[PSDK-111] Wallet Import/Export/Save/Load

Author: John-peterson-coinbase

README.md

@@ -1,9 +1,6 @@
 # Coinbase Node.js SDK
 
-The Coinbase Node.js SDK enables the simple integration of crypto into your app.
-By calling Coinbase's Platform APIs, the SDK allows you to provision crypto wallets,
-send crypto into/out of those wallets, track wallet balances, and trade crypto from
-one asset into another.
+The Coinbase Node.js SDK enables the simple integration of crypto into your app. By calling Coinbase's Platform APIs, the SDK allows you to provision crypto wallets, send crypto into/out of those wallets, track wallet balances, and trade crypto from one asset into another.
 
 The SDK currently supports Customer-custodied Wallets on the Base Sepolia test network.
 
@@ -12,8 +9,7 @@ The SDK currently supports Customer-custodied Wallets on the Base Sepolia test n
 - **may make backwards-incompatible changes between releases**
 - **should not be used on Mainnet (i.e. with real funds)**
 
-Currently, the SDK is intended for use on testnet for quick bootstrapping of crypto wallets at
-hackathons, code academies, and other development settings.
+Currently, the SDK is intended for use on testnet for quick bootstrapping of crypto wallets at hackathons, code academies, and other development settings.
 
 ## Documentation
 
@@ -38,8 +34,9 @@ yarn install @coinbase/coinbase-sdk
 After running `npx ts-node` to start the REPL, you can import the SDK as follows:
 
 ```typescript
-import { Coinbase } from '@coinbase/coinbase-sdk';
+import { Coinbase } from "@coinbase/coinbase-sdk";
 ```
+
 ### Requirements
 
 - Node.js 18 or higher
@@ -51,18 +48,17 @@ import { Coinbase } from '@coinbase/coinbase-sdk';
 To start, [create a CDP API Key](https://portal.cdp.coinbase.com/access/api). Then, initialize the Platform SDK by passing your API Key name and API Key's private key via the `Coinbase` constructor:
 
 ```typescript
-const apiKeyName = 'Copy your API Key name here.';
+const apiKeyName = "Copy your API Key name here.";
 
-const apiKeyPrivateKey = 'Copy your API Key\'s private key here.';
+const apiKeyPrivateKey = "Copy your API Key's private key here.";
 
 const coinbase = new Coinbase(apiKeyName, apiKeyPrivateKey);
 ```
 
-Another way to initialize the SDK is by sourcing the API key from the json file that contains your API key, 
-downloaded from CDP portal. 
+Another way to initialize the SDK is by sourcing the API key from the json file that contains your API key, downloaded from CDP portal.
 
 ```typescript
-const coinbase = Coinbase.configureFromJson('path/to/your/api-key.json');
+const coinbase = Coinbase.configureFromJson("path/to/your/api-key.json");
 ```
 
 This will allow you to authenticate with the Platform APIs and get access to the default `User`.
@@ -105,6 +101,50 @@ const anotherWallet = await user.createWallet();
 const transfer = await wallet.createTransfer(0.00001, Coinbase.assetList.Eth, anotherWallet);
 ```
 
+### Re-Instantiating Wallets
+
+The SDK creates Wallets with developer managed keys, which means you are responsible for securely storing the keys required to re-instantiate Wallets. The below code walks you through how to export a Wallets and store it in a secure location.
+
+```typescript
+// Export the data required to re-instantiate the Wallet.
+const data = wallet.export();
+```
+
+In order to persist the data for the Wallet, you will need to implement a store method to store the data export in a secure location. If you do not store the Wallet in a secure location you will lose access to the Wallet and all of the funds on it.
+
+```typescript
+// At this point, you should implement your own "store" method to securely persist
+// the data required to re-instantiate the Wallet at a later time.
+await store(data);
+```
+
+For convenience during testing, we provide a `saveWallet` method that stores the Wallet data in your local file system. This is an insecure method of storing wallet seeds and should only be used for development purposes.
+
+```typescript
+user.saveWallet(wallet);
+```
+
+To encrypt the saved data, set encrypt to true. Note that your CDP API key also serves as the encryption key for the data persisted locally. To re-instantiate wallets with encrypted data, ensure that your SDK is configured with the same API key when invoking `saveWallet` and `loadWallets`.
+
+```typescript
+user.saveWallet(wallet, true);
+```
+
+The below code demonstrates how to re-instantiate a Wallet from the data export.
+
+```typescript
+// The Wallet can be re-instantiated using the exported data.
+const importedWallet = await user.import(data);
+```
+
+To import Wallets that were persisted to your local file system using `saveWallet`, use the below code.
+
+```typescript
+// The Wallet can be re-instantiated using the exported data.
+const wallets = await user.loadWallets();
+const reinitWallet = wallets[wallet.getId()];
+```
+
 ## Development
 
 ### Node.js Version
@@ -155,8 +195,7 @@ npx jest ./src/coinbase/tests/wallet_test.ts
 
 ### REPL
 
-The repository is equipped with a REPL to allow developers to play with the SDK. To start
-it, run:
+The repository is equipped with a REPL to allow developers to play with the SDK. To start it, run:
 
 ```bash
 npx ts-node

src/coinbase/coinbase.ts

@@ -1,5 +1,5 @@
 import globalAxios from "axios";
-import fs from "fs";
+import * as fs from "fs";
 import {
   AddressesApiFactory,
   User as UserModel,
@@ -51,6 +51,20 @@ export class Coinbase {
    */
   static readonly WEI_PER_ETHER: bigint = BigInt("1000000000000000000");
 
+  /**
+   * The backup file path for Wallet seeds.
+   *
+   * @constant
+   */
+  static backupFilePath: string = "seed.json";
+
+  /**
+   * The CDP API key Private Key.
+   *
+   * @constant
+   */
+  static apiKeyPrivateKey: string;
+
   /**
    * Initializes the Coinbase SDK.
    *
@@ -59,6 +73,7 @@ export class Coinbase {
    * @param privateKey - The private key associated with the API key.
    * @param debugging - If true, logs API requests and responses to the console.
    * @param basePath - The base path for the API.
+   * @param backupFilePath - The path to the file containing the Wallet backup data.
    * @throws {InternalError} If the configuration is invalid.
    * @throws {InvalidAPIKeyFormat} If not able to create JWT token.
    */
@@ -67,6 +82,7 @@ export class Coinbase {
     privateKey: string,
     debugging = false,
     basePath: string = BASE_PATH,
+    backupFilePath?: string,
   ) {
     if (apiKeyName === "") {
       throw new InternalError("Invalid configuration: apiKeyName is empty");
@@ -92,6 +108,7 @@ export class Coinbase {
     Coinbase.apiClients.baseSepoliaProvider = new ethers.JsonRpcProvider(
       "https://sepolia.base.org",
     );
+    Coinbase.apiKeyPrivateKey = backupFilePath ? backupFilePath : privateKey;
   }
 
   /**
@@ -100,6 +117,7 @@ export class Coinbase {
    * @param filePath - The path to the JSON file containing the API key and private key.
    * @param debugging - If true, logs API requests and responses to the console.
    * @param basePath - The base path for the API.
+   * @param backupFilePath - The path to the file containing the Wallet backup data.
    * @returns A new instance of the Coinbase SDK.
    * @throws {InvalidAPIKeyFormat} If the file does not exist or the configuration values are missing/invalid.
    * @throws {InvalidConfiguration} If the configuration is invalid.
@@ -109,6 +127,7 @@ export class Coinbase {
     filePath: string = "coinbase_cloud_api_key.json",
     debugging: boolean = false,
     basePath: string = BASE_PATH,
+    backupFilePath?: string,
   ): Coinbase {
     if (!fs.existsSync(filePath)) {
       throw new InvalidConfiguration(`Invalid configuration: file not found at ${filePath}`);
@@ -120,7 +139,7 @@ export class Coinbase {
         throw new InvalidAPIKeyFormat("Invalid configuration: missing configuration values");
       }
 
-      return new Coinbase(config.name, config.privateKey, debugging, basePath);
+      return new Coinbase(config.name, config.privateKey, debugging, basePath, backupFilePath);
     } catch (e) {
       if (e instanceof SyntaxError) {
         throw new InvalidAPIKeyFormat("Not able to parse the configuration file");