3 files changed, 86 insertions, 3 deletions

diff --git a/packages/utils/src/abi_decoder.ts b/packages/utils/src/abi_decoder.ts
index ea8c91d10..ac3e54efb 100644
--- a/packages/utils/src/abi_decoder.ts
+++ b/packages/utils/src/abi_decoder.ts
@@ -9,7 +9,7 @@ import {
     RawLog,
     SolidityTypes,
 } from 'ethereum-types';
-import * as ethers from 'ethers';
+import { ethers } from 'ethers';
 import * as _ from 'lodash';
 
 import { addressUtils } from './address_utils';
@@ -41,7 +41,7 @@ export class AbiDecoder {
             return log;
         }
         const event = this._methodIds[methodId][numIndexedArgs];
-        const ethersInterface = new ethers.Interface([event]);
+        const ethersInterface = new ethers.utils.Interface([event]);
         const decodedParams: DecodedLogArgs = {};
         let topicsIndex = 1;
 
@@ -96,7 +96,7 @@ export class AbiDecoder {
         if (_.isUndefined(abiArray)) {
             return;
         }
-        const ethersInterface = new ethers.Interface(abiArray);
+        const ethersInterface = new ethers.utils.Interface(abiArray);
         _.map(abiArray, (abi: AbiDefinition) => {
             if (abi.type === AbiType.Event) {
                 const topic = ethersInterface.events[abi.name].topic;
diff --git a/packages/utils/src/index.ts b/packages/utils/src/index.ts
index 9d01e5bc5..0723e5788 100644
--- a/packages/utils/src/index.ts
+++ b/packages/utils/src/index.ts
@@ -9,3 +9,4 @@ export { abiUtils } from './abi_utils';
 export { NULL_BYTES } from './constants';
 export { errorUtils } from './error_utils';
 export { fetchAsync } from './fetch_async';
+export { signTypedDataUtils } from './sign_typed_data_utils';
diff --git a/packages/utils/src/sign_typed_data_utils.ts b/packages/utils/src/sign_typed_data_utils.ts
new file mode 100644
index 000000000..cd5bcb42f
--- /dev/null
+++ b/packages/utils/src/sign_typed_data_utils.ts
@@ -0,0 +1,82 @@
+import * as ethUtil from 'ethereumjs-util';
+import * as ethers from 'ethers';
+import * as _ from 'lodash';
+
+import { EIP712Object, EIP712ObjectValue, EIP712TypedData, EIP712Types } from '@0xproject/types';
+
+export const signTypedDataUtils = {
+    /**
+     * Generates the EIP712 Typed Data hash for signing
+     * @param   typedData An object that conforms to the EIP712TypedData interface
+     * @return  A Buffer containing the hash of the typed data.
+     */
+    generateTypedDataHash(typedData: EIP712TypedData): Buffer {
+        return ethUtil.sha3(
+            Buffer.concat([
+                Buffer.from('1901', 'hex'),
+                signTypedDataUtils._structHash('EIP712Domain', typedData.domain, typedData.types),
+                signTypedDataUtils._structHash(typedData.primaryType, typedData.message, typedData.types),
+            ]),
+        );
+    },
+    _findDependencies(primaryType: string, types: EIP712Types, found: string[] = []): string[] {
+        if (found.includes(primaryType) || types[primaryType] === undefined) {
+            return found;
+        }
+        found.push(primaryType);
+        for (const field of types[primaryType]) {
+            for (const dep of signTypedDataUtils._findDependencies(field.type, types, found)) {
+                if (!found.includes(dep)) {
+                    found.push(dep);
+                }
+            }
+        }
+        return found;
+    },
+    _encodeType(primaryType: string, types: EIP712Types): string {
+        let deps = signTypedDataUtils._findDependencies(primaryType, types);
+        deps = deps.filter(d => d !== primaryType);
+        deps = [primaryType].concat(deps.sort());
+        let result = '';
+        for (const dep of deps) {
+            result += `${dep}(${types[dep].map(({ name, type }) => `${type} ${name}`).join(',')})`;
+        }
+        return result;
+    },
+    _encodeData(primaryType: string, data: EIP712Object, types: EIP712Types): string {
+        const encodedTypes = ['bytes32'];
+        const encodedValues: Array<Buffer | EIP712ObjectValue> = [signTypedDataUtils._typeHash(primaryType, types)];
+        for (const field of types[primaryType]) {
+            const value = data[field.name];
+            if (field.type === 'string' || field.type === 'bytes') {
+                const hashValue = ethUtil.sha3(value as string);
+                encodedTypes.push('bytes32');
+                encodedValues.push(hashValue);
+            } else if (types[field.type] !== undefined) {
+                encodedTypes.push('bytes32');
+                const hashValue = ethUtil.sha3(
+                    // tslint:disable-next-line:no-unnecessary-type-assertion
+                    signTypedDataUtils._encodeData(field.type, value as EIP712Object, types),
+                );
+                encodedValues.push(hashValue);
+            } else if (field.type.lastIndexOf(']') === field.type.length - 1) {
+                throw new Error('Arrays currently unimplemented in encodeData');
+            } else {
+                encodedTypes.push(field.type);
+                const normalizedValue = signTypedDataUtils._normalizeValue(field.type, value);
+                encodedValues.push(normalizedValue);
+            }
+        }
+        return ethers.utils.defaultAbiCoder.encode(encodedTypes, encodedValues);
+    },
+    _normalizeValue(type: string, value: any): EIP712ObjectValue {
+        const normalizedValue = type === 'uint256' && _.isObject(value) && value.isBigNumber ? value.toString() : value;
+        return normalizedValue;
+    },
+    _typeHash(primaryType: string, types: EIP712Types): Buffer {
+        return ethUtil.sha3(signTypedDataUtils._encodeType(primaryType, types));
+    },
+    _structHash(primaryType: string, data: EIP712Object, types: EIP712Types): Buffer {
+        return ethUtil.sha3(signTypedDataUtils._encodeData(primaryType, data, types));
+    },
+};