java card open platform combines tomorrow's technology and platforms c:\presentations -...

$: Java Card Open Platform Combines tomorrow's technology and platforms C:\Presentations - JavaCard_OpenPlatform.ppt - bsc - 26.02.02 - page 1 Programming$
Java Card Open PlatformCombines tomorrow's technology and platforms

C:\Presentations - JavaCard_OpenPlatform.ppt - bsc - 26.02.02 - page 1

Programming a Java Card

• The Applet Model– Installation

• Create an applet instance• Register the applet with the JCRE

– Selection• Select the applet, do some initialization

– Processing• Process commands send from the host

– Deselection• Clean up and state saving

– get SIO• Deliver the reverence of the own instance

AppletInstall

Select

Process

Deselect

getShareableInterfaceObject



Programming a Java Card (2)

• Installation– Create an Applet instance

– Call the Constructor

– Create Applet objects

– Register the Applet with the JCRE

– Do Error Handling

package com.gieseckedevrient.applets.myfirst;

import javacard.framework.*;

public class MyFirst extends Applet{ // ---------------------------------------------- // Constructor // ---------------------------------------------- private MyFirst () {

register (); } // -- END - static elements ---------------------

// ---------------------------------------------- // Install method // ----------------------------------------------------------------- public static void install(byte[] buffer, short offset, byte length) { new MyFirst(); } // -- END - Public static void install( ... ) ----------------------



Programming a Java Card (3)• Selection / Deselection

– When an ISO 7816-4 select command is received

– JCRE checks if the AID corresponds to an registered applet

– If so, the active applet is first deselected and the applet with the correct AID is selected

– Otherwise the command is transfered to the selected applet for processing

• Command Processing– Get the APDU buffer

– Decode the command header

– Receive command data if needed

– Perform command

– Send response– Throw ISOException if status is not 90 00



Programming a Java Card (8) - Processing (1)

public void process(APDU o_apdu) throws ISOException

{

if( selectingApplet() )

{

m_sz_Verified = false;

return;

}

byte[] ba_buffer = o_apdu.getBuffer();

//Examination of the buffer.

switch( ba_buffer[ ISO7816.OFFSET_INS ] )

{

//PIN Verification as defined in ISO 7816-4.

case VERIFY: // ----------------------------

s_databytes = receive( o_apdu );

s_dataoffset = Util.getShort( ba_buffer, ISO7816.OFFSET_P1 );

b_result = Util.arrayCompare( ba_buffer, (short) (ISO7816.OFFSET_CDATA & 0x00FF), m_sba_aPin, (short)0,

s_databytes );



Programming a Java Card (8) - Processing (2) if( b_result == (byte)0x00 )

{

m_sz_Verified = true;

}

else

ISOException.throwIt( ISO7816.SW_SECURITY_STATUS_NOT_SATISFIED );

break;

case READ: // -----------------------------------------------------

if( !m_sz_Verified )

ISOException.throwIt(ISO7816.SW_SECURITY_STATUS_NOT_SATISFIED);

o_apdu.setOutgoing();

o_apdu.setOutgoingLength( (short) 80 );

o_apdu.sendBytesLong( m_sba_userdata, (short)0, (short)80 );

break;

default : // ------------------------------------------------------

ISOException.throwIt( ISO7816.SW_INS_NOT_SUPPORTED );

}

} // -- END - public void process( ... ) throws ISOException -----------------




• The ISO-7816 APDU communication model

Command APDU

Response APDU

Host Java Card




• Command APDU

– CLA - indicates the type of command (ISO, prop.)

– INS - specifies the instruction to be performed

– P1 and P2 - instruction parameters

– Lc - number of bytes in the data field

– Data - command optional data

– Le - number of bytes expected in the response

Header (mandatory)

CLA INS P1 P2

Body (optional)

Lc DATA Le




• Response APDU

– Data - command optional response

– SW1 and SW2 - status word

Trailer (mandatory)Body (optional)

SW1DATA SW2




• Naming conventions in Java Card

• All named resources use ISO 7816-5 AIDs

• Named resources are– Packages (for loading, linking and deletion)– Applet Classes (for installation of applets)– Applet Instances (the real card applications)

0 to 11 bytes

PIXproprietary identifier extension

RIDregister identifier

5 bytes

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