
+
+            // `transferFrom` will be called with the following parameters:
+            // assetData Encoded byte array.
+            // from Address to transfer asset from.
+            // to Address to transfer asset to.
+            // amount Amount of asset to transfer.
+            // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
+            if eq(selector, 0xa85e59e400000000000000000000000000000000000000000000000000000000) {
+
+                // To lookup a value in a mapping, we load from the storage location keccak256(k, p),
+                // where k is the key left padded to 32 bytes and p is the storage slot
+                let start := mload(64)
+                mstore(start, and(caller, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(start, 32), authorized_slot)
+
+                // Revert if authorized[msg.sender] == false
+                if iszero(sload(keccak256(start, 64))) {
+                    // Revert with `Error("SENDER_NOT_AUTHORIZED")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x0000001553454e4445525f4e4f545f415554484f52495a454400000000000000)
+                    mstore(96, 0)
+                    revert(0, 100)
+                }
+                
+                /////// Token contract address ///////
+                // The token address is found as follows:
+                // * It is stored at offset 4 in `assetData` contents.
+                // * This is stored at offset 32 from `assetData`.
+                // * The offset to `assetData` from Params is stored at offset
+                //   4 in calldata.
+                // * The offset of Params in calldata is 4.
+                // So we read location 4 and add 32 + 4 + 4 to it.
+                let token := calldataload(add(calldataload(4), 40))
+                
+                /////// Setup Header Area ///////
+                // This area holds the 4-byte `transferFrom` selector.
+                // Any trailing data in transferFromSelector will be
+                // overwritten in the next `mstore` call.
+                mstore(0, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
+                
+                /////// Setup Params Area ///////
+                // We copy the fields `from`, `to` and `amount` in bulk
+                // from our own calldata to the new calldata.
+                calldatacopy(4, 36, 96)
+
+                /////// Call `token.transferFrom` using the calldata ///////
+                let success := call(
+                    gas,            // forward all gas
+                    token,          // call address of token contract
+                    0,              // don't send any ETH
+                    0,              // pointer to start of input
+                    100,            // length of input
+                    0,              // write output over input
+                    32              // output size should be 32 bytes
+                )
+
+                /////// Check return data. ///////
+                // If there is no return data, we assume the token incorrectly
+                // does not return a bool. In this case we expect it to revert
+                // on failure, which was handled above.
+                // If the token does return data, we require that it is a single
+                // nonzero 32 bytes value.
+                // So the transfer succeeded if the call succeeded and either
+                // returned nothing, or returned a non-zero 32 byte value. 
+                success := and(success, or(
+                    iszero(returndatasize),
+                    and(
+                        eq(returndatasize, 32),
+                        gt(mload(0), 0)
+                    )
+                ))
+                if success {
+                    return(0, 0)
+                }
+                
+                // Revert with `Error("TRANSFER_FAILED")`
+                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
+                mstore(96, 0)
+                revert(0, 100)
+            }
+        }
+    }
+
+    /// @dev Gets the proxy id associated with the proxy address.
+    /// @return Proxy id.
+    function getProxyId()
+        external
+        pure
+        returns (bytes4)
+    {
+        return PROXY_ID;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
new file mode 100644
index 000000000..b73dc36cc
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
@@ -0,0 +1,218 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../utils/LibBytes/LibBytes.sol";
+import "./MixinAuthorizable.sol";
+
+contract ERC721Proxy is
+    MixinAuthorizable
+{
+    // Id of this proxy.
+    bytes4 constant PROXY_ID = bytes4(keccak256("ERC721Token(address,uint256,bytes)"));
+
+    function () 
+        external
+    {
+        assembly {
+            // The first 4 bytes of calldata holds the function selector
+            let selector := and(calldataload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
+
+            // `transferFrom` will be called with the following parameters:
+            // assetData Encoded byte array.
+            // from Address to transfer asset from.
+            // to Address to transfer asset to.
+            // amount Amount of asset to transfer.
+            // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
+            if eq(selector, 0xa85e59e400000000000000000000000000000000000000000000000000000000) {
+
+                // To lookup a value in a mapping, we load from the storage location keccak256(k, p),
+                // where k is the key left padded to 32 bytes and p is the storage slot
+                let start := mload(64)
+                mstore(start, and(caller, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(start, 32), authorized_slot)
+
+                // Revert if authorized[msg.sender] == false
+                if iszero(sload(keccak256(start, 64))) {
+                    // Revert with `Error("SENDER_NOT_AUTHORIZED")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x0000001553454e4445525f4e4f545f415554484f52495a454400000000000000)
+                    mstore(96, 0)
+                    revert(0, 100)
+                }
+
+                // `transferFrom`.
+                // The function is marked `external`, so no abi decodeding is done for
+                // us. Instead, we expect the `calldata` memory to contain the
+                // following:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 4 * 32  | function parameters:                |
+                // |          | 4      |         |   1. offset to assetData (*)        |
+                // |          | 36     |         |   2. from                           |
+                // |          | 68     |         |   3. to                             |
+                // |          | 100    |         |   4. amount                         |
+                // | Data     |        |         | assetData:                          |
+                // |          | 132    | 32      | assetData Length                    |
+                // |          | 164    | **      | assetData Contents                  |
+                //
+                // (*): offset is computed from start of function parameters, so offset
+                //      by an additional 4 bytes in the calldata.
+                //
+                // WARNING: The ABIv2 specification allows additional padding between
+                //          the Params and Data section. This will result in a larger
+                //          offset to assetData.
+                
+                // Asset data itself is encoded as follows:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 3 * 32  | function parameters:                |
+                // |          | 4      | 12 + 20 |   1. token address                  |
+                // |          | 36     |         |   2. tokenId                        |
+                // |          | 68     |         |   3. offset to receiverData (*)     |
+                // | Data     |        |         | receiverData:                       |
+                // |          | 100    | 32      | receiverData Length                 |
+                // |          | 132    | **      | receiverData Contents               |
+                
+                // We construct calldata for the `token.safeTransferFrom` ABI.
+                // The layout of this calldata is in the table below.
+                // 
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 4 * 32  | function parameters:                |
+                // |          | 4      |         |   1. from                           |
+                // |          | 36     |         |   2. to                             |
+                // |          | 68     |         |   3. tokenId                        |
+                // |          | 100    |         |   4. offset to receiverData (*)     |
+                // | Data     |        |         | receiverData:                       |
+                // |          | 132    | 32      | receiverData Length                 |
+                // |          | 164    | **      | receiverData Contents               |
+
+                // There exists only 1 of each token.
+                // require(amount == 1, "INVALID_AMOUNT")
+                if sub(calldataload(100), 1) {
+                    // Revert with `Error("INVALID_AMOUNT")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x0000000e494e56414c49445f414d4f554e540000000000000000000000000000)
+                    mstore(96, 0)
+                    revert(0, 100)
+                }
+                
+                // Require assetData to be at least 132 bytes
+                let offset := calldataload(4)
+                if lt(calldataload(add(offset, 4)), 132) {
+                    // Revert with `Error("LENGTH_GREATER_THAN_131_REQUIRED")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x000000204c454e4754485f475245415445525f5448414e5f3133315f52455155)
+                    mstore(96, 0x4952454400000000000000000000000000000000000000000000000000000000)
+                    revert(0, 100)
+                }
+                
+                /////// Setup State ///////
+                // `cdStart` is the start of the calldata for
+                // `token.safeTransferFrom` (equal to free memory ptr).
+                let cdStart := mload(64)
+                // `dataAreaLength` is the total number of words
+                // needed to store `receiverData`
+                // As-per the ABI spec, this value is padded up to
+                // the nearest multiple of 32,
+                // and includes 32-bytes for length.
+                // It's calculated as folows:
+                //      - Unpadded length in bytes = `mload(receiverData) + 32`
+                //      - Add 31 to convert rounding down to rounding up.
+                //        Combined with the previous and this is `63`.
+                //      - Round down to nearest multiple of 32 by clearing
+                //        bits 0x1F. This is done with `and` and a mask.
+
+                /////// Setup Header Area ///////
+                // This area holds the 4-byte `transferFromSelector`.
+                // Any trailing data in transferFromSelector will be
+                // overwritten in the next `mstore` call.
+                mstore(cdStart, 0xb88d4fde00000000000000000000000000000000000000000000000000000000)
+                
+                /////// Setup Params Area ///////
+                // Each parameter is padded to 32-bytes.
+                // The entire Params Area is 128 bytes.
+                // Notes:
+                //   1. A 20-byte mask is applied to addresses
+                //      to zero-out the unused bytes.
+                //   2. The offset to `receiverData` is the length
+                //      of the Params Area (128 bytes).
+                
+                let length := calldataload(add(offset, 136))
+                let token := calldataload(add(offset, 40))
+                
+                // Round length up to multiple of 32
+                length := and(add(length, 31), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE0)
+                
+                // Copy `from` and `to`
+                calldatacopy(add(cdStart, 4), 36, 64)
+                
+                // TokenId
+                mstore(add(cdStart, 68), calldataload(add(offset, 72)))
+                
+                // Offset to receiverData
+                mstore(add(cdStart, 100), 128)
+                
+                // receiverData (including length)
+                calldatacopy(add(cdStart, 132), add(offset, 136), add(length, 32))
+                
+                /////// Call `token.safeTransferFrom` using the calldata ///////
+                let success := call(
+                    gas,                    // forward all gas
+                    token,                  // call address of token contract
+                    0,                      // don't send any ETH
+                    cdStart,                // pointer to start of input
+                    add(length, 164),       // length of input
+                    0,                      // write output to null
+                    0                       // output size is 0 bytes
+                )
+                if success {
+                    return(0, 0)
+                }
+                
+                // Revert with `Error("TRANSFER_FAILED")`
+                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
+                mstore(96, 0)
+                revert(0, 100)
+            }
+        }
+    }
+
+    /// @dev Gets the proxy id associated with the proxy address.
+    /// @return Proxy id.
+    function getProxyId()
+        external
+        pure
+        returns (bytes4)
+    {
+        return PROXY_ID;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
new file mode 100644
index 000000000..3b9584a44
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
@@ -0,0 +1,118 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../utils/Ownable/Ownable.sol";
+import "./mixins/MAuthorizable.sol";
+
+contract MixinAuthorizable is
+    Ownable,
+    MAuthorizable
+{
+
+    /// @dev Only authorized addresses can invoke functions with this modifier.
+    modifier onlyAuthorized {
+        require(
+            authorized[msg.sender],
+            "SENDER_NOT_AUTHORIZED"
+        );
+        _;
+    }
+
+    mapping (address => bool) public authorized;
+    address[] public authorities;
+
+    /// @dev Authorizes an address.
+    /// @param target Address to authorize.
+    function addAuthorizedAddress(address target)
+        external
+        onlyOwner
+    {
+        require(
+            !authorized[target],
+            "TARGET_ALREADY_AUTHORIZED"
+        );
+
+        authorized[target] = true;
+        authorities.push(target);
+        emit AuthorizedAddressAdded(target, msg.sender);
+    }
+
+    /// @dev Removes authorizion of an address.
+    /// @param target Address to remove authorization from.
+    function removeAuthorizedAddress(address target)
+        external
+        onlyOwner
+    {
+        require(
+            authorized[target],
+            "TARGET_NOT_AUTHORIZED"
+        );
+
+        delete authorized[target];
+        for (uint256 i = 0; i < authorities.length; i++) {
+            if (authorities[i] == target) {
+                authorities[i] = authorities[authorities.length - 1];
+                authorities.length -= 1;
+                break;
+            }
+        }
+        emit AuthorizedAddressRemoved(target, msg.sender);
+    }
+
+    /// @dev Removes authorizion of an address.
+    /// @param target Address to remove authorization from.
+    /// @param index Index of target in authorities array.
+    function removeAuthorizedAddressAtIndex(
+        address target,
+        uint256 index
+    )
+        external
+        onlyOwner
+    {
+        require(
+            authorized[target],
+            "TARGET_NOT_AUTHORIZED"
+        );
+        require(
+            index < authorities.length,
+            "INDEX_OUT_OF_BOUNDS"
+        );
+        require(
+            authorities[index] == target,
+            "AUTHORIZED_ADDRESS_MISMATCH"
+        );
+
+        delete authorized[target];
+        authorities[index] = authorities[authorities.length - 1];
+        authorities.length -= 1;
+        emit AuthorizedAddressRemoved(target, msg.sender);
+    }
+
+    /// @dev Gets all authorized addresses.
+    /// @return Array of authorized addresses.
+    function getAuthorizedAddresses()
+        external
+        view
+        returns (address[] memory)
+    {
+        return authorities;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetData.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetData.sol
new file mode 100644
index 000000000..7ebd6acf0
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetData.sol
@@ -0,0 +1,38 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.23;
+
+// @dev Interface of the asset proxy's assetData.
+// The asset proxies take an ABI encoded `bytes assetData` as argument.
+// This argument is ABI encoded as one of the methods of this interface.
+interface IAssetData {
+    
+    function ERC20Token(address tokenContract)
+        external
+        pure;
+    
+    function ERC721Token(
+        address tokenContract,
+        uint256 tokenId,
+        bytes receiverData
+    )
+        external
+        pure;
+    
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
new file mode 100644
index 000000000..eacd5a412
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
@@ -0,0 +1,47 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./IAuthorizable.sol";
+
+contract IAssetProxy is
+    IAuthorizable
+{
+
+    /// @dev Transfers assets. Either succeeds or throws.
+    /// @param assetData Byte array encoded for the respective asset proxy.
+    /// @param from Address to transfer asset from.
+    /// @param to Address to transfer asset to.
+    /// @param amount Amount of asset to transfer.
+    function transferFrom(
+        bytes assetData,
+        address from,
+        address to,
+        uint256 amount
+    )
+        external;
+    
+    /// @dev Gets the proxy id associated with the proxy address.
+    /// @return Proxy id.
+    function getProxyId()
+        external
+        pure
+        returns (bytes4);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
new file mode 100644
index 000000000..cedd1744c
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
@@ -0,0 +1,53 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../../utils/Ownable/IOwnable.sol";
+
+contract IAuthorizable is
+    IOwnable
+{
+
+    /// @dev Gets all authorized addresses.
+    /// @return Array of authorized addresses.
+    function getAuthorizedAddresses()
+        external
+        view
+        returns (address[]);
+
+    /// @dev Authorizes an address.
+    /// @param target Address to authorize.
+    function addAuthorizedAddress(address target)
+        external;
+
+    /// @dev Removes authorizion of an address.
+    /// @param target Address to remove authorization from.
+    function removeAuthorizedAddress(address target)
+        external;
+
+    /// @dev Removes authorizion of an address.
+    /// @param target Address to remove authorization from.
+    /// @param index Index of target in authorities array.
+    function removeAuthorizedAddressAtIndex(
+        address target,
+        uint256 index
+    )
+        external;
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/libs/LibAssetProxyErrors.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
new file mode 100644
index 000000000..338cb12e2
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
@@ -0,0 +1,36 @@
+/*
+
+  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;
+
+/// @dev This contract documents the revert reasons used in the AssetProxy contracts.
+/// This contract is intended to serve as a reference, but is not actually used for efficiency reasons.
+contract LibAssetProxyErrors {
+
+    /// Authorizable errors ///
+    string constant SENDER_NOT_AUTHORIZED = "SENDER_NOT_AUTHORIZED";                        // Sender not authorized to call this method.
+    string constant TARGET_NOT_AUTHORIZED = "TARGET_NOT_AUTHORIZED";                        // Target address not authorized to call this method.
+    string constant TARGET_ALREADY_AUTHORIZED = "TARGET_ALREADY_AUTHORIZED";                // Target address must not already be authorized.
+    string constant INDEX_OUT_OF_BOUNDS = "INDEX_OUT_OF_BOUNDS";                            // Specified array index is out of bounds.
+    string constant AUTHORIZED_ADDRESS_MISMATCH = "AUTHORIZED_ADDRESS_MISMATCH";            // Address at index does not match given target address.
+
+    /// Transfer errors ///
+    string constant INVALID_AMOUNT = "INVALID_AMOUNT";                                      // Transfer amount must equal 1.
+    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                                    // Transfer failed.
+    string constant LENGTH_GREATER_THAN_131_REQUIRED = "LENGTH_GREATER_THAN_131_REQUIRED";  // Byte array must have a length greater than 0.
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
new file mode 100644
index 000000000..6f35bd7ec
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
@@ -0,0 +1,42 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../interfaces/IAuthorizable.sol";
+
+contract MAuthorizable is
+    IAuthorizable
+{
+
+    // Event logged when a new address is authorized.
+    event AuthorizedAddressAdded(
+        address indexed target,
+        address indexed caller
+    );
+
+    // Event logged when a currently authorized address is unauthorized.
+    event AuthorizedAddressRemoved(
+        address indexed target,
+        address indexed caller
+    );
+
+    /// @dev Only authorized addresses can invoke functions with this modifier.
+    modifier onlyAuthorized { revert(); _; }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
new file mode 100644
index 000000000..eb58b3374
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
@@ -0,0 +1,98 @@
+/*
+
+  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 ^0.4.10;
+
+import "../../multisig/MultiSigWalletWithTimeLock.sol";
+import "../../utils/LibBytes/LibBytes.sol";
+
+contract AssetProxyOwner is
+    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 `removeAuthorizedAddressAtIndex` method without a time lock.
+    mapping (address => bool) public isAssetProxyRegistered;
+
+    bytes4 constant REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR = bytes4(keccak256("removeAuthorizedAddressAtIndex(address,uint256)"));
+
+    /// @dev Function will revert if the transaction does not call `removeAuthorizedAddressAtIndex`
+    ///      on an approved AssetProxy contract.
+    modifier validRemoveAuthorizedAddressAtIndexTx(uint256 transactionId) {
+        Transaction storage tx = transactions[transactionId];
+        require(isAssetProxyRegistered[tx.destination]);
+        require(tx.data.readBytes4(0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR);
+        _;
+    }
+
+    /// @dev Contract constructor sets initial owners, required number of confirmations,
+    ///      time lock, and list of AssetProxy addresses.
+    /// @param _owners List of initial owners.
+    /// @param _assetProxyContracts Array of AssetProxy contract addresses.
+    /// @param _required Number of required confirmations.
+    /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
+    function AssetProxyOwner(
+        address[] memory _owners,
+        address[] memory _assetProxyContracts,
+        uint256 _required,
+        uint256 _secondsTimeLocked
+    )
+        public
+        MultiSigWalletWithTimeLock(_owners, _required, _secondsTimeLocked)
+    {
+        for (uint256 i = 0; i < _assetProxyContracts.length; i++) {
+            address assetProxy = _assetProxyContracts[i];
+            require(assetProxy != address(0));
+            isAssetProxyRegistered[assetProxy] = true;
+        }
+    }
+
+    /// @dev Registers or deregisters an AssetProxy to be able to execute
+    ///      `removeAuthorizedAddressAtIndex` without a timelock.
+    /// @param assetProxyContract Address of AssetProxy contract.
+    /// @param isRegistered Status of approval for AssetProxy contract.
+    function registerAssetProxy(address assetProxyContract, bool isRegistered)
+        public
+        onlyWallet
+        notNull(assetProxyContract)
+    {
+        isAssetProxyRegistered[assetProxyContract] = isRegistered;
+        AssetProxyRegistration(assetProxyContract, isRegistered);
+    }
+
+    /// @dev Allows execution of `removeAuthorizedAddressAtIndex` without time lock.
+    /// @param transactionId Transaction ID.
+    function executeRemoveAuthorizedAddressAtIndex(uint256 transactionId)
+        public
+        notExecuted(transactionId)
+        fullyConfirmed(transactionId)
+        validRemoveAuthorizedAddressAtIndexTx(transactionId)
+    {
+        Transaction storage tx = transactions[transactionId];
+        tx.executed = true;
+        if (tx.destination.call.value(tx.value)(tx.data))
+            Execution(transactionId);
+        else {
+            ExecutionFailure(transactionId);
+            tx.executed = false;
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
new file mode 100644
index 000000000..d36e9633e
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
@@ -0,0 +1,52 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibConstants.sol";
+import "./MixinExchangeCore.sol";
+import "./MixinSignatureValidator.sol";
+import "./MixinWrapperFunctions.sol";
+import "./MixinAssetProxyDispatcher.sol";
+import "./MixinTransactions.sol";
+import "./MixinMatchOrders.sol";
+
+contract Exchange is
+    MixinExchangeCore,
+    MixinMatchOrders,
+    MixinSignatureValidator,
+    MixinTransactions,
+    MixinAssetProxyDispatcher,
+    MixinWrapperFunctions
+{
+
+    string constant public VERSION = "2.0.1-alpha";
+
+    // Mixins are instantiated in the order they are inherited
+    constructor (bytes memory _zrxAssetData)
+        public
+        LibConstants(_zrxAssetData) // @TODO: Remove when we deploy.
+        MixinExchangeCore()
+        MixinMatchOrders()
+        MixinSignatureValidator()
+        MixinTransactions()
+        MixinAssetProxyDispatcher()
+        MixinWrapperFunctions()
+    {}
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
new file mode 100644
index 000000000..9e9d88ce7
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
@@ -0,0 +1,175 @@
+/*
+
+  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/Ownable/Ownable.sol";
+import "../../utils/LibBytes/LibBytes.sol";
+import "./mixins/MAssetProxyDispatcher.sol";
+import "../AssetProxy/interfaces/IAssetProxy.sol";
+
+contract MixinAssetProxyDispatcher is
+    Ownable,
+    MAssetProxyDispatcher
+{
+    using LibBytes for bytes;
+    
+    // Mapping from Asset Proxy Id's to their respective Asset Proxy
+    mapping (bytes4 => IAssetProxy) public assetProxies;
+
+    /// @dev Registers an asset proxy to its asset proxy id.
+    ///      Once an asset proxy is registered, it cannot be unregistered.
+    /// @param assetProxy Address of new asset proxy to register.
+    function registerAssetProxy(address assetProxy)
+        external
+        onlyOwner
+    {
+        IAssetProxy assetProxyContract = IAssetProxy(assetProxy);
+
+        // Ensure that no asset proxy exists with current id.
+        bytes4 assetProxyId = assetProxyContract.getProxyId();
+        address currentAssetProxy = assetProxies[assetProxyId];
+        require(
+            currentAssetProxy == address(0),
+            "ASSET_PROXY_ALREADY_EXISTS"
+        );
+
+        // Add asset proxy and log registration.
+        assetProxies[assetProxyId] = assetProxyContract;
+        emit AssetProxyRegistered(
+            assetProxyId,
+            assetProxy
+        );
+    }
+
+    /// @dev Gets an asset proxy.
+    /// @param assetProxyId Id of the asset proxy.
+    /// @return The asset proxy registered to assetProxyId. Returns 0x0 if no proxy is registered.
+    function getAssetProxy(bytes4 assetProxyId)
+        external
+        view
+        returns (address)
+    {
+        return assetProxies[assetProxyId];
+    }
+
+    /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
+    /// @param assetData Byte array encoded for the asset.
+    /// @param from Address to transfer token from.
+    /// @param to Address to transfer token to.
+    /// @param amount Amount of token to transfer.
+    function dispatchTransferFrom(
+        bytes memory assetData,
+        address from,
+        address to,
+        uint256 amount
+    )
+        internal
+    {
+        // Do nothing if no amount should be transferred.
+        if (amount > 0) {
+            // Ensure assetData length is valid
+            require(
+                assetData.length > 3,
+                "LENGTH_GREATER_THAN_3_REQUIRED"
+            );
+            
+            // Lookup assetProxy
+            bytes4 assetProxyId;
+            assembly {
+                assetProxyId := and(mload(
+                    add(assetData, 32)),
+                    0xFFFFFFFF00000000000000000000000000000000000000000000000000000000
+                )
+            }
+            address assetProxy = assetProxies[assetProxyId];
+
+            // Ensure that assetProxy exists
+            require(
+                assetProxy != address(0),
+                "ASSET_PROXY_DOES_NOT_EXIST"
+            );
+            
+            // We construct calldata for the `assetProxy.transferFrom` ABI.
+            // The layout of this calldata is in the table below.
+            // 
+            // | Area     | Offset | Length  | Contents                                    |
+            // | -------- |--------|---------|-------------------------------------------- |
+            // | Header   | 0      | 4       | function selector                           |
+            // | Params   |        | 4 * 32  | function parameters:                        |
+            // |          | 4      |         |   1. offset to assetData (*)                |
+            // |          | 36     |         |   2. from                                   |
+            // |          | 68     |         |   3. to                                     |
+            // |          | 100    |         |   4. amount                                 |
+            // | Data     |        |         | assetData:                                  |
+            // |          | 132    | 32      | assetData Length                            |
+            // |          | 164    | **      | assetData Contents                          |
+
+            assembly {
+                /////// Setup State ///////
+                // `cdStart` is the start of the calldata for `assetProxy.transferFrom` (equal to free memory ptr).
+                let cdStart := mload(64)
+                // `dataAreaLength` is the total number of words needed to store `assetData`
+                //  As-per the ABI spec, this value is padded up to the nearest multiple of 32,
+                //  and includes 32-bytes for length.
+                let dataAreaLength := and(add(mload(assetData), 63), 0xFFFFFFFFFFFE0)
+                // `cdEnd` is the end of the calldata for `assetProxy.transferFrom`.
+                let cdEnd := add(cdStart, add(132, dataAreaLength))
+
+                
+                /////// Setup Header Area ///////
+                // This area holds the 4-byte `transferFromSelector`.
+                // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
+                mstore(cdStart, 0xa85e59e400000000000000000000000000000000000000000000000000000000)
+                
+                /////// Setup Params Area ///////
+                // Each parameter is padded to 32-bytes. The entire Params Area is 128 bytes.
+                // Notes:
+                //   1. The offset to `assetData` is the length of the Params Area (128 bytes).
+                //   2. A 20-byte mask is applied to addresses to zero-out the unused bytes.
+                mstore(add(cdStart, 4), 128)
+                mstore(add(cdStart, 36), and(from, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(cdStart, 68), and(to, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(cdStart, 100), amount)
+                
+                /////// Setup Data Area ///////
+                // This area holds `assetData`.
+                let dataArea := add(cdStart, 132)
+                for {} lt(dataArea, cdEnd) {} {
+                    mstore(dataArea, mload(assetData))
+                    dataArea := add(dataArea, 32)
+                    assetData := add(assetData, 32)
+                }
+
+                /////// Call `assetProxy.transferFrom` using the constructed calldata ///////
+                let success := call(
+                    gas,                    // forward all gas
+                    assetProxy,             // call address of asset proxy
+                    0,                      // don't send any ETH
+                    cdStart,                // pointer to start of input
+                    sub(cdEnd, cdStart),    // length of input  
+                    cdStart,                // write output over input
+                    512                     // reserve 512 bytes for output
+                )
+                if iszero(success) {
+                    revert(cdStart, returndatasize())
+                }
+            }
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
new file mode 100644
index 000000000..c0ed023ac
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
@@ -0,0 +1,436 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibConstants.sol";
+import "./libs/LibFillResults.sol";
+import "./libs/LibOrder.sol";
+import "./libs/LibMath.sol";
+import "./mixins/MExchangeCore.sol";
+import "./mixins/MSignatureValidator.sol";
+import "./mixins/MTransactions.sol";
+import "./mixins/MAssetProxyDispatcher.sol";
+
+contract MixinExchangeCore is
+    LibConstants,
+    LibMath,
+    LibOrder,
+    LibFillResults,
+    MAssetProxyDispatcher,
+    MExchangeCore,
+    MSignatureValidator,
+    MTransactions
+{
+    // Mapping of orderHash => amount of takerAsset already bought by maker
+    mapping (bytes32 => uint256) public filled;
+
+    // Mapping of orderHash => cancelled
+    mapping (bytes32 => bool) public cancelled;
+
+    // Mapping of makerAddress => senderAddress => lowest salt an order can have in order to be fillable
+    // Orders with specified senderAddress and with a salt less than their epoch to are considered cancelled
+    mapping (address => mapping (address => uint256)) public orderEpoch;
+
+    ////// Core exchange functions //////
+
+    /// @dev Cancels all orders created by makerAddress with a salt less than or equal to the targetOrderEpoch
+    ///      and senderAddress equal to msg.sender (or null address if msg.sender == makerAddress).
+    /// @param targetOrderEpoch Orders created with a salt less or equal to this value will be cancelled.
+    function cancelOrdersUpTo(uint256 targetOrderEpoch)
+        external
+    {
+        address makerAddress = getCurrentContextAddress();
+        // If this function is called via `executeTransaction`, we only update the orderEpoch for the makerAddress/msg.sender combination.
+        // This allows external filter contracts to add rules to how orders are cancelled via this function.
+        address senderAddress = makerAddress == msg.sender ? address(0) : msg.sender;
+
+        // orderEpoch is initialized to 0, so to cancelUpTo we need salt + 1
+        uint256 newOrderEpoch = targetOrderEpoch + 1;  
+        uint256 oldOrderEpoch = orderEpoch[makerAddress][senderAddress];
+
+        // Ensure orderEpoch is monotonically increasing
+        require(
+            newOrderEpoch > oldOrderEpoch, 
+            "INVALID_NEW_ORDER_EPOCH"
+        );
+
+        // Update orderEpoch
+        orderEpoch[makerAddress][senderAddress] = newOrderEpoch;
+        emit CancelUpTo(makerAddress, senderAddress, newOrderEpoch);
+    }
+
+    /// @dev Fills the input order.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrder(
+        Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (FillResults memory fillResults)
+    {
+        // Fetch order info
+        OrderInfo memory orderInfo = getOrderInfo(order);
+
+        // Fetch taker address
+        address takerAddress = getCurrentContextAddress();
+
+        // Get amount of takerAsset to fill
+        uint256 remainingTakerAssetAmount = safeSub(order.takerAssetAmount, orderInfo.orderTakerAssetFilledAmount);
+        uint256 takerAssetFilledAmount = min256(takerAssetFillAmount, remainingTakerAssetAmount);
+
+        // Validate context
+        assertValidFill(
+            order,
+            orderInfo,
+            takerAddress,
+            takerAssetFillAmount,
+            takerAssetFilledAmount,
+            signature
+        );
+
+        // Compute proportional fill amounts
+        fillResults = calculateFillResults(order, takerAssetFilledAmount);
+
+        // Update exchange internal state
+        updateFilledState(
+            order,
+            takerAddress,
+            orderInfo.orderHash,
+            orderInfo.orderTakerAssetFilledAmount,
+            fillResults
+        );
+    
+        // Settle order
+        settleOrder(order, takerAddress, fillResults);
+
+        return fillResults;
+    }
+
+    /// @dev After calling, the order can not be filled anymore.
+    ///      Throws if order is invalid or sender does not have permission to cancel.
+    /// @param order Order to cancel. Order must be OrderStatus.FILLABLE.
+    function cancelOrder(Order memory order)
+        public
+    {
+        // Fetch current order status
+        OrderInfo memory orderInfo = getOrderInfo(order);
+
+        // Validate context
+        assertValidCancel(order, orderInfo);
+
+        // Perform cancel
+        updateCancelledState(order, orderInfo.orderHash);
+    }
+
+    /// @dev Gets information about an order: status, hash, and amount filled.
+    /// @param order Order to gather information on.
+    /// @return OrderInfo Information about the order and its state.
+    ///         See LibOrder.OrderInfo for a complete description.
+    function getOrderInfo(Order memory order)
+        public
+        view
+        returns (OrderInfo memory orderInfo)
+    {
+        // Compute the order hash
+        orderInfo.orderHash = getOrderHash(order);
+
+        // If order.makerAssetAmount is zero, we also reject the order.
+        // While the Exchange contract handles them correctly, they create
+        // edge cases in the supporting infrastructure because they have
+        // an 'infinite' price when computed by a simple division.
+        if (order.makerAssetAmount == 0) {
+            orderInfo.orderStatus = uint8(OrderStatus.INVALID_MAKER_ASSET_AMOUNT);
+            return orderInfo;
+        }
+
+        // If order.takerAssetAmount is zero, then the order will always
+        // be considered filled because 0 == takerAssetAmount == orderTakerAssetFilledAmount
+        // Instead of distinguishing between unfilled and filled zero taker
+        // amount orders, we choose not to support them.
+        if (order.takerAssetAmount == 0) {
+            orderInfo.orderStatus = uint8(OrderStatus.INVALID_TAKER_ASSET_AMOUNT);
+            return orderInfo;
+        }
+
+        // Validate order expiration
+        if (block.timestamp >= order.expirationTimeSeconds) {
+            orderInfo.orderStatus = uint8(OrderStatus.EXPIRED);
+            return orderInfo;
+        }
+
+        // Check if order has been cancelled
+        if (cancelled[orderInfo.orderHash]) {
+            orderInfo.orderStatus = uint8(OrderStatus.CANCELLED);
+            return orderInfo;
+        }
+        if (orderEpoch[order.makerAddress][order.senderAddress] > order.salt) {
+            orderInfo.orderStatus = uint8(OrderStatus.CANCELLED);
+            return orderInfo;
+        }
+
+        // Fetch filled amount and validate order availability
+        orderInfo.orderTakerAssetFilledAmount = filled[orderInfo.orderHash];
+        if (orderInfo.orderTakerAssetFilledAmount >= order.takerAssetAmount) {
+            orderInfo.orderStatus = uint8(OrderStatus.FULLY_FILLED);
+            return orderInfo;
+        }
+
+        // All other statuses are ruled out: order is Fillable
+        orderInfo.orderStatus = uint8(OrderStatus.FILLABLE);
+        return orderInfo;
+    }
+
+    /// @dev Updates state with results of a fill order.
+    /// @param order that was filled.
+    /// @param takerAddress Address of taker who filled the order.
+    /// @param orderTakerAssetFilledAmount Amount of order already filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function updateFilledState(
+        Order memory order,
+        address takerAddress,
+        bytes32 orderHash,
+        uint256 orderTakerAssetFilledAmount,
+        FillResults memory fillResults
+    )
+        internal
+    {
+        // Update state
+        filled[orderHash] = safeAdd(orderTakerAssetFilledAmount, fillResults.takerAssetFilledAmount);
+
+        // Log order
+        emit Fill(
+            order.makerAddress,
+            order.feeRecipientAddress,
+            takerAddress,
+            msg.sender,
+            fillResults.makerAssetFilledAmount,
+            fillResults.takerAssetFilledAmount,
+            fillResults.makerFeePaid,
+            fillResults.takerFeePaid,
+            orderHash,
+            order.makerAssetData,
+            order.takerAssetData
+        );
+    }
+
+    /// @dev Updates state with results of cancelling an order.
+    ///      State is only updated if the order is currently fillable.
+    ///      Otherwise, updating state would have no effect.
+    /// @param order that was cancelled.
+    /// @param orderHash Hash of order that was cancelled.
+    function updateCancelledState(
+        Order memory order,
+        bytes32 orderHash
+    )
+        internal
+    {
+        // Perform cancel
+        cancelled[orderHash] = true;
+
+        // Log cancel
+        emit Cancel(
+            order.makerAddress,
+            order.feeRecipientAddress,
+            msg.sender,
+            orderHash,
+            order.makerAssetData,
+            order.takerAssetData
+        );
+    }
+
+    /// @dev Validates context for fillOrder. Succeeds or throws.
+    /// @param order to be filled.
+    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
+    /// @param takerAddress Address of order taker.
+    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @param signature Proof that the orders was created by its maker.
+    function assertValidFill(
+        Order memory order,
+        OrderInfo memory orderInfo,
+        address takerAddress,
+        uint256 takerAssetFillAmount,
+        uint256 takerAssetFilledAmount,
+        bytes memory signature
+    )
+        internal
+        view
+    {
+        // An order can only be filled if its status is FILLABLE.
+        require(
+            orderInfo.orderStatus == uint8(OrderStatus.FILLABLE),
+            "ORDER_UNFILLABLE"
+        );
+
+        // Revert if fill amount is invalid
+        require(
+            takerAssetFillAmount != 0,
+            "INVALID_TAKER_AMOUNT"
+        );
+
+        // Validate sender is allowed to fill this order
+        if (order.senderAddress != address(0)) {
+            require(
+                order.senderAddress == msg.sender,
+                "INVALID_SENDER"
+            );
+        }
+
+        // Validate taker is allowed to fill this order
+        if (order.takerAddress != address(0)) {
+            require(
+                order.takerAddress == takerAddress,
+                "INVALID_TAKER"
+            );
+        }
+
+        // Validate Maker signature (check only if first time seen)
+        if (orderInfo.orderTakerAssetFilledAmount == 0) {
+            require(
+                isValidSignature(
+                    orderInfo.orderHash,
+                    order.makerAddress,
+                    signature
+                ),
+                "INVALID_ORDER_SIGNATURE"
+            );
+        }
+
+        // Validate fill order rounding
+        require(
+            !isRoundingError(
+                takerAssetFilledAmount,
+                order.takerAssetAmount,
+                order.makerAssetAmount
+            ),
+            "ROUNDING_ERROR"
+        );
+    }
+
+    /// @dev Validates context for cancelOrder. Succeeds or throws.
+    /// @param order to be cancelled.
+    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
+    function assertValidCancel(
+        Order memory order,
+        OrderInfo memory orderInfo
+    )
+        internal
+        view
+    {
+        // Ensure order is valid
+        // An order can only be cancelled if its status is FILLABLE.
+        require(
+            orderInfo.orderStatus == uint8(OrderStatus.FILLABLE),
+            "ORDER_UNFILLABLE"
+        );
+
+        // Validate sender is allowed to cancel this order
+        if (order.senderAddress != address(0)) {
+            require(
+                order.senderAddress == msg.sender,
+                "INVALID_SENDER"
+            );
+        }
+
+        // Validate transaction signed by maker
+        address makerAddress = getCurrentContextAddress();
+        require(
+            order.makerAddress == makerAddress,
+            "INVALID_MAKER"
+        );
+    }
+
+    /// @dev Calculates amounts filled and fees paid by maker and taker.
+    /// @param order to be filled.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function calculateFillResults(
+        Order memory order,
+        uint256 takerAssetFilledAmount
+    )
+        internal
+        pure
+        returns (FillResults memory fillResults)
+    {
+        // Compute proportional transfer amounts
+        // TODO: All three are multiplied by the same fraction. This can
+        // potentially be optimized.
+        fillResults.takerAssetFilledAmount = takerAssetFilledAmount;
+        fillResults.makerAssetFilledAmount = getPartialAmount(
+            fillResults.takerAssetFilledAmount,
+            order.takerAssetAmount,
+            order.makerAssetAmount
+        );
+        fillResults.makerFeePaid = getPartialAmount(
+            fillResults.takerAssetFilledAmount,
+            order.takerAssetAmount,
+            order.makerFee
+        );
+        fillResults.takerFeePaid = getPartialAmount(
+            fillResults.takerAssetFilledAmount,
+            order.takerAssetAmount,
+            order.takerFee
+        );
+
+        return fillResults;
+    }
+
+   /// @dev Settles an order by transferring assets between counterparties.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAddress Address selling takerAsset and buying makerAsset.
+    /// @param fillResults Amounts to be filled and fees paid by maker and taker.
+    function settleOrder(
+        LibOrder.Order memory order,
+        address takerAddress,
+        LibFillResults.FillResults memory fillResults
+    )
+        private
+    {
+        bytes memory zrxAssetData = ZRX_ASSET_DATA;
+        dispatchTransferFrom(
+            order.makerAssetData,
+            order.makerAddress,
+            takerAddress,
+            fillResults.makerAssetFilledAmount
+        );
+        dispatchTransferFrom(
+            order.takerAssetData,
+            takerAddress,
+            order.makerAddress,
+            fillResults.takerAssetFilledAmount
+        );
+        dispatchTransferFrom(
+            zrxAssetData,
+            order.makerAddress,
+            order.feeRecipientAddress,
+            fillResults.makerFeePaid
+        );
+        dispatchTransferFrom(
+            zrxAssetData,
+            takerAddress,
+            order.feeRecipientAddress,
+            fillResults.takerFeePaid
+        );
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
new file mode 100644
index 000000000..1a43eec79
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
@@ -0,0 +1,301 @@
+/*
+  Copyright 2018 ZeroEx Intl.
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibConstants.sol";
+import "./libs/LibMath.sol";
+import "./libs/LibOrder.sol";
+import "./libs/LibFillResults.sol";
+import "./mixins/MExchangeCore.sol";
+import "./mixins/MMatchOrders.sol";
+import "./mixins/MTransactions.sol";
+import "./mixins/MAssetProxyDispatcher.sol";
+
+contract MixinMatchOrders is
+    LibConstants,
+    LibMath,
+    MAssetProxyDispatcher,
+    MExchangeCore,
+    MMatchOrders,
+    MTransactions
+{
+    /// @dev Match two complementary orders that have a profitable spread.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the left order goes to the taker (who matched the two orders).
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftSignature Proof that order was created by the left maker.
+    /// @param rightSignature Proof that order was created by the right maker.
+    /// @return matchedFillResults Amounts filled and fees paid by maker and taker of matched orders.
+    /// TODO: Make this function external once supported by Solidity (See Solidity Issues #3199, #1603)
+    function matchOrders(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        bytes memory leftSignature,
+        bytes memory rightSignature
+    )
+        public
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults)
+    {
+        // We assume that rightOrder.takerAssetData == leftOrder.makerAssetData and rightOrder.makerAssetData == leftOrder.takerAssetData.
+        // If this assumption isn't true, the match will fail at signature validation.
+        rightOrder.makerAssetData = leftOrder.takerAssetData;
+        rightOrder.takerAssetData = leftOrder.makerAssetData;
+
+        // Get left & right order info
+        LibOrder.OrderInfo memory leftOrderInfo = getOrderInfo(leftOrder);
+        LibOrder.OrderInfo memory rightOrderInfo = getOrderInfo(rightOrder);
+
+        // Fetch taker address
+        address takerAddress = getCurrentContextAddress();
+
+        // Either our context is valid or we revert
+        assertValidMatch(leftOrder, rightOrder);
+
+        // Compute proportional fill amounts
+        matchedFillResults = calculateMatchedFillResults(
+            leftOrder,
+            rightOrder,
+            leftOrderInfo.orderTakerAssetFilledAmount,
+            rightOrderInfo.orderTakerAssetFilledAmount
+        );
+
+        // Validate fill contexts
+        assertValidFill(
+            leftOrder,
+            leftOrderInfo,
+            takerAddress,
+            matchedFillResults.left.takerAssetFilledAmount,
+            matchedFillResults.left.takerAssetFilledAmount,
+            leftSignature
+        );
+        assertValidFill(
+            rightOrder,
+            rightOrderInfo,
+            takerAddress,
+            matchedFillResults.right.takerAssetFilledAmount,
+            matchedFillResults.right.takerAssetFilledAmount,
+            rightSignature
+        );
+
+        // Update exchange state
+        updateFilledState(
+            leftOrder,
+            takerAddress,
+            leftOrderInfo.orderHash,
+            leftOrderInfo.orderTakerAssetFilledAmount,
+            matchedFillResults.left
+        );
+        updateFilledState(
+            rightOrder,
+            takerAddress,
+            rightOrderInfo.orderHash,
+            rightOrderInfo.orderTakerAssetFilledAmount,
+            matchedFillResults.right
+        );
+    
+        // Settle matched orders. Succeeds or throws.
+        settleMatchedOrders(
+            leftOrder,
+            rightOrder,
+            takerAddress,
+            matchedFillResults
+        );
+
+        return matchedFillResults;
+    }
+
+    /// @dev Validates context for matchOrders. Succeeds or throws.
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    function assertValidMatch(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder
+    )
+        internal
+        pure
+    {
+        // Make sure there is a profitable spread.
+        // There is a profitable spread iff the cost per unit bought (OrderA.MakerAmount/OrderA.TakerAmount) for each order is greater
+        // than the profit per unit sold of the matched order (OrderB.TakerAmount/OrderB.MakerAmount).
+        // This is satisfied by the equations below:
+        // <leftOrder.makerAssetAmount> / <leftOrder.takerAssetAmount> >= <rightOrder.takerAssetAmount> / <rightOrder.makerAssetAmount>
+        // AND
+        // <rightOrder.makerAssetAmount> / <rightOrder.takerAssetAmount> >= <leftOrder.takerAssetAmount> / <leftOrder.makerAssetAmount>
+        // These equations can be combined to get the following:
+        require(
+            safeMul(leftOrder.makerAssetAmount, rightOrder.makerAssetAmount) >=
+            safeMul(leftOrder.takerAssetAmount, rightOrder.takerAssetAmount),
+            "NEGATIVE_SPREAD_REQUIRED"
+        );
+    }
+
+    /// @dev Calculates fill amounts for the matched orders.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the leftOrder order goes to the taker (who matched the two orders).
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftOrderTakerAssetFilledAmount Amount of left order already filled.
+    /// @param rightOrderTakerAssetFilledAmount Amount of right order already filled.
+    /// @param matchedFillResults Amounts to fill and fees to pay by maker and taker of matched orders.
+    function calculateMatchedFillResults(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        uint256 leftOrderTakerAssetFilledAmount,
+        uint256 rightOrderTakerAssetFilledAmount
+    )
+        internal
+        pure
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults)
+    {
+        // We settle orders at the exchange rate of the right order.
+        // The amount saved by the left maker goes to the taker.
+        // Either the left or right order will be fully filled; possibly both.
+        // The left order is fully filled iff the right order can sell more than left can buy.
+        // That is: the amount required to fill the left order is less than or equal to
+        //          the amount we can spend from the right order:
+        //          <leftTakerAssetAmountRemaining> <= <rightTakerAssetAmountRemaining> * <rightMakerToTakerRatio>
+        //          <leftTakerAssetAmountRemaining> <= <rightTakerAssetAmountRemaining> * <rightOrder.makerAssetAmount> / <rightOrder.takerAssetAmount>
+        //          <leftTakerAssetAmountRemaining> * <rightOrder.takerAssetAmount> <= <rightTakerAssetAmountRemaining> * <rightOrder.makerAssetAmount>
+        uint256 leftTakerAssetAmountRemaining = safeSub(leftOrder.takerAssetAmount, leftOrderTakerAssetFilledAmount);
+        uint256 rightTakerAssetAmountRemaining = safeSub(rightOrder.takerAssetAmount, rightOrderTakerAssetFilledAmount);
+        uint256 leftTakerAssetFilledAmount;
+        uint256 rightTakerAssetFilledAmount;
+        if (
+            safeMul(leftTakerAssetAmountRemaining, rightOrder.takerAssetAmount) <=
+            safeMul(rightTakerAssetAmountRemaining, rightOrder.makerAssetAmount)
+        ) {
+            // Left order will be fully filled: maximally fill left
+            leftTakerAssetFilledAmount = leftTakerAssetAmountRemaining;
+
+            // The right order receives an amount proportional to how much was spent.
+            // TODO: Can we ensure rounding error is in the correct direction?
+            rightTakerAssetFilledAmount = getPartialAmount(
+                rightOrder.takerAssetAmount,
+                rightOrder.makerAssetAmount,
+                leftTakerAssetFilledAmount
+            );
+        } else {
+            // Right order will be fully filled: maximally fill right
+            rightTakerAssetFilledAmount = rightTakerAssetAmountRemaining;
+
+            // The left order receives an amount proportional to how much was spent.
+            // TODO: Can we ensure rounding error is in the correct direction?
+            leftTakerAssetFilledAmount = getPartialAmount(
+                rightOrder.makerAssetAmount,
+                rightOrder.takerAssetAmount,
+                rightTakerAssetFilledAmount
+            );
+        }
+
+        // Calculate fill results for left order
+        matchedFillResults.left = calculateFillResults(
+            leftOrder,
+            leftTakerAssetFilledAmount
+        );
+
+        // Calculate fill results for right order
+        matchedFillResults.right = calculateFillResults(
+            rightOrder,
+            rightTakerAssetFilledAmount
+        );
+
+        // Calculate amount given to taker
+        matchedFillResults.leftMakerAssetSpreadAmount = safeSub(
+            matchedFillResults.left.makerAssetFilledAmount,
+            matchedFillResults.right.takerAssetFilledAmount
+        );
+
+        // Return fill results
+        return matchedFillResults;
+    }
+
+    /// @dev Settles matched order by transferring appropriate funds between order makers, taker, and fee recipient.
+    /// @param leftOrder First matched order.
+    /// @param rightOrder Second matched order.
+    /// @param takerAddress Address that matched the orders. The taker receives the spread between orders as profit.
+    /// @param matchedFillResults Struct holding amounts to transfer between makers, taker, and fee recipients.
+    function settleMatchedOrders(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        address takerAddress,
+        LibFillResults.MatchedFillResults memory matchedFillResults
+    )
+        private
+    {
+        bytes memory zrxAssetData = ZRX_ASSET_DATA;
+        // Order makers and taker
+        dispatchTransferFrom(
+            leftOrder.makerAssetData,
+            leftOrder.makerAddress,
+            rightOrder.makerAddress,
+            matchedFillResults.right.takerAssetFilledAmount
+        );
+        dispatchTransferFrom(
+            rightOrder.makerAssetData,
+            rightOrder.makerAddress,
+            leftOrder.makerAddress,
+            matchedFillResults.left.takerAssetFilledAmount
+        );
+        dispatchTransferFrom(
+            leftOrder.makerAssetData,
+            leftOrder.makerAddress,
+            takerAddress,
+            matchedFillResults.leftMakerAssetSpreadAmount
+        );
+
+        // Maker fees
+        dispatchTransferFrom(
+            zrxAssetData,
+            leftOrder.makerAddress,
+            leftOrder.feeRecipientAddress,
+            matchedFillResults.left.makerFeePaid
+        );
+        dispatchTransferFrom(
+            zrxAssetData,
+            rightOrder.makerAddress,
+            rightOrder.feeRecipientAddress,
+            matchedFillResults.right.makerFeePaid
+        );
+
+        // Taker fees
+        if (leftOrder.feeRecipientAddress == rightOrder.feeRecipientAddress) {
+            dispatchTransferFrom(
+                zrxAssetData,
+                takerAddress,
+                leftOrder.feeRecipientAddress,
+                safeAdd(
+                    matchedFillResults.left.takerFeePaid,
+                    matchedFillResults.right.takerFeePaid
+                )
+            );
+        } else {
+            dispatchTransferFrom(
+                zrxAssetData,
+                takerAddress,
+                leftOrder.feeRecipientAddress,
+                matchedFillResults.left.takerFeePaid
+            );
+            dispatchTransferFrom(
+                zrxAssetData,
+                takerAddress,
+                rightOrder.feeRecipientAddress,
+                matchedFillResults.right.takerFeePaid
+            );
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
new file mode 100644
index 000000000..29172057a
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
@@ -0,0 +1,255 @@
+/*
+
+  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/LibBytes/LibBytes.sol";
+import "./mixins/MSignatureValidator.sol";
+import "./mixins/MTransactions.sol";
+import "./interfaces/IWallet.sol";
+import "./interfaces/IValidator.sol";
+
+contract MixinSignatureValidator is
+    MSignatureValidator,
+    MTransactions
+{
+    using LibBytes for bytes;
+    
+    // Mapping of hash => signer => signed
+    mapping (bytes32 => mapping (address => bool)) public preSigned;
+
+    // Mapping of signer => validator => approved
+    mapping (address => mapping (address => bool)) public allowedValidators;
+
+    /// @dev Approves a hash on-chain using any valid signature type.
+    ///      After presigning a hash, the preSign signature type will become valid for that hash and signer.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof that the hash has been signed by signer.
+    function preSign(
+        bytes32 hash,
+        address signerAddress,
+        bytes signature
+    )
+        external
+    {
+        require(
+            isValidSignature(
+                hash,
+                signerAddress,
+                signature
+            ),
+            "INVALID_SIGNATURE"
+        );
+        preSigned[hash][signerAddress] = true;
+    }
+
+    /// @dev Approves/unnapproves a Validator contract to verify signatures on signer's behalf.
+    /// @param validatorAddress Address of Validator contract.
+    /// @param approval Approval or disapproval of  Validator contract.
+    function setSignatureValidatorApproval(
+        address validatorAddress,
+        bool approval
+    )
+        external
+    {
+        address signerAddress = getCurrentContextAddress();
+        allowedValidators[signerAddress][validatorAddress] = approval;
+        emit SignatureValidatorApproval(
+            signerAddress,
+            validatorAddress,
+            approval
+        );
+    }
+
+    /// @dev Verifies that a hash has been signed by the given signer.
+    /// @param hash Any 32 byte hash.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof that the hash has been signed by signer.
+    /// @return True if the address recovered from the provided signature matches the input signer address.
+    function isValidSignature(
+        bytes32 hash,
+        address signerAddress,
+        bytes memory signature
+    )
+        public
+        view
+        returns (bool isValid)
+    {
+        // TODO: Domain separation: make hash depend on role. (Taker sig should not be valid as maker sig, etc.)
+        require(
+            signature.length > 0,
+            "LENGTH_GREATER_THAN_0_REQUIRED"
+        );
+
+        // Ensure signature is supported
+        uint8 signatureTypeRaw = uint8(signature.popLastByte());
+        require(
+            signatureTypeRaw < uint8(SignatureType.NSignatureTypes),
+            "SIGNATURE_UNSUPPORTED"
+        );
+
+        // Pop last byte off of signature byte array.
+        SignatureType signatureType = SignatureType(signatureTypeRaw);
+
+        // Variables are not scoped in Solidity.
+        uint8 v;
+        bytes32 r;
+        bytes32 s;
+        address recovered;
+
+        // Always illegal signature.
+        // This is always an implicit option since a signer can create a
+        // signature array with invalid type or length. We may as well make
+        // it an explicit option. This aids testing and analysis. It is
+        // also the initialization value for the enum type.
+        if (signatureType == SignatureType.Illegal) {
+            revert("SIGNATURE_ILLEGAL");
+
+        // Always invalid signature.
+        // Like Illegal, this is always implicitly available and therefore
+        // offered explicitly. It can be implicitly created by providing
+        // a correctly formatted but incorrect signature.
+        } else if (signatureType == SignatureType.Invalid) {
+            require(
+                signature.length == 0,
+                "LENGTH_0_REQUIRED"
+            );
+            isValid = false;
+            return isValid;
+
+        // Signature using EIP712
+        } else if (signatureType == SignatureType.EIP712) {
+            require(
+                signature.length == 65,
+                "LENGTH_65_REQUIRED"
+            );
+            v = uint8(signature[0]);
+            r = signature.readBytes32(1);
+            s = signature.readBytes32(33);
+            recovered = ecrecover(hash, v, r, s);
+            isValid = signerAddress == recovered;
+            return isValid;
+
+        // Signed using web3.eth_sign
+        } else if (signatureType == SignatureType.EthSign) {
+            require(
+                signature.length == 65,
+                "LENGTH_65_REQUIRED"
+            );
+            v = uint8(signature[0]);
+            r = signature.readBytes32(1);
+            s = signature.readBytes32(33);
+            recovered = ecrecover(
+                keccak256(abi.encodePacked(
+                    "\x19Ethereum Signed Message:\n32",
+                    hash
+                )),
+                v,
+                r,
+                s
+            );
+            isValid = signerAddress == recovered;
+            return isValid;
+
+        // Implicitly signed by caller.
+        // The signer has initiated the call. In the case of non-contract
+        // accounts it means the transaction itself was signed.
+        // Example: let's say for a particular operation three signatures
+        // A, B and C are required. To submit the transaction, A and B can
+        // give a signature to C, who can then submit the transaction using
+        // `Caller` for his own signature. Or A and C can sign and B can
+        // submit using `Caller`. Having `Caller` allows this flexibility.
+        } else if (signatureType == SignatureType.Caller) {
+            require(
+                signature.length == 0,
+                "LENGTH_0_REQUIRED"
+            );
+            isValid = signerAddress == msg.sender;
+            return isValid;
+
+        // Signature verified by wallet contract.
+        // If used with an order, the maker of the order is the wallet contract.
+        } else if (signatureType == SignatureType.Wallet) {
+            isValid = IWallet(signerAddress).isValidSignature(hash, signature);
+            return isValid;
+
+        // Signature verified by validator contract.
+        // If used with an order, the maker of the order can still be an EOA.
+        // A signature using this type should be encoded as:
+        // | Offset   | Length | Contents                        |
+        // | 0x00     | x      | Signature to validate           |
+        // | 0x00 + x | 20     | Address of validator contract   |
+        // | 0x14 + x | 1      | Signature type is always "\x06" |
+        } else if (signatureType == SignatureType.Validator) {
+            // Pop last 20 bytes off of signature byte array.
+
+            address validatorAddress = signature.popLast20Bytes();
+            
+            // Ensure signer has approved validator.
+            if (!allowedValidators[signerAddress][validatorAddress]) {
+                return false;
+            }
+            isValid = IValidator(validatorAddress).isValidSignature(
+                hash,
+                signerAddress,
+                signature
+            );
+            return isValid;
+
+        // Signer signed hash previously using the preSign function.
+        } else if (signatureType == SignatureType.PreSigned) {
+            isValid = preSigned[hash][signerAddress];
+            return isValid;
+
+        // Signature from Trezor hardware wallet.
+        // It differs from web3.eth_sign in the encoding of message length
+        // (Bitcoin varint encoding vs ascii-decimal, the latter is not
+        // self-terminating which leads to ambiguities).
+        // See also:
+        // https://en.bitcoin.it/wiki/Protocol_documentation#Variable_length_integer
+        // https://github.com/trezor/trezor-mcu/blob/master/firmware/ethereum.c#L602
+        // https://github.com/trezor/trezor-mcu/blob/master/firmware/crypto.c#L36
+        } else if (signatureType == SignatureType.Trezor) {
+            require(
+                signature.length == 65,
+                "LENGTH_65_REQUIRED"
+            );
+            v = uint8(signature[0]);
+            r = signature.readBytes32(1);
+            s = signature.readBytes32(33);
+            recovered = ecrecover(
+                keccak256(abi.encodePacked(
+                    "\x19Ethereum Signed Message:\n\x20",
+                    hash
+                )),
+                v,
+                r,
+                s
+            );
+            isValid = signerAddress == recovered;
+            return isValid;
+        }
+
+        // Anything else is illegal (We do not return false because
+        // the signature may actually be valid, just not in a format
+        // that we currently support. In this case returning false
+        // may lead the caller to incorrectly believe that the
+        // signature was invalid.)
+        revert("SIGNATURE_UNSUPPORTED");
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
new file mode 100644
index 000000000..31f7f2847
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
@@ -0,0 +1,154 @@
+/*
+
+  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 "./libs/LibExchangeErrors.sol";
+import "./mixins/MSignatureValidator.sol";
+import "./mixins/MTransactions.sol";
+import "./libs/LibEIP712.sol";
+
+contract MixinTransactions is
+    LibEIP712,
+    MSignatureValidator,
+    MTransactions
+{
+
+    // Mapping of transaction hash => executed
+    // This prevents transactions from being executed more than once.
+    mapping (bytes32 => bool) public transactions;
+
+    // Address of current transaction signer
+    address public currentContextAddress;
+
+    // Hash for the EIP712 ZeroEx Transaction Schema
+    bytes32 constant EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH = keccak256(abi.encodePacked(
+        "ZeroExTransaction(",
+        "uint256 salt,",
+        "address signerAddress,",
+        "bytes data",
+        ")"
+    ));
+
+    /// @dev Calculates EIP712 hash of the Transaction.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param data AbiV2 encoded calldata.
+    /// @return EIP712 hash of the Transaction.
+    function hashZeroExTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes memory data
+    )
+        internal
+        pure
+        returns (bytes32 result)
+    {
+        bytes32 schemaHash = EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH;
+        bytes32 dataHash = keccak256(data);
+        // Assembly for more efficiently computing:
+        // keccak256(abi.encode(
+        //   EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH,
+        //   salt,
+        //   signerAddress,
+        //   keccak256(data)
+        //  ));
+        assembly {
+            let memPtr := mload(64)
+            mstore(memPtr, schemaHash)
+            mstore(add(memPtr, 32), salt)
+            mstore(add(memPtr, 64), and(signerAddress, 0xffffffffffffffffffffffffffffffffffffffff))
+            mstore(add(memPtr, 96), dataHash)
+            result := keccak256(memPtr, 128)
+        }
+
+        return result;
+    }
+
+    /// @dev Executes an exchange method call in the context of signer.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param data AbiV2 encoded calldata.
+    /// @param signature Proof of signer transaction by signer.
+    function executeTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes data,
+        bytes signature
+    )
+        external
+    {
+        // Prevent reentrancy
+        require(
+            currentContextAddress == address(0),
+            "REENTRANCY_ILLEGAL"
+        );
+
+        bytes32 transactionHash = hashEIP712Message(hashZeroExTransaction(
+            salt,
+            signerAddress,
+            data
+        ));
+
+        // Validate transaction has not been executed
+        require(
+            !transactions[transactionHash],
+            "INVALID_TX_HASH"
+        );
+
+        // Transaction always valid if signer is sender of transaction
+        if (signerAddress != msg.sender) {
+            // Validate signature
+            require(
+                isValidSignature(
+                    transactionHash,
+                    signerAddress,
+                    signature
+                ),
+                "INVALID_TX_SIGNATURE"
+            );
+
+            // Set the current transaction signer
+            currentContextAddress = signerAddress;
+        }
+
+        // Execute transaction
+        transactions[transactionHash] = true;
+        require(
+            address(this).delegatecall(data),
+            "FAILED_EXECUTION"
+        );
+
+        // Reset current transaction signer
+        // TODO: Check if gas is paid when currentContextAddress is already 0.
+        currentContextAddress = address(0);
+    }
+
+    /// @dev The current function will be called in the context of this address (either 0x transaction signer or `msg.sender`).
+    ///      If calling a fill function, this address will represent the taker.
+    ///      If calling a cancel function, this address will represent the maker.
+    /// @return Signer of 0x transaction if entry point is `executeTransaction`.
+    ///         `msg.sender` if entry point is any other function.
+    function getCurrentContextAddress()
+        internal
+        view
+        returns (address)
+    {
+        address contextAddress = currentContextAddress == address(0) ? msg.sender : currentContextAddress;
+        return contextAddress;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
new file mode 100644
index 000000000..00668ca43
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
@@ -0,0 +1,531 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./libs/LibMath.sol";
+import "./libs/LibOrder.sol";
+import "./libs/LibFillResults.sol";
+import "./mixins/MExchangeCore.sol";
+
+contract MixinWrapperFunctions is
+    LibMath,
+    LibFillResults,
+    MExchangeCore
+{
+    /// @dev Fills the input order. Reverts if exact takerAssetFillAmount not filled.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    function fillOrKillOrder(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (FillResults memory fillResults)
+    {
+        fillResults = fillOrder(
+            order,
+            takerAssetFillAmount,
+            signature
+        );
+        require(
+            fillResults.takerAssetFilledAmount == takerAssetFillAmount,
+            "COMPLETE_FILL_FAILED"
+        );
+        return fillResults;
+    }
+
+    /// @dev Fills an order with specified parameters and ECDSA signature.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrderNoThrow(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (FillResults memory fillResults)
+    {
+        // We need to call MExchangeCore.fillOrder using a delegatecall in
+        // assembly so that we can intercept a call that throws. For this, we
+        // need the input encoded in memory in the Ethereum ABIv2 format [1].
+
+        // | Area     | Offset | Length  | Contents                                    |
+        // | -------- |--------|---------|-------------------------------------------- |
+        // | Header   | 0x00   | 4       | function selector                           |
+        // | Params   |        | 3 * 32  | function parameters:                        |
+        // |          | 0x00   |         |   1. offset to order (*)                    |
+        // |          | 0x20   |         |   2. takerAssetFillAmount                   |
+        // |          | 0x40   |         |   3. offset to signature (*)                |
+        // | Data     |        | 12 * 32 | order:                                      |
+        // |          | 0x000  |         |   1.  senderAddress                         |
+        // |          | 0x020  |         |   2.  makerAddress                          |
+        // |          | 0x040  |         |   3.  takerAddress                          |
+        // |          | 0x060  |         |   4.  feeRecipientAddress                   |
+        // |          | 0x080  |         |   5.  makerAssetAmount                      |
+        // |          | 0x0A0  |         |   6.  takerAssetAmount                      |
+        // |          | 0x0C0  |         |   7.  makerFeeAmount                        |
+        // |          | 0x0E0  |         |   8.  takerFeeAmount                        |
+        // |          | 0x100  |         |   9.  expirationTimeSeconds                 |
+        // |          | 0x120  |         |   10. salt                                  |
+        // |          | 0x140  |         |   11. Offset to makerAssetData (*)          |
+        // |          | 0x160  |         |   12. Offset to takerAssetData (*)          |
+        // |          | 0x180  | 32      | makerAssetData Length                       |
+        // |          | 0x1A0  | **      | makerAssetData Contents                     |
+        // |          | 0x1C0  | 32      | takerAssetData Length                       |
+        // |          | 0x1E0  | **      | takerAssetData Contents                     |
+        // |          | 0x200  | 32      | signature Length                            |
+        // |          | 0x220  | **      | signature Contents                          |
+
+        // * Offsets are calculated from the beginning of the current area: Header, Params, Data:
+        //     An offset stored in the Params area is calculated from the beginning of the Params section.
+        //     An offset stored in the Data area is calculated from the beginning of the Data section.
+
+        // ** The length of dynamic array contents are stored in the field immediately preceeding the contents.
+
+        // [1]: https://solidity.readthedocs.io/en/develop/abi-spec.html
+
+        bytes4 fillOrderSelector = this.fillOrder.selector;
+
+        assembly {
+
+            // Areas below may use the following variables:
+            //   1. <area>Start   -- Start of this area in memory
+            //   2. <area>End     -- End of this area in memory. This value may
+            //                       be precomputed (before writing contents),
+            //                       or it may be computed as contents are written.
+            //   3. <area>Offset  -- Current offset into area. If an area's End
+            //                       is precomputed, this variable tracks the
+            //                       offsets of contents as they are written.
+
+            /////// Setup Header Area ///////
+            // Load free memory pointer
+            let headerAreaStart := mload(0x40)
+            mstore(headerAreaStart, fillOrderSelector)
+            let headerAreaEnd := add(headerAreaStart, 0x4)
+
+            /////// Setup Params Area ///////
+            // This area is preallocated and written to later.
+            // This is because we need to fill in offsets that have not yet been calculated.
+            let paramsAreaStart := headerAreaEnd
+            let paramsAreaEnd := add(paramsAreaStart, 0x60)
+            let paramsAreaOffset := paramsAreaStart
+
+            /////// Setup Data Area ///////
+            let dataAreaStart := paramsAreaEnd
+            let dataAreaEnd := dataAreaStart
+
+            // Offset from the source data we're reading from
+            let sourceOffset := order
+            // arrayLenBytes and arrayLenWords track the length of a dynamically-allocated bytes array.
+            let arrayLenBytes := 0
+            let arrayLenWords := 0
+
+            /////// Write order Struct ///////
+            // Write memory location of Order, relative to the start of the
+            // parameter list, then increment the paramsAreaOffset respectively.
+            mstore(paramsAreaOffset, sub(dataAreaEnd, paramsAreaStart))
+            paramsAreaOffset := add(paramsAreaOffset, 0x20)
+
+            // Write values for each field in the order
+            // It would be nice to use a loop, but we save on gas by writing
+            // the stores sequentially.
+            mstore(dataAreaEnd, mload(sourceOffset))                            // makerAddress
+            mstore(add(dataAreaEnd, 0x20), mload(add(sourceOffset, 0x20)))      // takerAddress
+            mstore(add(dataAreaEnd, 0x40), mload(add(sourceOffset, 0x40)))      // feeRecipientAddress
+            mstore(add(dataAreaEnd, 0x60), mload(add(sourceOffset, 0x60)))      // senderAddress
+            mstore(add(dataAreaEnd, 0x80), mload(add(sourceOffset, 0x80)))      // makerAssetAmount
+            mstore(add(dataAreaEnd, 0xA0), mload(add(sourceOffset, 0xA0)))      // takerAssetAmount
+            mstore(add(dataAreaEnd, 0xC0), mload(add(sourceOffset, 0xC0)))      // makerFeeAmount
+            mstore(add(dataAreaEnd, 0xE0), mload(add(sourceOffset, 0xE0)))      // takerFeeAmount
+            mstore(add(dataAreaEnd, 0x100), mload(add(sourceOffset, 0x100)))    // expirationTimeSeconds
+            mstore(add(dataAreaEnd, 0x120), mload(add(sourceOffset, 0x120)))    // salt
+            mstore(add(dataAreaEnd, 0x140), mload(add(sourceOffset, 0x140)))    // Offset to makerAssetData
+            mstore(add(dataAreaEnd, 0x160), mload(add(sourceOffset, 0x160)))    // Offset to takerAssetData
+            dataAreaEnd := add(dataAreaEnd, 0x180)
+            sourceOffset := add(sourceOffset, 0x180)
+
+            // Write offset to <order.makerAssetData>
+            mstore(add(dataAreaStart, mul(10, 0x20)), sub(dataAreaEnd, dataAreaStart))
+
+            // Calculate length of <order.makerAssetData>
+            sourceOffset := mload(add(order, 0x140)) // makerAssetData
+            arrayLenBytes := mload(sourceOffset)
+            sourceOffset := add(sourceOffset, 0x20)
+            arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
+
+            // Write length of <order.makerAssetData>
+            mstore(dataAreaEnd, arrayLenBytes)
+            dataAreaEnd := add(dataAreaEnd, 0x20)
+
+            // Write contents of <order.makerAssetData>
+            for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
+                mstore(dataAreaEnd, mload(sourceOffset))
+                dataAreaEnd := add(dataAreaEnd, 0x20)
+                sourceOffset := add(sourceOffset, 0x20)
+            }
+
+            // Write offset to <order.takerAssetData>
+            mstore(add(dataAreaStart, mul(11, 0x20)), sub(dataAreaEnd, dataAreaStart))
+
+            // Calculate length of <order.takerAssetData>
+            sourceOffset := mload(add(order, 0x160)) // takerAssetData
+            arrayLenBytes := mload(sourceOffset)
+            sourceOffset := add(sourceOffset, 0x20)
+            arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
+
+            // Write length of <order.takerAssetData>
+            mstore(dataAreaEnd, arrayLenBytes)
+            dataAreaEnd := add(dataAreaEnd, 0x20)
+
+            // Write contents of  <order.takerAssetData>
+            for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
+                mstore(dataAreaEnd, mload(sourceOffset))
+                dataAreaEnd := add(dataAreaEnd, 0x20)
+                sourceOffset := add(sourceOffset, 0x20)
+            }
+
+            /////// Write takerAssetFillAmount ///////
+            mstore(paramsAreaOffset, takerAssetFillAmount)
+            paramsAreaOffset := add(paramsAreaOffset, 0x20)
+
+            /////// Write signature ///////
+            // Write offset to paramsArea
+            mstore(paramsAreaOffset, sub(dataAreaEnd, paramsAreaStart))
+
+            // Calculate length of signature
+            sourceOffset := signature
+            arrayLenBytes := mload(sourceOffset)
+            sourceOffset := add(sourceOffset, 0x20)
+            arrayLenWords := div(add(arrayLenBytes, 0x1F), 0x20)
+
+            // Write length of signature
+            mstore(dataAreaEnd, arrayLenBytes)
+            dataAreaEnd := add(dataAreaEnd, 0x20)
+
+            // Write contents of signature
+            for {let i := 0} lt(i, arrayLenWords) {i := add(i, 1)} {
+                mstore(dataAreaEnd, mload(sourceOffset))
+                dataAreaEnd := add(dataAreaEnd, 0x20)
+                sourceOffset := add(sourceOffset, 0x20)
+            }
+
+            // Execute delegatecall
+            let success := delegatecall(
+                gas,                                // forward all gas, TODO: look into gas consumption of assert/throw
+                address,                            // call address of this contract
+                headerAreaStart,                    // pointer to start of input
+                sub(dataAreaEnd, headerAreaStart),  // length of input
+                headerAreaStart,                    // write output over input
+                128                                 // output size is 128 bytes
+            )
+            switch success
+            case 0 {
+                mstore(fillResults, 0)
+                mstore(add(fillResults, 32), 0)
+                mstore(add(fillResults, 64), 0)
+                mstore(add(fillResults, 96), 0)
+            }
+            case 1 {
+                mstore(fillResults, mload(headerAreaStart))
+                mstore(add(fillResults, 32), mload(add(headerAreaStart, 32)))
+                mstore(add(fillResults, 64), mload(add(headerAreaStart, 64)))
+                mstore(add(fillResults, 96), mload(add(headerAreaStart, 96)))
+            }
+        }
+        return fillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrder.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    ///         NOTE: makerAssetFilledAmount and takerAssetFilledAmount may include amounts filled of different assets.
+    function batchFillOrders(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        for (uint256 i = 0; i < orders.length; i++) {
+            FillResults memory singleFillResults = fillOrder(
+                orders[i],
+                takerAssetFillAmounts[i],
+                signatures[i]
+            );
+            addFillResults(totalFillResults, singleFillResults);
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrKill.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    ///         NOTE: makerAssetFilledAmount and takerAssetFilledAmount may include amounts filled of different assets.
+    function batchFillOrKillOrders(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        for (uint256 i = 0; i < orders.length; i++) {
+            FillResults memory singleFillResults = fillOrKillOrder(
+                orders[i],
+                takerAssetFillAmounts[i],
+                signatures[i]
+            );
+            addFillResults(totalFillResults, singleFillResults);
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Fills an order with specified parameters and ECDSA signature.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    ///         NOTE: makerAssetFilledAmount and takerAssetFilledAmount may include amounts filled of different assets.
+    function batchFillOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        for (uint256 i = 0; i < orders.length; i++) {
+            FillResults memory singleFillResults = fillOrderNoThrow(
+                orders[i],
+                takerAssetFillAmounts[i],
+                signatures[i]
+            );
+            addFillResults(totalFillResults, singleFillResults);
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellOrders(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory takerAssetData = orders[0].takerAssetData;
+    
+        for (uint256 i = 0; i < orders.length; i++) {
+
+            // We assume that asset being sold by taker is the same for each order.
+            // Rather than passing this in as calldata, we use the takerAssetData from the first order in all later orders.
+            orders[i].takerAssetData = takerAssetData;
+
+            // Calculate the remaining amount of takerAsset to sell
+            uint256 remainingTakerAssetFillAmount = safeSub(takerAssetFillAmount, totalFillResults.takerAssetFilledAmount);
+
+            // Attempt to sell the remaining amount of takerAsset
+            FillResults memory singleFillResults = fillOrder(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of takerAsset has been sold
+            if (totalFillResults.takerAssetFilledAmount == takerAssetFillAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory takerAssetData = orders[0].takerAssetData;
+
+        for (uint256 i = 0; i < orders.length; i++) {
+
+            // We assume that asset being sold by taker is the same for each order.
+            // Rather than passing this in as calldata, we use the takerAssetData from the first order in all later orders.
+            orders[i].takerAssetData = takerAssetData;
+
+            // Calculate the remaining amount of takerAsset to sell
+            uint256 remainingTakerAssetFillAmount = safeSub(takerAssetFillAmount, totalFillResults.takerAssetFilledAmount);
+
+            // Attempt to sell the remaining amount of takerAsset
+            FillResults memory singleFillResults = fillOrderNoThrow(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of takerAsset has been sold
+            if (totalFillResults.takerAssetFilledAmount == takerAssetFillAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of makerAsset is bought by taker.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyOrders(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory makerAssetData = orders[0].makerAssetData;
+
+        for (uint256 i = 0; i < orders.length; i++) {
+
+            // We assume that asset being bought by taker is the same for each order.
+            // Rather than passing this in as calldata, we copy the makerAssetData from the first order onto all later orders.
+            orders[i].makerAssetData = makerAssetData;
+
+            // Calculate the remaining amount of makerAsset to buy
+            uint256 remainingMakerAssetFillAmount = safeSub(makerAssetFillAmount, totalFillResults.makerAssetFilledAmount);
+
+            // Convert the remaining amount of makerAsset to buy into remaining amount
+            // of takerAsset to sell, assuming entire amount can be sold in the current order
+            uint256 remainingTakerAssetFillAmount = getPartialAmount(
+                orders[i].takerAssetAmount,
+                orders[i].makerAssetAmount,
+                remainingMakerAssetFillAmount
+            );
+
+            // Attempt to sell the remaining amount of takerAsset
+            FillResults memory singleFillResults = fillOrder(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of makerAsset has been bought
+            if (totalFillResults.makerAssetFilledAmount == makerAssetFillAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously executes multiple fill orders in a single transaction until total amount is bought by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (FillResults memory totalFillResults)
+    {
+        bytes memory makerAssetData = orders[0].makerAssetData;
+
+        for (uint256 i = 0; i < orders.length; i++) {
+
+            // We assume that asset being bought by taker is the same for each order.
+            // Rather than passing this in as calldata, we copy the makerAssetData from the first order onto all later orders.
+            orders[i].makerAssetData = makerAssetData;
+
+            // Calculate the remaining amount of makerAsset to buy
+            uint256 remainingMakerAssetFillAmount = safeSub(makerAssetFillAmount, totalFillResults.makerAssetFilledAmount);
+
+            // Convert the remaining amount of makerAsset to buy into remaining amount
+            // of takerAsset to sell, assuming entire amount can be sold in the current order
+            uint256 remainingTakerAssetFillAmount = getPartialAmount(
+                orders[i].takerAssetAmount,
+                orders[i].makerAssetAmount,
+                remainingMakerAssetFillAmount
+            );
+
+            // Attempt to sell the remaining amount of takerAsset
+            FillResults memory singleFillResults = fillOrderNoThrow(
+                orders[i],
+                remainingTakerAssetFillAmount,
+                signatures[i]
+            );
+
+            // Update amounts filled and fees paid by maker and taker
+            addFillResults(totalFillResults, singleFillResults);
+
+            // Stop execution if the entire amount of makerAsset has been bought
+            if (totalFillResults.makerAssetFilledAmount == makerAssetFillAmount) {
+                break;
+            }
+        }
+        return totalFillResults;
+    }
+
+    /// @dev Synchronously cancels multiple orders in a single transaction.
+    /// @param orders Array of order specifications.
+    function batchCancelOrders(LibOrder.Order[] memory orders)
+        public
+    {
+        for (uint256 i = 0; i < orders.length; i++) {
+            cancelOrder(orders[i]);
+        }
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
new file mode 100644
index 000000000..66f3b5796
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
@@ -0,0 +1,36 @@
+/*
+
+  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 IAssetProxyDispatcher {
+
+    /// @dev Registers an asset proxy to its asset proxy id.
+    ///      Once an asset proxy is registered, it cannot be unregistered.
+    /// @param assetProxy Address of new asset proxy to register.
+    function registerAssetProxy(address assetProxy)
+        external;
+
+    /// @dev Gets an asset proxy.
+    /// @param assetProxyId Id of the asset proxy.
+    /// @return The asset proxy registered to assetProxyId. Returns 0x0 if no proxy is registered.
+    function getAssetProxy(bytes4 assetProxyId)
+        external
+        view
+        returns (address);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchange.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchange.sol
new file mode 100644
index 000000000..9f21c18d7
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchange.sol
@@ -0,0 +1,36 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "./IExchangeCore.sol";
+import "./IMatchOrders.sol";
+import "./ISignatureValidator.sol";
+import "./ITransactions.sol";
+import "./IAssetProxyDispatcher.sol";
+import "./IWrapperFunctions.sol";
+
+contract IExchange is
+    IExchangeCore,
+    IMatchOrders,
+    ISignatureValidator,
+    ITransactions,
+    IAssetProxyDispatcher,
+    IWrapperFunctions
+{}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchangeCore.sol
new file mode 100644
index 000000000..98222f33f
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchangeCore.sol
@@ -0,0 +1,59 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+
+contract IExchangeCore {
+
+    /// @dev Cancels all orders created by makerAddress with a salt less than or equal to the targetOrderEpoch
+    ///      and senderAddress equal to msg.sender (or null address if msg.sender == makerAddress).
+    /// @param targetOrderEpoch Orders created with a salt less or equal to this value will be cancelled.
+    function cancelOrdersUpTo(uint256 targetOrderEpoch)
+        external;
+
+    /// @dev Fills the input order.
+    /// @param order Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrder(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (LibFillResults.FillResults memory fillResults);
+
+    /// @dev After calling, the order can not be filled anymore.
+    /// @param order Order struct containing order specifications.
+    function cancelOrder(LibOrder.Order memory order)
+        public;
+
+    /// @dev Gets information about an order: status, hash, and amount filled.
+    /// @param order Order to gather information on.
+    /// @return OrderInfo Information about the order and its state.
+    ///                   See LibOrder.OrderInfo for a complete description.
+    function getOrderInfo(LibOrder.Order memory order)
+        public
+        view
+        returns (LibOrder.OrderInfo memory orderInfo);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IMatchOrders.sol
new file mode 100644
index 000000000..df009d063
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IMatchOrders.sol
@@ -0,0 +1,44 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+
+contract IMatchOrders {
+
+    /// @dev Match two complementary orders that have a profitable spread.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the left order goes to the taker (who matched the two orders).
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftSignature Proof that order was created by the left maker.
+    /// @param rightSignature Proof that order was created by the right maker.
+    /// @return matchedFillResults Amounts filled and fees paid by maker and taker of matched orders.
+    /// TODO: Make this function external once supported by Solidity (See Solidity Issues #3199, #1603)
+    function matchOrders(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        bytes memory leftSignature,
+        bytes memory rightSignature
+    )
+        public
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ISignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ISignatureValidator.sol
new file mode 100644
index 000000000..511463309
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ISignatureValidator.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;
+
+contract ISignatureValidator {
+
+    /// @dev Approves a hash on-chain using any valid signature type.
+    ///      After presigning a hash, the preSign signature type will become valid for that hash and signer.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof that the hash has been signed by signer.
+    function preSign(
+        bytes32 hash,
+        address signerAddress,
+        bytes signature
+    )
+        external;
+    
+    /// @dev Approves/unnapproves a Validator contract to verify signatures on signer's behalf.
+    /// @param validatorAddress Address of Validator contract.
+    /// @param approval Approval or disapproval of  Validator contract.
+    function setSignatureValidatorApproval(
+        address validatorAddress,
+        bool approval
+    )
+        external;
+
+    /// @dev Verifies that a signature is valid.
+    /// @param hash Message hash that is signed.
+    /// @param signerAddress Address of signer.
+    /// @param signature Proof of signing.
+    /// @return Validity of order signature.
+    function isValidSignature(
+        bytes32 hash,
+        address signerAddress,
+        bytes memory signature
+    )
+        public
+        view
+        returns (bool isValid);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ITransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ITransactions.sol
new file mode 100644
index 000000000..a7cab8f55
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ITransactions.sol
@@ -0,0 +1,34 @@
+/*
+
+  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 ITransactions {
+
+    /// @dev Executes an exchange method call in the context of signer.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param data AbiV2 encoded calldata.
+    /// @param signature Proof of signer transaction by signer.
+    function executeTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes data,
+        bytes signature
+    )
+        external;
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IValidator.sol
new file mode 100644
index 000000000..0b1796a66
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IValidator.sol
@@ -0,0 +1,36 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.23;
+
+contract IValidator {
+
+    /// @dev Verifies that a signature is valid.
+    /// @param hash Message hash that is signed.
+    /// @param signerAddress Address that should have signed the given hash.
+    /// @param signature Proof of signing.
+    /// @return Validity of order signature.
+    function isValidSignature(
+        bytes32 hash,
+        address signerAddress,
+        bytes signature
+    )
+        external
+        view
+        returns (bool isValid);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWallet.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWallet.sol
new file mode 100644
index 000000000..c86a2c057
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWallet.sol
@@ -0,0 +1,34 @@
+/*
+
+  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 IWallet {
+
+    /// @dev Verifies that a signature is valid.
+    /// @param hash Message hash that is signed.
+    /// @param signature Proof of signing.
+    /// @return Validity of order signature.
+    function isValidSignature(
+        bytes32 hash,
+        bytes signature
+    )
+        external
+        view
+        returns (bool isValid);
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWrapperFunctions.sol
new file mode 100644
index 000000000..84bb683bc
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWrapperFunctions.sol
@@ -0,0 +1,150 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+
+contract IWrapperFunctions {
+    /// @dev Fills the input order. Reverts if exact takerAssetFillAmount not filled.
+    /// @param order LibOrder.Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    function fillOrKillOrder(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (LibFillResults.FillResults memory fillResults);
+
+    /// @dev Fills an order with specified parameters and ECDSA signature.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param order LibOrder.Order struct containing order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signature Proof that order has been created by maker.
+    /// @return Amounts filled and fees paid by maker and taker.
+    function fillOrderNoThrow(
+        LibOrder.Order memory order,
+        uint256 takerAssetFillAmount,
+        bytes memory signature
+    )
+        public
+        returns (LibFillResults.FillResults memory fillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrder.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function batchFillOrders(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrKill.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function batchFillOrKillOrders(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Fills an order with specified parameters and ECDSA signature.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmounts Array of desired amounts of takerAsset to sell in orders.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function batchFillOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256[] memory takerAssetFillAmounts,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signatures Proofs that orders have been created by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellOrders(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of takerAsset is sold by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketSellOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256 takerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple calls of fillOrder until total amount of makerAsset is bought by taker.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyOrders(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously executes multiple fill orders in a single transaction until total amount is bought by taker.
+    ///      Returns false if the transaction would otherwise revert.
+    /// @param orders Array of order specifications.
+    /// @param makerAssetFillAmount Desired amount of makerAsset to buy.
+    /// @param signatures Proofs that orders have been signed by makers.
+    /// @return Amounts filled and fees paid by makers and taker.
+    function marketBuyOrdersNoThrow(
+        LibOrder.Order[] memory orders,
+        uint256 makerAssetFillAmount,
+        bytes[] memory signatures
+    )
+        public
+        returns (LibFillResults.FillResults memory totalFillResults);
+
+    /// @dev Synchronously cancels multiple orders in a single transaction.
+    /// @param orders Array of order specifications.
+    function batchCancelOrders(LibOrder.Order[] memory orders)
+        public;
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibConstants.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibConstants.sol
new file mode 100644
index 000000000..488ca956c
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibConstants.sol
@@ -0,0 +1,34 @@
+/*
+
+  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 LibConstants {
+   
+    // Asset data for ZRX token. Used for fee transfers.
+    // @TODO: Hardcode constant when we deploy. Currently 
+    //        not constant to make testing easier.
+    bytes public ZRX_ASSET_DATA;
+
+    // @TODO: Remove when we deploy.
+    constructor (bytes memory zrxAssetData)
+        public
+    {
+        ZRX_ASSET_DATA = zrxAssetData;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
new file mode 100644
index 000000000..b983347a4
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
@@ -0,0 +1,64 @@
+/*
+
+  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 LibEIP712 {
+    // EIP191 header for EIP712 prefix
+    string constant EIP191_HEADER = "\x19\x01";
+
+    // EIP712 Domain Name value
+    string constant EIP712_DOMAIN_NAME = "0x Protocol";
+
+    // EIP712 Domain Version value
+    string constant EIP712_DOMAIN_VERSION = "2";
+
+    // Hash of the EIP712 Domain Separator Schema
+    bytes32 public constant EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH = keccak256(abi.encodePacked(
+        "EIP712Domain(",
+        "string name,",
+        "string version,",
+        "address verifyingContract",
+        ")"
+    ));
+
+    // Hash of the EIP712 Domain Separator data
+    bytes32 public EIP712_DOMAIN_HASH;
+
+    constructor ()
+        public
+    {
+        EIP712_DOMAIN_HASH = keccak256(abi.encode(
+            EIP712_DOMAIN_SEPARATOR_SCHEMA_HASH,
+            keccak256(bytes(EIP712_DOMAIN_NAME)),
+            keccak256(bytes(EIP712_DOMAIN_VERSION)),
+            address(this)
+        ));
+    }
+
+    /// @dev Calculates EIP712 encoding for a hash struct in this EIP712 Domain.
+    /// @param hashStruct The EIP712 hash struct.
+    /// @return EIP712 hash applied to this EIP712 Domain.
+    function hashEIP712Message(bytes32 hashStruct)
+        internal
+        view
+        returns (bytes32)
+    {
+        return keccak256(abi.encodePacked(EIP191_HEADER, EIP712_DOMAIN_HASH, hashStruct));
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibExchangeErrors.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibExchangeErrors.sol
new file mode 100644
index 000000000..01aa78a1d
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibExchangeErrors.sol
@@ -0,0 +1,68 @@
+/*
+
+  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;
+
+/// @dev This contract documents the revert reasons used in the Exchange contract.
+/// This contract is intended to serve as a reference, but is not actually used for efficiency reasons.
+contract LibExchangeErrors {
+
+    /// Order validation errors ///
+    string constant ORDER_UNFILLABLE = "ORDER_UNFILLABLE";                              // Order cannot be filled.
+    string constant INVALID_MAKER = "INVALID_MAKER";                                    // Invalid makerAddress.
+    string constant INVALID_TAKER = "INVALID_TAKER";                                    // Invalid takerAddress.
+    string constant INVALID_SENDER = "INVALID_SENDER";                                  // Invalid `msg.sender`.
+    string constant INVALID_ORDER_SIGNATURE = "INVALID_ORDER_SIGNATURE";                // Signature validation failed. 
+    
+    /// fillOrder validation errors ///
+    string constant INVALID_TAKER_AMOUNT = "INVALID_TAKER_AMOUNT";                      // takerAssetFillAmount cannot equal 0.
+    string constant ROUNDING_ERROR = "ROUNDING_ERROR";                                  // Rounding error greater than 0.1% of takerAssetFillAmount. 
+    
+    /// Signature validation errors ///
+    string constant INVALID_SIGNATURE = "INVALID_SIGNATURE";                            // Signature validation failed. 
+    string constant SIGNATURE_ILLEGAL = "SIGNATURE_ILLEGAL";                            // Signature type is illegal.
+    string constant SIGNATURE_UNSUPPORTED = "SIGNATURE_UNSUPPORTED";                    // Signature type unsupported.
+    
+    /// cancelOrdersUptTo errors ///
+    string constant INVALID_NEW_ORDER_EPOCH = "INVALID_NEW_ORDER_EPOCH";                // Specified salt must be greater than or equal to existing orderEpoch.
+
+    /// fillOrKillOrder errors ///
+    string constant COMPLETE_FILL_FAILED = "COMPLETE_FILL_FAILED";                      // Desired takerAssetFillAmount could not be completely filled. 
+
+    /// matchOrders errors ///
+    string constant NEGATIVE_SPREAD_REQUIRED = "NEGATIVE_SPREAD_REQUIRED";              // Matched orders must have a negative spread.
+
+    /// Transaction errors ///
+    string constant REENTRANCY_ILLEGAL = "REENTRANCY_ILLEGAL";                          // Recursive reentrancy is not allowed. 
+    string constant INVALID_TX_HASH = "INVALID_TX_HASH";                                // Transaction has already been executed. 
+    string constant INVALID_TX_SIGNATURE = "INVALID_TX_SIGNATURE";                      // Signature validation failed. 
+    string constant FAILED_EXECUTION = "FAILED_EXECUTION";                              // Transaction execution failed. 
+    
+    /// registerAssetProxy errors ///
+    string constant ASSET_PROXY_ALREADY_EXISTS = "ASSET_PROXY_ALREADY_EXISTS";          // AssetProxy with same id already exists.
+
+    /// dispatchTransferFrom errors ///
+    string constant ASSET_PROXY_DOES_NOT_EXIST = "ASSET_PROXY_DOES_NOT_EXIST";          // No assetProxy registered at given id.
+    string constant TRANSFER_FAILED = "TRANSFER_FAILED";                                // Asset transfer unsuccesful.
+
+    /// Length validation errors ///
+    string constant LENGTH_GREATER_THAN_0_REQUIRED = "LENGTH_GREATER_THAN_0_REQUIRED";  // Byte array must have a length greater than 0.
+    string constant LENGTH_GREATER_THAN_3_REQUIRED = "LENGTH_GREATER_THAN_3_REQUIRED";  // Byte array must have a length greater than 3.
+    string constant LENGTH_0_REQUIRED = "LENGTH_0_REQUIRED";                            // Byte array must have a length of 0.
+    string constant LENGTH_65_REQUIRED = "LENGTH_65_REQUIRED";                          // Byte array must have a length of 65.
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
new file mode 100644
index 000000000..63f1b8c87
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
@@ -0,0 +1,53 @@
+/*
+
+  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/SafeMath/SafeMath.sol";
+
+contract LibFillResults is
+    SafeMath
+{
+
+    struct FillResults {
+        uint256 makerAssetFilledAmount;  // Total amount of makerAsset(s) filled.
+        uint256 takerAssetFilledAmount;  // Total amount of takerAsset(s) filled.
+        uint256 makerFeePaid;            // Total amount of ZRX paid by maker(s) to feeRecipient(s).
+        uint256 takerFeePaid;            // Total amount of ZRX paid by taker to feeRecipients(s).
+    }
+
+    struct MatchedFillResults {
+        FillResults left;                    // Amounts filled and fees paid of left order.
+        FillResults right;                   // Amounts filled and fees paid of right order.
+        uint256 leftMakerAssetSpreadAmount;  // Spread between price of left and right order, denominated in the left order's makerAsset, paid to taker.
+    }
+
+    /// @dev Adds properties of both FillResults instances.
+    ///      Modifies the first FillResults instance specified.
+    /// @param totalFillResults Fill results instance that will be added onto.
+    /// @param singleFillResults Fill results instance that will be added to totalFillResults.
+    function addFillResults(FillResults memory totalFillResults, FillResults memory singleFillResults)
+        internal
+        pure
+    {
+        totalFillResults.makerAssetFilledAmount = safeAdd(totalFillResults.makerAssetFilledAmount, singleFillResults.makerAssetFilledAmount);
+        totalFillResults.takerAssetFilledAmount = safeAdd(totalFillResults.takerAssetFilledAmount, singleFillResults.takerAssetFilledAmount);
+        totalFillResults.makerFeePaid = safeAdd(totalFillResults.makerFeePaid, singleFillResults.makerFeePaid);
+        totalFillResults.takerFeePaid = safeAdd(totalFillResults.takerFeePaid, singleFillResults.takerFeePaid);
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
new file mode 100644
index 000000000..bfe2fd33f
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
@@ -0,0 +1,72 @@
+/*
+
+  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/SafeMath/SafeMath.sol";
+
+contract LibMath is
+    SafeMath
+{
+
+    /// @dev Calculates partial value given a numerator and denominator.
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target.
+    function getPartialAmount(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target)
+        internal
+        pure
+        returns (uint256 partialAmount)
+    {
+        partialAmount = safeDiv(
+            safeMul(numerator, target),
+            denominator
+        );
+        return partialAmount;
+    }
+
+    /// @dev Checks if rounding error > 0.1%.
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to multiply with numerator/denominator.
+    /// @return Rounding error is present.
+    function isRoundingError(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target)
+        internal
+        pure
+        returns (bool isError)
+    {
+        uint256 remainder = mulmod(target, numerator, denominator);
+        if (remainder == 0) {
+            return false; // No rounding error.
+        }
+
+        uint256 errPercentageTimes1000000 = safeDiv(
+            safeMul(remainder, 1000000),
+            safeMul(numerator, target)
+        );
+        isError = errPercentageTimes1000000 > 1000;
+        return isError;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
new file mode 100644
index 000000000..954f94f76
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
@@ -0,0 +1,135 @@
+/*
+
+  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 "./LibEIP712.sol";
+
+contract LibOrder is
+    LibEIP712
+{
+
+    // Hash for the EIP712 Order Schema
+    bytes32 constant EIP712_ORDER_SCHEMA_HASH = keccak256(abi.encodePacked(
+        "Order(",
+        "address makerAddress,",
+        "address takerAddress,",
+        "address feeRecipientAddress,",
+        "address senderAddress,",
+        "uint256 makerAssetAmount,",
+        "uint256 takerAssetAmount,",
+        "uint256 makerFee,",
+        "uint256 takerFee,",
+        "uint256 expirationTimeSeconds,",
+        "uint256 salt,",
+        "bytes makerAssetData,",
+        "bytes takerAssetData",
+        ")"
+    ));
+
+    // A valid order remains fillable until it is expired, fully filled, or cancelled.
+    // An order's state is unaffected by external factors, like account balances.
+    enum OrderStatus {
+        INVALID,                     // Default value
+        INVALID_MAKER_ASSET_AMOUNT,  // Order does not have a valid maker asset amount
+        INVALID_TAKER_ASSET_AMOUNT,  // Order does not have a valid taker asset amount
+        FILLABLE,                    // Order is fillable
+        EXPIRED,                     // Order has already expired
+        FULLY_FILLED,                // Order is fully filled
+        CANCELLED                    // Order has been cancelled
+    }
+
+    struct Order {
+        address makerAddress;           // Address that created the order.      
+        address takerAddress;           // Address that is allowed to fill the order. If set to 0, any address is allowed to fill the order.          
+        address feeRecipientAddress;    // Address that will recieve fees when order is filled.      
+        address senderAddress;          // Address that is allowed to call Exchange contract methods that affect this order. If set to 0, any address is allowed to call these methods.
+        uint256 makerAssetAmount;       // Amount of makerAsset being offered by maker. Must be greater than 0.        
+        uint256 takerAssetAmount;       // Amount of takerAsset being bid on by maker. Must be greater than 0.        
+        uint256 makerFee;               // Amount of ZRX paid to feeRecipient by maker when order is filled. If set to 0, no transfer of ZRX from maker to feeRecipient will be attempted.
+        uint256 takerFee;               // Amount of ZRX paid to feeRecipient by taker when order is filled. If set to 0, no transfer of ZRX from taker to feeRecipient will be attempted.
+        uint256 expirationTimeSeconds;  // Timestamp in seconds at which order expires.          
+        uint256 salt;                   // Arbitrary number to facilitate uniqueness of the order's hash.     
+        bytes makerAssetData;           // Encoded data that can be decoded by a specified proxy contract when transferring makerAsset. The last byte references the id of this proxy.
+        bytes takerAssetData;           // Encoded data that can be decoded by a specified proxy contract when transferring takerAsset. The last byte references the id of this proxy.
+    }
+
+    struct OrderInfo {
+        uint8 orderStatus;                    // Status that describes order's validity and fillability.
+        bytes32 orderHash;                    // EIP712 hash of the order (see LibOrder.getOrderHash).
+        uint256 orderTakerAssetFilledAmount;  // Amount of order that has already been filled.
+    }
+
+    /// @dev Calculates Keccak-256 hash of the order.
+    /// @param order The order structure.
+    /// @return Keccak-256 EIP712 hash of the order.
+    function getOrderHash(Order memory order)
+        internal
+        view
+        returns (bytes32 orderHash)
+    {
+        orderHash = hashEIP712Message(hashOrder(order));
+        return orderHash;
+    }
+
+    /// @dev Calculates EIP712 hash of the order.
+    /// @param order The order structure.
+    /// @return EIP712 hash of the order.
+    function hashOrder(Order memory order)
+        internal
+        pure
+        returns (bytes32 result)
+    {
+        bytes32 schemaHash = EIP712_ORDER_SCHEMA_HASH;
+        bytes32 makerAssetDataHash = keccak256(order.makerAssetData);
+        bytes32 takerAssetDataHash = keccak256(order.takerAssetData);
+        // Assembly for more efficiently computing:
+        //   keccak256(abi.encode(
+        //       order.makerAddress,
+        //       order.takerAddress,
+        //       order.feeRecipientAddress,
+        //       order.senderAddress,
+        //       order.makerAssetAmount,
+        //       order.takerAssetAmount,
+        //       order.makerFee,
+        //       order.takerFee,
+        //       order.expirationTimeSeconds,
+        //       order.salt,
+        //       keccak256(order.makerAssetData),
+        //       keccak256(order.takerAssetData)
+        //   ));
+        assembly {
+            // Backup
+            let temp1 := mload(sub(order,  32))
+            let temp2 := mload(add(order, 320))
+            let temp3 := mload(add(order, 352))
+            
+            // Hash in place
+            mstore(sub(order,  32), schemaHash)
+            mstore(add(order, 320), makerAssetDataHash)
+            mstore(add(order, 352), takerAssetDataHash)
+            result := keccak256(sub(order, 32), 416)
+            
+            // Restore
+            mstore(sub(order,  32), temp1)
+            mstore(add(order, 320), temp2)
+            mstore(add(order, 352), temp3)
+        }
+        return result;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
new file mode 100644
index 000000000..5bf59c6ce
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
@@ -0,0 +1,46 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../interfaces/IAssetProxyDispatcher.sol";
+
+contract MAssetProxyDispatcher is
+    IAssetProxyDispatcher
+{
+
+    // Logs registration of new asset proxy
+    event AssetProxyRegistered(
+        bytes4 id,              // Id of new registered AssetProxy.
+        address assetProxy      // Address of new registered AssetProxy.
+    );
+
+    /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
+    /// @param assetData Byte array encoded for the asset.
+    /// @param from Address to transfer token from.
+    /// @param to Address to transfer token to.
+    /// @param amount Amount of token to transfer.
+    function dispatchTransferFrom(
+        bytes memory assetData,
+        address from,
+        address to,
+        uint256 amount
+    )
+        internal;
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
new file mode 100644
index 000000000..6e406e1c4
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
@@ -0,0 +1,127 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+import "../interfaces/IExchangeCore.sol";
+
+contract MExchangeCore is
+    IExchangeCore
+{
+    // Fill event is emitted whenever an order is filled.
+    event Fill(
+        address indexed makerAddress,         // Address that created the order.      
+        address indexed feeRecipientAddress,  // Address that received fees.
+        address takerAddress,                 // Address that filled the order.
+        address senderAddress,                // Address that called the Exchange contract (msg.sender).
+        uint256 makerAssetFilledAmount,       // Amount of makerAsset sold by maker and bought by taker. 
+        uint256 takerAssetFilledAmount,       // Amount of takerAsset sold by taker and bought by maker.
+        uint256 makerFeePaid,                 // Amount of ZRX paid to feeRecipient by maker.
+        uint256 takerFeePaid,                 // Amount of ZRX paid to feeRecipient by taker.
+        bytes32 indexed orderHash,            // EIP712 hash of order (see LibOrder.getOrderHash).
+        bytes makerAssetData,                 // Encoded data specific to makerAsset. 
+        bytes takerAssetData                  // Encoded data specific to takerAsset.
+    );
+
+    // Cancel event is emitted whenever an individual order is cancelled.
+    event Cancel(
+        address indexed makerAddress,         // Address that created the order.      
+        address indexed feeRecipientAddress,  // Address that would have recieved fees if order was filled.   
+        address senderAddress,                // Address that called the Exchange contract (msg.sender).
+        bytes32 indexed orderHash,            // EIP712 hash of order (see LibOrder.getOrderHash).
+        bytes makerAssetData,                 // Encoded data specific to makerAsset. 
+        bytes takerAssetData                  // Encoded data specific to takerAsset.
+    );
+
+    // CancelUpTo event is emitted whenever `cancelOrdersUpTo` is executed succesfully.
+    event CancelUpTo(
+        address indexed makerAddress,         // Orders cancelled must have been created by this address.
+        address indexed senderAddress,        // Orders cancelled must have a `senderAddress` equal to this address.
+        uint256 orderEpoch                    // Orders specified makerAddress and senderAddress with a salt <= this value are considered cancelled.
+    );
+
+    /// @dev Updates state with results of a fill order.
+    /// @param order that was filled.
+    /// @param takerAddress Address of taker who filled the order.
+    /// @param orderTakerAssetFilledAmount Amount of order already filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function updateFilledState(
+        LibOrder.Order memory order,
+        address takerAddress,
+        bytes32 orderHash,
+        uint256 orderTakerAssetFilledAmount,
+        LibFillResults.FillResults memory fillResults
+    )
+        internal;
+
+    /// @dev Updates state with results of cancelling an order.
+    ///      State is only updated if the order is currently fillable.
+    ///      Otherwise, updating state would have no effect.
+    /// @param order that was cancelled.
+    /// @param orderHash Hash of order that was cancelled.
+    function updateCancelledState(
+        LibOrder.Order memory order,
+        bytes32 orderHash
+    )
+        internal;
+
+    /// @dev Validates context for fillOrder. Succeeds or throws.
+    /// @param order to be filled.
+    /// @param orderInfo Status, orderHash, and amount already filled of order.
+    /// @param takerAddress Address of order taker.
+    /// @param takerAssetFillAmount Desired amount of order to fill by taker.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @param signature Proof that the orders was created by its maker.
+    function assertValidFill(
+        LibOrder.Order memory order,
+        LibOrder.OrderInfo memory orderInfo,
+        address takerAddress,
+        uint256 takerAssetFillAmount,
+        uint256 takerAssetFilledAmount,
+        bytes memory signature
+    )
+        internal
+        view;
+
+
+    /// @dev Validates context for cancelOrder. Succeeds or throws.
+    /// @param order to be cancelled.
+    /// @param orderInfo OrderStatus, orderHash, and amount already filled of order.
+    function assertValidCancel(
+        LibOrder.Order memory order,
+        LibOrder.OrderInfo memory orderInfo
+    )
+        internal
+        view;
+
+    /// @dev Calculates amounts filled and fees paid by maker and taker.
+    /// @param order to be filled.
+    /// @param takerAssetFilledAmount Amount of takerAsset that will be filled.
+    /// @return fillResults Amounts filled and fees paid by maker and taker.
+    function calculateFillResults(
+        LibOrder.Order memory order,
+        uint256 takerAssetFilledAmount
+    )
+        internal
+        pure
+        returns (LibFillResults.FillResults memory fillResults);
+
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
new file mode 100644
index 000000000..abe7c3596
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
@@ -0,0 +1,58 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../libs/LibOrder.sol";
+import "../libs/LibFillResults.sol";
+import "../interfaces/IMatchOrders.sol";
+
+contract MMatchOrders is
+    IMatchOrders
+{
+
+    /// @dev Validates context for matchOrders. Succeeds or throws.
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    function assertValidMatch(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder
+    )
+        internal
+        pure;
+
+    /// @dev Calculates fill amounts for the matched orders.
+    ///      Each order is filled at their respective price point. However, the calculations are
+    ///      carried out as though the orders are both being filled at the right order's price point.
+    ///      The profit made by the leftOrder order goes to the taker (who matched the two orders).
+    /// @param leftOrder First order to match.
+    /// @param rightOrder Second order to match.
+    /// @param leftOrderTakerAssetFilledAmount Amount of left order already filled.
+    /// @param rightOrderTakerAssetFilledAmount Amount of right order already filled.
+    /// @param matchedFillResults Amounts to fill and fees to pay by maker and taker of matched orders.
+    function calculateMatchedFillResults(
+        LibOrder.Order memory leftOrder,
+        LibOrder.Order memory rightOrder,
+        uint256 leftOrderTakerAssetFilledAmount,
+        uint256 rightOrderTakerAssetFilledAmount
+    )
+        internal
+        pure
+        returns (LibFillResults.MatchedFillResults memory matchedFillResults);
+
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MSignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MSignatureValidator.sol
new file mode 100644
index 000000000..6cc1d7a10
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MSignatureValidator.sol
@@ -0,0 +1,45 @@
+/*
+
+  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 "../interfaces/ISignatureValidator.sol";
+
+contract MSignatureValidator is
+    ISignatureValidator
+{
+    event SignatureValidatorApproval(
+        address indexed signerAddress,     // Address that approves or disapproves a contract to verify signatures.
+        address indexed validatorAddress,  // Address of signature validator contract.
+        bool approved                      // Approval or disapproval of validator contract.
+    );
+
+    // Allowed signature types.
+    enum SignatureType {
+        Illegal,         // 0x00, default value
+        Invalid,         // 0x01
+        EIP712,          // 0x02
+        EthSign,         // 0x03
+        Caller,          // 0x04
+        Wallet,          // 0x05
+        Validator,       // 0x06
+        PreSigned,       // 0x07
+        Trezor,          // 0x08
+        NSignatureTypes  // 0x09, number of signature types. Always leave at end.
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
new file mode 100644
index 000000000..e2f89de01
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
@@ -0,0 +1,35 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+pragma solidity ^0.4.24;
+
+import "../interfaces/ITransactions.sol";
+
+contract MTransactions is
+    ITransactions
+{
+
+    /// @dev The current function will be called in the context of this address (either 0x transaction signer or `msg.sender`).
+    ///      If calling a fill function, this address will represent the taker.
+    ///      If calling a cancel function, this address will represent the maker.
+    /// @return Signer of 0x transaction if entry point is `executeTransaction`.
+    ///         `msg.sender` if entry point is any other function.
+    function getCurrentContextAddress()
+        internal
+        view
+        returns (address);
+}