Make Read Only access for Mifare UltraLight using Android

Question

I can write my data on card successfully. I want that no one can write on my card, but that they can only read. Is this possible to achieve? Or is there any key where I can assign some password protection before writing data on my card?

To write data using:

public void writeTag(Tag tag) {
        MifareUltralight ultralight = MifareUltralight.get(tag);
        String[] mg= getParts(s, 4);

        try {
            ultralight.connect();
            int j=4;
            for (int i = 0; i < mg.length; i++) {

                ultralight.writePage(j, mg[i].getBytes(Charset.forName("US-ASCII")));
                j++;
            }
            Toast.makeText(getApplicationContext(), "Write Done!", Toast.LENGTH_LONG).show()
        } catch (IOException e) {
            Log.e(TAG, "IOException while closing MifareUltralight...", e);
        } finally {
            try {
                ultralight.close();
            } catch (IOException e) {
                Log.e(TAG, "IOException while closing MifareUltralight...", e);
            }
        }
    }

Any help would be appreciated!

Have you read: http://stackoverflow.com/questions/5669833/can-nfc-tags-be-protected-from-being-over-written — Morrison Chang, Feb 25 '15 at 06:04
@MorrisonChang yes I read it, but i couldn't find any practical solution. — Bhoomika Brahmbhatt, Feb 25 '15 at 06:30
I have problem when write data to MIFARE Ultralight NFC.You can show simple code for me when call on getParts(s, 4); method how you setdata string from editext please help thanks. — Htut, Dec 08 '15 at 11:55

score 3 · Accepted Answer · answered Feb 25 '15 at 07:54

3

The lock bits for MIFARE Ultralight are located on bytes 2-3 in page 2 (note that Ultralight C and Ultralight derivates like NTAG may have additional lock bits on other pages, see the datasheet for their location). Each of the lock bits controls the lock state of certain pages of the memory area. In order to activate locking, you have to set the lock bit to '1' by issuing a write command for the pages containing the lock bits. So for the simplest scenario of locking the whole tag, you could do something like this:

    // write all-ones to the lock bits on page 0x02
    byte[] result;
    result = ultralight.transceive(new byte[]{
            (byte)0xA2,  // Command: WRITE
            (byte)0x02,  // Address: page 0x02 (2)
            (byte)0x00, (byte)0x00, (byte)0xFF, (byte)0xFF  // Data: set bytes 2-3 to all '1'
    });

answered Feb 25 '15 at 07:54

Michael Roland

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I just added your code in my writeTag method, Now I am not able to write data on it,Thats good. But what if anyother user set lock bit to '0'? Is it possible to unlock tag? – Bhoomika Brahmbhatt Feb 25 '15 at 08:27
No, the lock bits are only programmable, i.e. you can only set them to `1` but you cannot change them back to `0`. – Michael Roland Feb 25 '15 at 08:57
Ohh yes!! I just read it this info on https://www.defcon.org/images/defcon-21/dc-21-presentations/bughardy-Eagle1753/DEFCON-21-bughardy-Eagle1753-OPT-circumventing-in-MIFARE-ULTRALIGHT-WP-Updated.pdf Thank you so much!! – Bhoomika Brahmbhatt Feb 25 '15 at 09:11
but some of application gives feature of set password on MiFare Ultralight card also you can remove password. – Gaurav Mandlik Aug 15 '22 at 12:48
Have u done this before? then pls share with us if u found more about this – Gaurav Mandlik Aug 15 '22 at 12:49
I successfully write data in MiFare Ultralight card as you questions. – Gaurav Mandlik Aug 15 '22 at 12:50

Make Read Only access for Mifare UltraLight using Android

1 Answers1