Sample Javacard 2.2.1 Electronic wallet, Loyalty Points & StudentID applet

Question

Hi All,
After nine months of researching and developing a java card applet and terminal side interface for my final year university project I was frustrated with the lack of sample code and tutorials available online.
My applet is aimed at students as an id card containing a student id, all the features of an electronic wallet, loyalty point system protected by a pin number. Pin is changeable.
The terminal interaction or host side application that communicates with this applet can be found in this forum under the heading "Sample Smartcardio (Host side) applet interaction application".
As I have no finished my project I would like to share it with anyone that would like to see it.
While I would love to write a tutorial I simply do not have the time however below is the applet I used in my project, I how for anyone that has read through java sun's tutorials this will be a help:
package account;
import javacard.framework.APDU;
import javacard.framework.APDUException;
import javacard.framework.ISO7816;
import javacard.framework.Applet;
import javacard.framework.ISOException;
import javacard.framework.OwnerPIN;
import javacard.framework.TransactionException;
import javacard.framework.Util;
* @Raymond_Garrett
* DT 354-4
*Applet ID 41 63 63 6F 75 6E 74 41 70 70 6C 65 74
public class AccountApplet extends Applet {
     // codes of CLA byte in the command APDUs
     final static byte ACCOUNT_CLA = (byte)0xA0;
     // codes of INS byte in the command APDUs
     final static byte VERIFY_INS = (byte) 0x20;
     final static byte CREDIT_INS = (byte) 0x30;
     final static byte DEBIT_INS = (byte) 0x40;
     final static byte GET_LOYALTYPOINTS_BALANCE_INS = (byte) 0x45;
     final static byte CREDIT_LOYALTYPOINTS_INS = (byte) 0x47;
     final static byte GET_BALANCE_INS = (byte) 0x50;
     final static byte UPDATE_PIN_INS = (byte) 0x60;
     final static byte ADMIN_RESET_INS = (byte) 0x70;
     final static byte PIN_TRIES_REMAINING_INS = (byte) 0x80;
     final static byte STUDENT_NUMBER_INS = (byte) 0x90;
     // maximum Account balance
     final static short MAX_BALANCE = 10000;
     // maximum transaction amount
     final static short MAX_TRANSACTION_AMOUNT = 5000;
     // maximum number of incorrect tries before the
     // PIN is blocked
     //Changed to 4, as a safe guard all. All tests, messages and checks will use 3
     final static byte PIN_TRY_LIMIT =(byte)0x04;
     // maximum size PIN
     final static byte MAX_PIN_SIZE =(byte)0x08;
     // Applet-specific status words:
     final static short SW_NO_ERROR = (short) 0x9000;
     final static short SW_VERIFICATION_FAILED = 0x6300;
     final static short SW_PIN_VERIFICATION_REQUIRED = 0x6301;
     final static short SW_INVALID_TRANSACTION_AMOUNT = 0x6E83;
     final static short SW_EXCEED_MAXIMUM_BALANCE = 0x6E84;
     final static short SW_NEGATIVE_BALANCE = 0x6E85;
     final static short SW_PIN_TO_LONG = 0x6E86;
     final static short SW_PIN_TO_SHORT = 0x6E87;
//     Student number (Ascii)d05106012 - (Hex)44 30 35 31 30 36 30 31 32
     private static byte[] STUDENT_NUMBER_ARRAY = {(byte)0x44, (byte)0x30, (byte)0x35, (byte)0x31, (byte)0x30, (byte)0x36, (byte)0x30, (byte)0x31, (byte)0x32};
     // instance variables declaration
     OwnerPIN pin;
     short balance = 1000; // Starting balance of decimal 1000 is 3E8 in hex
     short loyaltyPoints = 0; //Loyalty points
     // 1 Loyalty point awarded for every 100 cent spent.
      * install method
     public static void install(byte[] bArray, short bOffset, byte bLength) {
          // GP-compliant JavaCard applet registration
          new AccountApplet(bArray, (short) (bOffset + 1), bArray[bOffset]);
      * Constructor
      * @param bArray
      * @param bOffset
      * @param bLength
     private AccountApplet(byte[] bArray, short bOffset, byte bLength){
          pin = new OwnerPIN(PIN_TRY_LIMIT, MAX_PIN_SIZE);
          // bArray contains the default PIN initialization value (12345)
          bArray[0] = 01;
          bArray[1] = 02;
          bArray[2] = 03;
          bArray[3] = 04;
          bArray[4] = 05;
          bOffset = 0;
          bLength = 5;
          pin.update(bArray, bOffset, bLength);
          // register the applet instance with the JCRE
          register();
     } // end of the constructor
      * Boolean is selected
     public boolean select() {
          // the applet declines to be selected
          // if the pin is blocked
          if (pin.getTriesRemaining() == 0)
               return false;
          return true;
     } // end of select method
      * deselect
     public void deselect() {
          // reset the pin
          pin.reset();
      * Key method the gets the APDU reads the INS and calls the appropiate method
      * Process APDUs
      * @param apdu
     public void process(APDU apdu) {
          // APDU object carries a byte array (buffer) to
          // transfer incoming and outgoing APDU header
          // and data bytes between the card and the host
          // at this point, only the first five bytes
          // [CLA, INS, P1, P2, P3] are available in
          // the APDU buffer
          byte[] buffer = apdu.getBuffer();
          // return if the APDU is the applet SELECT command
          if (selectingApplet())
               return;
          // verify the CLA byte
          if (buffer[ISO7816.OFFSET_CLA] != ACCOUNT_CLA)
               ISOException.throwIt(ISO7816.SW_CLA_NOT_SUPPORTED);
          // check the INS byte to decide which service method to call
          switch (buffer[ISO7816.OFFSET_INS]) {
          case GET_BALANCE_INS:                    getBalance(apdu);                return;
          case DEBIT_INS:                              debit(apdu);                       return;
          case CREDIT_INS:                         credit(apdu);                     return;
          case VERIFY_INS:                         verify(apdu);                    return;
          case UPDATE_PIN_INS:                    updatePin(apdu);               return;
          case ADMIN_RESET_INS:                    adminRest();                    return;
          case PIN_TRIES_REMAINING_INS:           getPinTriesRemaining(apdu); return;
          case STUDENT_NUMBER_INS:                getStudentNumber(apdu);       return;
          case GET_LOYALTYPOINTS_BALANCE_INS:     getLoyaltyPoints(apdu);      return;
          case CREDIT_LOYALTYPOINTS_INS:       creditLoyaltyPoints(apdu);      return;
          default:                    ISOException.throwIt
          (ISO7816.SW_INS_NOT_SUPPORTED);
     } // end of process method
      * verify then
      * withdraw money from the Account balance
      * @param apdu
     private void debit(APDU apdu) {
          // verify authentication
          if (!pin.isValidated()){
               ISOException.throwIt(SW_PIN_VERIFICATION_REQUIRED);
          byte[] buffer = apdu.getBuffer();
          // get the number of bytes in the
          // data field of the command APDU
          byte numBytes = buffer[ISO7816.OFFSET_LC];
          //receive data
          //data is read into apdu buffer
          //at offset ISO7816.OFFSET_CDATA
          byte byteRead = (byte)(apdu.setIncomingAndReceive());
          short shortAmount = 0;
          if (numBytes == 2){
               shortAmount = (short) Util.getShort(buffer, ISO7816.OFFSET_CDATA);
          else if (numBytes == 1) {
               shortAmount = (short) buffer[ISO7816.OFFSET_CDATA];
          // check the debit amount
          if (( shortAmount > MAX_TRANSACTION_AMOUNT)     || ( shortAmount < 0 )) {
               ISOException.throwIt(SW_INVALID_TRANSACTION_AMOUNT);
          // check the new balance
          if ((short)( balance - shortAmount)  < 0) {
               ISOException.throwIt(SW_NEGATIVE_BALANCE);
          // debit the amount
          balance = (short)(balance - shortAmount);
          //Add loyalty points
          loyaltyPoints = (short) (loyaltyPoints + (short)(shortAmount/100));
          return;
     }          // end of debit method
     

Answer 1

Code continued>>>>>>>>
      * Verify then
      * add money (credit) to the Account balance
      * @param apdu
     private void credit(APDU apdu) {
          // verify authentication
          if (!pin.isValidated()){
               ISOException.throwIt(SW_PIN_VERIFICATION_REQUIRED);
          byte[] buffer = apdu.getBuffer();
          // get the number of bytes in the     
          // data field of the command APDU
          byte numBytes = buffer[ISO7816.OFFSET_LC];
          //receive data
          //data is read into apdu buffer
          //at offset ISO7816.OFFSET_CDATA
          byte byteRead = (byte)(apdu.setIncomingAndReceive());
          short shortAmount = 0;
          if (numBytes == 2){
               shortAmount = (short) Util.getShort(buffer, ISO7816.OFFSET_CDATA);
          else if (numBytes == 1) {
               shortAmount = (short) buffer[ISO7816.OFFSET_CDATA];
          // check the credit amount
          if (( shortAmount > MAX_TRANSACTION_AMOUNT)     || ( shortAmount < 0 )) {
               ISOException.throwIt(SW_INVALID_TRANSACTION_AMOUNT);
          // check the new balance
          if ((short)( balance + shortAmount)  > MAX_BALANCE) {
               ISOException.throwIt(SW_EXCEED_MAXIMUM_BALANCE);
          // credit the amount
          balance = (short)(balance + shortAmount);
          return;
     }                                                       // end of deposit method
      * Verify then
      * Update/change pin
      * byte[] bArray is the pin
      * short bOffset is the position in the array the pin starts in the bArray
      * byte bLength is the lenght of the pin
      * @param apdu
     private void updatePin(APDU apdu) {
          //     byte[] bArray, short bOffset, byte bLength){
          //           First check the original pin
          //          verify authentication
          if (! pin.isValidated())
               ISOException.throwIt(SW_PIN_VERIFICATION_REQUIRED);
          byte[] buffer = apdu.getBuffer();
          // get the number of bytes in the
          // data field of the command APDU -- OFFSET_LC = positon 4
          byte numBytes = buffer[ISO7816.OFFSET_LC];
          // recieve data
          // data are read into the apdu buffer
          // at the offset ISO7816.OFFSET_CDATA
          byte byteRead = (byte)(apdu.setIncomingAndReceive());
          // error if the number of data bytes
          // read does not match the number in the Lc byte
          if (byteRead != numBytes) {
               ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
          if ( numBytes > 8 )
               ISOException.throwIt(SW_PIN_TO_LONG);
          if ( numBytes < 4 )
               ISOException.throwIt(SW_PIN_TO_SHORT);
          short offset_cdata = 05;          
          pin.update(buffer, offset_cdata, numBytes);
          pin.resetAndUnblock();
      *  Admin method
      *  Rest the pin attempts and unblock
      *  @param apdu
     private void adminRest() {
          try {
               pin.resetAndUnblock();
          } catch (RuntimeException e) {
               // TODO Auto-generated catch block
          return;
      * Credit loyatly card pints in multiples of 100
      * @param apdu
     private void creditLoyaltyPoints(APDU apdu) {
          short creditAmount = (short) ((loyaltyPoints/ 100) * 100);
          balance = (short) (balance + creditAmount);
          loyaltyPoints = (short) (loyaltyPoints - creditAmount);
          return;
      * Get number of remaining pin tries
      * @param apdu
     private void getPinTriesRemaining(APDU apdu) {
          try {
               byte[] buffer = apdu.getBuffer();
               // inform the JCRE that the applet has data to return
               short le = apdu.setOutgoing();
               // set the actual number of the outgoing data bytes
               apdu.setOutgoingLength((byte)2);
               // write the PinTriesRemaining into the APDU buffer at the offset 0
               Util.setShort(buffer, (short)0, pin.getTriesRemaining());
               // send the 2-byte balance at the offset
               // 0 in the apdu buffer
               apdu.sendBytes((short)0, (short)2);
          } catch (APDUException e) {
               // TODO Auto-generated catch block
          } catch (TransactionException e) {
               // TODO Auto-generated catch block
          } catch (ArrayIndexOutOfBoundsException e) {
               // TODO Auto-generated catch block
          } catch (NullPointerException e) {
               // TODO Auto-generated catch block
     } // end of getPinTriesRemaining method
      * No verification needed
      * the method returns the Account’s balance
      * @param apdu
     private void getBalance(APDU apdu) {
          byte[] buffer = apdu.getBuffer();
          // inform the JCRE that the applet has data to return
          short le = apdu.setOutgoing();
          // set the actual number of the outgoing data bytes
          apdu.setOutgoingLength((byte)2);
          // write the balance into the APDU buffer at the offset 0
          Util.setShort(buffer, (short)0, (balance));
          // send the 2-byte balance at the offset
          // 0 in the apdu buffer
          apdu.sendBytes((short)0, (short)2);
      * No verification needed
      * the method returns the Account’s loyaltyPoints balance
      * @param apdu
     private void getLoyaltyPoints(APDU apdu){
          byte[] buffer = apdu.getBuffer();
          // inform the JCRE that the applet has data to return
          short le = apdu.setOutgoing();
          // set the actual number of the outgoing data bytes
          apdu.setOutgoingLength((byte)2);
          // write the loyaltyPoints balance into the APDU buffer at the offset 0
          Util.setShort(buffer, (short)0, (loyaltyPoints));
          // send the 2-byte loyaltyPoints balance at the offset
          // 0 in the apdu buffer
          apdu.sendBytes((short)0, (short)2);
      * No verification needed
      * the method returns the student number
      * @param apdu
     private void getStudentNumber(APDU apdu) {
          byte[] buffer = apdu.getBuffer();
          // inform the JCRE that the applet has data to return
          short le = apdu.setOutgoing();
          // set the actual number of the outgoing data bytes
          apdu.setOutgoingLength((byte)STUDENT_NUMBER_ARRAY.length);
          // write the balance into the APDU buffer at the offset 0
          apdu.sendBytesLong(STUDENT_NUMBER_ARRAY, (short)0, (short) STUDENT_NUMBER_ARRAY.length);
          //     Util.setShort(buffer, (short)0, STUDENT_NUMBER_ARRAY);
          // send the 2-byte balance at the offset
          // 0 in the apdu buffer
          try {
               apdu.sendBytes((short)0, (short)STUDENT_NUMBER_ARRAY.length);
          } catch (APDUException e) {
               // TODO Auto-generated catch block
     } // end of getBalance method
      * Verification method to verify the PIN
      * @param apdu
     private void verify(APDU apdu) {
          byte[] buffer = apdu.getBuffer();
          // receive the PIN data for validation.
          byte byteRead = (byte)(apdu.setIncomingAndReceive());
          // check pin
          // the PIN data is read into the APDU buffer
          // starting at the offset ISO7816.OFFSET_CDATA
          // the PIN data length = byteRead
          if (pin.check(buffer, ISO7816.OFFSET_CDATA,byteRead)
                    == false)
               ISOException.throwIt(SW_VERIFICATION_FAILED);
     } // end of verify method
} // end of class AccountEdited by: Raymond.garrett-Dublin on Jun 17, 2009 11:30 PM