I am considering getting an RFID module because I found one just for 3$ here http://nskelectronics.com/rfid-_ttl.html. That is really an amazing price.
But I was considering the security issues. Besides RFID cloning I found one more security issue. The reader communicates using serial. So the RFID reader has to be placed near the door away from the Arduino. So one could just remove the RFID module and make a micocontroller tell the arduino that it read the tag of the choice of the attacker.
I also noticed the same problem with Finger print scanners. You could just make an arduino act like a finger print scanner and fool the system. Is there a work around for this.
Normally systems have wiring to detect when something is disconnected, so the removal of the device will trigger an alarm.
Also to physically get at the wiring you normally have to have access to the other side of the door, then you are in anyway.
What Mike said. I have a RFID scanner, and the scanner is inside the house (you can use the card through the wood of the doorway).
Plus, getting at the wiring doesn't help, you would have to fake up an actual valid ID. How would you know what that was? You may as well say you could open the door with a key. Problem is you don't know what shape to cut the key.
Ufoguy:
I also noticed the same problem with Finger print scanners. You could just make an arduino act like a finger print scanner and fool the system. Is there a work around for this.
I don't know about fingerprint scanners, but if they send a "good" or "bad" signal, yes that could be a problem. But if they have to send a code to the receiver, again you won't know what that code is.