Quickstart

Add an embedded Ethereum wallet with a signing-gated PIN to a Flutter app in under 10 minutes.

This guide walks you through the most common integration path: provision an on-device wallet, set a PIN, and produce your first signature. It uses all three packages together, but each one is optional — skip the steps that don’t apply to your use-case.

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Prerequisites

• Flutter >=3.3.0 / Dart >=3.11
• Android minSdk 24+ or iOS 13.0+

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1. Add the packages

   Add all three packages to pubspec.yaml:

   dependencies:
     bmoni_embedded_sdk: ^0.0.1
     bkey_uikit: ^0.0.1
     bmoni_embedded_wallets_cards: ^0.0.1
   

   Then fetch them:

   flutter pub get
   
2. Apply the BMONI theme

   Wrap your app root with BMoniTheme.darkTheme() (or lightTheme()) so every widget in the tree picks up the correct colours and typography automatically.

   import 'package:bkey_uikit/bkey_uikit.dart';
   import 'package:flutter/material.dart';
   
   void main() {
     BmoniEmbeddedSdk.initialize(pinLength: 6, requirePin: true);
     runApp(
       MaterialApp(
         theme: BMoniTheme.darkTheme(),
         home: const MyHomePage(),
       ),
     );
   }
   
3. Initialise the SDK

   Call BmoniEmbeddedSdk.initialize once — before runApp is the recommended place. The defaults are pinLength: 6 and requirePin: true.

   import 'package:bmoni_embedded_sdk/bmoni_embedded_sdk.dart';
   
   void main() {
     BmoniEmbeddedSdk.initialize(pinLength: 6, requirePin: true);
     runApp(const MyApp());
   }
   
4. Provision a wallet

   On first launch, call initWallet() to generate a secp256k1 keypair inside the device’s secure hardware. The returned EIP-55 address is automatically cached in flutter_secure_storage.

   final String address = await BmoniEmbeddedSdk.hasWallet()
       ? (await BmoniEmbeddedSdk.walletAddress())!
       : await BmoniEmbeddedSdk.initWallet();
   
   print('Wallet: $address');
   
5. Set a PIN

   The PIN gates future signing operations. It is stored only as a PBKDF2-HMAC-SHA256 digest — the raw value never touches disk.

   if (!await BmoniEmbeddedSdk.hasPin()) {
     await BmoniEmbeddedSdk.setPin('123456');
   }
   
6. Sign a message

   Use signMessage for EIP-191 personal-sign flows (SIWE, login challenges):

   final String sig = await BmoniEmbeddedSdk.signMessage(
     'Welcome to BMONI!',
     pin: '123456',
   );
   // sig is 0x-prefixed, 130-char hex: r(32) || s(32) || v(1)
   

   Or signTransactionHash for a pre-computed 32-byte digest (ERC-4337 userOpHash, EIP-712, raw tx hash):

   final String sig = await BmoniEmbeddedSdk.signTransactionHash(
     '0x1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8',
     pin: '123456',
   );
   
7. Handle errors

   Wrap SDK calls in a try/catch and branch on BmoniSignerErrorCode:

   try {
     await BmoniEmbeddedSdk.initWallet();
   } on BmoniSignerException catch (e) {
     switch (e.errorCode) {
       case BmoniSignerErrorCode.walletAlreadyExists:
         // Show a re-provision dialog.
         break;
       case BmoniSignerErrorCode.pinMismatch:
         // Ask the user to re-enter their PIN.
         break;
       default:
         debugPrint('SDK error: ${e.message}');
     }
   }
   

   See the full error reference for all codes.

8. Render a wallet card (optional)

   If you also have bmoni_embedded_wallets_cards, wire a notifier and drop in the card widget:

   import 'package:flutter_riverpod/flutter_riverpod.dart';
   import 'package:bmoni_embedded_wallets_cards/bmoni_embedded_wallets_cards.dart';
   
   // In your Riverpod provider setup:
   final walletListProvider =
       StateNotifierProvider<EmbeddedWalletListNotifier, EmbeddedWalletListState>(
     (ref) => EmbeddedWalletListNotifier(
       walletDataSource: ref.watch(walletDataSourceProvider),
       storage: ref.watch(walletStorageProvider),
     ),
   );
   
   // In your widget:
   EmbeddedWalletCard(
     wallet: wallet,
     isBalanceHidden: false,
     onToggleHideBalance: () { /* toggle in your state */ },
   );
   

   See the full wallets & cards guide for the complete wiring.

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Next steps

SDK configuration

Customise PIN length and the requirePin gate.

PIN management

Change, verify, and remove PINs.

Design tokens

Use BMONI colours and typography in your own widgets.

Wallet card widgets

Full API for EmbeddedWalletCard and the transactions section.