EMV JavaCard APDU Response in TLV Format

问题

I have a simple JavaCard HelloWorld script, i execute it in JCIDE with virtual reader then i send apdu commands from pyapdutool: 00a404000e aid then 80000000 and i receive javacard string, everything runs fine. My question is: how can i return a tlv format data instead of that response ? I was looking in the emv book 4.3 about this and also on google haven't found a single example to implement emv tlv tags in javacard script. Can someone put me on correct path to understand this ?

package helloworld;
import javacard.framework.*;

public class helloworld extends Applet
{
private static final byte[] javacard = {(byte)'J',(byte)'a',(byte)'v'(byte)'a',(byte)' ',(byte)'C',(byte)'a',(byte)'r',(byte)'d',(byte)'!',};
private static final byte JC_CLA = (byte)0x80;
private static final byte JC_INS = (byte)0x00;

public static void install(byte[] bArray, short bOffset, byte bLength)
{
   new helloworld().register(bArray, (short) (bOffset + 1), bArray[bOffset]);
}

public void process(APDU apdu)
{
   if (selectingApplet())
  {
     return;
  }

  byte[] buf = apdu.getBuffer();

  byte CLA = (byte) (buf[ISO7816.OFFSET_CLA] & 0xFF);
    byte INS = (byte) (buf[ISO7816.OFFSET_INS] & 0xFF);

    if (CLA != JC_CLA)
    {
        ISOException.throwIt(ISO7816.SW_CLA_NOT_SUPPORTED);
    }

  switch (buf[ISO7816.OFFSET_INS])
  {
  case (byte)0x00:
     OutPut(apdu);
     break;
  default:
     ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
  }
}

private void OutPut( APDU apdu)
    {
    byte[] buffer = apdu.getBuffer();
    short length = (short) javacard.length;
    Util.arrayCopyNonAtomic(javacard, (short)0, buffer, (short)0, (short)  length);
    apdu.setOutgoingAndSend((short)0, length);
     }
   }

In short: I want to be able to send response in this format, something like: 6F1A840E315041592E5359532E4444463031A5088801025F2D02656E then when i go to http://www.emvlab.org/tlvutils/ to be able to decode it.

回答1:

There is several TLV classes in Javacard, but they are optional and to my knowledge there is not any card issuer that implemented these classes. So you can either:

hardcode any TLV objects if they don't change at all
you can build the parts manually and concatenate them in your code for every new TLV object occurance or
you build your own TLV parser/encoder

Last option is pretty difficult to be error-free and performant in javacard, so if you are a beginner stick with the first options and once you are too annoyed you can try to build a tlv parser

来源：https://stackoverflow.com/questions/36375710/emv-javacard-apdu-response-in-tlv-format

标签

smartcard

javacard

apdu

emv

tlv