6 files changed, 51 insertions, 18 deletions
diff --git a/packages/subproviders/CHANGELOG.md b/packages/subproviders/CHANGELOG.md
index b4cce6be0..358fcfa15 100644
--- a/packages/subproviders/CHANGELOG.md
+++ b/packages/subproviders/CHANGELOG.md
@@ -1,4 +1,5 @@
 # CHANGELOG
 
-vx.x.x
+v0.x.x - _TBD, 2017_
 ------------------------
+    * Improve the performance of address fetching (#271)
diff --git a/packages/subproviders/package.json b/packages/subproviders/package.json
index 8a222457d..56fc9bf8b 100644
--- a/packages/subproviders/package.json
+++ b/packages/subproviders/package.json
@@ -23,6 +23,7 @@
     "es6-promisify": "^5.0.0",
     "ethereumjs-tx": "^1.3.3",
     "ethereumjs-util": "^5.1.1",
+    "hdkey": "^0.7.1",
     "ledgerco": "0xProject/ledger-node-js-api",
     "lodash": "^4.17.4",
     "semaphore-async-await": "^1.5.1",
diff --git a/packages/subproviders/src/globals.d.ts b/packages/subproviders/src/globals.d.ts
index adef23806..3800c970f 100644
--- a/packages/subproviders/src/globals.d.ts
+++ b/packages/subproviders/src/globals.d.ts
@@ -48,7 +48,7 @@ declare module 'ledgerco' {
         public comm: comm;
         constructor(comm: comm);
         public getAddress_async(path: string, display?: boolean, chaincode?: boolean):
-               Promise<{publicKey: string; address: string}>;
+               Promise<{publicKey: string; address: string; chainCode: string}>;
         public signTransaction_async(path: string, rawTxHex: string): Promise<ECSignatureString>;
         public getAppConfiguration_async(): Promise<{ arbitraryDataEnabled: number; version: string }>;
         public signPersonalMessage_async(path: string, messageHex: string): Promise<ECSignature>;
@@ -91,3 +91,14 @@ declare module 'web3-provider-engine' {
   }
   export = Web3ProviderEngine;
 }
+
+// hdkey declarations
+declare module 'hdkey' {
+    class HDNode {
+        public publicKey: Buffer;
+        public chainCode: Buffer;
+        public constructor();
+        public derive(path: string): HDNode;
+    }
+    export = HDNode;
+}
diff --git a/packages/subproviders/src/subproviders/ledger.ts b/packages/subproviders/src/subproviders/ledger.ts
index 9ffc105a4..f9922fdda 100644
--- a/packages/subproviders/src/subproviders/ledger.ts
+++ b/packages/subproviders/src/subproviders/ledger.ts
@@ -2,6 +2,7 @@ import {assert} from '@0xproject/assert';
 import {addressUtils} from '@0xproject/utils';
 import EthereumTx = require('ethereumjs-tx');
 import ethUtil = require('ethereumjs-util');
+import HDNode = require('hdkey');
 import * as _ from 'lodash';
 import Semaphore from 'semaphore-async-await';
 import Web3 = require('web3');
@@ -20,7 +21,7 @@ import {Subprovider} from './subprovider';
 const DEFAULT_DERIVATION_PATH = `44'/60'/0'`;
 const NUM_ADDRESSES_TO_FETCH = 10;
 const ASK_FOR_ON_DEVICE_CONFIRMATION = false;
-const SHOULD_GET_CHAIN_CODE = false;
+const SHOULD_GET_CHAIN_CODE = true;
 
 export class LedgerSubprovider extends Subprovider {
     private _nonceLock: Semaphore;
@@ -127,21 +128,30 @@ export class LedgerSubprovider extends Subprovider {
     public async getAccountsAsync(): Promise<string[]> {
         this._ledgerClientIfExists = await this.createLedgerClientAsync();
 
-        // TODO: replace with generating addresses without hitting Ledger
+        let ledgerResponse;
+        try {
+            ledgerResponse = await this._ledgerClientIfExists.getAddress_async(
+                this._derivationPath, this._shouldAlwaysAskForConfirmation, SHOULD_GET_CHAIN_CODE,
+            );
+        } finally {
+            await this.destoryLedgerClientAsync();
+        }
+
+        const hdKey = new HDNode();
+        hdKey.publicKey = new Buffer(ledgerResponse.publicKey, 'hex');
+        hdKey.chainCode = new Buffer(ledgerResponse.chainCode, 'hex');
+
         const accounts = [];
         for (let i = 0; i < NUM_ADDRESSES_TO_FETCH; i++) {
-            try {
-                const derivationPath = `${this._derivationPath}/${i + this._derivationPathIndex}`;
-                const result = await this._ledgerClientIfExists.getAddress_async(
-                    derivationPath, this._shouldAlwaysAskForConfirmation, SHOULD_GET_CHAIN_CODE,
-                );
-                accounts.push(result.address.toLowerCase());
-            } catch (err) {
-                await this.destoryLedgerClientAsync();
-                throw err;
-            }
+            const derivedHDNode = hdKey.derive(`m/${i + this._derivationPathIndex}`);
+            const derivedPublicKey = derivedHDNode.publicKey;
+            const shouldSanitizePublicKey = true;
+            const ethereumAddressUnprefixed = ethUtil.publicToAddress(
+                derivedPublicKey, shouldSanitizePublicKey,
+            ).toString('hex');
+            const ethereumAddressPrefixed = ethUtil.addHexPrefix(ethereumAddressUnprefixed);
+            accounts.push(ethereumAddressPrefixed.toLowerCase());
         }
-        await this.destoryLedgerClientAsync();
         return accounts;
     }
     public async signTransactionAsync(txParams: PartialTxParams): Promise<string> {
diff --git a/packages/subproviders/src/types.ts b/packages/subproviders/src/types.ts
index 1e7d3eab0..c5ccf1fda 100644
--- a/packages/subproviders/src/types.ts
+++ b/packages/subproviders/src/types.ts
@@ -10,8 +10,10 @@ export interface LedgerCommunicationClient {
  * NodeJs and Browser communication are supported.
  */
 export interface LedgerEthereumClient {
+    // shouldGetChainCode is defined as `true` instead of `boolean` because other types rely on the assumption
+    // that we get back the chain code and we don't have dependent types to express it properly
     getAddress_async: (derivationPath: string, askForDeviceConfirmation: boolean,
-                       shouldGetChainCode: boolean) => Promise<LedgerGetAddressResult>;
+                       shouldGetChainCode: true) => Promise<LedgerGetAddressResult>;
     signPersonalMessage_async: (derivationPath: string, messageHex: string) => Promise<ECSignature>;
     signTransaction_async: (derivationPath: string, txHex: string) => Promise<ECSignatureString>;
     comm: LedgerCommunicationClient;
@@ -63,6 +65,8 @@ export interface SignatureData {
 
 export interface LedgerGetAddressResult {
     address: string;
+    publicKey: string;
+    chainCode: string;
 }
 
 export interface LedgerWalletSubprovider {
diff --git a/packages/subproviders/test/unit/ledger_subprovider_test.ts b/packages/subproviders/test/unit/ledger_subprovider_test.ts
index bd4d93325..237090051 100644
--- a/packages/subproviders/test/unit/ledger_subprovider_test.ts
+++ b/packages/subproviders/test/unit/ledger_subprovider_test.ts
@@ -18,7 +18,7 @@ import {reportCallbackErrors} from '../utils/report_callback_errors';
 
 chaiSetup.configure();
 const expect = chai.expect;
-const FAKE_ADDRESS = '0x9901c66f2d4b95f7074b553da78084d708beca70';
+const FAKE_ADDRESS = '0xb088a3bc93f71b4de97b9de773e9647645983688';
 
 describe('LedgerSubprovider', () => {
     const networkId: number = 42;
@@ -28,8 +28,14 @@ describe('LedgerSubprovider', () => {
             // tslint:disable:no-object-literal-type-assertion
             const ledgerEthClient = {
                 getAddress_async: async () => {
+                    // tslint:disable-next-line:max-line-length
+                    const publicKey = '04f428290f4c5ed6a198f71b8205f488141dbb3f0840c923bbfa798ecbee6370986c03b5575d94d506772fb48a6a44e345e4ebd4f028a6f609c44b655d6d3e71a1';
+                    const chainCode = 'ac055a5537c0c7e9e02d14a197cad6b857836da2a12043b46912a37d959b5ae8';
+                    const address = '0xBa388BA5e5EEF2c6cE42d831c2B3A28D3c99bdB1';
                     return {
-                        address: FAKE_ADDRESS,
+                        publicKey,
+                        address,
+                        chainCode,
                     };
                 },
                 signPersonalMessage_async: async () => {