Unless he thinks a audience member will have a similar RFID chip in their hand and ruin the trick, I don’t see why you need the private key in this case. Any reader can still detect the chip which I assume is what is needed for the trick.
Hell, it could even check the public key of the RFID chip, so you’re still safe unless an audience member clones your hand chip and embeds it in their hand.
Unless he thinks a audience member will have a similar RFID chip in their hand and ruin the trick, I don’t see why you need the private key in this case. Any reader can still detect the chip which I assume is what is needed for the trick.
Hell, it could even check the public key of the RFID chip, so you’re still safe unless an audience member clones your hand chip and embeds it in their hand.
Unless I’m missing something.