Not too much you can do. When we design security systems, we have folks just like you in mind. I admit, no security system is 100% secure, but you are up for a challenge. Basically, the RFID reader is going to tell you what type of ID reader your college issues. There's actually only a few types, and they do their thing at a few different frequencies. I assume since you are looking into an RFID reader, the ID readers your college uses are proximity ('contactless' being the technical term). There's mainly two accepted standards: the old dumb cards operate at 135 KHz, the newer smart cards work at 12 MHz. These freqs aren't correct I'm sure, but they're close. So your RFID reader is going to tell you which (of two) frequencies the readers use. If you present your ID to the reader at the same time you flip on the RFID reader, it's also going to tell you the data that's on the card the reader is reading. But that doesn't matter, cuz your card will gain you access to certain areas and not others. It's the areas you can't get into that you're concerned about. And in order to get into those areas you'd have to replicate the data on a card that DOES have access to that area. In other words, you'd have to use the reader to read the data on a card that has access without the owner of the card knowing about it. Then you'd have to build your own replicator to send the data to the reader wirelessly. It'd be easier to ask the owner of the card if you could borrow it so you could get into the restricted area. That's an overhead view. You have a lot of work to do before you can start causing any headaches/problems, or get where you're not supposed to go. Most of the time, your average ID holder isn't security minded. You can usually just follow somebody into an area after they badge in. And you didn't have to buy an RFID reader, or build a replicator.