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A Technical RFID Primer
gManZboy writes "Roy Want, principal engineer at Intel Research, has a pretty meaty technical overview of RFID up at Queue. If you ever wondered how these little things actually work it's worth a read. For instance, I was intrigued to find out how the tags (which are generally battery-free) can absorb enough energy from RFID readers to then power up and transmit their own signal back to the reader."
Are they biodegradable?
vicious, untreated political sewage...niche entertainment for the spiritually unattractive...worshipless pap
I am looking into wiring the office with RFID readers and equipping the engineers with RFID tags that will allow them to beep in and out of the office. Without a valid tag, the doors would not unlock. I've seen this done with smart cards previously, but would like to do it with a more lightweight technology.
The most obvious security risk is that someone steals a tag and enters the premises unnoticed. But there are others that I worry about. Stuff like the ease of replicating an RFID tag or even a hacker passively reading a tag in public then recreating it and gaining access.
I understand the problems many people have with RFID, especially stuff like tracking of purchased items and the like, but I'm more interested in using it for security clearances. Unfortunately, the web is not full of information about this (whereas it is full of information about how RFID is a privacy threat). More information about the practical uses of RFID would be greatly desired.
Tinfoil ON!. Everyone knows they get there energy from stealing your soul a little at a time, sucking the very life essence from your body. Then when they have all your energy they march you into a retirement home which is just a block away from the new universal nutrient - soylent green! Tinfoil OFF!
Mind the gap...
printf("Goodbye cruel world!\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b");
From the article,
In fact, various forms of crude RFID have been used since World War II.
What I think he is refering to but failing to mention by name is the aircraft friend or foe reflector. A tuned cavity was placed on an air craft that would reflect a radar signal many times inside the cavity then emit it back. This delay produced a second reflection to a radar scan. If the shadow image of the plane was on the display, it was a Friend. If it was absent, it was a Foe. It was known as a FOF transponder. (Friend Or Foe)
It has been upgraded to return the plane identification.
The truth shall set you free!
And I thought they worked by Magic !!
Redundancy check completed !
Ooo! A store can track my purchases up to 10 feet beyond their door! Wow! I better call Secret Squirrel for some countermeasure tips!
And of course it had the old idea of an ubergovernment plan of having sensors in every toilet seat and lamp post so that they can track how often I change my underwear.
Honestly, people... The X-Files is over, and our government can't keep Chechnyan rebels from crossing in from Mexico. They can't even prevent the vast waste and fraud perpetrated by the uneducated masses against the various money giveaway programs.
So they're suddenly get their act together and implement a shiny, sparkly supersensor array in order to track which communist manifesto you bought this week down at the Chairman Meow Bookshop/Animal Companion Emporium?
Regardless of how much a retailer's internal facility might disrupt their ability to monitor me, I still plan on getting one of RSA's RFID jammers when they're out.
Huh. Interesting. Do any descendants of P. T. Barnum work at RSA? I think you'd be better served by an orgone energy accumulator.
--- Ban humanity.
RFID has so many uses, but we all know it's ultimate purpose is to be used as the Mark of the Beast as soon as the Antichrist appears.
You first heard it from me.
Real programmers can write assembly code in any language. -- Larry Wall
For instance, I was intrigued to find out how the tags (which are generally battery-free) can absorb enough energy from RFID readers to then power up and transmit their own signal back to the reader."
I don't mean to be argumentative, but are you serious? This was the first time you had heard about this? I thought this was the fundamental feature for RFID--the idea that the tag doesn't require any kind of battery or other external power supply.
It scares me that on a technical site like slashdot the submitter is much more likely to know every privacy concern about RFID, yet know very little about the underlying technology. Isn't it supposed to be the other way around? When did "Your rights online" trump technical information on slashdot?
For a complete developers guide you can check EM Microelectronic-Marin SA Application Note
However for and introduction, check Wikipedia, or if you just want to start play with it, take a look at some RFID readers.
The passive devices that power up and send back data have nothing on the crystal radios that were used during the 1930's and 1940's. With nothing but an antenna a few feet or yards long,a semiconductor(crystal) and earphones, it was possible to receive enough power to hear radio stations. The so called "Fox Hole Radio" of World War II used a pin made of tin and to contact a "Blue Blade" razor to make the crystal. This simple setup received enough power from the antenna to give audible power to the earphones. I duplicated this years later but used a 1N34 germanium crystal. (And no, you don't need a tuning circuit if you have one strong signal and the others are weak.) The blue blade razors were out of production before I knew that they could be used.
I was intrigued to find out how the tags (which are generally battery-free) can absorb enough energy from RFID readers to then power up and transmit their own signal back to the reader."
The high frequency tags don't actually transmit. They change the impedance of their antenna to modulate the reflection back to the transmitter.
Another problem the article didn't mention is that bags lined with aluminum or copper foil will thwart these systems.
Wansu, th' chinese sailor
The most interesting thing that I learned was that most all RFID tags have a 128 byte "user data" buffer than can be read or written by ANY RFID gate. (Ie: you can put an RFID interface on your laptop and query the tags and change the "user data" portion on them.)
Obviously, this means that any application that is sensitive to tampering should only use the hard-coded serial numbers, not the "user data" area... but history has told us how well people stick to "common sense" security practices in their implementations.
His paper and the Linux tool that allows you to query and change the data are located here: http://www.blackhat.com/html/bh-media-archives/bh- archives-2004.html (scroll down to Lukas Grunwald under "Layer 0".
Before this we had swipe cards. Now all we have to do is walk up to the door and the door reader will go beep and open the lock.
I have been trying to open it up to take a look but it's complete sealed. I have been told it's water proof, heat proof and so on. It's labelled by a company called Sonitrol. Their website is at http://www.sonitrol.com/ but it doesn't show any actual products.
Don't think commies (although they can be blamed for anything:). Think marketing and muggers. As you walk around town you'll get a marketing profile from all the RFID tags delivered to everyplace you go. Problem is, you won't be able to stop this kind of targeted marketing because your clothing will be tagless - and you don't want to cut a hole in your brand new pants. Heck I'm wearing a tagless tshirt like that right now.
I don't know about you, but I'm pretty anti-marketing myself. The idea of "minority report" style marketing makes me want to puke. The idea that someone not only knows the manufacturer and model of my shirt, but whether or not I'm wearing boxers or briefs gives me the ebee-jeebies. It would also give muggers a priceless resource for picking victims. It wont take very long for public databases of RFID tags to manufactureres to start appearing. A few RFID scanners for the public are also already available.
10 feet is plenty of space on most streets, restaraunts or bars to find out if someone is worth mugging. Even more if people start making out of spec scanners that put out more power to get a stronger (longer range) return signal. Now, all that being said, I'm not oppposed to RFID at all, I think it has excellent potential. The problem is that RFID tags are being expressly designed directly into future products to prevent you from removing a tag without damaging or destroying the product.
Hate do be a bug, but please mod the parent down. Site is performing fine, so no need to post here.
... used by Exxon (and called Speedpass), I can tell you that they are pretty cool in technology... and yet lame at the same time.
Yes, it is true, there is a blast of energy (usually at a really low wave length - around 100Khz to 180Khz - they aren't very well tuned despite the lit).
For the paranoid, chewing gum wrappers do a good job of blocking them. Actually, a lot of tinted windshields do a good job as well (they tend to contain metal, typically iron from what I am told).
Interference is a big factor with these guys. A noisy engine (spark plugs badly gapped?) can cause problems. But the end result was that the company bought it.
Do I fear the use of it? Not really. But at the same time I don't like them used without my permission. As any device that is used to "track", it needs to have my consent.
That said, they are kinda' cool.
IANAL, but I've seen actors play them on TV
Yah, but the transmitters are not clean (how the eff do they get them through FCC?). They splatter around their set frequency. Really a freakin mess.
-The energy sent BACK is very weak. So you really don't need much to block it. White noise around 125 Khz should be enough. Or, as I mentioned before, chewing gum wrapper. Take your pick.
-Random codes won't do it. Sorry, but there IS a check (pretty pitiful, but there is one) and if the checksum don't match, nothing goes through. Nothing gets stuffed. Most readers use 8051 or something lightweight. If it doesn't pass first base, it doesn't go no where.
-Pliers work real good at breaking them. Easier than EMP (which might be noticed). They also break pretty easily on their own.
IANAL, but I've seen actors play them on TV