Slashdot Mirror
Engineers Say They've Created Way To Detect Weapons Using Wi-Fi (gizmodo.com)
An anonymous reader quotes a report from Gizmodo: The researchers, which include engineers from Rutgers University-New Brunswick, Indiana University-Purdue University Indianapolis (IUPUI), and Binghamton University, published a study this month detailing a method in which common wifi can be used to easily and efficiently identify weapons, bombs, and explosive chemicals in public spaces that don't typically have affordable screening options. The researchers' system uses channel state information (CSI) from run-of-the-mill wifi. It can first identify whether there are dangerous objects in baggage without having to physically rifle through it. It then determines what the material is and what the risk level is. The researchers tested the detection system using 15 different objects across three categories -- metal, liquid, and non-dangerous -- as well as with six bags and boxes across three categories -- backpack or handbag, cardboard box, and a thick plastic bag.
The findings were pretty impressive. According to the researchers, their system is 99 percent accurate when it comes to identifying dangerous and non-dangerous objects. It is 97 percent accurate when determining whether the dangerous object is metal or liquid, the study says. When it comes to detecting suspicious objects in various bags, the system was over 95 percent accurate. The researchers state in the paper that their detection system only needs a wifi device with two to three antennas, and can run on existing networks.
The findings were pretty impressive. According to the researchers, their system is 99 percent accurate when it comes to identifying dangerous and non-dangerous objects. It is 97 percent accurate when determining whether the dangerous object is metal or liquid, the study says. When it comes to detecting suspicious objects in various bags, the system was over 95 percent accurate. The researchers state in the paper that their detection system only needs a wifi device with two to three antennas, and can run on existing networks.
This is absolutely horrific. You are telling me that these idiots who've gone along with the NSA illegally monitoring our traffic can now use state backdoors to identify every bit of gold/silver/gun wealth and resistance across the country? Wifi is everywhere and *I* can get into half the systems using nothing but default credentials.
This is using 2.4GHz microwaves to scan for certain types of objects (large metal objects, nitrogen-containing explosives). Basically a more advanced metal detector.
Even 99% accurate is absolutely horrid for real-life situations. Let's take a case where one in a thousand items encountered are dangerous. I'm going to scale the numbers to make the results come out as integers. At 1 in 1000, if we start with 100,000 items we'll have 100 dangerous items and 99,900 non-dangerous. Of the dangerous items, the system will flag 99 as dangerous and 1 as non-dangerous. Of the non-dangerous items, the system will flag 98,901 as non-dangerous and 999 as dangerous. So out of 1,098 items flaged as dangerous, 90.98% of them will be non-dangerous. So a system that claims a 99% accuracy rate will have a 91% error rate when it comes to sounding the "Danger!" alarm. Only 9% of the time will that alarm actually indicate danger, the other 91% of the time it's a false alarm.
The above is why 5-nines (99.999% accuracy) is the baseline for workable systems.
I always figured the way to beat baggage screening was a kind of x-ray stenography. Pack your contraband items in close proximity to familiar and non-contraband items that are readily identifiable to x-ray screeners. Unless its entirely obvious, they will just assume the contraband is another similar item to what they can "see" and let it pass, or the item density and overlap will be such they can't quite make out anything and might just assume it's a collection of toiletries or some other innocuous content.
Of course I just made this all up and don't have any experience in smuggling, so perhaps this is all just errant speculation.
> trivial countermeasures, like lining the suitcases with aluminum foil
Yes, because having a suitcase lined with aluminum foil is totally benign.
> You can't see what doesn't reflect or reflects all or absorbs a lot.
No, but you can make a note of something that DOES all those things. Normal suitcases don't.
They forgot I think to think about the trivial countermeasures
Not really because these have trivial solutions: just flag any bag which shows a huge amount of reflection or none at all as suspicious. Then, instead of a quick automated scan, you can be detained by security and wait while they rummage through your bag.
This was an interesting experiment done by some students. It's not some amazing new idea that is going to revolutionize security. First off, they only tested it by putting the object directly between the transmitter and the receiver. And like 10m apart. So, basically like every other type of scanner around. You're still going to have to walk through it. So while that might make it easier to implement a scanner type device, it's not like suddenly anywhere with WIFI can start scanning all the people around it at will.
Unfortunately, the reporting is lacking in highlighting this. I suspect, frankly, because those reporting on it don't really understand what they're looking at.
The method of detection in this case is rather crude. In reality, no fancy countermeasures are necessary. Take your contraband item and simply enclose it in the shape of something harmless, and this system would be immediately fooled.