In this Instructable I will describe different ways to block or kill RFID tags. RFID stands for Radio Frequency Identification. If you do not know about this technology yet, you should definitely start familiarizing yourself with it, because the number of different devices that utilize these types of tags is growing exponentially.
RFID chips are very similar to barcodes in the sense that a certain amount of data is contained within them, and then transmitted to a reading device which then processes and utilizes the information. The major difference is that barcodes have to be physically visible to the reading device, which is usually only able to scan them at a distance of a 12 inches or less. RFID tags, on the other hand, do not have to be visible to the reading device. They can be scanned through clothes, wallets, and even cars. The distance from which they can be read is also much greater than that of a barcode. At DEFCON an RFID tag was scanned at a distance of 69 feet, and that was back in 2005, the possible reading distance now is probably much greater than that.
There are a few different categories of RFID tags, but the most common ones, and the ones we will be dealing with in this instructable, are the "passive" type. Passive RFID chips contain no internal power supply. They contain an antenna which is able to have a current induced in it when within range of the RFID reader. The tag then uses that electricity to power the internal chip, which bounces its data back out through the antenna, where it will be picked up by the reader.
For more information on RFID tags check out the wikipedia entry.
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Step 1: Reasons for Blocking / Destroying RFID Chips
The main reason someone would want to block or destroy RFID chips would be to maintain privacy. In the last step I explained that RFID tags can be read from very long distances. The potential for abuse of this technology grows as more and more products and devices are being created with these tags built in.
Companies are getting consumers to blindly accept many RFID tagged products with the promise of convenience; however, most of the devices that contain RFID tags don't really need them. The tags may save a few seconds, but sacrifice an enormous amount of privacy and security. It is now possible for someone, with relatively simple equipment, to walk down a busy sidewalk and pickup the personal information of people carrying RFID tagged devices, without them even knowing.
Being able to block or destroy these chips allows people to decide what type of information they are willing to sacrifice for convenience.
Step 2: Where Can RFID Chips Be Found
As RFID chips become cheaper, the number of devices that include them grows.
Currently there are RFID tags in:
- US passports: The RFID tag contains all the information that is written in the passport, along with a digital picture
- Transportation payments: Things like New York's EZ Pass, Florida's Sun Pass, and California's Fast Trak are all RFID based toll payment systems.
- Access control: Many buildings and schools require RFID tagged cards to be used for entry.
- Credit cards: Chase, and a few other banks, now issue credit cards embedded with RFID chips, called "blink". They are able to convince people it is an added convenience, but in reality it is a huge security risk.
There are many other devices which contain RFID tags; however, the ones listed are the most common and offer the greatest security risk.
Step 3: How to Block a RFID Tag
Luckily RFID tag signals can easily be blocked. This means that you will have the option to use the tag whenever you want, and prevent others from being able to read it.
The signal sent out by a RFID tag is easily blocked by metal. This means that placing the RFID tag inside of a Faraday cage will prevent the information from being read.
There are already two Instructables on how to build RFID blocking containers:
RFID Secure Wallet
Make a RFID Shielding Pouch Out of Trash
Or if you would rather spend money on something you could build, head over to Think Geek for their RFID blocking wallet and RFID blocking Passport Holder.
Step 4: How to Kill Your RFID Chip
In this step I will describe a few ways to permanently disable or kill an RFID chip. Most products that you own that contain RFID tags belong to you, so you have the right to destroy them; however, tampering with a US passport is a federal offense. Luckily there are ways to kill an RFID tag without leaving any evidence, so as long as you are careful, it would be pretty hard to prove that you did anything illegal.
-The easiest way to kill an RFID, and be sure that it is dead, is to throw it in the microwave for 5 seconds. Doing this will literally melt the chip and antenna making it impossible for the chip to ever be read again. Unfortunately this method has a certain fire risk associated with it. Killing an RFID chip this way will also leave visible evidence that it has been tampered with, making it an unsuitable method for killing the RFID tag in passports. Doing this to a credit card will probably also screw with the magnetic strip on the back making it un-swipeable.
-The second, slightly more convert and less damaging, way to kill an RFID tag is by piercing the chip with a knife or other sharp object. This can only be done if you know exactly where the chip is located within the tag. This method also leaves visible evidence of intentional damage done to the chip, so it is unsuitable for passports.
-The third method is cutting the antenna very close to the chip. By doing this the chip will have no way of receiving electricity, or transmitting its signal back to the reader. This technique also leaves minimal signs of damage, so it would probably not be a good idea to use this on a passport.
-The last (and most covert) method for destroying a RFID tag is to hit it with a hammer. Just pick up any ordinary hammer and give the chip a few swift hard whacks. This will destroy the chip, and leave no evidence that the tag has been tampered with. This method is suitable for destroying the tags in passports, because there will be no proof that you intentionally destroyed the chip.