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Get 6F00 when sending INS_START command

JavaCard Applet Development Related Questions and Answers.
Tinatco
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Joined: Wed Feb 24, 2016 3:04 am
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Get 6F00 when sending INS_START command

Post by Tinatco » Mon Jan 09, 2017 2:19 am

I finished an applet which does mutual challenge response. All commands can work but INS_START Command. Regarding INS_START Command, I got the 6F00 all the time.
Here is my code. hope somebody help me point out where I did wrong.

Code: Select all

package challengeresponse;

import javacard.framework.APDU;
import javacard.framework.Applet;
import javacard.framework.ISO7816;
import javacard.framework.ISOException;
import javacard.framework.JCSystem;
import javacard.framework.Util;
import javacard.security.AESKey;
import javacard.security.KeyBuilder;
import javacard.security.RandomData;
import javacardx.crypto.Cipher;


public class ChallengeResponse extends Applet {
     
     // Instruction- and class-bytes
     final static byte CLASS = (byte) 0x80;
     final static byte INS_START = (byte) 0x01;
     final static byte INS_CHAL_READER = (byte) 0x02;
     
     // bArray contains (length of AID, AID, length of App. priv., App. priv., installation parameters)
     final static byte INST_PARAM_OFFSET = (byte) 0x0F;
     final static byte[] PADDING = {0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F, 0x0F};
   
    private AESKey aeskey;
    private byte[] id;
    private byte[] challenge_card_stored;
    private RandomData challenge_card_sent;
    private Cipher cipher;
   
     private ChallengeResponse(byte bArray[], short bOffset, byte bLength) {
       
          // Extract AES key form installation parameters and build it
          aeskey = (AESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_AES, KeyBuilder.LENGTH_AES_128, false);
          aeskey.setKey(bArray,(short) INST_PARAM_OFFSET);
         
          // Extract ID from installation parameters
          id = new byte[5];
          Util.arrayCopy(bArray, (short) (INST_PARAM_OFFSET + 16), id, (short) 0, (short) 5);
         
          // Use transient arrays for security reasons
          challenge_card_stored = JCSystem.makeTransientByteArray((short)8, JCSystem.CLEAR_ON_DESELECT);
          challenge_card_sent = RandomData.getInstance(RandomData.ALG_SECURE_RANDOM);
          cipher = Cipher.getInstance(Cipher.ALG_AES_BLOCK_128_ECB_NOPAD,false);
         
          // Register in card manager
          register();
     }

     public static void install(byte bArray[], short bOffset, byte bLength)
               throws ISOException {
         
          // Install method has arguments (AES key, ID) in bArray
          new ChallengeResponse(bArray,bOffset,bLength);
     }

     public void process(APDU apdu) throws ISOException {
         
          byte[] apdu_buffer = apdu.getBuffer();

          // return if APDU is SELECT command
          if (selectingApplet())
               return;
         
        switch(apdu_buffer[ISO7816.OFFSET_INS]) {
               
             case INS_START:
                   
                    // When start command is received do:
                   
                    // Create challenge and write it into apdu buffer and challenge_card_stored array as reference
                    challenge_card_sent.generateData(apdu_buffer,(short)(ISO7816.OFFSET_CDATA), (short)8);
                    Util.arrayCopy(apdu_buffer,(short)(ISO7816.OFFSET_CDATA),challenge_card_stored,(short)0,(short)8);
                               
                    // Write padding
                 Util.arrayCopy(PADDING, (short)0, apdu_buffer, (short)(ISO7816.OFFSET_CDATA+8), (short)8);
                   
                    // Encrypt message
                 cipher.init(aeskey, Cipher.MODE_ENCRYPT);
                 cipher.doFinal(apdu_buffer, (short)ISO7816.OFFSET_CDATA, (short)16, apdu_buffer, (short)ISO7816.OFFSET_CDATA);
                             
                    // Send message AES{challenge_card_stored,PADDING}
                    apdu.setOutgoingAndSend(ISO7816.OFFSET_CDATA, (short)16);
                 
             case INS_CHAL_READER:
(...)

User avatar
BrooksIQ
Posts: 18
Joined: Mon Jun 15, 2015 11:12 pm
Points :182
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Re: Get 6F00 when sending INS_START command

Post by BrooksIQ » Mon Jan 09, 2017 5:28 am

Note that there is break; operators in a switch-case statement.

Code: Select all

switch(apdu_buffer[ISO7816.OFFSET_INS]) {
               
             case INS_START:
                   
                    // When start command is received do:
                   
                    // Create challenge and write it into apdu buffer and challenge_card_stored array as reference
                    challenge_card_sent.generateData(apdu_buffer,(short)(ISO7816.OFFSET_CDATA), (short)8);
                    Util.arrayCopy(apdu_buffer,(short)(ISO7816.OFFSET_CDATA),challenge_card_stored,(short)0,(short)8);
                               
                    // Write padding
                 Util.arrayCopy(PADDING, (short)0, apdu_buffer, (short)(ISO7816.OFFSET_CDATA+8), (short)8);
                   
                    // Encrypt message
                 cipher.init(aeskey, Cipher.MODE_ENCRYPT);
                 cipher.doFinal(apdu_buffer, (short)ISO7816.OFFSET_CDATA, (short)16, apdu_buffer, (short)ISO7816.OFFSET_CDATA);
                             
                    // Send message AES{challenge_card_stored,PADDING}
                    apdu.setOutgoingAndSend(ISO7816.OFFSET_CDATA, (short)16);
                  break;
             case INS_CHAL_READER:
Your mind will answer most questions if you learn to relax and wait for the answer---William S. Burroughs

Tinatco
Posts: 12
Joined: Wed Feb 24, 2016 3:04 am
Points :128
Contact:

Re: Get 6F00 when sending INS_START command

Post by Tinatco » Tue Jan 10, 2017 12:07 am

How careless of me! Thanks for your help.

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