Copy paste NFC

will121162 · August 6, 2019

Hi guys, new to the world of NFC and wat to know if I can recreate my hotel room key in my phone. If so how? I'm hoping that NFC doesn't have a MAC address of sorts that I cannot change but rather one that I can reprogram to open my door.

All info about this is really helpful as I know very little about this stuff. Hope you all have great days!

Mira Yurizaki · August 6, 2019

The first thing you have to figure out is what frequency the wireless cards operate at. Chances are it's not the same as phones. Or if it is, something else isn't the same like data rates. Next is if you can figure out the communication protocol. That is if you send out the right combination of bits, you can get the card to act the way you want.

I'm sure there's documentation floating around on the web somewhere.

colonel_mortis · August 6, 2019

Some NFC tags can be cloned, and on Android you can use an app like NFC Tools for that. However, most tags that you come across in daily life, like keys, transit cards and ID badges, use a hardware encryption protocol which makes it impossible* to clone them without the encryption key.

*There are weaknesses in the encryption protocol used by some older cards, in particular those using the Mifare Classic chip, which in theory could allow them to be cloned. However, I think you need special hardware (or possibly a rooted phone and a lot of effort) to do that. You also obviously shouldn't try to crack encryption on something like a hotel key.