[resolved]GET_BALANCE return 6E 00 or 6F 00
Posted: Mon Aug 31, 2020 5:28 pm
Hi, i have an applet, running on simulator or on real card, method getbalance return always 6E00
veryfy pin i ok
credit is ok
debit is ok
change is ok
but getbalance return 6E00
the code:
i use java card J2A040, JCD2.2.2
i don't undertand the problem.
Thanks for your help.
veryfy pin i ok
credit is ok
debit is ok
change is ok
but getbalance return 6E00
the code:
Code: Select all
package PackageWallet ;
import javacard.framework.APDU;
import javacard.framework.Applet;
import javacard.framework.ISO7816;
import javacard.framework.ISOException;
import javacard.framework.OwnerPIN;
public class AppletWallet extends Applet {
/* constants declaration */
// code of CLA byte in the command APDU header
final static byte Wallet_CLA =(byte)0xB0;
// 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;
final static byte CHANGE = (byte) 0x60;
// 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;
final static byte MIN_PIN_SIZE = (byte)0x04;
// 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;
// pin is locked
final static short SW_CARD_IS_LOCKED = 0x6304;
final static short SW_NEW_PIN_TOO_LONG = 0x6307;
final static short SW_NEW_PIN_TOO_SHORT = 0x6308;
// 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 AppletWallet (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
pin = new OwnerPIN(PIN_TRY_LIMIT, MAX_PIN_SIZE);
pin.update(bArray, (short)(bOffset + 1), aLen);
// Above command causes error.
register();
} // end of the constructor
public static void install(byte[] bArray, short bOffset, byte bLength) {
// create a Wallet applet instance
new AppletWallet(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();
}
public void process(APDU apdu) {
// APDU object carries a byte array (buffer) to
// transfer incoming and outgoing APDU header
// and data bytes between card and CAD
// At this point, only the first header bytes
// [CLA, INS, P1, P2, P3] are available in
// the APDU buffer.
// The interface javacard.framework.ISO7816
// declares constants to denote the offset of
// these bytes in the APDU buffer
byte[] buffer = apdu.getBuffer();
// check SELECT APDU command
if (apdu.isISOInterindustryCLA()) {
if (buffer[ISO7816.OFFSET_INS] == (byte)(0xA4)) {
return;
} else {
ISOException.throwIt (ISO7816.SW_CLA_NOT_SUPPORTED);
}
}
// verify the reset of commands have the
// correct CLA byte, which specifies the
// command structure
if (buffer[ISO7816.OFFSET_CLA] != Wallet_CLA)
ISOException.throwIt(ISO7816.SW_CLA_NOT_SUPPORTED);
switch (buffer[ISO7816.OFFSET_INS]) {
case GET_BALANCE:
getBalance(apdu);
return;
case DEBIT:
debit(apdu);
return;
case CREDIT:
credit(apdu);
return;
case VERIFY:
verify(apdu);
return;
case CHANGE:
change(apdu);
return;
default:
ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
}
} // end of process method
private void credit(APDU apdu) {
// access authentication
if ( ! pin.isValidated() )
ISOException.throwIt(SW_PIN_VERIFICATION_REQUIRED);
byte[] buffer = apdu.getBuffer();
// Lc byte denotes the number of bytes in the
// data field of the command APDU
byte numBytes = buffer[ISO7816.OFFSET_LC];
// indicate that this APDU has incoming data
// and receive data starting from the offset
// ISO7816.OFFSET_CDATA following the 5 header
// bytes.
byte byteRead =
(byte)(apdu.setIncomingAndReceive());
// it is an error if the number of data bytes
// read does not match the number in Lc byte
if ( ( numBytes != 1 ) || (byteRead != 1) )
ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
// get the credit amount
byte creditAmount = buffer[ISO7816.OFFSET_CDATA];
// check the credit amount
if ( ( creditAmount > MAX_TRANSACTION_AMOUNT)
|| ( creditAmount < 0 ) )
ISOException.throwIt(SW_INVALID_TRANSACTION_AMOUNT);
// check the new balance
if ( (short)( balance + creditAmount) > MAX_BALANCE )
ISOException.throwIt(SW_EXCEED_MAXIMUM_BALANCE);
// credit the amount
balance = (short)(balance + creditAmount);
} // end of deposit method
private void debit(APDU apdu) {
// access authentication
if ( ! pin.isValidated() )
ISOException.throwIt(SW_PIN_VERIFICATION_REQUIRED);
byte[] buffer = apdu.getBuffer();
byte numBytes =
(byte)(buffer[ISO7816.OFFSET_LC]);
byte byteRead =
(byte)(apdu.setIncomingAndReceive());
if ( ( numBytes != 1 ) || (byteRead != 1) )
ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
// get debit amount
byte debitAmount = buffer[ISO7816.OFFSET_CDATA];
// check debit amount
if ( ( debitAmount > MAX_TRANSACTION_AMOUNT)
|| ( debitAmount < 0 ) )
ISOException.throwIt(SW_INVALID_TRANSACTION_AMOUNT);
// check the new balance
if ( (short)( balance - debitAmount ) < (short)0 )
ISOException.throwIt(SW_NEGATIVE_BALANCE);
balance = (short) (balance - debitAmount);
} // end of debit method
private void getBalance(APDU apdu) {
byte[] buffer = apdu.getBuffer();
// inform system that the applet has finished
// processing the command and the system should
// now prepare to construct a response APDU
// which contains data field
short le = apdu.setOutgoing();
if ( le < 2 )
ISOException.throwIt(ISO7816.SW_WRONG_LENGTH);
//informs the CAD the actual number of bytes
//returned
apdu.setOutgoingLength((byte)2);
// move the balance data into the APDU buffer
// starting at the offset 0
buffer[0] = (byte)(balance >> 8);
buffer[1] = (byte)(balance & 0xFF);
// send the 2-byte balance at the offset
// 0 in the apdu buffer
apdu.sendBytes((short)0, (short)4);
} // end of getBalance method
private void verify(APDU apdu) {
byte[] buffer = apdu.getBuffer();
if(pin.getTriesRemaining() == (byte)0)
ISOException.throwIt(SW_CARD_IS_LOCKED);
// retrieve the PIN data for validation.
byte byteRead = (byte)(apdu.setIncomingAndReceive());
// check pin
// the PIN data is read into the APDU buffer
// 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 validate method
private void change(APDU apdu) {
byte[] buffer = apdu.getBuffer();
if(pin.getTriesRemaining() == (byte)0)
ISOException.throwIt(SW_CARD_IS_LOCKED);
if ( ! pin.isValidated() )
ISOException.throwIt(SW_PIN_VERIFICATION_REQUIRED);
// retrieve the PIN data for validation.
byte byteRead = (byte)(apdu.setIncomingAndReceive());
if(byteRead > MAX_PIN_SIZE)
ISOException.throwIt(SW_NEW_PIN_TOO_LONG);
if(byteRead < MIN_PIN_SIZE)
ISOException.throwIt(SW_NEW_PIN_TOO_SHORT);
pin.update(buffer, (short) ISO7816.OFFSET_CDATA, (byte)byteRead);
} // end of validate method
} // end of class Wallet
i don't undertand the problem.
Thanks for your help.
