How to change Keys A/B in Mifare Classic ?

[Manish]

I want to change A/B Keys for default classic sector in Mifare Classic NFC.

I am using very basic code writing/reading and worked very well.

int blockTorw = Consts.DEFAULT_SECTOR_CLASSIC;

        int sectorOfBlock = 0;

        try {



            //Call connect first is the Reader is not connected

            if (!mifareClassic.getReader().isConnected()) {

                mifareClassic.getReader().connect();

            }



            sectorOfBlock = mifareClassic.blockToSector(blockTorw);

            mifareClassic.authenticateSectorWithKeyA(sectorOfBlock, default_ff_key);



            if (is_write) {

                /** write data to block **/

                //int newerBalance = Integer.parseInt(olderBalance) + topupAmount;

                int newerBalance = topupAmount;

                byte[] balanceBytes = Utils.getChipBalanceBytes(newerBalance);

                mifareClassic.writeBlock(blockTorw, balanceBytes);

                ToastManager.showToast(getString(R.string.topup_successful));

                updateBalanceTextView(String.valueOf(newerBalance));

                is_write = false;

                //topupAmount = 0;

            }



        } catch (Exception e) {

            Log.e(TAG, "Classic tag error: " + e.getMessage());

        }

I am using

 implementation ('taplinx-android:nxpnfcandroidlib:1.5@aar'){

        transitive = true

        changing = true

    }

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[TapLinx Support]

This post was already replied.

The TapLinx team

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[Saimi Sinha]

Hey I also need answer how to change A/B Keys for default classic sector in Mifare Classic NFC. It would be great if anyone can help me. Thanks in advance

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[TapLinx Support]

Hi Saimi,

To change a key you simply write the data to the sector trailer. But be careful! I recommend to read the block, change the six key bytes and write the block back. You should re-authenticate to the sector after changing the key bytes.

The TapLinx team

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[Sion Jain]

Thanks sir, I also needed the answer

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[George Lust]

Thanks for the answer.

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