Unable to retrieve the ATR of second card when using Smart Card IO

Question

For some background, I have used the In_List_Passive_Target command specified in the PN532 user manual to retrieve the UID's of all the cards in the terminals field. I'm also using the pseudo command FF 00 00 00 04 for the ACR122U to send these commands to the PN532.

>>  FF 00 00 00 04 D4 4A 01 00           # In_List_Passive_Target (1)
<<  D5 4B 01 01 00 04 08 04 3E 58 A7 D1  # Response including UID (1)
>>  FF 00 00 00 04 D4 4A 01 00           # In_List_Passive_Target (2)
<<  D5 4B 01 01 00 04 08 04 9E 69 A7 D1  # Response including UID (2)
>>  FF 00 00 00 04 D4 4A 01 00           # In_List_Passive_Target (3)
<<  D5 4B 00                             # No more cards in field (3)

Now that I have done this, I want to select these one by one. I can do this by halting a card (In_Deselect) when I have finished with it and then selecting the next one by using In_List_Passive_Target command with it's UID.

However, every time I select a card, I want to know the ATR it returns. This is proving to be difficult with the Java Smart Card IO API, as the card object created by the terminal is always the same card (and consequently returns the same ATR), even if I disconnect the card and then create a new one. This is strange considering if I communicate with the card through the PN532 terminal command In_Data_Exchange, it is the correct different card (not the old one accessible through the Card object). I need the ATR to be able to detect which type of card it is (Mifare Classic, Desfire, Ultralight, etc.)

Here is the function I have created for collecting the cards:

public static void getCardsInField()
    {
        cardList = new ArrayList();
        Boolean loop = true;

        // Card already connected to the terminal
        byte[] firstCardUID = transmitADPUCommand(GET_ADDRESS);
        MifareClassic firstCard = new MifareClassic(cardChannel, firstCardUID);
        cardList.add(firstCard);

        System.out.println(firstCard);
        System.out.println(readable(card.getATR().getBytes()));

        while(loop)
        {
            byte[] inDeselectResponse = transmitADPUCommand(IN_DESELECT); // Deselect current card
            byte[] inListPassiveTargetsResponse = transmitADPUCommand(IN_LIST_PASSIVE_TARGETS); // Select a new card

            System.out.println(">>  " + readable(IN_LIST_PASSIVE_TARGETS));
            System.out.println("<<  " + readable(inListPassiveTargetsResponse));

            // Trying to create a new card object for new card
            try
            {
                card.disconnect(true);
                card = cardTerminal.connect("*");
                cardChannel = card.getBasicChannel();
            }
            catch (CardException e)
            {
                e.printStackTrace();
            }

            if (Arrays.equals(inListPassiveTargetsResponse, IN_LIST_PASSIVE_TARGET_RESPONSE_NO_TARGETS)) // no more targets
            {
                loop = false;
            }
            else
            {
                byte[] loopCardUID = extractUID(inListPassiveTargetsResponse);
                MifareClassic loopCard = new MifareClassic(cardChannel, loopCardUID);
                cardList.add(loopCard);

                System.out.println(loopCard);
                System.out.println(readable(card.getATR().getBytes())); // this should be different ATR but it is the old cards atr
            }
        }
    }

Unable to retrieve the ATR of second card when using Smart Card IO

Answers (1)

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