Restrict an NFC reader to only read cards with certain prefixes

Question

I'd like to know if I can limit what cards can be read with an NFC reader. Maybe with some kind of prefix on the cards, I could say e.g. "If the card doesn't start with 90H, reject it immediately."

To be clear, I want to restrict access in a way where even if the reader itself was plugged into another computer, it still couldn't be used except with cards that I've encoded myself. Could this be done via a certain configuration to the reader? I'd really like to know if it's possible before I dive into my project.

I'm using the ACR122U USB NFC reader with RFID cards. My goal is to use it with an online application to authenticate cards and grant access to certain services.

Answer 1

Typical smartcard readers are rather dumb devices that only take commands from a host system (e.g. PC) and use them to access (contactless) smartcards. Hence, you cannot reprogram the smartcard reader to deny access to certain cards. Instead, this is something you would need to do on the host side (and/or card side).

So you would typically write your application (that uses the ACR122U to access cards) in a way that it only talks to certain cards. Moreover, depending on the smartcard, you might also want to setup authentication keys that are only known to your application in order to prevent access to the card from other applications.