Java Card APDU Error

Question

I am trying to send a simple APDU to a Java Card( I attached the simple code of the applet below).I already tested the applet in the Eclipse simulator but when I want to send an APDU to the applet it fails with the following error : send_APDU() returns 0x80206E00 (6E00: Wrong CLA byte.) .Applet is already installed into the card ( I used GpShell to do that ) .Here is the full output from the script I used to send the APDU.

D:\GPShell-1.4.4>GPShell.exe send_APDU.txt
establish_context
enable_trace
enable_timer
card_connect
command time: 15 ms
send_apdu -sc 0 -APDU b0000000010000
Command --> B0000000010000
Wrapped command --> B0000000010000
Response <-- 6E00
send_APDU() returns 0x80206E00 (6E00: Wrong CLA byte.)
command time: 860 ms
card_disconnect
command time: 31 ms
release_context
command time: 0 ms

Here is the full code of the applet.

public class Contor extends Applet {

private byte contor = 0;
private final static byte CLS=(byte)0xB0;
private final static byte INC=(byte)0x00;
private final static byte DEC=(byte)0x01;
private final static byte GET=(byte)0x02;
private final static byte INIT=(byte)0x03;

private Contor() {
}

public static void install(byte bArray[], short bOffset, byte bLength) throws ISOException {
    new Contor().register();
}

public void process(APDU apdu) throws ISOException {
    if(this.selectingApplet())return;
    byte[] buffer = apdu.getBuffer();
    if(buffer[ISO7816.OFFSET_CLA] != CLS)
        ISOException.throwIt(ISO7816.SW_CLA_NOT_SUPPORTED);
    switch(buffer[ISO7816.OFFSET_INS])
    {
        case INC:contor++;  break;
        case DEC:contor--;  break;
        case GET:
            buffer[0] = contor;
            apdu.setOutgoingAndSend((short)0,(short)1);
            break;
        case INIT:
            apdu.setIncomingAndReceive();
            contor = buffer[ISO7816.OFFSET_CDATA];
            break;
    }

}

Answer 1

In order to have a communication with your applet, you must select your applet first.

To do that you have two options. The first option is making your applet Default Selected in the applet installation phase and make it implicitly selected applet after each power up. The second option is sending SELECT APDU command concatenated with your applet AUD before sending other commands.

SELECT APDU Command = 00A40400 <AID Length> <AID>

Other wise, the entity that respond to your command, is not your applet and most probably it is the default Default-Selected applet, i.e. Card Manager.