Having problem with des encryption in jcwde

Question

I have problem with encrypting data using des encryption.... when i debug, it is stopping at the dofinal() method....help needed.
public class wallet extends Applet {
     public short balance= (short) 22;
     final static byte Wallet_CLA = ( byte ) 0xB0;
     public short isVerified;
     // public short tryCounter;//number of tries for pin
     public byte[] pin=new byte[]{ 0x10, 0x10};
     public byte[] key_array=new byte[]{(byte)0x09,(byte)0x0e,(byte)0x0d,(byte)0x0c,(byte)0x0b,(byte)0x0a,(byte)0x09,(byte)0x08};
     public OwnerPIN m_pin;
     // public Cipher m_cipher;
     public DESKey m_desKey;
     public Cipher m_cipher;
     final static byte ENCRYPT= (byte) 0x10;
     final static byte VERIFY = ( byte ) 0x20;
     final static byte CREDIT = ( byte ) 0x30;
     final static byte DEBIT = ( byte ) 0x40;
     final static byte GET_BALANCE = ( byte ) 0x50;
     final static short SW_INVALID_DEBIT_AMOUNT = 0x6A83;
     final static short SW_INVALID_CREDIT_AMOUNT = 0x6A84;
     final static short SW_VERIFICATION_FAILED = 0x6A85;
     final static short SW_PIN_BLOCKED = 0x6A86;
     final static short SW_CIPHER_DATA_LENGTH_BAD= 0x6A87;
     private wallet(byte bArray[], short bOffset, byte bLength) {
          isVerified=0;
          //tryCounter=3;
          m_pin = new OwnerPIN((byte) 3, (byte) 4);
          m_pin.update(pin, (short) 0, (byte) pin.length);
          m_desKey=(DESKey) KeyBuilder.buildKey(KeyBuilder.TYPE_DES, KeyBuilder.LENGTH_DES, false);
          m_desKey.setKey(key_array, (short)0);
          m_cipher =Cipher.getInstance(Cipher.ALG_DES_CBC_ISO9797_M2, false);
          m_cipher.init(m_desKey,Cipher.MODE_ENCRYPT);
          //register(bArray,(short)(bOffset+1),bArray[bOffset]);
     public static void install(byte bArray[], short bOffset, byte bLength)
               throws ISOException {
          new wallet(bArray, bOffset, bLength).register();
     public void process(APDU apdu) throws ISOException {
          // TODO Auto-generated method stub
          byte[] buff = apdu.getBuffer();
          if(selectingApplet())
               return;
          //byte[] buff = apdu.getBuffer();
if(buff[ISO7816.OFFSET_CLA] == Wallet_CLA)
     switch (buff[ISO7816.OFFSET_INS])
     case ENCRYPT:
          encrypt(apdu);
          return;
     case VERIFY:
          verify(apdu);
          return;
     case CREDIT:
          credit(apdu);
          return;
     case DEBIT:
          debit(apdu);
          return;
     case GET_BALANCE:
          getBalance(apdu);
          return;
     default:
          ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
return;     
     private void getBalance(APDU apdu) {
          // TODO Auto-generated method stub
          if(!(m_pin.getTriesRemaining()>0))
               ISOException.throwIt(SW_PIN_BLOCKED);
          if(!(m_pin.isValidated()))
               ISOException.throwIt(SW_VERIFICATION_FAILED);
          byte[] buffer = apdu.getBuffer();
          //buffer[0]=(byte) balance;
          apdu.setOutgoing();//indicates apdu has outgoing data
          apdu.setOutgoingLength ( ( short ) 2 ) ; //outgoing data length(le)
          //storing balance in buffer array
          buffer [ 0 ] = ( byte ) ( balance >> 8 ) ;
          buffer [ 1 ] = ( byte ) ( balance & 0xFF ) ;
          apdu.sendBytes ( ( short ) 0, ( short ) 2 ) ;
          //apdu.setOutgoingLength(len)
          return;
     private void debit(APDU apdu) {
          // TODO Auto-generated method stub
          if(!(m_pin.getTriesRemaining()>0))
               ISOException.throwIt(SW_PIN_BLOCKED);
          if(!(m_pin.isValidated()))
               ISOException.throwIt(SW_VERIFICATION_FAILED);
          byte[] buffer = apdu.getBuffer();
          byte numBytes=(byte) apdu.getIncomingLength();//number of bytes received
          if(numBytes!=1)
               ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
          byte byteRead= (byte)apdu.setIncomingAndReceive();
          byte debitAmount=buffer[ISO7816.OFFSET_CDATA];
          if(balance > (short)debitAmount)
          balance=(short) (balance-(short)debitAmount);
          else
               ISOException.throwIt(SW_INVALID_DEBIT_AMOUNT);
     private void credit(APDU apdu) {
          // TODO Auto-generated method stub
          if(!(m_pin.getTriesRemaining()>0))
               ISOException.throwIt(SW_PIN_BLOCKED);
          if(!(m_pin.isValidated()))
               ISOException.throwIt(SW_VERIFICATION_FAILED);
          byte[] buffer = apdu.getBuffer();
          byte numBytes=(byte) apdu.getIncomingLength();
          if(numBytes!=1)
               ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
          //setting the apdu direction as incoming and getting number of bytes
          byte byteRead= (byte)apdu.setIncomingAndReceive();
          byte creditAmount=buffer[ISO7816.OFFSET_CDATA];
          if(creditAmount<0)
          ISOException.throwIt(SW_INVALID_CREDIT_AMOUNT);
          balance=(short) (balance+(short)creditAmount);
     private void verify(APDU apdu)
          byte[] buffer = apdu.getBuffer();
          byte numBytes=(byte) apdu.getIncomingLength();
          byte byteRead= (byte)apdu.setIncomingAndReceive();
          //byte pass=buffer[ISO7816.OFFSET_CDATA];
          if(m_pin.getTriesRemaining()>0)//check whether the try limit has been crossed
               //if(Util.arrayCompare(buffer, (short)ISO7816.OFFSET_CDATA, pin, (short)0, (short)2)==0)//comparing pins
               if(m_pin.check(buffer, (short)ISO7816.OFFSET_CDATA,byteRead))
               isVerified=1;//setting status as verified
               else//wrong password
               //tryCounter--;
               ISOException.throwIt(SW_VERIFICATION_FAILED);
          else
               ISOException.throwIt(SW_PIN_BLOCKED);
          // TODO Auto-generated method stub
     private void encrypt(APDU apdu)
          byte[] buffer=apdu.getBuffer();
          short bytelen=(short)(apdu.setIncomingAndReceive());
          //short byteRead=(short) (buffer[ISO7816.OFFSET_LC] & 0x00FF);
          byte[] outbuff=new byte[(short)16];
          if(((short)bytelen%8)!=0)ISOException.throwIt(SW_CIPHER_DATA_LENGTH_BAD);
          //m_cipher.update(buffer, ISO7816.OFFSET_CDATA, (short)bytelen, outbuff, (short)0);
          m_cipher.doFinal(buffer,(short) ISO7816.OFFSET_CDATA, (short)bytelen, buffer, (short)0); //"DEBUGGER STOPS AT THIS LINE"
          Util.arrayCopyNonAtomic(outbuff, (short)0, buffer, (short)ISO7816.OFFSET_CDATA, (short)bytelen);
          apdu.setOutgoing();
          apdu.setOutgoingLength((short)bytelen);
          apdu.sendBytesLong(outbuff,(short)ISO7816.OFFSET_CDATA,(short)bytelen);
          //apdu.setOutgoingAndSend(ISO7816.OFFSET_CDATA, (short)bytelen);
Edited by: 977213 on Dec 16, 2012 10:24 PM

Answer 1

Hi,
Check out Cipher. dofinal method,
the 4th parameter should be the destination which is outbuff.
it shoul be change to :
m_cipher.doFinal(buffer,(short) ISO7816.OFFSET_CDATA, (short)bytelen, outbuff, (short)0); when I run your code the result was all 00, that was because of this error,
maybe the debugger has the same problem,
check it and tell me the result
Regards,
Hana