Wallet Pregeneration

Para’s Wallet Pregeneration feature allows you to create wallets for users before they authenticate, giving you control over when and how users claim ownership of their wallets. This is particularly powerful in mobile applications, where you can leverage device-specific storage capabilities for enhanced user experiences.

Mobile-Specific Benefits

While pregeneration works the same across all Para SDKs, Flutter applications offer unique advantages:

Seamless Web2 to Web3 Transition

Local Secure Storage

Device-Specific Wallets

App Clips and Instant Experiences

Pregeneration is especially valuable for devices that may not have full WebAuthn support for passkeys. It allows you to create Para wallets for users on any device while managing the security of the wallet yourself.

Creating Pregenerated Wallets

In Flutter, you can create pregenerated wallets of multiple types with a single method call:

import 'package:para/para.dart';

Future<List<Wallet>> createPregenWallets() async {
  final pregenWalletsFuture = para.createPregenWalletPerType(
    pregenId: {'EMAIL': 'user@example.com'}, // Map format for pregen ID
    types: [WalletType.evm], // Optionally specify wallet types
  );
  
  final pregenWallets = await pregenWalletsFuture.future;
  
  // Get the user share
  final userShareFuture = para.getUserShare();
  final userShare = await userShareFuture.future;
  
  // Store user share securely (see storage options below)
  
  return pregenWallets;
}

Mobile Storage Options

In Flutter applications, you have several options for securely storing the user share:

Flutter Secure Storage
Encrypted Shared Preferences

import 'package:flutter_secure_storage/flutter_secure_storage.dart';

final storage = FlutterSecureStorage();

// Store the user share
Future<void> storeUserShare(String userShare) async {
  try {
    await storage.write(
      key: 'para_user_share',
      value: userShare,
    );
  } catch (e) {
    // Handle error
  }
}

// Retrieve the user share
Future<String?> retrieveUserShare() async {
  try {
    return await storage.read(key: 'para_user_share');
  } catch (e) {
    // Handle error
    return null;
  }
}

import 'package:encrypted_shared_preferences/encrypted_shared_preferences.dart';

final encryptedPrefs = EncryptedSharedPreferences();

// Store the user share
Future<void> storeUserShare(String userShare) async {
  try {
    await encryptedPrefs.setString('para_user_share', userShare);
  } catch (e) {
    // Handle error
  }
}

// Retrieve the user share
Future<String?> retrieveUserShare() async {
  try {
    return await encryptedPrefs.getString('para_user_share');
  } catch (e) {
    // Handle error
    return null;
  }
}

Whichever storage method you choose, ensure you implement proper security measures. The user share is critical for wallet access, and if lost, the wallet becomes permanently inaccessible.

Using Pregenerated Wallets in Flutter Apps

Once you have created a pregenerated wallet and stored the user share, you can use it for signing operations:

import 'dart:convert';
import 'package:para/para.dart';

Future<String> usePregenWallet(String walletId) async {
  // Retrieve the user share from your secure storage
  final userShare = await retrieveUserShare();
  
  if (userShare == null) {
    throw Exception("User share not found");
  }
  
  // Load the user share into the Para client
  await para.setUserShare(userShare);
  
  // Now you can perform signing operations
  final messageBase64 = base64Encode(utf8.encode("Hello, World!"));
  final signatureFuture = para.signMessage(
    walletId: walletId,
    messageBase64: messageBase64,
  );
  
  final signatureResult = await signatureFuture.future;
  // The signature is in the signedTransaction property
  return (signatureResult as SuccessfulSignatureResult).signedTransaction;
}

Mobile-Specific Use Cases

Device-Specific Wallets

Create wallets that are bound to a specific device by using device-specific identifiers combined with secure local storage. This approach is ideal for multi-device users who need different wallets for different devices.

import 'package:device_info_plus/device_info_plus.dart';
import 'package:para/para.dart';

Future<List<Wallet>> createDeviceWallet() async {
  final deviceInfo = DeviceInfoPlugin();
  String deviceId;
  
  if (Platform.isAndroid) {
    final androidInfo = await deviceInfo.androidInfo;
    deviceId = androidInfo.id;
  } else if (Platform.isIOS) {
    final iosInfo = await deviceInfo.iosInfo;
    deviceId = iosInfo.identifierForVendor ?? 'unknown';
  } else {
    deviceId = 'unknown';
  }
  
  final pregenWalletsFuture = para.createPregenWalletPerType(
    pregenId: {'CUSTOM_ID': 'device-$deviceId'},
  );
  
  final pregenWallets = await pregenWalletsFuture.future;
  
  // Store the user share in device-specific secure storage
  final userShare = await para.getUserShare().future;
  await storeUserShare(userShare);
  
  return pregenWallets;
}

Transparent Web3 Integration

Seamlessly introduce blockchain functionality to your existing app users without requiring them to understand wallets or crypto.

import 'package:para/para.dart';

Future<List<Wallet>> createWalletForExistingUser(String userId) async {
  final pregenIdentifier = "user-$userId";
  
  try {
    final pregenWalletsFuture = para.createPregenWalletPerType(
      pregenId: {'CUSTOM_ID': pregenIdentifier},
    );
    
    final pregenWallets = await pregenWalletsFuture.future;
    
    final userShare = await para.getUserShare().future;
    await storeUserShare(userShare);
    
    return pregenWallets;
  } catch (e) {
    // Handle errors
    throw e;
  }
}

Claiming Pregenerated Wallets

When a user is ready to take ownership of their pregenerated wallet, they can claim it once they’ve authenticated with Para:

import 'package:para/para.dart';

Future<String> claimWallet(Map<String, String> pregenId) async {
  // Ensure user is authenticated
  if (!(await para.isSessionActive().future)) {
    throw Exception("User must be authenticated to claim wallets");
  }
  
  // Retrieve and load the user share
  final userShare = await retrieveUserShare();
  if (userShare != null) {
    await para.setUserShare(userShare);
  }
  
  // Claim the wallet with the pregen ID
  final claimFuture = para.claimPregenWallets(
    pregenId: pregenId, // e.g., {'EMAIL': 'user@example.com'}
  );
  final recoverySecret = await claimFuture.future;
  
  // Optionally, clear the locally stored user share after claiming
  // since Para now manages it through the user's authentication
  await clearUserShare();
  
  return recoverySecret;
}

After claiming, Para will manage the user share through the user’s authentication methods. You can safely remove the user share from your local storage if you no longer need to access the wallet directly.

Best Practices for Mobile

Utilize Device Security: Leverage biometric authentication (TouchID/FaceID) to protect access to locally stored user shares.
Implement Device Sync: For users with multiple devices, consider implementing your own synchronization mechanism for user shares across devices.
Handle Offline States: Mobile applications often work offline. Design your pregenerated wallet system to function properly even when connectivity is limited.
Backup Strategies: Provide users with options to back up their wallet data, especially for device-specific wallets that might not be associated with their Para account.
Clear Security Boundaries: Clearly communicate to users when they’re using an app-managed wallet versus a personally-owned wallet.

Getting Started

Framework Setup

Authentication & Users

External Wallets

Web3 Library Guides

Reference & Support

Wallet Pregeneration

Mobile-Specific Benefits

Seamless Web2 to Web3 Transition

Local Secure Storage

Device-Specific Wallets

App Clips and Instant Experiences

Creating Pregenerated Wallets

Mobile Storage Options

Using Pregenerated Wallets in Flutter Apps

Mobile-Specific Use Cases

Claiming Pregenerated Wallets

Best Practices for Mobile

Social Login

Session Management

​Mobile-Specific Benefits

Seamless Web2 to Web3 Transition

Local Secure Storage

Device-Specific Wallets

App Clips and Instant Experiences

​Creating Pregenerated Wallets

​Mobile Storage Options

​Using Pregenerated Wallets in Flutter Apps

​Mobile-Specific Use Cases

​Claiming Pregenerated Wallets

​Best Practices for Mobile

​Related Resources

Social Login

Session Management

Mobile-Specific Benefits

Creating Pregenerated Wallets

Mobile Storage Options

Using Pregenerated Wallets in Flutter Apps

Mobile-Specific Use Cases

Claiming Pregenerated Wallets

Best Practices for Mobile

Related Resources