Java Card

Java Card is a technology introduced and maintained by Sun Microsystems, Inc.

Smartcards running Java Card contain an interpreter for bytecode generated from programs written in Java. This code can be loaded onto the card after it has been preverified, i.e. checked for consistency and compatibility. Since Java is a standardized programming language, this approach allows vendor independent development of applications.

In addition, modern JavaCards are equipped with a sophisticated operating enviroment including an Operating System like JCOP which lets the user dynamically add and remove applications. This makes it possible to run banking applications, access control for a company gate and an electronic ticket for the public transportation system all on one single plastic card. The biggest challenge of those systems is to assure at any time that under no circumstances an application gains knowledge of another concurrently installed program and its data.

private Wallet (byte[] bArray,short bOffset,byte
bLength){
public static void install(by

te[] bArray,
short bOffset, byte bLength){

public boolean select() {

public void deselect() {

byte buffer[] = apdu.get Buffer();

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;
default: ISOException.throwIt
(ISO7816.SW_INS_NOT_SUPPORTED);
}

} // end of process method.