Ludovic Rousseau's blog: PCSC sample in Java using intarsys smartcard-io

Here is a new PCSC sample in Java language I promised in PC/SC sample in different languages.

We already saw in a previous article "PCSC sample in Java" that the standard JVM includes javax.smartcardio to access smart cards. We will now see another Java wrapper.

intarsys smartcard-io

The project intarsys smartcard-io is hosted at https://github.com/intarsys/smartcard-io.
The licence is 3-Clause BSD.

Installation

Installation is easy. Just get the provided is-smartcard-io.jar files from deploy/ directory and the 3 runtime dependencies from lib/ directory.

I have not tried to rebuild the library from source.

Source code

The API is easy to use since it is a direct mapping to the PC/SC WinScard API.

package com.company;

import de.intarsys.security.smartcard.pcsc.IPCSCCardReader;
import de.intarsys.security.smartcard.pcsc.IPCSCConnection;
import de.intarsys.security.smartcard.pcsc.IPCSCContext;
import de.intarsys.security.smartcard.pcsc.PCSCContextFactory;
import de.intarsys.security.smartcard.pcsc.nativec._IPCSC;

import java.util.List;

public class Blog {
    public static void main(String[] args) {
        try {
            /* Establish context */
            IPCSCContext context = PCSCContextFactory.get().establishContext();

            /* Display the list of readers */
            List<IPCSCCardReader> readers = context.listReaders();
            for (IPCSCCardReader reader : readers) {
                System.out.println("found " + reader + " named " + reader.getName());
            }

            /* Use the first reader */
            IPCSCCardReader reader = readers.get(0);

            /* Connect to the card */
            IPCSCConnection connection = context.connect(
                    reader.getName(), _IPCSC.SCARD_SHARE_SHARED,
                    _IPCSC.SCARD_PROTOCOL_Tx);

            /* Send Select Applet command */
            byte[] select = {0x00, (byte)0xA4, 0x04, 0x00, 10, (byte)0xA0, 0x00, 0x00, 0x00, 0x62, 0x03, 0x01, 0x0C, 0x06, 0x01};
            byte[] answer;
            answer = connection.transmit(select, 0, select.length, 256, false);
            System.out.println("answer: " + answer.length + " bytes");
            for (int i=0; i<answer.length; i++) {
                System.out.print(String.format("%02X ", answer[i]));
            }
            System.out.println();

            /* Send test command */
            byte[] command = {0x00, 0x00, 0x00, 0x00};
            answer = connection.transmit(command, 0, command.length, 256, false);
            System.out.println("answer: " + answer.length + " bytes");
            for (int i=0; i<answer.length; i++) {
                System.out.print(String.format("%02X ", answer[i]));
            }
            System.out.println();
            for (int i=0; i<answer.length - 2; i++) {
                System.out.print((char)answer[i]);
            }
            System.out.println();

            /* Disconnect */
            connection.disconnect(_IPCSC.SCARD_LEAVE_CARD);

            /* Release context */
            context.dispose();
        } catch(Exception e) {
            System.out.println("Ouch: " + e.toString());
        }
    }
}

Output

found pcscreader 0 named Gemalto PC Twin Reader
found pcscreader 1 named Cherry KC 1000 SC Z
answer: 2 bytes
90 00 
answer: 14 bytes
48 65 6C 6C 6F 20 77 6F 72 6C 64 21 90 00 
Hello world!

High level API

Intarsys smartcard-io also provides a higher level API compatible with javax.smartcardio.
As documented in the project README:

javax.smartcardio Provider

The library comes with an alternative javax.smartcardio provider. There are a couple of things to consider:

Intended differences

dedicated PCSC context for terminals, terminal and card

waitForChange(timeout) semantics improved(?), state change is reset even in case of timeout

reader insertion is handled, too

no finalizer for card!

javax.smartcardio bug/limitation

One big problem with the SUN/Oracle implementation of javax.smartcardio is that only one PC/SC context is created.
It works fine with a mono-threaded application. But it is very problematic with a multi-threaded application if you want to access different readers at the same time from different threads.

As documented in pcsc-lite SCardEstablishContext():

Each thread of an application shall use its own SCARDCONTEXT

This is because only one thread can use a SCARDCONTEXT at the same time. So 2 SCardTransmit() calls on 2 different cards from 2 threads but using the same SCARDCONTEXT will be serialized by pcsc-lite. This is NOT what you want if you intent to execute the 2 card commands at the same time.

The problem is not present on Windows because the Microsoft WinSCard implement is different.
I don't know how javax.smartcardio behaves on macOS. The WinSCard on macOS has been rewritten using the low level API CryptoTokenKit since macOS Yosemite 10.10 in 2014 (see "OS X Yosemite and smart cards status") and is no more using pcsc-lite.