Storing API credentials in a flutter application

Question

I am using googleapis services in my flutter app which requires some credentials in JSON format. What is the best way to store this credentials in my App?

Can I keep a JSON file in my asset folder and read it in my main function?

Or should I hardcode the credentials in my main function? I'm new to flutter development.

My code looks like the following

import 'package:googleapis/storage/v1.dart';
import 'package:googleapis_auth/auth_io.dart';

final _credentials = new ServiceAccountCredentials.fromJson(r'''
{
  "private_key_id": ...,
  "private_key": ...,
  "client_email": ...,
  "client_id": ...,
  "type": "service_account"
}
''');

const _SCOPES = const [StorageApi.DevstorageReadOnlyScope];

void main() {
  clientViaServiceAccount(_credentials, _SCOPES).then((http_client) {
    var storage = new StorageApi(http_client);
    storage.buckets.list('dart-on-cloud').then((buckets) {
      print("Received ${buckets.items.length} bucket names:");
      for (var file in buckets.items) {
        print(file.name);
      }
    });
  });
}

Where I should keep the following credentials:

{
  "private_key_id": ...,
  "private_key": ...,
  "client_email": ...,
  "client_id": ...,
  "type": "service_account"
}

I don't think hardcoding like above is a good idea.

I think this should work:https://medium.com/@sokrato/storing-your-secret-keys-in-flutter-c0b9af1c0f69

Thanks.

Answer 1

For storing sensitive information like credentials you should use the Keychain unter iOS and the Keystore under Android.

There is a perfect library for that called flutter_secure_storage.

Here's how to use that:

// Create storage
final storage = new FlutterSecureStorage();

// Store password 
await storage.write(key: "password", value: "my-secret-password");

// Read value 
String myPassword = await storage.read(key: "password");

To use it add flutter_secure_storage: 3.2.1+1 to you pubspec.yaml and run flutter packages get in a terminal.

Here is the package and a more detailled example on how to use it: https://pub.dartlang.org/packages/flutter_secure_storage