nfc_host_card_emulation

Description:

nfc host card emulation

nfc_host_card_emulation #
The Flutter plugin implementing Host Card Emulation (HCE) with the APDU communication interface. Supported only on Android now.
Features #
Implemented an interface for working with SELECT (by AID) APDU commands. The structure of APDU commands is as follows:



CLA
INS
P1
P2 (port)
AID Length
AID
Additional data




0x00
0xA4
0x04
0 - 255
5 - 16
ByteArray with defined length
ByteArray



The P2 parameter is adjustable and is used in the plugin as a port for registering the APDU response. The structure of APDU response is as follows:



DATA
STATUS




User-defined response or nothing
Two status bytes defined in ISO7816-4 standart



Android Setup #
Add NFC permissions to Android manifest file locating at android/app/src/main/AndroidManifest.xml:
<uses-permission android:name="android.permission.NFC" />
<uses-feature android:name="android.hardware.nfc" android:required="false" />
<uses-feature android:name="android.hardware.nfc.hce" android:required="false" />
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Add host APDU service to the < application > block in the same Android manifest file:
<service
android:name="io.flutter.plugins.nfc_host_card_emulation.AndroidHceService"
android:exported="true"
android:permission="android.permission.BIND_NFC_SERVICE">
<intent-filter>
<action android:name="android.nfc.cardemulation.action.HOST_APDU_SERVICE" />
</intent-filter>
<meta-data
android:name="android.nfc.cardemulation.host_apdu_service"
android:resource="@xml/apduservice" />
</service>
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The host APDU service refers to a meta-data file apduservice.xml . It must be created in the android/app/src/main/res/xml folder. If you don't have an xml folder, just create one. This file contains information about the available AIDs for the host APDU service. So add the following text to apduservice.xml.
<host-apdu-service xmlns:android="http://schemas.android.com/apk/res/android"
android:requireDeviceUnlock="false">
<aid-group android:category="other">
<aid-filter android:name="A000DADADADADA"/>
</aid-group>
</host-apdu-service>
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This aid-filter means that the application will only accept ( 0xA0, 0x00, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA ) AID. But you can change it to any other with length from 5 to 16 or add more aid-filters.
Flutter Setup #
Add to pubspec.yaml:
dependencies:
nfc_host_card_emulation: <latest version>
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And import it to your code:
import 'package:nfc_host_card_emulation/nfc_host_card_emulation.dart';
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Usage #
Check if your device supports NFC and if the NFC-module is enabled:
final nfcState = await NfcHce.checkDeviceNfcState();
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If nfcState is NfcState.enabled, then you can use other NfcHce functions. Otherwise, the functions will work, but will have no effect and you won't be able to use APDU.
So after you have checked that Nfc is enabled, initialize the HCE service with the following command:
await NfcHce.init(
    // AID that match at least one aid-filter in apduservice.xml.
    // In my case it is A000DADADADADA.
    aid: Uint8List.fromList([0xA0, 0x00, 0xDA, 0xDA, 0xDA, 0xDA, 0xDA]),

    // next parameter determines whether APDU responses from the ports
    // on which the connection occurred will be deleted.
    // If `true`, responses will be deleted, otherwise won't.
    permanentApduResponses: true,

    // next parameter determines whether APDU commands received on ports
    // to which there are no responses will be added to the stream.
    // If `true`, command won't be added, otherwise will.
    listenOnlyConfiguredPorts: false,
  );
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Subscribe to NfcHce stream changes:
NfcHce.stream.listen((command) {
// some action here
});
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Add or remove APDU responses to desired ports:
// this line adds [0,1,2,3,4,5] response to 0 port
await NfcHce.addApduResponse(0, [0,1,2,3,4,5]);

// this line remove response from 0 port
await NfcHce.removeApduResponse(port);
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Bring your device to the NFC module, which can send APDU commands.

License

For personal and professional use. You cannot resell or redistribute these repositories in their original state.

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