Refactor @0x/contracts-utils from @0x/contracts-core

19 files changed, 2241 insertions, 0 deletions

diff --git a/contracts/utils/.solhint.json b/contracts/utils/.solhint.json
new file mode 100644
index 000000000..076afe9f3
--- /dev/null
+++ b/contracts/utils/.solhint.json
@@ -0,0 +1,20 @@
+{
+    "extends": "default",
+    "rules": {
+        "avoid-low-level-calls": false,
+        "avoid-tx-origin": "warn",
+        "bracket-align": false,
+        "code-complexity": false,
+        "const-name-snakecase": "error",
+        "expression-indent": "error",
+        "function-max-lines": false,
+        "func-order": "error",
+        "indent": ["error", 4],
+        "max-line-length": ["warn", 160],
+        "no-inline-assembly": false,
+        "quotes": ["error", "double"],
+        "separate-by-one-line-in-contract": "error",
+        "space-after-comma": "error",
+        "statement-indent": "error"
+    }
+}
diff --git a/contracts/utils/README.md b/contracts/utils/README.md
new file mode 100644
index 000000000..e7c7b49ff
--- /dev/null
+++ b/contracts/utils/README.md
@@ -0,0 +1,70 @@
+## Contracts utils
+
+Smart contracts utils used in the 0x protocol.
+
+## Usage
+
+Contracts can be found in the [contracts](./contracts) directory. The contents of this directory are broken down into the following subdirectories:
+
+*   [utils](./contracts/utils)
+    *   This directory contains libraries and utils.
+*   [test](./contracts/test)
+    *   This directory contains mocks and other contracts that are used solely for testing contracts within the other directories.
+
+## Contributing
+
+We strongly recommend that the community help us make improvements and determine the future direction of the protocol. To report bugs within this package, please create an issue in this repository.
+
+For proposals regarding the 0x protocol's smart contract architecture, message format, or additional functionality, go to the [0x Improvement Proposals (ZEIPs)](https://github.com/0xProject/ZEIPs) repository and follow the contribution guidelines provided therein.
+
+Please read our [contribution guidelines](../../CONTRIBUTING.md) before getting started.
+
+### Install Dependencies
+
+If you don't have yarn workspaces enabled (Yarn < v1.0) - enable them:
+
+```bash
+yarn config set workspaces-experimental true
+```
+
+Then install dependencies
+
+```bash
+yarn install
+```
+
+### Build
+
+To build this package and all other monorepo packages that it depends on, run the following from the monorepo root directory:
+
+```bash
+PKG=@0x/contracts-utils yarn build
+```
+
+Or continuously rebuild on change:
+
+```bash
+PKG=@0x/contracts-utils yarn watch
+```
+
+### Clean
+
+```bash
+yarn clean
+```
+
+### Lint
+
+```bash
+yarn lint
+```
+
+### Run Tests
+
+```bash
+yarn test
+```
+
+#### Testing options
+
+Contracts testing options like coverage, profiling, revert traces or backing node choosing - are described [here](../TESTING.md).
diff --git a/contracts/utils/compiler.json b/contracts/utils/compiler.json
new file mode 100644
index 000000000..1524c1eaa
--- /dev/null
+++ b/contracts/utils/compiler.json
@@ -0,0 +1,22 @@
+{
+    "artifactsDir": "./generated-artifacts",
+    "contractsDir": "./contracts",
+    "compilerSettings": {
+        "optimizer": {
+            "enabled": true,
+            "runs": 1000000
+        },
+        "outputSelection": {
+            "*": {
+                "*": [
+                    "abi",
+                    "evm.bytecode.object",
+                    "evm.bytecode.sourceMap",
+                    "evm.deployedBytecode.object",
+                    "evm.deployedBytecode.sourceMap"
+                ]
+            }
+        }
+    },
+    "contracts": ["TestConstants", "TestLibBytes", "LibBytes", "Ownable", "IOwnable", "ReentrancyGuard", "SafeMath"]
+}
diff --git a/contracts/utils/contracts/test/TestConstants/TestConstants.sol b/contracts/utils/contracts/test/TestConstants/TestConstants.sol
new file mode 100644
index 000000000..3c852173b
--- /dev/null
+++ b/contracts/utils/contracts/test/TestConstants/TestConstants.sol
@@ -0,0 +1,57 @@
+/*
+
+  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 "@0x/contracts-utils/contracts/utils/LibBytes/LibBytes.sol";
+
+
+// solhint-disable max-line-length
+contract TestConstants {
+   
+    using LibBytes for bytes;
+
+    bytes4 constant internal ERC20_PROXY_ID = bytes4(keccak256("ERC20Token(address)"));
+    
+    address constant internal KOVAN_ZRX_ADDRESS = 0x6Ff6C0Ff1d68b964901F986d4C9FA3ac68346570;
+    bytes constant internal KOVAN_ZRX_ASSET_DATA = "\xf4\x72\x61\xb0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x6f\xf6\xc0\xff\x1d\x68\xb9\x64\x90\x1f\x98\x6d\x4c\x9f\xa3\xac\x68\x34\x65\x70";
+    
+    address constant internal MAINNET_ZRX_ADDRESS = 0xE41d2489571d322189246DaFA5ebDe1F4699F498;
+    bytes constant public MAINNET_ZRX_ASSET_DATA = "\xf4\x72\x61\xb0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xe4\x1d\x24\x89\x57\x1d\x32\x21\x89\x24\x6d\xaf\xa5\xeb\xde\x1f\x46\x99\xf4\x98";
+    
+    function assertValidZrxAssetData()
+        public
+        pure
+        returns (bool)
+    {
+        bytes memory kovanZrxAssetData = abi.encodeWithSelector(ERC20_PROXY_ID, KOVAN_ZRX_ADDRESS);
+        require(
+            kovanZrxAssetData.equals(KOVAN_ZRX_ASSET_DATA),
+            "INVALID_KOVAN_ZRX_ASSET_DATA"
+        );
+
+        bytes memory mainetZrxAssetData = abi.encodeWithSelector(ERC20_PROXY_ID, MAINNET_ZRX_ADDRESS);
+        require(
+            mainetZrxAssetData.equals(MAINNET_ZRX_ASSET_DATA),
+            "INVALID_MAINNET_ZRX_ASSET_DATA"
+        );
+
+        return true;
+    }
+}
+// solhint-enable max-line-length
\ No newline at end of file
diff --git a/contracts/utils/contracts/test/TestLibBytes/TestLibBytes.sol b/contracts/utils/contracts/test/TestLibBytes/TestLibBytes.sol
new file mode 100644
index 000000000..444a3e717
--- /dev/null
+++ b/contracts/utils/contracts/test/TestLibBytes/TestLibBytes.sol
@@ -0,0 +1,269 @@
+/*
+
+  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 "@0x/contracts-utils/contracts/utils/LibBytes/LibBytes.sol";
+
+
+contract TestLibBytes {
+    
+    using LibBytes for bytes;
+
+    /// @dev Pops the last byte off of a byte array by modifying its length.
+    /// @param b Byte array that will be modified.
+    /// @return The byte that was popped off.
+    function publicPopLastByte(bytes memory b)
+        public
+        pure
+        returns (bytes memory, bytes1 result)
+    {
+        result = b.popLastByte();
+        return (b, result);
+    }
+
+    /// @dev Pops the last 20 bytes off of a byte array by modifying its length.
+    /// @param b Byte array that will be modified.
+    /// @return The 20 byte address that was popped off.
+    function publicPopLast20Bytes(bytes memory b)
+        public
+        pure
+        returns (bytes memory, address result)
+    {
+        result = b.popLast20Bytes();
+        return (b, result);
+    }
+
+    /// @dev Tests equality of two byte arrays.
+    /// @param lhs First byte array to compare.
+    /// @param rhs Second byte array to compare.
+    /// @return True if arrays are the same. False otherwise.
+    function publicEquals(bytes memory lhs, bytes memory rhs)
+        public
+        pure
+        returns (bool equal)
+    {
+        equal = lhs.equals(rhs);
+        return equal;
+    }
+    
+    function publicEqualsPop1(bytes memory lhs, bytes memory rhs)
+        public
+        pure
+        returns (bool equal)
+    {
+        lhs.popLastByte();
+        rhs.popLastByte();
+        equal = lhs.equals(rhs);
+        return equal;
+    }
+
+    /// @dev Performs a deep copy of a byte array onto another byte array of greater than or equal length.
+    /// @param dest Byte array that will be overwritten with source bytes.
+    /// @param source Byte array to copy onto dest bytes.
+    function publicDeepCopyBytes(
+        bytes memory dest,
+        bytes memory source
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        LibBytes.deepCopyBytes(dest, source);
+        return dest;
+    }
+
+    /// @dev Reads an address from a position in a byte array.
+    /// @param b Byte array containing an address.
+    /// @param index Index in byte array of address.
+    /// @return address from byte array.
+    function publicReadAddress(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (address result)
+    {
+        result = b.readAddress(index);
+        return result;
+    }
+
+    /// @dev Writes an address into a specific position in a byte array.
+    /// @param b Byte array to insert address into.
+    /// @param index Index in byte array of address.
+    /// @param input Address to put into byte array.
+    function publicWriteAddress(
+        bytes memory b,
+        uint256 index,
+        address input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        b.writeAddress(index, input);
+        return b;
+    }
+
+    /// @dev Reads a bytes32 value from a position in a byte array.
+    /// @param b Byte array containing a bytes32 value.
+    /// @param index Index in byte array of bytes32 value.
+    /// @return bytes32 value from byte array.
+    function publicReadBytes32(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (bytes32 result)
+    {
+        result = b.readBytes32(index);
+        return result;
+    }
+
+    /// @dev Writes a bytes32 into a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes32 to put into byte array.
+    function publicWriteBytes32(
+        bytes memory b,
+        uint256 index,
+        bytes32 input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        b.writeBytes32(index, input);
+        return b;
+    }
+
+    /// @dev Reads a uint256 value from a position in a byte array.
+    /// @param b Byte array containing a uint256 value.
+    /// @param index Index in byte array of uint256 value.
+    /// @return uint256 value from byte array.
+    function publicReadUint256(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (uint256 result)
+    {
+        result = b.readUint256(index);
+        return result;
+    }
+
+    /// @dev Writes a uint256 into a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input uint256 to put into byte array.
+    function publicWriteUint256(
+        bytes memory b,
+        uint256 index,
+        uint256 input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        b.writeUint256(index, input);
+        return b;
+    }
+
+    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
+    /// @param b Byte array containing a bytes4 value.
+    /// @param index Index in byte array of bytes4 value.
+    /// @return bytes4 value from byte array.
+    function publicReadBytes4(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (bytes4 result)
+    {
+        result = b.readBytes4(index);
+        return result;
+    }
+
+    /// @dev Reads nested bytes from a specific position.
+    /// @param b Byte array containing nested bytes.
+    /// @param index Index of nested bytes.
+    /// @return result Nested bytes.
+    function publicReadBytesWithLength(
+        bytes memory b,
+        uint256 index
+    )
+        public
+        pure
+        returns (bytes memory result)
+    {
+        result = b.readBytesWithLength(index);
+        return result;
+    }
+
+    /// @dev Inserts bytes at a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes to insert.
+    /// @return b Updated input byte array
+    function publicWriteBytesWithLength(
+        bytes memory b,
+        uint256 index,
+        bytes memory input
+    )
+        public
+        pure
+        returns (bytes memory)
+    {
+        b.writeBytesWithLength(index, input);
+        return b;
+    }
+    
+    /// @dev Copies a block of memory from one location to another.
+    /// @param mem Memory contents we want to apply memCopy to
+    /// @param dest Destination offset into <mem>.
+    /// @param source Source offset into <mem>.
+    /// @param length Length of bytes to copy from <source> to <dest>
+    /// @return mem Memory contents after calling memCopy.
+    function testMemcpy(
+        bytes mem,
+        uint256 dest,
+        uint256 source,
+        uint256 length
+    )
+        public // not external, we need input in memory
+        pure
+        returns (bytes)
+    {
+        // Sanity check. Overflows are not checked.
+        require(source + length <= mem.length);
+        require(dest + length <= mem.length);
+
+        // Get pointer to memory contents
+        uint256 offset = mem.contentAddress();
+
+        // Execute memCopy adjusted for memory array location
+        LibBytes.memCopy(offset + dest, offset + source, length);
+
+        // Return modified memory contents
+        return mem;
+    }
+}
diff --git a/contracts/utils/contracts/utils/LibBytes/LibBytes.sol b/contracts/utils/contracts/utils/LibBytes/LibBytes.sol
new file mode 100644
index 000000000..369f588ad
--- /dev/null
+++ b/contracts/utils/contracts/utils/LibBytes/LibBytes.sol
@@ -0,0 +1,567 @@
+/*
+
+  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;
+
+
+library LibBytes {
+
+    using LibBytes for bytes;
+
+    /// @dev Gets the memory address for a byte array.
+    /// @param input Byte array to lookup.
+    /// @return memoryAddress Memory address of byte array. This
+    ///         points to the header of the byte array which contains
+    ///         the length.
+    function rawAddress(bytes memory input)
+        internal
+        pure
+        returns (uint256 memoryAddress)
+    {
+        assembly {
+            memoryAddress := input
+        }
+        return memoryAddress;
+    }
+    
+    /// @dev Gets the memory address for the contents of a byte array.
+    /// @param input Byte array to lookup.
+    /// @return memoryAddress Memory address of the contents of the byte array.
+    function contentAddress(bytes memory input)
+        internal
+        pure
+        returns (uint256 memoryAddress)
+    {
+        assembly {
+            memoryAddress := add(input, 32)
+        }
+        return memoryAddress;
+    }
+
+    /// @dev Copies `length` bytes from memory location `source` to `dest`.
+    /// @param dest memory address to copy bytes to.
+    /// @param source memory address to copy bytes from.
+    /// @param length number of bytes to copy.
+    function memCopy(
+        uint256 dest,
+        uint256 source,
+        uint256 length
+    )
+        internal
+        pure
+    {
+        if (length < 32) {
+            // Handle a partial word by reading destination and masking
+            // off the bits we are interested in.
+            // This correctly handles overlap, zero lengths and source == dest
+            assembly {
+                let mask := sub(exp(256, sub(32, length)), 1)
+                let s := and(mload(source), not(mask))
+                let d := and(mload(dest), mask)
+                mstore(dest, or(s, d))
+            }
+        } else {
+            // Skip the O(length) loop when source == dest.
+            if (source == dest) {
+                return;
+            }
+
+            // For large copies we copy whole words at a time. The final
+            // word is aligned to the end of the range (instead of after the
+            // previous) to handle partial words. So a copy will look like this:
+            //
+            //  ####
+            //      ####
+            //          ####
+            //            ####
+            //
+            // We handle overlap in the source and destination range by
+            // changing the copying direction. This prevents us from
+            // overwriting parts of source that we still need to copy.
+            //
+            // This correctly handles source == dest
+            //
+            if (source > dest) {
+                assembly {
+                    // We subtract 32 from `sEnd` and `dEnd` because it
+                    // is easier to compare with in the loop, and these
+                    // are also the addresses we need for copying the
+                    // last bytes.
+                    length := sub(length, 32)
+                    let sEnd := add(source, length)
+                    let dEnd := add(dest, length)
+
+                    // Remember the last 32 bytes of source
+                    // This needs to be done here and not after the loop
+                    // because we may have overwritten the last bytes in
+                    // source already due to overlap.
+                    let last := mload(sEnd)
+
+                    // Copy whole words front to back
+                    // Note: the first check is always true,
+                    // this could have been a do-while loop.
+                    // solhint-disable-next-line no-empty-blocks
+                    for {} lt(source, sEnd) {} {
+                        mstore(dest, mload(source))
+                        source := add(source, 32)
+                        dest := add(dest, 32)
+                    }
+                    
+                    // Write the last 32 bytes
+                    mstore(dEnd, last)
+                }
+            } else {
+                assembly {
+                    // We subtract 32 from `sEnd` and `dEnd` because those
+                    // are the starting points when copying a word at the end.
+                    length := sub(length, 32)
+                    let sEnd := add(source, length)
+                    let dEnd := add(dest, length)
+
+                    // Remember the first 32 bytes of source
+                    // This needs to be done here and not after the loop
+                    // because we may have overwritten the first bytes in
+                    // source already due to overlap.
+                    let first := mload(source)
+
+                    // Copy whole words back to front
+                    // We use a signed comparisson here to allow dEnd to become
+                    // negative (happens when source and dest < 32). Valid
+                    // addresses in local memory will never be larger than
+                    // 2**255, so they can be safely re-interpreted as signed.
+                    // Note: the first check is always true,
+                    // this could have been a do-while loop.
+                    // solhint-disable-next-line no-empty-blocks
+                    for {} slt(dest, dEnd) {} {
+                        mstore(dEnd, mload(sEnd))
+                        sEnd := sub(sEnd, 32)
+                        dEnd := sub(dEnd, 32)
+                    }
+                    
+                    // Write the first 32 bytes
+                    mstore(dest, first)
+                }
+            }
+        }
+    }
+
+    /// @dev Returns a slices from a byte array.
+    /// @param b The byte array to take a slice from.
+    /// @param from The starting index for the slice (inclusive).
+    /// @param to The final index for the slice (exclusive).
+    /// @return result The slice containing bytes at indices [from, to)
+    function slice(
+        bytes memory b,
+        uint256 from,
+        uint256 to
+    )
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        require(
+            from <= to,
+            "FROM_LESS_THAN_TO_REQUIRED"
+        );
+        require(
+            to < b.length,
+            "TO_LESS_THAN_LENGTH_REQUIRED"
+        );
+        
+        // Create a new bytes structure and copy contents
+        result = new bytes(to - from);
+        memCopy(
+            result.contentAddress(),
+            b.contentAddress() + from,
+            result.length
+        );
+        return result;
+    }
+    
+    /// @dev Returns a slice from a byte array without preserving the input.
+    /// @param b The byte array to take a slice from. Will be destroyed in the process.
+    /// @param from The starting index for the slice (inclusive).
+    /// @param to The final index for the slice (exclusive).
+    /// @return result The slice containing bytes at indices [from, to)
+    /// @dev When `from == 0`, the original array will match the slice. In other cases its state will be corrupted.
+    function sliceDestructive(
+        bytes memory b,
+        uint256 from,
+        uint256 to
+    )
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        require(
+            from <= to,
+            "FROM_LESS_THAN_TO_REQUIRED"
+        );
+        require(
+            to < b.length,
+            "TO_LESS_THAN_LENGTH_REQUIRED"
+        );
+        
+        // Create a new bytes structure around [from, to) in-place.
+        assembly {
+            result := add(b, from)
+            mstore(result, sub(to, from))
+        }
+        return result;
+    }
+
+    /// @dev Pops the last byte off of a byte array by modifying its length.
+    /// @param b Byte array that will be modified.
+    /// @return The byte that was popped off.
+    function popLastByte(bytes memory b)
+        internal
+        pure
+        returns (bytes1 result)
+    {
+        require(
+            b.length > 0,
+            "GREATER_THAN_ZERO_LENGTH_REQUIRED"
+        );
+
+        // Store last byte.
+        result = b[b.length - 1];
+
+        assembly {
+            // Decrement length of byte array.
+            let newLen := sub(mload(b), 1)
+            mstore(b, newLen)
+        }
+        return result;
+    }
+
+    /// @dev Pops the last 20 bytes off of a byte array by modifying its length.
+    /// @param b Byte array that will be modified.
+    /// @return The 20 byte address that was popped off.
+    function popLast20Bytes(bytes memory b)
+        internal
+        pure
+        returns (address result)
+    {
+        require(
+            b.length >= 20,
+            "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED"
+        );
+
+        // Store last 20 bytes.
+        result = readAddress(b, b.length - 20);
+
+        assembly {
+            // Subtract 20 from byte array length.
+            let newLen := sub(mload(b), 20)
+            mstore(b, newLen)
+        }
+        return result;
+    }
+
+    /// @dev Tests equality of two byte arrays.
+    /// @param lhs First byte array to compare.
+    /// @param rhs Second byte array to compare.
+    /// @return True if arrays are the same. False otherwise.
+    function equals(
+        bytes memory lhs,
+        bytes memory rhs
+    )
+        internal
+        pure
+        returns (bool equal)
+    {
+        // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
+        // We early exit on unequal lengths, but keccak would also correctly
+        // handle this.
+        return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
+    }
+
+    /// @dev Reads an address from a position in a byte array.
+    /// @param b Byte array containing an address.
+    /// @param index Index in byte array of address.
+    /// @return address from byte array.
+    function readAddress(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (address result)
+    {
+        require(
+            b.length >= index + 20,  // 20 is length of address
+            "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED"
+        );
+
+        // Add offset to index:
+        // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
+        // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
+        index += 20;
+
+        // Read address from array memory
+        assembly {
+            // 1. Add index to address of bytes array
+            // 2. Load 32-byte word from memory
+            // 3. Apply 20-byte mask to obtain address
+            result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
+        }
+        return result;
+    }
+
+    /// @dev Writes an address into a specific position in a byte array.
+    /// @param b Byte array to insert address into.
+    /// @param index Index in byte array of address.
+    /// @param input Address to put into byte array.
+    function writeAddress(
+        bytes memory b,
+        uint256 index,
+        address input
+    )
+        internal
+        pure
+    {
+        require(
+            b.length >= index + 20,  // 20 is length of address
+            "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED"
+        );
+
+        // Add offset to index:
+        // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
+        // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
+        index += 20;
+
+        // Store address into array memory
+        assembly {
+            // The address occupies 20 bytes and mstore stores 32 bytes.
+            // First fetch the 32-byte word where we'll be storing the address, then
+            // apply a mask so we have only the bytes in the word that the address will not occupy.
+            // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
+
+            // 1. Add index to address of bytes array
+            // 2. Load 32-byte word from memory
+            // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
+            let neighbors := and(
+                mload(add(b, index)),
+                0xffffffffffffffffffffffff0000000000000000000000000000000000000000
+            )
+            
+            // Make sure input address is clean.
+            // (Solidity does not guarantee this)
+            input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
+
+            // Store the neighbors and address into memory
+            mstore(add(b, index), xor(input, neighbors))
+        }
+    }
+
+    /// @dev Reads a bytes32 value from a position in a byte array.
+    /// @param b Byte array containing a bytes32 value.
+    /// @param index Index in byte array of bytes32 value.
+    /// @return bytes32 value from byte array.
+    function readBytes32(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (bytes32 result)
+    {
+        require(
+            b.length >= index + 32,
+            "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED"
+        );
+
+        // Arrays are prefixed by a 256 bit length parameter
+        index += 32;
+
+        // Read the bytes32 from array memory
+        assembly {
+            result := mload(add(b, index))
+        }
+        return result;
+    }
+
+    /// @dev Writes a bytes32 into a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes32 to put into byte array.
+    function writeBytes32(
+        bytes memory b,
+        uint256 index,
+        bytes32 input
+    )
+        internal
+        pure
+    {
+        require(
+            b.length >= index + 32,
+            "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED"
+        );
+
+        // Arrays are prefixed by a 256 bit length parameter
+        index += 32;
+
+        // Read the bytes32 from array memory
+        assembly {
+            mstore(add(b, index), input)
+        }
+    }
+
+    /// @dev Reads a uint256 value from a position in a byte array.
+    /// @param b Byte array containing a uint256 value.
+    /// @param index Index in byte array of uint256 value.
+    /// @return uint256 value from byte array.
+    function readUint256(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (uint256 result)
+    {
+        result = uint256(readBytes32(b, index));
+        return result;
+    }
+
+    /// @dev Writes a uint256 into a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input uint256 to put into byte array.
+    function writeUint256(
+        bytes memory b,
+        uint256 index,
+        uint256 input
+    )
+        internal
+        pure
+    {
+        writeBytes32(b, index, bytes32(input));
+    }
+
+    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
+    /// @param b Byte array containing a bytes4 value.
+    /// @param index Index in byte array of bytes4 value.
+    /// @return bytes4 value from byte array.
+    function readBytes4(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (bytes4 result)
+    {
+        require(
+            b.length >= index + 4,
+            "GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED"
+        );
+
+        // Arrays are prefixed by a 32 byte length field
+        index += 32;
+
+        // Read the bytes4 from array memory
+        assembly {
+            result := mload(add(b, index))
+            // Solidity does not require us to clean the trailing bytes.
+            // We do it anyway
+            result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
+        }
+        return result;
+    }
+
+    /// @dev Reads nested bytes from a specific position.
+    /// @dev NOTE: the returned value overlaps with the input value.
+    ///            Both should be treated as immutable.
+    /// @param b Byte array containing nested bytes.
+    /// @param index Index of nested bytes.
+    /// @return result Nested bytes.
+    function readBytesWithLength(
+        bytes memory b,
+        uint256 index
+    )
+        internal
+        pure
+        returns (bytes memory result)
+    {
+        // Read length of nested bytes
+        uint256 nestedBytesLength = readUint256(b, index);
+        index += 32;
+
+        // Assert length of <b> is valid, given
+        // length of nested bytes
+        require(
+            b.length >= index + nestedBytesLength,
+            "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED"
+        );
+        
+        // Return a pointer to the byte array as it exists inside `b`
+        assembly {
+            result := add(b, index)
+        }
+        return result;
+    }
+
+    /// @dev Inserts bytes at a specific position in a byte array.
+    /// @param b Byte array to insert <input> into.
+    /// @param index Index in byte array of <input>.
+    /// @param input bytes to insert.
+    function writeBytesWithLength(
+        bytes memory b,
+        uint256 index,
+        bytes memory input
+    )
+        internal
+        pure
+    {
+        // Assert length of <b> is valid, given
+        // length of input
+        require(
+            b.length >= index + 32 + input.length,  // 32 bytes to store length
+            "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED"
+        );
+
+        // Copy <input> into <b>
+        memCopy(
+            b.contentAddress() + index,
+            input.rawAddress(), // includes length of <input>
+            input.length + 32   // +32 bytes to store <input> length
+        );
+    }
+
+    /// @dev Performs a deep copy of a byte array onto another byte array of greater than or equal length.
+    /// @param dest Byte array that will be overwritten with source bytes.
+    /// @param source Byte array to copy onto dest bytes.
+    function deepCopyBytes(
+        bytes memory dest,
+        bytes memory source
+    )
+        internal
+        pure
+    {
+        uint256 sourceLen = source.length;
+        // Dest length must be >= source length, or some bytes would not be copied.
+        require(
+            dest.length >= sourceLen,
+            "GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED"
+        );
+        memCopy(
+            dest.contentAddress(),
+            source.contentAddress(),
+            sourceLen
+        );
+    }
+}
diff --git a/contracts/utils/contracts/utils/Ownable/IOwnable.sol b/contracts/utils/contracts/utils/Ownable/IOwnable.sol
new file mode 100644
index 000000000..5deb13497
--- /dev/null
+++ b/contracts/utils/contracts/utils/Ownable/IOwnable.sol
@@ -0,0 +1,8 @@
+pragma solidity 0.4.24;
+
+
+contract IOwnable {
+
+    function transferOwnership(address newOwner)
+        public;
+}
diff --git a/contracts/utils/contracts/utils/Ownable/Ownable.sol b/contracts/utils/contracts/utils/Ownable/Ownable.sol
new file mode 100644
index 000000000..0c830be68
--- /dev/null
+++ b/contracts/utils/contracts/utils/Ownable/Ownable.sol
@@ -0,0 +1,33 @@
+pragma solidity 0.4.24;
+
+import "./IOwnable.sol";
+
+
+contract Ownable is
+    IOwnable
+{
+    address public owner;
+
+    constructor ()
+        public
+    {
+        owner = msg.sender;
+    }
+
+    modifier onlyOwner() {
+        require(
+            msg.sender == owner,
+            "ONLY_CONTRACT_OWNER"
+        );
+        _;
+    }
+
+    function transferOwnership(address newOwner)
+        public
+        onlyOwner
+    {
+        if (newOwner != address(0)) {
+            owner = newOwner;
+        }
+    }
+}
diff --git a/contracts/utils/contracts/utils/ReentrancyGuard/ReentrancyGuard.sol b/contracts/utils/contracts/utils/ReentrancyGuard/ReentrancyGuard.sol
new file mode 100644
index 000000000..9f98a7a16
--- /dev/null
+++ b/contracts/utils/contracts/utils/ReentrancyGuard/ReentrancyGuard.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;
+
+
+contract ReentrancyGuard {
+
+    // Locked state of mutex
+    bool private locked = false;
+
+    /// @dev Functions with this modifer cannot be reentered. The mutex will be locked
+    ///      before function execution and unlocked after.
+    modifier nonReentrant() {
+        // Ensure mutex is unlocked
+        require(
+            !locked,
+            "REENTRANCY_ILLEGAL"
+        );
+
+        // Lock mutex before function call
+        locked = true;
+
+        // Perform function call
+        _;
+
+        // Unlock mutex after function call
+        locked = false;
+    }
+}
diff --git a/contracts/utils/contracts/utils/SafeMath/SafeMath.sol b/contracts/utils/contracts/utils/SafeMath/SafeMath.sol
new file mode 100644
index 000000000..2855edb9d
--- /dev/null
+++ b/contracts/utils/contracts/utils/SafeMath/SafeMath.sol
@@ -0,0 +1,87 @@
+pragma solidity 0.4.24;
+
+
+contract SafeMath {
+
+    function safeMul(uint256 a, uint256 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        if (a == 0) {
+            return 0;
+        }
+        uint256 c = a * b;
+        require(
+            c / a == b,
+            "UINT256_OVERFLOW"
+        );
+        return c;
+    }
+
+    function safeDiv(uint256 a, uint256 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        uint256 c = a / b;
+        return c;
+    }
+
+    function safeSub(uint256 a, uint256 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        require(
+            b <= a,
+            "UINT256_UNDERFLOW"
+        );
+        return a - b;
+    }
+
+    function safeAdd(uint256 a, uint256 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        uint256 c = a + b;
+        require(
+            c >= a,
+            "UINT256_OVERFLOW"
+        );
+        return c;
+    }
+
+    function max64(uint64 a, uint64 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        return a >= b ? a : b;
+    }
+
+    function min64(uint64 a, uint64 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        return a < b ? a : b;
+    }
+
+    function max256(uint256 a, uint256 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        return a >= b ? a : b;
+    }
+
+    function min256(uint256 a, uint256 b)
+        internal
+        pure
+        returns (uint256)
+    {
+        return a < b ? a : b;
+    }
+}
diff --git a/contracts/utils/package.json b/contracts/utils/package.json
new file mode 100644
index 000000000..94b3cb7c7
--- /dev/null
+++ b/contracts/utils/package.json
@@ -0,0 +1,89 @@
+{
+    "private": true,
+    "name": "@0x/contracts-utils",
+    "version": "1.0.0",
+    "engines": {
+        "node": ">=6.12"
+    },
+    "description": "Smart contract utils of 0x protocol",
+    "main": "lib/src/index.js",
+    "directories": {
+        "test": "test"
+    },
+    "scripts": {
+        "build": "yarn pre_build && tsc -b",
+        "build:ci": "yarn build",
+        "pre_build": "run-s compile generate_contract_wrappers",
+        "test": "yarn run_mocha",
+        "rebuild_and_test": "run-s build test",
+        "test:coverage": "SOLIDITY_COVERAGE=true run-s build run_mocha coverage:report:text coverage:report:lcov",
+        "test:profiler": "SOLIDITY_PROFILER=true run-s build run_mocha profiler:report:html",
+        "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
+        "run_mocha":
+            "mocha --require source-map-support/register --require make-promises-safe 'lib/test/**/*.js' --timeout 100000 --bail --exit",
+        "compile": "sol-compiler --contracts-dir contracts",
+        "clean": "shx rm -rf lib generated-artifacts generated-wrappers",
+        "generate_contract_wrappers": "abi-gen --abis  ${npm_package_config_abis} --template ../../node_modules/@0x/abi-gen-templates/contract.handlebars --partials '../../node_modules/@0x/abi-gen-templates/partials/**/*.handlebars' --output generated-wrappers --backend ethers",
+        "lint": "tslint --format stylish --project . --exclude ./generated-wrappers/**/* --exclude ./generated-artifacts/**/* --exclude **/lib/**/* && yarn lint-contracts",
+        "coverage:report:text": "istanbul report text",
+        "coverage:report:html": "istanbul report html && open coverage/index.html",
+        "profiler:report:html": "istanbul report html && open coverage/index.html",
+        "coverage:report:lcov": "istanbul report lcov",
+        "test:circleci": "yarn test",
+        "lint-contracts": "solhint contracts/**/**/**/**/*.sol"
+    },
+    "config": {
+        "abis": "generated-artifacts/@(IOwnable|Ownable|LibBytes|ReentrancyGuard|SafeMath|TestConstants|TestLibBytes).json"
+    },
+    "repository": {
+        "type": "git",
+        "url": "https://github.com/0xProject/0x-monorepo.git"
+    },
+    "license": "Apache-2.0",
+    "bugs": {
+        "url": "https://github.com/0xProject/0x-monorepo/issues"
+    },
+    "homepage": "https://github.com/0xProject/0x-monorepo/contracts/core/README.md",
+    "devDependencies": {
+        "@0x/contracts-test-utils": "^1.0.0",
+        "@0x/abi-gen": "^1.0.17",
+        "@0x/dev-utils": "^1.0.19",
+        "@0x/sol-compiler": "^1.1.14",
+        "@0x/sol-cov": "^2.1.14",
+        "@0x/subproviders": "^2.1.6",
+        "@0x/tslint-config": "^1.0.10",
+        "@types/bn.js": "^4.11.0",
+        "@types/lodash": "4.14.104",
+        "@types/node": "*",
+        "@types/yargs": "^10.0.0",
+        "chai": "^4.0.1",
+        "chai-as-promised": "^7.1.0",
+        "chai-bignumber": "^2.0.1",
+        "dirty-chai": "^2.0.1",
+        "make-promises-safe": "^1.1.0",
+        "ethereumjs-abi": "0.6.5",
+        "mocha": "^4.1.0",
+        "npm-run-all": "^4.1.2",
+        "shx": "^0.2.2",
+        "solc": "^0.4.24",
+        "solhint": "^1.2.1",
+        "tslint": "5.11.0",
+        "typescript": "3.0.1",
+        "yargs": "^10.0.3"
+    },
+    "dependencies": {
+        "@0x/base-contract": "^3.0.8",
+        "@0x/order-utils": "^3.0.4",
+        "@0x/contracts-multisig": "^1.0.0",
+        "@0x/types": "^1.3.0",
+        "@0x/typescript-typings": "^3.0.4",
+        "@0x/utils": "^2.0.6",
+        "@0x/web3-wrapper": "^3.1.6",
+        "ethereum-types": "^1.1.2",
+        "ethereumjs-util": "^5.1.1",
+        "lodash": "^4.17.5"
+    },
+    "publishConfig": {
+        "access": "public"
+    }
+}
diff --git a/contracts/utils/src/artifacts/index.ts b/contracts/utils/src/artifacts/index.ts
new file mode 100644
index 000000000..a5c2b215c
--- /dev/null
+++ b/contracts/utils/src/artifacts/index.ts
@@ -0,0 +1,19 @@
+import { ContractArtifact } from 'ethereum-types';
+
+import * as IOwnable from '../../generated-artifacts/IOwnable.json';
+import * as LibBytes from '../../generated-artifacts/LibBytes.json';
+import * as Ownable from '../../generated-artifacts/Ownable.json';
+import * as ReentrancyGuard from '../../generated-artifacts/ReentrancyGuard.json';
+import * as SafeMath from '../../generated-artifacts/SafeMath.json';
+import * as TestConstants from '../../generated-artifacts/TestConstants.json';
+import * as TestLibBytes from '../../generated-artifacts/TestLibBytes.json';
+
+export const artifacts = {
+    TestConstants: TestConstants as ContractArtifact,
+    TestLibBytes: TestLibBytes as ContractArtifact,
+    IOwnable: IOwnable as ContractArtifact,
+    LibBytes: LibBytes as ContractArtifact,
+    Ownable: Ownable as ContractArtifact,
+    SafeMath: SafeMath as ContractArtifact,
+    ReentrancyGuard: ReentrancyGuard as ContractArtifact,
+};
diff --git a/contracts/utils/src/index.ts b/contracts/utils/src/index.ts
new file mode 100644
index 000000000..d55f08ea2
--- /dev/null
+++ b/contracts/utils/src/index.ts
@@ -0,0 +1,2 @@
+export * from './artifacts';
+export * from './wrappers';
diff --git a/contracts/utils/src/wrappers/index.ts b/contracts/utils/src/wrappers/index.ts
new file mode 100644
index 000000000..823b7fa4b
--- /dev/null
+++ b/contracts/utils/src/wrappers/index.ts
@@ -0,0 +1,2 @@
+export * from '../../generated-wrappers/test_constants';
+export * from '../../generated-wrappers/test_lib_bytes';
diff --git a/contracts/utils/test/global_hooks.ts b/contracts/utils/test/global_hooks.ts
new file mode 100644
index 000000000..f8ace376a
--- /dev/null
+++ b/contracts/utils/test/global_hooks.ts
@@ -0,0 +1,17 @@
+import { env, EnvVars } from '@0x/dev-utils';
+
+import { coverage, profiler, provider } from '@0x/contracts-test-utils';
+before('start web3 provider', () => {
+    provider.start();
+});
+after('generate coverage report', async () => {
+    if (env.parseBoolean(EnvVars.SolidityCoverage)) {
+        const coverageSubprovider = coverage.getCoverageSubproviderSingleton();
+        await coverageSubprovider.writeCoverageAsync();
+    }
+    if (env.parseBoolean(EnvVars.SolidityProfiler)) {
+        const profilerSubprovider = profiler.getProfilerSubproviderSingleton();
+        await profilerSubprovider.writeProfilerOutputAsync();
+    }
+    provider.stop();
+});
diff --git a/contracts/utils/test/lib_bytes.ts b/contracts/utils/test/lib_bytes.ts
new file mode 100644
index 000000000..985a98943
--- /dev/null
+++ b/contracts/utils/test/lib_bytes.ts
@@ -0,0 +1,875 @@
+import {
+    chaiSetup,
+    constants,
+    expectContractCallFailedAsync,
+    provider,
+    txDefaults,
+    typeEncodingUtils,
+    web3Wrapper,
+} from '@0x/contracts-test-utils';
+import { BlockchainLifecycle } from '@0x/dev-utils';
+import { generatePseudoRandomSalt } from '@0x/order-utils';
+import { RevertReason } from '@0x/types';
+import { BigNumber } from '@0x/utils';
+import BN = require('bn.js');
+import * as chai from 'chai';
+import ethUtil = require('ethereumjs-util');
+import * as _ from 'lodash';
+
+import { TestLibBytesContract } from '../generated-wrappers/test_lib_bytes';
+import { artifacts } from '../src';
+
+chaiSetup.configure();
+const expect = chai.expect;
+const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
+
+// BUG: Ideally we would use Buffer.from(memory).toString('hex')
+// https://github.com/Microsoft/TypeScript/issues/23155
+const toHex = (buf: Uint8Array): string => buf.reduce((a, v) => a + ('00' + v.toString(16)).slice(-2), '0x');
+
+const fromHex = (str: string): Uint8Array => Uint8Array.from(Buffer.from(str.slice(2), 'hex'));
+
+describe('LibBytes', () => {
+    let libBytes: TestLibBytesContract;
+    const byteArrayShorterThan32Bytes = '0x012345';
+    const byteArrayShorterThan20Bytes = byteArrayShorterThan32Bytes;
+    const byteArrayLongerThan32Bytes =
+        '0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef';
+    const byteArrayLongerThan32BytesFirstBytesSwapped =
+        '0x2301456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef';
+    const byteArrayLongerThan32BytesLastBytesSwapped =
+        '0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef0123456789abefcd';
+    let testAddress: string;
+    let testAddressB: string;
+    const testBytes32 = '0x102030405060708090a0b0c0d0e0f0102030405060708090a0b0c0d0e0f01020';
+    const testBytes32B = '0x534877abd8443578526845cdfef020047528759477fedef87346527659aced32';
+    const testUint256 = new BigNumber(testBytes32, 16);
+    const testUint256B = new BigNumber(testBytes32B, 16);
+    const testBytes4 = '0xabcdef12';
+    const testByte = '0xab';
+    let shortData: string;
+    let shortTestBytes: string;
+    let shortTestBytesAsBuffer: Buffer;
+    let wordOfData: string;
+    let wordOfTestBytes: string;
+    let wordOfTestBytesAsBuffer: Buffer;
+    let longData: string;
+    let longTestBytes: string;
+    let longTestBytesAsBuffer: Buffer;
+
+    before(async () => {
+        await blockchainLifecycle.startAsync();
+    });
+    after(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+    before(async () => {
+        // Setup accounts & addresses
+        const accounts = await web3Wrapper.getAvailableAddressesAsync();
+        testAddress = accounts[1];
+        testAddressB = accounts[2];
+        // Deploy LibBytes
+        libBytes = await TestLibBytesContract.deployFrom0xArtifactAsync(artifacts.TestLibBytes, provider, txDefaults);
+        // Verify lengths of test data
+        const byteArrayShorterThan32BytesLength = ethUtil.toBuffer(byteArrayShorterThan32Bytes).byteLength;
+        expect(byteArrayShorterThan32BytesLength).to.be.lessThan(32);
+        const byteArrayLongerThan32BytesLength = ethUtil.toBuffer(byteArrayLongerThan32Bytes).byteLength;
+        expect(byteArrayLongerThan32BytesLength).to.be.greaterThan(32);
+        const testBytes32Length = ethUtil.toBuffer(testBytes32).byteLength;
+        expect(testBytes32Length).to.be.equal(32);
+        // Create short test bytes
+        shortData = '0xffffaa';
+        const encodedShortData = ethUtil.toBuffer(shortData);
+        const shortDataLength = new BigNumber(encodedShortData.byteLength);
+        const encodedShortDataLength = typeEncodingUtils.encodeUint256(shortDataLength);
+        shortTestBytesAsBuffer = Buffer.concat([encodedShortDataLength, encodedShortData]);
+        shortTestBytes = ethUtil.bufferToHex(shortTestBytesAsBuffer);
+        // Create test bytes one word in length
+        wordOfData = ethUtil.bufferToHex(typeEncodingUtils.encodeUint256(generatePseudoRandomSalt()));
+        const encodedWordOfData = ethUtil.toBuffer(wordOfData);
+        const wordOfDataLength = new BigNumber(encodedWordOfData.byteLength);
+        const encodedWordOfDataLength = typeEncodingUtils.encodeUint256(wordOfDataLength);
+        wordOfTestBytesAsBuffer = Buffer.concat([encodedWordOfDataLength, encodedWordOfData]);
+        wordOfTestBytes = ethUtil.bufferToHex(wordOfTestBytesAsBuffer);
+        // Create long test bytes (combines short test bytes with word of test bytes)
+        longData = ethUtil.bufferToHex(Buffer.concat([encodedShortData, encodedWordOfData]));
+        const longDataLength = new BigNumber(encodedShortData.byteLength + encodedWordOfData.byteLength);
+        const encodedLongDataLength = typeEncodingUtils.encodeUint256(longDataLength);
+        longTestBytesAsBuffer = Buffer.concat([encodedLongDataLength, encodedShortData, encodedWordOfData]);
+        longTestBytes = ethUtil.bufferToHex(longTestBytesAsBuffer);
+    });
+    beforeEach(async () => {
+        await blockchainLifecycle.startAsync();
+    });
+    afterEach(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+
+    describe('popLastByte', () => {
+        it('should revert if length is 0', async () => {
+            return expectContractCallFailedAsync(
+                libBytes.publicPopLastByte.callAsync(constants.NULL_BYTES),
+                RevertReason.LibBytesGreaterThanZeroLengthRequired,
+            );
+        });
+        it('should pop the last byte from the input and return it when array holds more than 1 byte', async () => {
+            const [newBytes, poppedByte] = await libBytes.publicPopLastByte.callAsync(byteArrayLongerThan32Bytes);
+            const expectedNewBytes = byteArrayLongerThan32Bytes.slice(0, -2);
+            const expectedPoppedByte = `0x${byteArrayLongerThan32Bytes.slice(-2)}`;
+            expect(newBytes).to.equal(expectedNewBytes);
+            expect(poppedByte).to.equal(expectedPoppedByte);
+        });
+        it('should pop the last byte from the input and return it when array is exactly 1 byte', async () => {
+            const [newBytes, poppedByte] = await libBytes.publicPopLastByte.callAsync(testByte);
+            const expectedNewBytes = '0x';
+            expect(newBytes).to.equal(expectedNewBytes);
+            return expect(poppedByte).to.be.equal(testByte);
+        });
+    });
+
+    describe('popLast20Bytes', () => {
+        it('should revert if length is less than 20', async () => {
+            return expectContractCallFailedAsync(
+                libBytes.publicPopLast20Bytes.callAsync(byteArrayShorterThan20Bytes),
+                RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
+            );
+        });
+        it('should pop the last 20 bytes from the input and return it when array holds more than 20 bytes', async () => {
+            const [newBytes, poppedAddress] = await libBytes.publicPopLast20Bytes.callAsync(byteArrayLongerThan32Bytes);
+            const expectedNewBytes = byteArrayLongerThan32Bytes.slice(0, -40);
+            const expectedPoppedAddress = `0x${byteArrayLongerThan32Bytes.slice(-40)}`;
+            expect(newBytes).to.equal(expectedNewBytes);
+            expect(poppedAddress).to.equal(expectedPoppedAddress);
+        });
+        it('should pop the last 20 bytes from the input and return it when array is exactly 20 bytes', async () => {
+            const [newBytes, poppedAddress] = await libBytes.publicPopLast20Bytes.callAsync(testAddress);
+            const expectedNewBytes = '0x';
+            const expectedPoppedAddress = testAddress;
+            expect(newBytes).to.equal(expectedNewBytes);
+            expect(poppedAddress).to.equal(expectedPoppedAddress);
+        });
+    });
+
+    describe('equals', () => {
+        it('should return true if byte arrays are equal (both arrays < 32 bytes)', async () => {
+            const isEqual = await libBytes.publicEquals.callAsync(
+                byteArrayShorterThan32Bytes,
+                byteArrayShorterThan32Bytes,
+            );
+            return expect(isEqual).to.be.true();
+        });
+        it('should return true if byte arrays are equal (both arrays > 32 bytes)', async () => {
+            const isEqual = await libBytes.publicEquals.callAsync(
+                byteArrayLongerThan32Bytes,
+                byteArrayLongerThan32Bytes,
+            );
+            return expect(isEqual).to.be.true();
+        });
+        it('should return false if byte arrays are not equal (first array < 32 bytes, second array > 32 bytes)', async () => {
+            const isEqual = await libBytes.publicEquals.callAsync(
+                byteArrayShorterThan32Bytes,
+                byteArrayLongerThan32Bytes,
+            );
+            return expect(isEqual).to.be.false();
+        });
+        it('should return false if byte arrays are not equal (first array > 32 bytes, second array < 32 bytes)', async () => {
+            const isEqual = await libBytes.publicEquals.callAsync(
+                byteArrayLongerThan32Bytes,
+                byteArrayShorterThan32Bytes,
+            );
+            return expect(isEqual).to.be.false();
+        });
+        it('should return false if byte arrays are not equal (same length, but a byte in first word differs)', async () => {
+            const isEqual = await libBytes.publicEquals.callAsync(
+                byteArrayLongerThan32BytesFirstBytesSwapped,
+                byteArrayLongerThan32Bytes,
+            );
+            return expect(isEqual).to.be.false();
+        });
+        it('should return false if byte arrays are not equal (same length, but a byte in last word differs)', async () => {
+            const isEqual = await libBytes.publicEquals.callAsync(
+                byteArrayLongerThan32BytesLastBytesSwapped,
+                byteArrayLongerThan32Bytes,
+            );
+            return expect(isEqual).to.be.false();
+        });
+
+        describe('should ignore trailing data', () => {
+            it('should return true when both < 32 bytes', async () => {
+                const isEqual = await libBytes.publicEqualsPop1.callAsync('0x0102', '0x0103');
+                return expect(isEqual).to.be.true();
+            });
+        });
+    });
+
+    describe('deepCopyBytes', () => {
+        it('should revert if dest is shorter than source', async () => {
+            return expectContractCallFailedAsync(
+                libBytes.publicDeepCopyBytes.callAsync(byteArrayShorterThan32Bytes, byteArrayLongerThan32Bytes),
+                RevertReason.LibBytesGreaterOrEqualToSourceBytesLengthRequired,
+            );
+        });
+        it('should overwrite dest with source if source and dest have equal length', async () => {
+            const zeroedByteArrayLongerThan32Bytes = `0x${_.repeat('0', byteArrayLongerThan32Bytes.length - 2)}`;
+            const zeroedBytesAfterCopy = await libBytes.publicDeepCopyBytes.callAsync(
+                zeroedByteArrayLongerThan32Bytes,
+                byteArrayLongerThan32Bytes,
+            );
+            return expect(zeroedBytesAfterCopy).to.be.equal(byteArrayLongerThan32Bytes);
+        });
+        it('should overwrite the leftmost len(source) bytes of dest if dest is larger than source', async () => {
+            const zeroedByteArrayLongerThan32Bytes = `0x${_.repeat('0', byteArrayLongerThan32Bytes.length * 2)}`;
+            const zeroedBytesAfterCopy = await libBytes.publicDeepCopyBytes.callAsync(
+                zeroedByteArrayLongerThan32Bytes,
+                byteArrayLongerThan32Bytes,
+            );
+            const copiedBytes = zeroedBytesAfterCopy.slice(0, byteArrayLongerThan32Bytes.length);
+            return expect(copiedBytes).to.be.equal(byteArrayLongerThan32Bytes);
+        });
+        it('should not overwrite the rightmost bytes of dest if dest is larger than source', async () => {
+            const zeroedByteArrayLongerThan32Bytes = `0x${_.repeat('0', byteArrayLongerThan32Bytes.length * 2)}`;
+            const zeroedBytesAfterCopy = await libBytes.publicDeepCopyBytes.callAsync(
+                zeroedByteArrayLongerThan32Bytes,
+                byteArrayLongerThan32Bytes,
+            );
+            const expectedNotCopiedBytes = zeroedByteArrayLongerThan32Bytes.slice(byteArrayLongerThan32Bytes.length);
+            const notCopiedBytes = zeroedBytesAfterCopy.slice(byteArrayLongerThan32Bytes.length);
+            return expect(notCopiedBytes).to.be.equal(expectedNotCopiedBytes);
+        });
+    });
+
+    describe('readAddress', () => {
+        it('should successfully read address when the address takes up the whole array', async () => {
+            const byteArray = ethUtil.addHexPrefix(testAddress);
+            const testAddressOffset = new BigNumber(0);
+            const address = await libBytes.publicReadAddress.callAsync(byteArray, testAddressOffset);
+            return expect(address).to.be.equal(testAddress);
+        });
+        it('should successfully read address when it is offset in the array', async () => {
+            const addressByteArrayBuffer = ethUtil.toBuffer(testAddress);
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, addressByteArrayBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testAddressOffset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const address = await libBytes.publicReadAddress.callAsync(combinedByteArray, testAddressOffset);
+            return expect(address).to.be.equal(testAddress);
+        });
+        it('should fail if the byte array is too short to hold an address', async () => {
+            const shortByteArray = '0xabcdef';
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadAddress.callAsync(shortByteArray, offset),
+                RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
+            );
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold an address', async () => {
+            const byteArray = testAddress;
+            const badOffset = new BigNumber(ethUtil.toBuffer(byteArray).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadAddress.callAsync(byteArray, badOffset),
+                RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
+            );
+        });
+    });
+
+    describe('writeAddress', () => {
+        it('should successfully write address when the address takes up the whole array', async () => {
+            const byteArray = testAddress;
+            const testAddressOffset = new BigNumber(0);
+            const newByteArray = await libBytes.publicWriteAddress.callAsync(
+                byteArray,
+                testAddressOffset,
+                testAddressB,
+            );
+            return expect(newByteArray).to.be.equal(testAddressB);
+        });
+        it('should successfully write address when it is offset in the array', async () => {
+            const addressByteArrayBuffer = ethUtil.toBuffer(testAddress);
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, addressByteArrayBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testAddressOffset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const newByteArray = await libBytes.publicWriteAddress.callAsync(
+                combinedByteArray,
+                testAddressOffset,
+                testAddressB,
+            );
+            const newByteArrayBuffer = ethUtil.toBuffer(newByteArray);
+            const addressFromOffsetBuffer = newByteArrayBuffer.slice(prefixByteArrayBuffer.byteLength);
+            const addressFromOffset = ethUtil.addHexPrefix(ethUtil.bufferToHex(addressFromOffsetBuffer));
+            return expect(addressFromOffset).to.be.equal(testAddressB);
+        });
+        it('should fail if the byte array is too short to hold an address', async () => {
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicWriteAddress.callAsync(byteArrayShorterThan20Bytes, offset, testAddress),
+                RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
+            );
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold an address', async () => {
+            const byteArray = byteArrayLongerThan32Bytes;
+            const badOffset = new BigNumber(ethUtil.toBuffer(byteArray).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicWriteAddress.callAsync(byteArray, badOffset, testAddress),
+                RevertReason.LibBytesGreaterOrEqualTo20LengthRequired,
+            );
+        });
+    });
+
+    describe('readBytes32', () => {
+        it('should successfully read bytes32 when the bytes32 takes up the whole array', async () => {
+            const testBytes32Offset = new BigNumber(0);
+            const bytes32 = await libBytes.publicReadBytes32.callAsync(testBytes32, testBytes32Offset);
+            return expect(bytes32).to.be.equal(testBytes32);
+        });
+        it('should successfully read bytes32 when it is offset in the array', async () => {
+            const bytes32ByteArrayBuffer = ethUtil.toBuffer(testBytes32);
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, bytes32ByteArrayBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testBytes32Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const bytes32 = await libBytes.publicReadBytes32.callAsync(combinedByteArray, testBytes32Offset);
+            return expect(bytes32).to.be.equal(testBytes32);
+        });
+        it('should fail if the byte array is too short to hold a bytes32', async () => {
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytes32.callAsync(byteArrayShorterThan32Bytes, offset),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold a bytes32', async () => {
+            const badOffset = new BigNumber(ethUtil.toBuffer(testBytes32).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytes32.callAsync(testBytes32, badOffset),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+    });
+
+    describe('writeBytes32', () => {
+        it('should successfully write bytes32 when the address takes up the whole array', async () => {
+            const byteArray = testBytes32;
+            const testBytes32Offset = new BigNumber(0);
+            const newByteArray = await libBytes.publicWriteBytes32.callAsync(
+                byteArray,
+                testBytes32Offset,
+                testBytes32B,
+            );
+            return expect(newByteArray).to.be.equal(testBytes32B);
+        });
+        it('should successfully write bytes32 when it is offset in the array', async () => {
+            const bytes32ByteArrayBuffer = ethUtil.toBuffer(testBytes32);
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, bytes32ByteArrayBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testBytes32Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const newByteArray = await libBytes.publicWriteBytes32.callAsync(
+                combinedByteArray,
+                testBytes32Offset,
+                testBytes32B,
+            );
+            const newByteArrayBuffer = ethUtil.toBuffer(newByteArray);
+            const bytes32FromOffsetBuffer = newByteArrayBuffer.slice(prefixByteArrayBuffer.byteLength);
+            const bytes32FromOffset = ethUtil.addHexPrefix(ethUtil.bufferToHex(bytes32FromOffsetBuffer));
+            return expect(bytes32FromOffset).to.be.equal(testBytes32B);
+        });
+        it('should fail if the byte array is too short to hold a bytes32', async () => {
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicWriteBytes32.callAsync(byteArrayShorterThan32Bytes, offset, testBytes32),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold a bytes32', async () => {
+            const byteArray = byteArrayLongerThan32Bytes;
+            const badOffset = new BigNumber(ethUtil.toBuffer(byteArray).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicWriteBytes32.callAsync(byteArray, badOffset, testBytes32),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+    });
+
+    describe('readUint256', () => {
+        it('should successfully read uint256 when the uint256 takes up the whole array', async () => {
+            const formattedTestUint256 = new BN(testUint256.toString(10));
+            const testUint256AsBuffer = ethUtil.toBuffer(formattedTestUint256);
+            const byteArray = ethUtil.bufferToHex(testUint256AsBuffer);
+            const testUint256Offset = new BigNumber(0);
+            const uint256 = await libBytes.publicReadUint256.callAsync(byteArray, testUint256Offset);
+            return expect(uint256).to.bignumber.equal(testUint256);
+        });
+        it('should successfully read uint256 when it is offset in the array', async () => {
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const formattedTestUint256 = new BN(testUint256.toString(10));
+            const testUint256AsBuffer = ethUtil.toBuffer(formattedTestUint256);
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, testUint256AsBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const uint256 = await libBytes.publicReadUint256.callAsync(combinedByteArray, testUint256Offset);
+            return expect(uint256).to.bignumber.equal(testUint256);
+        });
+        it('should fail if the byte array is too short to hold a uint256', async () => {
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadUint256.callAsync(byteArrayShorterThan32Bytes, offset),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold a uint256', async () => {
+            const formattedTestUint256 = new BN(testUint256.toString(10));
+            const testUint256AsBuffer = ethUtil.toBuffer(formattedTestUint256);
+            const byteArray = ethUtil.bufferToHex(testUint256AsBuffer);
+            const badOffset = new BigNumber(testUint256AsBuffer.byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadUint256.callAsync(byteArray, badOffset),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+    });
+
+    describe('writeUint256', () => {
+        it('should successfully write uint256 when the address takes up the whole array', async () => {
+            const byteArray = testBytes32;
+            const testUint256Offset = new BigNumber(0);
+            const newByteArray = await libBytes.publicWriteUint256.callAsync(
+                byteArray,
+                testUint256Offset,
+                testUint256B,
+            );
+            const newByteArrayAsUint256 = new BigNumber(newByteArray, 16);
+            return expect(newByteArrayAsUint256).to.be.bignumber.equal(testUint256B);
+        });
+        it('should successfully write uint256 when it is offset in the array', async () => {
+            const bytes32ByteArrayBuffer = ethUtil.toBuffer(testBytes32);
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, bytes32ByteArrayBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const newByteArray = await libBytes.publicWriteUint256.callAsync(
+                combinedByteArray,
+                testUint256Offset,
+                testUint256B,
+            );
+            const newByteArrayBuffer = ethUtil.toBuffer(newByteArray);
+            const uint256FromOffsetBuffer = newByteArrayBuffer.slice(prefixByteArrayBuffer.byteLength);
+            const uint256FromOffset = new BigNumber(
+                ethUtil.addHexPrefix(ethUtil.bufferToHex(uint256FromOffsetBuffer)),
+                16,
+            );
+            return expect(uint256FromOffset).to.be.bignumber.equal(testUint256B);
+        });
+        it('should fail if the byte array is too short to hold a uint256', async () => {
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicWriteUint256.callAsync(byteArrayShorterThan32Bytes, offset, testUint256),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold a uint256', async () => {
+            const byteArray = byteArrayLongerThan32Bytes;
+            const badOffset = new BigNumber(ethUtil.toBuffer(byteArray).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicWriteUint256.callAsync(byteArray, badOffset, testUint256),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+    });
+
+    describe('readBytes4', () => {
+        // AssertionError: expected promise to be rejected with an error including 'revert' but it was fulfilled with '0x08c379a0'
+        it('should revert if byte array has a length < 4', async () => {
+            const byteArrayLessThan4Bytes = '0x010101';
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytes4.callAsync(byteArrayLessThan4Bytes, offset),
+                RevertReason.LibBytesGreaterOrEqualTo4LengthRequired,
+            );
+        });
+        it('should return the first 4 bytes of a byte array of arbitrary length', async () => {
+            const first4Bytes = await libBytes.publicReadBytes4.callAsync(byteArrayLongerThan32Bytes, new BigNumber(0));
+            const expectedFirst4Bytes = byteArrayLongerThan32Bytes.slice(0, 10);
+            expect(first4Bytes).to.equal(expectedFirst4Bytes);
+        });
+        it('should successfully read bytes4 when the bytes4 takes up the whole array', async () => {
+            const testBytes4Offset = new BigNumber(0);
+            const bytes4 = await libBytes.publicReadBytes4.callAsync(testBytes4, testBytes4Offset);
+            return expect(bytes4).to.be.equal(testBytes4);
+        });
+        it('should successfully read bytes4 when it is offset in the array', async () => {
+            const bytes4ByteArrayBuffer = ethUtil.toBuffer(testBytes4);
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, bytes4ByteArrayBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testBytes4Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const bytes4 = await libBytes.publicReadBytes4.callAsync(combinedByteArray, testBytes4Offset);
+            return expect(bytes4).to.be.equal(testBytes4);
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold a bytes4', async () => {
+            const badOffset = new BigNumber(ethUtil.toBuffer(testBytes4).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytes4.callAsync(testBytes4, badOffset),
+                RevertReason.LibBytesGreaterOrEqualTo4LengthRequired,
+            );
+        });
+    });
+
+    describe('readBytesWithLength', () => {
+        it('should successfully read short, nested array of bytes when it takes up the whole array', async () => {
+            const testBytesOffset = new BigNumber(0);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(shortTestBytes, testBytesOffset);
+            return expect(bytes).to.be.equal(shortData);
+        });
+        it('should successfully read short, nested array of bytes when it is offset in the array', async () => {
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, shortTestBytesAsBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(combinedByteArray, testUint256Offset);
+            return expect(bytes).to.be.equal(shortData);
+        });
+        it('should successfully read a nested array of bytes - one word in length - when it takes up the whole array', async () => {
+            const testBytesOffset = new BigNumber(0);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(wordOfTestBytes, testBytesOffset);
+            return expect(bytes).to.be.equal(wordOfData);
+        });
+        it('should successfully read a nested array of bytes - one word in length - when it is offset in the array', async () => {
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, wordOfTestBytesAsBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(combinedByteArray, testUint256Offset);
+            return expect(bytes).to.be.equal(wordOfData);
+        });
+        it('should successfully read long, nested array of bytes when it takes up the whole array', async () => {
+            const testBytesOffset = new BigNumber(0);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(longTestBytes, testBytesOffset);
+            return expect(bytes).to.be.equal(longData);
+        });
+        it('should successfully read long, nested array of bytes when it is offset in the array', async () => {
+            const prefixByteArrayBuffer = ethUtil.toBuffer('0xabcdef');
+            const combinedByteArrayBuffer = Buffer.concat([prefixByteArrayBuffer, longTestBytesAsBuffer]);
+            const combinedByteArray = ethUtil.bufferToHex(combinedByteArrayBuffer);
+            const testUint256Offset = new BigNumber(prefixByteArrayBuffer.byteLength);
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(combinedByteArray, testUint256Offset);
+            return expect(bytes).to.be.equal(longData);
+        });
+        it('should fail if the byte array is too short to hold the length of a nested byte array', async () => {
+            // The length of the nested array is 32 bytes. By storing less than 32 bytes, a length cannot be read.
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytesWithLength.callAsync(byteArrayShorterThan32Bytes, offset),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+        it('should fail if we store a nested byte array length, without a nested byte array', async () => {
+            const offset = new BigNumber(0);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytesWithLength.callAsync(testBytes32, offset),
+                RevertReason.LibBytesGreaterOrEqualToNestedBytesLengthRequired,
+            );
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold the length of a nested byte array', async () => {
+            const badOffset = new BigNumber(ethUtil.toBuffer(byteArrayShorterThan32Bytes).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytesWithLength.callAsync(byteArrayShorterThan32Bytes, badOffset),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold the nested byte array', async () => {
+            const badOffset = new BigNumber(ethUtil.toBuffer(testBytes32).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicReadBytesWithLength.callAsync(testBytes32, badOffset),
+                RevertReason.LibBytesGreaterOrEqualTo32LengthRequired,
+            );
+        });
+    });
+
+    describe('writeBytesWithLength', () => {
+        it('should successfully write short, nested array of bytes when it takes up the whole array', async () => {
+            const testBytesOffset = new BigNumber(0);
+            const emptyByteArray = ethUtil.bufferToHex(new Buffer(shortTestBytesAsBuffer.byteLength));
+            const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                testBytesOffset,
+                shortData,
+            );
+            const bytesRead = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
+            return expect(bytesRead).to.be.equal(shortData);
+        });
+        it('should successfully write short, nested array of bytes when it is offset in the array', async () => {
+            // Write a prefix to the array
+            const prefixData = '0xabcdef';
+            const prefixDataAsBuffer = ethUtil.toBuffer(prefixData);
+            const prefixOffset = new BigNumber(0);
+            const emptyByteArray = ethUtil.bufferToHex(
+                new Buffer(prefixDataAsBuffer.byteLength + shortTestBytesAsBuffer.byteLength),
+            );
+            let bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                prefixOffset,
+                prefixData,
+            );
+            // Write data after prefix
+            const testBytesOffset = new BigNumber(prefixDataAsBuffer.byteLength);
+            bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                bytesWritten,
+                testBytesOffset,
+                shortData,
+            );
+            // Read data after prefix and validate
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
+            return expect(bytes).to.be.equal(shortData);
+        });
+        it('should successfully write a nested array of bytes - one word in length - when it takes up the whole array', async () => {
+            const testBytesOffset = new BigNumber(0);
+            const emptyByteArray = ethUtil.bufferToHex(new Buffer(wordOfTestBytesAsBuffer.byteLength));
+            const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                testBytesOffset,
+                wordOfData,
+            );
+            const bytesRead = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
+            return expect(bytesRead).to.be.equal(wordOfData);
+        });
+        it('should successfully write a nested array of bytes - one word in length - when it is offset in the array', async () => {
+            // Write a prefix to the array
+            const prefixData = '0xabcdef';
+            const prefixDataAsBuffer = ethUtil.toBuffer(prefixData);
+            const prefixOffset = new BigNumber(0);
+            const emptyByteArray = ethUtil.bufferToHex(
+                new Buffer(prefixDataAsBuffer.byteLength + wordOfTestBytesAsBuffer.byteLength),
+            );
+            let bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                prefixOffset,
+                prefixData,
+            );
+            // Write data after prefix
+            const testBytesOffset = new BigNumber(prefixDataAsBuffer.byteLength);
+            bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                bytesWritten,
+                testBytesOffset,
+                wordOfData,
+            );
+            // Read data after prefix and validate
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
+            return expect(bytes).to.be.equal(wordOfData);
+        });
+        it('should successfully write a long, nested bytes when it takes up the whole array', async () => {
+            const testBytesOffset = new BigNumber(0);
+            const emptyByteArray = ethUtil.bufferToHex(new Buffer(longTestBytesAsBuffer.byteLength));
+            const bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                testBytesOffset,
+                longData,
+            );
+            const bytesRead = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
+            return expect(bytesRead).to.be.equal(longData);
+        });
+        it('should successfully write long, nested array of bytes when it is offset in the array', async () => {
+            // Write a prefix to the array
+            const prefixData = '0xabcdef';
+            const prefixDataAsBuffer = ethUtil.toBuffer(prefixData);
+            const prefixOffset = new BigNumber(0);
+            const emptyByteArray = ethUtil.bufferToHex(
+                new Buffer(prefixDataAsBuffer.byteLength + longTestBytesAsBuffer.byteLength),
+            );
+            let bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(
+                emptyByteArray,
+                prefixOffset,
+                prefixData,
+            );
+            // Write data after prefix
+            const testBytesOffset = new BigNumber(prefixDataAsBuffer.byteLength);
+            bytesWritten = await libBytes.publicWriteBytesWithLength.callAsync(bytesWritten, testBytesOffset, longData);
+            // Read data after prefix and validate
+            const bytes = await libBytes.publicReadBytesWithLength.callAsync(bytesWritten, testBytesOffset);
+            return expect(bytes).to.be.equal(longData);
+        });
+        it('should fail if the byte array is too short to hold the length of a nested byte array', async () => {
+            const offset = new BigNumber(0);
+            const emptyByteArray = ethUtil.bufferToHex(new Buffer(1));
+            return expectContractCallFailedAsync(
+                libBytes.publicWriteBytesWithLength.callAsync(emptyByteArray, offset, longData),
+                RevertReason.LibBytesGreaterOrEqualToNestedBytesLengthRequired,
+            );
+        });
+        it('should fail if the length between the offset and end of the byte array is too short to hold the length of a nested byte array', async () => {
+            const emptyByteArray = ethUtil.bufferToHex(new Buffer(shortTestBytesAsBuffer.byteLength));
+            const badOffset = new BigNumber(ethUtil.toBuffer(shortTestBytesAsBuffer).byteLength);
+            return expectContractCallFailedAsync(
+                libBytes.publicWriteBytesWithLength.callAsync(emptyByteArray, badOffset, shortData),
+                RevertReason.LibBytesGreaterOrEqualToNestedBytesLengthRequired,
+            );
+        });
+    });
+
+    describe('memCopy', () => {
+        // Create memory 0x000102...FF
+        const memSize = 256;
+        // tslint:disable:no-shadowed-variable
+        const memory = new Uint8Array(memSize).map((_, i) => i);
+        const memHex = toHex(memory);
+
+        // Reference implementation to test against
+        const refMemcpy = (mem: Uint8Array, dest: number, source: number, length: number): Uint8Array =>
+            Uint8Array.from(mem).copyWithin(dest, source, source + length);
+
+        // Test vectors: destination, source, length, job description
+        type Tests = Array<[number, number, number, string]>;
+
+        const test = (tests: Tests) =>
+            tests.forEach(([dest, source, length, job]) =>
+                it(job, async () => {
+                    const expected = refMemcpy(memory, dest, source, length);
+                    const resultStr = await libBytes.testMemcpy.callAsync(
+                        memHex,
+                        new BigNumber(dest),
+                        new BigNumber(source),
+                        new BigNumber(length),
+                    );
+                    const result = fromHex(resultStr);
+                    expect(result).to.deep.equal(expected);
+                }),
+            );
+
+        test([[0, 0, 0, 'copies zero bytes with overlap']]);
+
+        describe('copies forward', () =>
+            test([
+                [128, 0, 0, 'zero bytes'],
+                [128, 0, 1, 'one byte'],
+                [128, 0, 11, 'eleven bytes'],
+                [128, 0, 31, 'thirty-one bytes'],
+                [128, 0, 32, 'one word'],
+                [128, 0, 64, 'two words'],
+                [128, 0, 96, 'three words'],
+                [128, 0, 33, 'one word and one byte'],
+                [128, 0, 72, 'two words and eight bytes'],
+                [128, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward within one word', () =>
+            test([
+                [16, 0, 0, 'zero bytes'],
+                [16, 0, 1, 'one byte'],
+                [16, 0, 11, 'eleven bytes'],
+                [16, 0, 16, 'sixteen bytes'],
+            ]));
+
+        describe('copies forward with one byte overlap', () =>
+            test([
+                [0, 0, 1, 'one byte'],
+                [10, 0, 11, 'eleven bytes'],
+                [30, 0, 31, 'thirty-one bytes'],
+                [31, 0, 32, 'one word'],
+                [32, 0, 33, 'one word and one byte'],
+                [71, 0, 72, 'two words and eight bytes'],
+                [99, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with thirty-one bytes overlap', () =>
+            test([
+                [0, 0, 31, 'thirty-one bytes'],
+                [1, 0, 32, 'one word'],
+                [2, 0, 33, 'one word and one byte'],
+                [41, 0, 72, 'two words and eight bytes'],
+                [69, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with one word overlap', () =>
+            test([
+                [0, 0, 32, 'one word'],
+                [1, 0, 33, 'one word and one byte'],
+                [41, 0, 72, 'two words and eight bytes'],
+                [69, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with one word and one byte overlap', () =>
+            test([
+                [0, 0, 33, 'one word and one byte'],
+                [40, 0, 72, 'two words and eight bytes'],
+                [68, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward with two words overlap', () =>
+            test([
+                [0, 0, 64, 'two words'],
+                [8, 0, 72, 'two words and eight bytes'],
+                [36, 0, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward within one word and one byte overlap', () =>
+            test([[0, 0, 1, 'one byte'], [10, 0, 11, 'eleven bytes'], [15, 0, 16, 'sixteen bytes']]));
+
+        describe('copies backward', () =>
+            test([
+                [0, 128, 0, 'zero bytes'],
+                [0, 128, 1, 'one byte'],
+                [0, 128, 11, 'eleven bytes'],
+                [0, 128, 31, 'thirty-one bytes'],
+                [0, 128, 32, 'one word'],
+                [0, 128, 64, 'two words'],
+                [0, 128, 96, 'three words'],
+                [0, 128, 33, 'one word and one byte'],
+                [0, 128, 72, 'two words and eight bytes'],
+                [0, 128, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward within one word', () =>
+            test([
+                [0, 16, 0, 'zero bytes'],
+                [0, 16, 1, 'one byte'],
+                [0, 16, 11, 'eleven bytes'],
+                [0, 16, 16, 'sixteen bytes'],
+            ]));
+
+        describe('copies backward with one byte overlap', () =>
+            test([
+                [0, 0, 1, 'one byte'],
+                [0, 10, 11, 'eleven bytes'],
+                [0, 30, 31, 'thirty-one bytes'],
+                [0, 31, 32, 'one word'],
+                [0, 32, 33, 'one word and one byte'],
+                [0, 71, 72, 'two words and eight bytes'],
+                [0, 99, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with thirty-one bytes overlap', () =>
+            test([
+                [0, 0, 31, 'thirty-one bytes'],
+                [0, 1, 32, 'one word'],
+                [0, 2, 33, 'one word and one byte'],
+                [0, 41, 72, 'two words and eight bytes'],
+                [0, 69, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with one word overlap', () =>
+            test([
+                [0, 0, 32, 'one word'],
+                [0, 1, 33, 'one word and one byte'],
+                [0, 41, 72, 'two words and eight bytes'],
+                [0, 69, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with one word and one byte overlap', () =>
+            test([
+                [0, 0, 33, 'one word and one byte'],
+                [0, 40, 72, 'two words and eight bytes'],
+                [0, 68, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies backward with two words overlap', () =>
+            test([
+                [0, 0, 64, 'two words'],
+                [0, 8, 72, 'two words and eight bytes'],
+                [0, 36, 100, 'three words and four bytes'],
+            ]));
+
+        describe('copies forward within one word and one byte overlap', () =>
+            test([[0, 0, 1, 'one byte'], [0, 10, 11, 'eleven bytes'], [0, 15, 16, 'sixteen bytes']]));
+    });
+});
+// tslint:disable:max-file-line-count
diff --git a/contracts/utils/test/libs.ts b/contracts/utils/test/libs.ts
new file mode 100644
index 000000000..81596b2e4
--- /dev/null
+++ b/contracts/utils/test/libs.ts
@@ -0,0 +1,34 @@
+import { chaiSetup, provider, txDefaults, web3Wrapper } from '@0x/contracts-test-utils';
+import { BlockchainLifecycle } from '@0x/dev-utils';
+import * as chai from 'chai';
+
+import { TestConstantsContract } from '../generated-wrappers/test_constants';
+import { artifacts } from '../src';
+
+chaiSetup.configure();
+const expect = chai.expect;
+
+const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
+
+describe('Libs', () => {
+    beforeEach(async () => {
+        await blockchainLifecycle.startAsync();
+    });
+    afterEach(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+
+    describe('LibConstants', () => {
+        describe('ZRX_ASSET_DATA', () => {
+            it('should have the correct ZRX_ASSET_DATA', async () => {
+                const testConstants = await TestConstantsContract.deployFrom0xArtifactAsync(
+                    artifacts.TestConstants,
+                    provider,
+                    txDefaults,
+                );
+                const isValid = await testConstants.assertValidZrxAssetData.callAsync();
+                expect(isValid).to.be.equal(true);
+            });
+        });
+    });
+});
diff --git a/contracts/utils/tsconfig.json b/contracts/utils/tsconfig.json
new file mode 100644
index 000000000..68251e6b0
--- /dev/null
+++ b/contracts/utils/tsconfig.json
@@ -0,0 +1,19 @@
+{
+    "extends": "../../tsconfig",
+    "compilerOptions": {
+        "outDir": "lib",
+        "rootDir": ".",
+        "resolveJsonModule": true
+    },
+    "include": ["./src/**/*", "./test/**/*", "./generated-wrappers/**/*"],
+    "files": [
+        "./generated-artifacts/TestConstants.json",
+        "./generated-artifacts/TestLibBytes.json",
+        "./generated-artifacts/IOwnable.json",
+        "./generated-artifacts/Ownable.json",
+        "./generated-artifacts/LibBytes.json",
+        "./generated-artifacts/SafeMath.json",
+        "./generated-artifacts/ReentrancyGuard.json"
+    ],
+    "exclude": ["./deploy/solc/solc_bin"]
+}
diff --git a/contracts/utils/tslint.json b/contracts/utils/tslint.json
new file mode 100644
index 000000000..1bb3ac2a2
--- /dev/null
+++ b/contracts/utils/tslint.json
@@ -0,0 +1,6 @@
+{
+    "extends": ["@0x/tslint-config"],
+    "rules": {
+        "custom-no-magic-numbers": false
+    }
+}