Despite what some authors would have you think, RFID is pretty far from being a “big brother” technology. The “identity” of each RFID tag is just a number. What you do with that information is up to you. There is no single universal RFID protocol, nor are there readers that can read every tag out there. There’s no secret database somewhere that holds all the RFID numbers and associates them with the things they’re attached to, or worse, the people who own those things. To make RFID meaningful, you have to build your own database associating the tags you distribute with the objects to which you attach them, and you have to make sure that you’re using readers that can read that particular brand of tag. The range of passive RFID systems is very short, and most of the time you have to be very close to a tag to read it. With most readers, you can only read one tag at a time; a cluster of tags together generally won’t be read. If you’re really concerned about the security of an RFID tag, you can always wrap it in a shield of conductive fabric or aluminum foil, which will make it difficult or impossible to read. There is a lot you can do with RFID within those limitations, and the more you understand how it works, the more you can use it to your advantage.
The projects shown here barely scratch the surface of what you can do with RFID. Even staying within the limits of passive RFID tags and inexpensive readers, there is more you can do. For example, most tags are not just readable, but also writeable; you can store small amounts of data on them. To do this, you need a reading device that’s capable of both reading from tags and writing to them, unlike the one shown here.
If you’re interested in other passive RFID readers, several of them are covered in Making Things Talk, second edition. A few of my favorites are listed below:
These are reader/writer modules for the 13.56 MHz ISO14443A Mifare standard tags. Mifare is a very popular tag standard, used by many transit systems around the world. SonMicro’s modules give you the ability to both read to and write from these tags.
These cover a wide range of physical forms and RFID protocols. The company makes some super-compact ID-12 and ID-20 readers for 125KHz tags, and recently added ID-20MF Mifare read/write modules as well. It also makes long-range passive RFID readers, which claim to be able to read up to 1.2 meters.
TI makes a wide range of both passive and active RFID readers, particularly in the 134.2kHz range that’s popular with pet tagging systems.
This reader is particularly interesting to try. Compatible with the Mifare tags, it can also communicate with near field communications devices that are coming on the market now. NFC is an extension of RFID, a communications protocol for devices that are very close to each other or touching. Look for many interesting NFC applications in the near future, as cards, tags, and other small objects begin to acquire interesting behaviors.