Shared preferences are a simple key-value storage mechanism that can be used to store small amounts
of data. However, since shared preferences are stored in plain text, it is not suitable for storing
sensitive information. To address this issue, you can use AES encryption to encrypt the data before
saving it to shared preferences.

To use shared preferences with AES encryption support, you can add this package to your project as
dependency.

Open pub.dev

void main() async {
  await EncryptedSharedPreferences.initialize(keyLength: 16);
  var sharedPref = EncryptedSharedPreferences.getInstance();

  await sharedPref.setString('user_token', 'xxxxxxxxxxxx', notify: true); ////notify = true by default

  sharedPref.getString('user_token'); //xxxxxxxxxxxx

  await sharedPref.setInt('age', 99, notify: true); //notify = true by default

  sharedPref.getInt('age'); //99

  await sharedPref.setDouble('pi', 3.14, notify: true); //notify = true by default

  sharedPref.getDouble('pi'); //3.14

  await sharedPref.setBoolean('isPremium', true, notify: true); //notify = true by default

  sharedPref.getBoolean('isPremium'); //true

  await sharedPref.remove('user_token', notify: true); //notify = true by default

  await sharedPref.clear(notify: true); //notify = true by default

  await sharedPref.reload();

  sharedPref.observe(key: 'token').listen((event) {
    // event = key
    print(event);
  });

  sharedPref.observeSet(keys: {'key1', 'key2', 'keyN'}).listen((event) {
    // event = key
    print(event);
  });
}

[Shared builder] Here is example of how to use SharedBuilder widget

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: SharedBuilder(
          listenKeys: const {"key1", "key2"}, //Optional
          builder: (EncryptedSharedPreferences encryptedSharedPreferences) {
            return Text("value : ${encryptedSharedPreferences.getString("key1")}");
          },
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () async {
            EncryptedSharedPreferences.getInstance()
                .setString('key1', 'dataValue');
            Future.delayed(const Duration(seconds: 3), () {
              EncryptedSharedPreferences.getInstance()
                  .setString('key2', 'dataValue');
            });
          },
        ),
      ),
    );
  }
}