T=0 and T=1 and Get Response command relation? - javacard

Question

I have a Java Card with an applet installed on it that returns the following response when I send 00 40 00 00 to it:
Connect successful.
Send: 00 40 00 00
Recv: 61 32
Time used: 15.000 ms
Send: 00 C0 00 00 32
Recv: 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F 30 31 32 90 00
Time used: 15.000 ms
The tool that I use (PyAPDUTool), have an option labeled "Auto Get Response". When I check this option, I don't need to send Get Response command (00 c0 00 00 32) anymore:
Send: 00 40 00 00
Recv: 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F 30 31 32 90 00
Time used: 15.000 ms
Okay. Now I want to have the above behavior on another Java Card. So I wrote the following program:
package testPrjPack;
import javacard.framework.*;
public class TestPrj extends Applet
{
public static byte[] data = {(byte)0x01 ,(byte)0x02 ,(byte)0x03 ,(byte)0x04 ,(byte)0x05 ,(byte)0x06 ,(byte)0x07 ,(byte)0x08 ,(byte)0x09 ,(byte)0x0A ,(byte)0x0B ,(byte)0x0C ,(byte)0x0D ,(byte)0x0E ,(byte)0x0F ,(byte)0x10 ,(byte)0x11 ,(byte)0x12 ,(byte)0x13 ,(byte)0x14 ,(byte)0x15 ,(byte)0x16 ,(byte)0x17 ,(byte)0x18 ,(byte)0x19 ,(byte)0x1A ,(byte)0x1B ,(byte)0x1C ,(byte)0x1D ,(byte)0x1E ,(byte)0x1F ,(byte)0x20 ,(byte)0x21 ,(byte)0x22 ,(byte)0x23 ,(byte)0x24 ,(byte)0x25 ,(byte)0x26 ,(byte)0x27 ,(byte)0x28 ,(byte)0x29 ,(byte)0x2A ,(byte)0x2B ,(byte)0x2C ,(byte)0x2D ,(byte)0x2E ,(byte)0x2F ,(byte)0x30 ,(byte)0x31 ,(byte)0x32};
public static void install(byte[] bArray, short bOffset, byte bLength)
{
new TestPrj().register(bArray, (short) (bOffset + 1), bArray[bOffset]);
}
public void process(APDU apdu)
{
if (selectingApplet())
{
return;
}
byte[] buf = apdu.getBuffer();
switch (buf[ISO7816.OFFSET_INS])
{
case (byte)0x40:
ISOException.throwIt((short)0x6132);
break;
case (byte)0xC0:
Util.arrayCopyNonAtomic(data,(short)0, buf, (short)0, (short)0x32);
apdu.setOutgoingAndSend((short)0,(short)0x32);
break;
default:
ISOException.throwIt(ISO7816.SW_INS_NOT_SUPPORTED);
}
}
}
After installing the .cap file on the new Java Card, I have the following response for both Auto Get Response option checked and unchecked:
As you see above, the Auto Get Response doesn't work anymore and I need to send Get Response command manually.
I'm curious to know what is wrong with this tool or my program? Is the issue related to the communication protocol? (The first card working with T=0 and the second one working with T=1).

Answer 1

Nothing is wrong. T=1 just doesn't use GET RESPONSE at all, so there is no reason for Python to handle it automatically.
Important: note that Java Card also handles the GET RESPONSE automatically, so you should never have to implement it explicitly.