Add this in your pubspec.yaml file.
dependencies: tezster_dart: ^2.1.1
Download the Sodium.js.
flutter-project
-lib/
-pubspec.yaml
...
-web/
-sodium.js // here
-index.js
and add it to your flutter web directory. Then in your web/index.html add
<head> ...<script src="sodium.js"></script></head>
Now in your Dart code, you can use:
import 'package:tezster_dart/tezster_dart.dart';