JavaCard OS

Code: Select all

package com.sun.javacard.samples.wallet;
import javacard.framework.*;

public class Wallet extends Applet {

    /* constants declaration */
    
    // code of CLA byte in the command APDU header
    final static byte Wallet_CLA =(byte)0x80;
    
    // codes of INS byte in the command APDU header
    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;
    
    // maximum balance
    final static short MAX_BALANCE = 0x7FFF;
    // maximum transaction amount
    final static byte MAX_TRANSACTION_AMOUNT = 127;
    
    // maximum number of incorrect tries before the
    // PIN is blocked
    final static byte PIN_TRY_LIMIT =(byte)0x03;
    // maximum size PIN
    final static byte MAX_PIN_SIZE =(byte)0x08;
    
    // signal that the PIN verification failed
    final static short SW_VERIFICATION_FAILED =
    0x6300;
    // signal the the PIN validation is required
    // for a credit or a debit transaction
    final static short SW_PIN_VERIFICATION_REQUIRED =
                                            0x6301;
    // signal invalid transaction amount
    // amount > MAX_TRANSACTION_AMOUNT or amount < 0
    final static short SW_INVALID_TRANSACTION_AMOUNT = 0x6A83;
    
    // signal that the balance exceed the maximum
    final static short SW_EXCEED_MAXIMUM_BALANCE = 0x6A84;
    // signal the the balance becomes negative
    final static short SW_NEGATIVE_BALANCE = 0x6A85;
    
    /* instance variables declaration */
    OwnerPIN pin;
    short balance;
    
    private Wallet (byte[] bArray,short bOffset,byte bLength) {
      
        // It is good programming practice to allocate
        // all the memory that an applet needs during
        // its lifetime inside the constructor
        pin = new OwnerPIN(PIN_TRY_LIMIT,   MAX_PIN_SIZE);
        
        byte iLen = bArray[bOffset]; // aid length
        bOffset = (short) (bOffset+iLen+1);
        byte cLen = bArray[bOffset]; // info length
        bOffset = (short) (bOffset+cLen+1);
        byte aLen = bArray[bOffset]; // applet data length
        
        // The installation parameters contain the PIN
        // initialization value
        pin.update(bArray, (short)(bOffset+1), aLen);
        register();
    
    } // end of the constructor
    
    public static void install(byte[] bArray, short bOffset, byte bLength) {
        // create a Wallet applet instance
        new Wallet(bArray, bOffset, bLength);
    } // end of install method
    
    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
    
    public void deselect() {
        
        // reset the pin value
        pin.reset();
        
    }