encrypted_box.md

Encrypted box

Sometimes it is necessary to store data securely on the disk. Hive supports AES-256 encryption out of the box (literally).

The only thing you need is a 256-bit (32 bytes) encryption key. Hive provides a helper function to generate a secure encryption key using the Fortuna random number generator.

Just pass the key when you open a box:

import 'dart:convert';
import 'package:hive/hive.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';

void main() async {
  const secureStorage = FlutterSecureStorage();
  // if key not exists return null
  final encryptionKeyString = await secureStorage.read(key: 'key');
  if (encryptionKeyString == null) {
    final key = Hive.generateSecureKey();
    await secureStorage.write(
      key: 'key',
      value: base64UrlEncode(key),
    );
  }
  final key = await secureStorage.read(key: 'key');
  final encryptionKeyUint8List = base64Url.decode(key!);
  print('Encryption key Uint8List: $encryptionKeyUint8List');
  final encryptedBox = await Hive.openBox('vaultBox', encryptionCipher: HiveAesCipher(encryptionKeyUint8List));
  encryptedBox.put('secret', 'Hive is cool');
  print(encryptedBox.get('secret'));
}

!> The example above stores the encryption key using the flutter_secure_storage package, but you can use any package/method you prefer for securely storing the encryption key when your application is closed.

Important:

• Only values are encrypted while keys are stored in plaintext.
• There is no check if the encryption key is correct. If it isn't, there may be unexpected behavior.