Setting Custom Key for MIFARE Card Read/Write Operations

Question

I'm currently working on a project that involves reading and writing data to MIFARE cards. I've successfully managed to read and write data using the KEY_DEFAULT, but now I want to enhance the security of my application by using a custom key for these operations.

Here's what I've achieved so far:

1. Successful read/write operations using KEY_DEFAULT.
2. Established communication with the MIFARE card and retrieved card information.

However, I'm unsure about the process of setting and using a custom key for secure read/write operations. I understand that using the default key poses security risks, and I'd like to implement my own key management system.

Here's a snippet of my current code for reference:

val isAuthenticated =
                isAuthenticated(
                    mif = mif,
                    sectorIndex = SECTOR_INDEX,
                    customKey = MifareClassic.KEY_DEFAULT
                )

private fun readDataFromBlock(mif: MifareClassic?, blockIndex: Int, sectorIndex: Int) {
        val block = mif?.readBlock(blockIndex)
        val readData = String(block!!, Charsets.US_ASCII).trimEnd('\u0000')
        Log.e(TAG, readData)
        if (blockIndex == BLOCK_INDEX) {
            val dataFromReadOperation = try {
                readData.toInt()
            } catch (_: Exception) {
                0
            }
        }
        Log.d(
            TAG,
            "Sector: $sectorIndex Block: $blockIndex $readData"
        )
    }

 private fun isAuthenticated(
    mif: MifareClassic,
    sectorIndex: Int? = SECTOR_INDEX,
    customKey: ByteArray
): Boolean {
    var isAuthenticated = false
    Log.e(TAG, "" + mif.sectorToBlock(SECTOR_INDEX) + " " + sectorIndex)

    if (mif.authenticateSectorWithKeyA(sectorIndex!!, customKey)) {
        isAuthenticated = true
        Log.d(TAG, "Authentication successful with custom key A")
    } else if (mif.authenticateSectorWithKeyB(sectorIndex, customKey)) {
        isAuthenticated = true
        Log.d(TAG, "Authentication successful with custom key B")
    } else {
        Log.d(TAG, "Authorization denied")
    }

    return isAuthenticated
}

so as per the mentioned code above everything can be read and write through the KEY_DEFAULT. I want my custom keys to play role in so that nobody else can read and write the data in it without the keys.