JAVA Card: Applet Code

From :Jan Vossaert`s Smart Card Tutorial

package be.msec.smartcard;

import com.sun.javacard.crypto.ad;

import javacard.framework.APDU;
import javacard.framework.Applet;
import javacard.framework.ISO7816;
import javacard.framework.ISOException;
import javacard.framework.OwnerPIN;

public class IdentityCard extends Applet {
private final static byte IDENTITY_CARD_CLA =(byte)0x80;

private static final byte VALIDATE_PIN_INS = 0x22;
private static final byte GET_SERIAL_INS = 0x26;

private static final byte GET_IDENTITY_NO = 0x25;

private final static byte PIN_TRY_LIMIT =(byte)0x03;
private final static byte PIN_SIZE =(byte)0x04;

private final static short SW_VERIFICATION_FAILED = 0x6300;
private final static short SW_PIN_VERIFICATION_REQUIRED = 0x6301;

private byte[] serial = new byte[]{(byte)0x4A, (byte)0x61, (byte)0x6e};
private OwnerPIN pin;

private IdentityCard() {
/*
* During instantiation of the applet, all objects are created.
* In this example, this is the 'pin' object.
*/
pin = new OwnerPIN(PIN_TRY_LIMIT,PIN_SIZE);
pin.update(new byte[]{0x01,0x02,0x03,0x04},(short) 0, PIN_SIZE);

/*
* This method registers the applet with the JCRE on the card.
*/
register();
}

/*
* This method is called by the JCRE when installing the applet on the card.
*/
public static void install(byte bArray[], short bOffset, byte bLength)
throws ISOException {
new IdentityCard();
}

/*
* If no tries are remaining, the applet refuses selection.
* The card can, therefore, no longer be used for identification.
*/
public boolean select() {
if (pin.getTriesRemaining()==0)
return false;
return true;
}

/*
* This method is called when the applet is selected and an APDU arrives.
*/
public void process(APDU apdu) throws ISOException {
//A reference to the buffer, where the APDU data is stored, is retrieved.
byte[] buffer = apdu.getBuffer();

//If the APDU selects the applet, no further processing is required.
if(this.selectingApplet())
return;

//Check whether the indicated class of instructions is compatible with this applet.
if (buffer[ISO7816.OFFSET_CLA] != IDENTITY_CARD_CLA)ISOException.throwIt(ISO7816.SW_CLA_NOT_SUPPORTED);
//A switch statement is used to select a method depending on the instruction
switch(buffer[ISO7816.OFFSET_INS]){
case VALIDATE_PIN_INS:
validatePIN(apdu);
break;
case GET_SERIAL_INS:
getSerial(apdu);
break;
//If no matching instructions are found it is indicated in the status word of the response.
//This can be done by using this method. As an argument a short is given that indicates
//the type of warning. There are several predefined warnings in the 'ISO7816' class.
default: ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
}
}

/*
* This method is used to authenticate the owner of the card using a PIN code.
*/
private void validatePIN(APDU apdu){
byte[] buffer = apdu.getBuffer();
//The input data needs to be of length 'PIN_SIZE'.
//Note that the byte values in the Lc and Le fields represent values between
//0 and 255. Therefore, if a short representation is required, the following
//code needs to be used: short Lc = (short) (buffer[ISO7816.OFFSET_LC] & 0x00FF);
if(buffer[ISO7816.OFFSET_LC]==PIN_SIZE){
//This method is used to copy the incoming data in the APDU buffer.
apdu.setIncomingAndReceive();
//Note that the incoming APDU data size may be bigger than the APDU buffer
//size and may, therefore, need to be read in portions by the applet.
//Most recent smart cards, however, have buffers that can contain the maximum
//data size. This can be found in the smart card specifications.
//If the buffer is not large enough, the following method can be used:
//
//byte[] buffer = apdu.getBuffer();
//short bytesLeft = (short) (buffer[ISO7816.OFFSET_LC] & 0x00FF);
//Util.arrayCopy(buffer, START, storage, START, (short)5);
//short readCount = apdu.setIncomingAndReceive();
//short i = ISO7816.OFFSET_CDATA;
//while ( bytesLeft > 0){
// Util.arrayCopy(buffer, ISO7816.OFFSET_CDATA, storage, i, readCount);
// bytesLeft -= readCount;
// i+=readCount;
// readCount = apdu.receiveBytes(ISO7816.OFFSET_CDATA);
//}
if (pin.check(buffer, ISO7816.OFFSET_CDATA,PIN_SIZE)==false)
ISOException.throwIt(SW_VERIFICATION_FAILED);
}else ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
}

/*
* This method checks whether the user is authenticated and sends
* the serial number.
*/
private void getSerial(APDU apdu){
//If the pin is not validated, a response APDU with the
//'SW_PIN_VERIFICATION_REQUIRED' status word is transmitted.
if(!pin.isValidated())ISOException.throwIt(SW_PIN_VERIFICATION_REQUIRED);
else{
//This sequence of three methods sends the data contained in
//'serial' with offset '0' and length 'serial.length'
//to the host application.
apdu.setOutgoing();
apdu.setOutgoingLength((short)serial.length);
apdu.sendBytesLong(serial,(short)0,(short)serial.length);

}
}
}

DOCS 

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https://www.msec.be/jan/java%20cards/ho_pres.pdf

https://www.msec.be/jan/