2 files changed, 82 insertions, 0 deletions
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..902d8530c
--- /dev/null
+++ b/packages/utils/src/sign_typed_data_utils.ts
@@ -0,0 +1,81 @@
+import * as ethUtil from 'ethereumjs-util';
+import * as ethers from 'ethers';
+
+export interface EIP712Parameter {
+    name: string;
+    type: string;
+}
+
+export interface EIP712Types {
+    [key: string]: EIP712Parameter[];
+}
+export interface EIP712TypedData {
+    types: EIP712Types;
+    domain: any;
+    message: any;
+    primaryType: string;
+}
+
+export const signTypedDataUtils = {
+    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: any, types: EIP712Types): string {
+        const encodedTypes = ['bytes32'];
+        const encodedValues = [signTypedDataUtils.typeHash(primaryType, types)];
+        for (const field of types[primaryType]) {
+            let value = data[field.name];
+            if (field.type === 'string' || field.type === 'bytes') {
+                value = ethUtil.sha3(value);
+                encodedTypes.push('bytes32');
+                encodedValues.push(value);
+            } else if (types[field.type] !== undefined) {
+                encodedTypes.push('bytes32');
+                value = ethUtil.sha3(signTypedDataUtils.encodeData(field.type, value, types));
+                encodedValues.push(value);
+            } else if (field.type.lastIndexOf(']') === field.type.length - 1) {
+                throw new Error('Arrays currently unimplemented in encodeData');
+            } else {
+                encodedTypes.push(field.type);
+                encodedValues.push(value);
+            }
+        }
+        return ethers.utils.defaultAbiCoder.encode(encodedTypes, encodedValues);
+    },
+    typeHash(primaryType: string, types: EIP712Types): Buffer {
+        return ethUtil.sha3(signTypedDataUtils.encodeType(primaryType, types));
+    },
+    structHash(primaryType: string, data: any, types: EIP712Types): Buffer {
+        return ethUtil.sha3(signTypedDataUtils.encodeData(primaryType, data, types));
+    },
+    signTypedDataHash(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),
+            ]),
+        );
+    },
+};