Line data    Source code

       1              : import 'package:encrypt/encrypt.dart';
       2              : import 'package:flutter_secure_storage/flutter_secure_storage.dart';
       3              : 
       4              : const _keyLength = 32;
       5              : const _ivLength = 16;
       6              : 
       7              : /// Ciper storage
       8              : class CipherStorage {
       9              :   /// Create a new cipher storage
      10            4 :   CipherStorage();
      11              : 
      12              :   static const String _keyKey = 'cipher_storage_key';
      13              :   static const String _ivKey = 'cipher_storage_iv';
      14              :   late FlutterSecureStorage _storage;
      15              :   late final Key _key;
      16              :   late final IV _iv;
      17              : 
      18              :   /// Init ciper storage
      19            4 :   Future<void> init() async {
      20           12 :     _storage = FlutterSecureStorage(aOptions: _getAndroidOptions());
      21              : 
      22            8 :     final rows = await _storage.readAll();
      23            4 :     final key = rows[_keyKey];
      24            4 :     final iv = rows[_ivKey];
      25              : 
      26              :     if (key != null && iv != null) {
      27            6 :       _key = keyFromBase64(key);
      28            6 :       _iv = ivFromBase64(iv);
      29              : 
      30              :       return;
      31              :     }
      32              : 
      33              :     if ((key == null && iv != null) || (key != null && iv == null)) {
      34            2 :       throw StateError(
      35              :         'key and iv reading error: one of them is null while another is not',
      36              :       );
      37              :     }
      38              : 
      39            8 :     _key = keyFromSecureRandom();
      40            8 :     _iv = ivFromSecureRandom();
      41              : 
      42           16 :     await _storage.write(key: _keyKey, value: _key.base64);
      43           16 :     await _storage.write(key: _ivKey, value: _iv.base64);
      44              :   }
      45              : 
      46              :   /// Get key
      47            8 :   Key get key => _key;
      48              : 
      49              :   /// Get initialization vector
      50            8 :   IV get iv => _iv;
      51              : 
      52            4 :   AndroidOptions _getAndroidOptions() => const AndroidOptions(
      53              :         encryptedSharedPreferences: true,
      54              :       );
      55              : 
      56              :   /// Generate key from base64
      57            6 :   static Key keyFromBase64(String key) => Key.fromBase64(key);
      58              : 
      59              :   /// Generate initialization vector from base64
      60            8 :   static IV ivFromBase64(String iv) => IV.fromBase64(iv);
      61              : 
      62              :   /// Generate a new key
      63            8 :   static Key keyFromSecureRandom() => Key.fromSecureRandom(_keyLength);
      64              : 
      65              :   /// Generate a new initialization vector
      66            8 :   static IV ivFromSecureRandom() => IV.fromSecureRandom(_ivLength);
      67              : }