Here is a new PC/SC sample in Dart language I
promised in
PC/SC sample in different languages.
Fabien Rousseau wrote a PC/SC wrapper for Dart (the language) and Flutter (the UI toolkit).
The library is at
https://pub.dev/packages/flutter_pcsc. It is available for GNU/Linux, macOS and Windows.
The source code is at
https://github.com/fabienrousseau/flutter_pcsc and uses the MIT license. The current version is 0.0.4.
Fabien also provides an sample code at https://github.com/fabienrousseau/flutter_pcsc/blob/main/flutter_pcsc/example/lib/main.dart. I reused this code for my example bellow.
Installation
I just cloned the flutter_pcsc git repository.
You also need to install the flutter SDK to build and run the application. But if you use Flutter I imagine your already have the SDK installed.
Source code
You can use flutter create test to create a sample application with the correct structure and configuration files.
Then edit the pubspec.yaml file to add in the dependencies: section something like:
dependencies:
flutter_pcsc:
path: /home/rousseau/Documents/github/flutter_pcsc/flutter_pcsc
Of course you adapt the path to the location of your flutter_pcsc directory.
The source code of the sample application lib/main.dart is:
import 'package:flutter/material.dart';
import 'dart:async';
import 'dart:convert';
import 'package:flutter_pcsc/flutter_pcsc.dart';
void main() {
MyApp? myApp;
runZonedGuarded(() async {
WidgetsFlutterBinding.ensureInitialized();
FlutterError.onError = (FlutterErrorDetails details) {
FlutterError.dumpErrorToConsole(details);
myApp?.addError(details.toString());
};
runApp(myApp = MyApp());
}, (Object error, StackTrace stack) {
myApp?.addError(error.toString());
});
}
class MyApp extends StatelessWidget {
final GlobalKey<_MyAppBodyState> _myAppKey = GlobalKey();
MyApp({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: const Text('PCSC example app'),
),
body: MyAppBody(key: _myAppKey)),
);
}
void addError(String msg) {
_myAppKey.currentState?.messages.add(Message.error(msg));
}
}
class MyAppBody extends StatefulWidget {
const MyAppBody({required Key key}) : super(key: key);
@override
_MyAppBodyState createState() {
return _MyAppBodyState();
}
}
enum MessageType { info, error }
class Message {
final String content;
final MessageType type;
Message(this.type, this.content);
static info(String content) {
return Message(MessageType.info, content);
}
static error(String content) {
return Message(MessageType.error, content);
}
}
class _MyAppBodyState extends State<MyAppBody> {
static const List<int> selectAppletCommand = [
0x00, 0xA4, 0x04, 0x00, 0x0A, 0xA0, 0x00, 0x00, 0x00, 0x62,
0x03, 0x01, 0x0C, 0x06, 0x01
];
static const List<int> appCommand = [
0x00, 0x00, 0x00, 0x00
];
final ScrollController _scrollController = ScrollController();
final List<Message> messages = [];
@override
void initState() {
super.initState();
helloWorld();
}
Future<void> helloWorld() async {
/* establish PCSC context */
int ctx = await Pcsc.establishContext(PcscSCope.user);
CardStruct? card;
try {
/* get the reader list */
List<String> readers = await Pcsc.listReaders(ctx);
if (readers.isEmpty) {
messages.add(Message.error('Could not detect any reader'));
} else {
/* use the first reader */
String reader = readers[0];
setState(() {
messages.add(Message.info('Using reader: $reader'));
});
/* connect to the card */
card = await Pcsc.cardConnect(
ctx, reader, PcscShare.shared, PcscProtocol.any);
/* send select applet APDU */
var response = await Pcsc.transmit(card, selectAppletCommand);
messages.add(Message.info('Card returned: ${hexDump(response)}'));
/* send applet test command */
response = await Pcsc.transmit(card, appCommand);
var sw = response.sublist(response.length - 2);
var bytes = response.sublist(0, response.length - 2);
var text = utf8.decode(bytes);
messages.add(Message.info('Card returned: ${hexDump(response)}'));
if (sw[0] != 0x90 || sw[1] != 0x00) {
setState(() {
messages
.add(Message.error('Card returned an error: ${hexDump(sw)}'));
});
} else {
setState(() {
messages.add(Message.info('text is: ${text}'));
});
}
}
} finally {
if (card != null) {
try {
/* disconnect from the card */
await Pcsc.cardDisconnect(card.hCard, PcscDisposition.resetCard);
} on Exception catch (e) {
messages.add(Message.error(e.toString()));
}
}
try {
/* release PCSC context */
await Pcsc.releaseContext(ctx);
} on Exception catch (e) {
messages.add(Message.error(e.toString()));
}
}
}
static String hexDump(List<int> csn) {
return csn
.map((i) => i.toRadixString(16).padLeft(2, '0').toUpperCase())
.join(' ');
}
_scrollToBottom() {
_scrollController.jumpTo(_scrollController.position.maxScrollExtent);
}
@override
Widget build(BuildContext context) {
TextStyle errorStyle = const TextStyle(color: Colors.red);
WidgetsBinding.instance?.addPostFrameCallback((_) => _scrollToBottom());
return Row(crossAxisAlignment: CrossAxisAlignment.start, children: [
Expanded(
child: Column(children: [
Expanded(
child: ListView(
controller: _scrollController,
children: messages
.map((e) => Text(e.content,
style: e.type == MessageType.error ? errorStyle : null))
.toList())),
Container(
margin: const EdgeInsets.all(10),
child: ElevatedButton(
onPressed: () async {
await tryAgain();
},
child: const Text("Try again")))
]))
]);
}
tryAgain() async {
messages.clear();
await helloWorld();
}
}
Output
$ flutter run
hanging current working directory to: /home/rousseau/Documents/flutter/blog
Launching lib/main.dart on Linux in debug mode...
Building Linux application...
Syncing files to device Linux... 55ms
Flutter run key commands.
r Hot reload. 🔥🔥🔥
R Hot restart.
h List all available interactive commands.
d Detach (terminate "flutter run" but leave application running).
c Clear the screen
q Quit (terminate the application on the device).
💪 Running with sound null safety 💪
An Observatory debugger and profiler on Linux is available at:
http://127.0.0.1:34019/ORqpNzBQLEQ=/
The Flutter DevTools debugger and profiler on Linux is available at:
http://127.0.0.1:9100?uri=http://127.0.0.1:34019/ORqpNzBQLEQ=/
Flutter is a framework to create graphical applications. So when you run the sample code you get a new window.
Remarks
The code is long because it is a complete Flutter application so you have to handle the graphical interface.
I asked Fabien for a Dart only interface but flutter_pcsc depends on some Flutter mechanisms to handle asynchronism. So it is not possible to write a PC/SC application for the console just using Dart. But if you use Dart I guess you also use flutter.
Despite of his (nice) name Fabien Rousseau is not part of my direct family. So I do not have a potential conflict of interest here 😜.
Conclusion
Thanks to Fabien for telling about his Dart/Flutter project.
If you work on a Free Software PC/SC wrapper that is not yet in my list please let me know.
