1 files changed, 58 insertions, 0 deletions
diff --git a/packages/subproviders/src/walletUtils.ts b/packages/subproviders/src/walletUtils.ts
new file mode 100644
index 000000000..631636a71
--- /dev/null
+++ b/packages/subproviders/src/walletUtils.ts
@@ -0,0 +1,58 @@
+import ethUtil = require('ethereumjs-util');
+import HDNode = require('hdkey');
+import * as _ from 'lodash';
+
+import { DerivedHDKey, WalletSubproviderErrors } from './types';
+
+const DEFAULT_ADDRESS_SEARCH_OFFSET = 0;
+const BATCH_SIZE = 10;
+export const walletUtils = {
+    _calculateDerivedHDKeys(
+        initialHDKey: HDNode,
+        derivationPath: string,
+        searchLimit: number,
+        offset: number = DEFAULT_ADDRESS_SEARCH_OFFSET,
+    ): DerivedHDKey[] {
+        const derivedKeys: DerivedHDKey[] = [];
+        _.times(searchLimit, i => {
+            const path = `m/${derivationPath}/${i + offset}`;
+            const hdKey = initialHDKey.derive(path);
+            const derivedPublicKey = hdKey.publicKey;
+            const shouldSanitizePublicKey = true;
+            const ethereumAddressUnprefixed = ethUtil
+                .publicToAddress(derivedPublicKey, shouldSanitizePublicKey)
+                .toString('hex');
+            const address = ethUtil.addHexPrefix(ethereumAddressUnprefixed);
+            const derivedKey: DerivedHDKey = {
+                derivationPath: path,
+                hdKey,
+                address,
+            };
+            derivedKeys.push(derivedKey);
+        });
+        return derivedKeys;
+    },
+
+    _findDerivedKeyByAddress(
+        address: string,
+        initialHDKey: HDNode,
+        derivationPath: string,
+        searchLimit: number,
+    ): DerivedHDKey | undefined {
+        let matchedKey: DerivedHDKey | undefined;
+        for (let index = 0; index < searchLimit; index = index + BATCH_SIZE) {
+            const derivedKeys = walletUtils._calculateDerivedHDKeys(initialHDKey, derivationPath, BATCH_SIZE, index);
+            matchedKey = _.find(derivedKeys, derivedKey => derivedKey.address === address);
+            if (matchedKey) {
+                break;
+            }
+        }
+        return matchedKey;
+    },
+
+    _firstDerivedKey(initialHDKey: HDNode, derivationPath: string): DerivedHDKey {
+        const derivedKeys = walletUtils._calculateDerivedHDKeys(initialHDKey, derivationPath, 1);
+        const firstDerivedKey = derivedKeys[0];
+        return firstDerivedKey;
+    },
+};