GPShell: How to use the -instParam correctly?

Question

Good day,
I want (actually have to for Bachelor's Thesis) to pass some arguments in the install command. (Later it should be the AES-Key and the ID of the card).
For testing purposes, I wrote the following short applet :
package challengeresponse;
import javacard.framework.Applet;
import javacard.framework.ISO7816;
import javacard.framework.ISOException;
import javacard.framework.Util;
import javacard.framework.APDU;
public class ChallengeResponse extends Applet {
     // Instruction- and class-bytes
     final static byte CLASS = (byte) 0x80;
     final static byte INS_START = (byte) 0x01;
        static byte[] testdata;
     private ChallengeResponse(byte bArray[], short bOffset, byte bLength) {
          testdata = new byte[2];
          Util.arrayCopy(bArray, (short)0, testdata, (short)bOffset, (short)bLength);
          register();
     public static void install(byte bArray[], short bOffset, byte bLength)
               throws ISOException {
          new ChallengeResponse(bArray,bOffset,bLength);
     public void process(APDU apdu) throws ISOException {
          byte[] apdu_buffer = apdu.getBuffer();
          apdu.setIncomingAndReceive();
          switch(apdu_buffer[ISO7816.OFFSET_INS]) {
          case INS_START:
               // When start-command is received do:
               Util.arrayCopy(testdata, (short)0, apdu_buffer, (short)ISO7816.OFFSET_CDATA, (short)2);
               apdu.setOutgoingAndSend(ISO7816.OFFSET_CDATA, (short)2);
          default:
               ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
}This should just send what I give the applet as install parameter, doesn't it?
And I install it using gpshell with the following file:
mode_211
enable_trace
enable_timer
establish_context
card_connect
select -AID a000000003000000
open_sc -security 1 -keyind 0 -keyver 0 -mac_key 404142434445464748494a4b4c4d4e4f -enc_key 404142434445464748494a4b4c4d4e4f // Open secure channel
delete -AID D0D1D2D3D4D50101
delete -AID D0D1D2D3D4D501
delete -AID 0202030405060708090303
delete -AID 02020304050607080900
install -file C:\Users\Mark\workspace\ChallengeResponse\bin\challengeresponse\javacard\challengeresponse.cap -nvDataLimit 2000 -instParam C9021234 -priv 2
card_disconnect
release_contextThe instParam should mean:
C9: instructions for applet
02: length of data (2 Bytes)
12 34: Data
However, I get the following response:
install_for_install_and_make_selectable() returns 0x80206A80 (6A80: Wrong data /
Incorrect values in command data.)What do I do wrong? Please help!

Answer 1

Hi,
The problem is with your following part of the code:
     private ChallengeResponse(byte bArray[], short bOffset, byte bLength)
          testdata = new byte[2];
          Util.arrayCopy(bArray, (short)0, testdata, (short)bOffset, (short)bLength);
          register();
     }Here your testdata size is 2 but you are storing more data than its size (bLength). If you use                    Util.arrayCopy(bArray, (short)0, testdata, (short)0, (short)2);your applet will work fine.