Oct 19, 2021It's been a while since I have had to set the record straight regarding an article in the mainstream news about radio frequency identification, but our senior writer Claire Swedberg forwarded me an article published by the AP that was so misleading I felt I had to reply. The article, titled "Military units track guns with tech that could aid foes," starts out by claiming "Determined to keep track of their guns, some U.S. military units have turned to a technology that could let enemies detect troops on the battlefield, The Associated Press has found."
Wow. Sounds like a real scoop. Also, aren't those folks at the Department of Defense really dumb? Who would track weapons with technology that enemies could use to locate and kill your troops?
Unfortunately, the authors clearly do not understand the capabilities and limits of RFID and didn't really think through the implications of their own reporting. They write: "When embedded in military guns, RFID tags can trim hours off time-intensive tasks, such as weapon counts and distribution. Outside the armory, however, the same silent, invisible signals that help automate inventory checks could become an unwanted tracking beacon."
Well, first off, the tags don't beacon. They don't do anything until they receive energy from a reader antenna. The reader emits a relatively strong signal. The tags receive that energy, store it briefly and reflect back a very weak signal that can be read from 20 or 30 feet away (a distance at which you could easily shoot the enemy).
The authors claim their tests show the tags can be read from "significantly farther" away than the 20 or 30 feet from which you can usually read tags. In the tests run by the AP writers with some help, they detected tags from 210 feet away (64 meters) in an open field. An M16 has an effective range for 550 meters (1,800 feet), so it would be possible to shoot the enemy long before he got within range to read the gun's tag. What's more, he would of course not be able to read the tag of a gun inside a building from anywhere near that range. He might not even be able to read it from right outside the building, depending on the density of the walls.
The authors write that an enemy using equipment more powerful than allowed by government regulation could "detect tags miles away." Miles is highly unlikely, if not impossible, but here is the more important point that doesn't seem to have dawned on the authors: The enemy would need to broadcast a very strong radio signal from a reader antenna, which the U.S. military could use to detect that enemy's position long before it got anywhere near U.S. soldiers.
Consider this analogy: The enemy is going around shouting at the top of its lungs (or, in the case of an illegally boosted reader, using a loudspeaker), "Where are you? Where are you?", and the AP reporters are concerned about a soldier whispering, "I'm over here." If the enemy can detect the faint signal from an RFID tag from "miles away," then clearly the U.S. military could detect the signal from an amped-up reader antenna from hundreds of miles away and order a drone strike or mortar fire on its position.
Another point not mentioned in the article is that the tags simply have serial numbers in them, without context. The numbers could represent weapons, or they could be for sacks of flour or ladies' handbags. If the enemy were reading tags from "miles away" (again, that's not possible, but I'm explaining why the authors' logic doesn't work), they'd pick up lots of tags from many locations within range, and they'd have no idea what the serial numbers represented. They could wind up launching a raid on a fashion store.
In a war zone, one might assume there would be no other tags present than those on weapons, and that no one other than the DoD would be using RFID. Even so, it would be easy to set a trap in that scenario—the U.S. military could simply put a bunch of tags in an empty building, wait for the enemy to show up and use their high-powered reader to find them, and then, when they entered the building, surround it and kill them all.
The authors make much of their ability to clone a tag. They read the tag number on a rifle, write that number to another tag and then read it. This, they claim, shows that a rifle could be stolen, and that a tag could be placed in its empty carrying case. The RFID reader would still think the rifle was in the case, they say, and the rifles would not be reported stolen until the cases were opened.
This is, of course, possible with some passive UHF tags—but if security was a big concern, the DoD could associate the unique ID number that the chip maker wrote into the chip with the unique serial number, and if those two didn't match, it would know the tag was cloned. I don't know if the military is doing this or not. It slows inventory taking down a bit, so they probably aren't unless theft poses a real problem. The authors don't seem to know that this is even possible.
RFID is used by the military to manage the inventory of guns and many other things. It has been a very effective tool that has saved U.S. taxpayers hundreds of millions of dollars since it was first introduced nearly 20 years ago. And there have always been overblown concerns about the enemy reading the military's tags, which has not actually been a problem.
At RFID Journal LIVE! 2005, Alan Estevez, then the United States' assistant deputy undersecretary of defense for supply chain integration, gave a keynote address explaining the DoD's plans to use passive UHF RFID to track shipments to war zones. During the Q&A period, someone asked about the possibility of an enemy reading tags on shipments and estimating the number of troops within a given area. "Look," Estevez replied, "these are short-range devices. If we have people close enough to our positions to read our tags, we have bigger problems than that they are reading our tags."
Mark Roberti is the founder and editor of RFID Journal.
