FOIA docs show feds can lojack mobiles without telco help

ars technica ^ | November 16, 2008 | Julian Sanchez

[mad_as_he$$]

Courts in recent years have been raising the evidentiary bar law enforcement agents must meet in order to obtain historical cell phone records that reveal information about a target's location. But documents obtained by civil liberties groups under a Freedom of Information Act request suggest that "triggerfish" technology can be used to pinpoint cell phones without involving cell phone providers at all.

[Still Thinking]

Well, it’s not even the hostility level of the government. It’s just that they are supposed to work for us and should treat us like their masters and not their slaves.

In a sense you can’t really get mad at them for pushing the limits of their place. That’s what governments do. Getting mad at them for it is like getting mad at your dog for farting in the house. The correct response is to defeat their overstepping to the best of your ability.

[ResponseAbility]

So in my mind a proper response would not be to minimize the risk that the OP entails, but to buttress the OP by stating that there is a litany of other ways to be tracked and patriots should be wary. To ask what the big deal is minimizes the very real threat to many not at your level of awareness. Do you want a cadre of incompetents working with you when it is most important?

[FreedomPoster]

>>Is it true that my passport or drivers licence will be invalidated if the RFID chip is disabled?

On that note:

The RFID Shield
http://www.rfid-shield.com/
The RFID Shield is a protective sleeve that prevents anyone from reading private information stored on your RFID cards and passports.

[amchugh]

Isn’t doing this without a warrant technically a felony?

[slnk_rules]

In a sense you can’t really get mad at them for pushing the limits of their place. That’s what governments do. Getting mad at them for it is like getting mad at your dog for farting in the house. The correct response is to defeat their overstepping to the best of your ability.

Thought that one bore repeating... so I reapeated it. Well said.

[mad_as_he$$]

Probably but you would have to prove it and they would not bring it up in any case. They would use it to gather info and then “develop” the case against you from that.

[Petronski]

Good old fashioned tail...

[Petronski]

Lord, I apologize for that last post...

[GOPsterinMA]

Thank you for the information. I have been keeping my passport wrapped in tin foil.

[E=MC2]

I doubt such technology is terribly useful against wanted criminals. Only a total idiot would carry around a cell phone that is directly associated with them, while trying to avoid law enforcement.

Most run of the mill crooks fall into the "total idiot" category.

[Constitution Day]

I am not. Hehe.

[CodeMasterPhilzar]

Don't know about invalidating them, but you can mask it. I've heard - but haven't investigated, that simply wrapping them in aluminum foil acts like a Faraday cage. This would prevent the RFID reader's signal from getting to the chip, and/or the chip's even lower-power response from getting out.

The other technique I've heard about involves carrying a "blocking" tag. As I understand it, the way RFID works is the sort of a query-response model. The reader sends out a "hello everyone" and any/all tags respond with their binary ID number. (something like 128 bits) If only one tag is present, the exchange is over, and the reader knows what device (via the serial number) is out there. Of course, the reader would need a database of what tags were issued to who/what to know.

Anyway, if there are multiple tags in range of the reader, they all respond, "stepping on" each other's signal. The reader detects this and re-issues the query "who's out there with a number that starts with 0" Similar result, either it gets 1 reply, or multiple. The reader is basically traversing a tree of 1s and 0s, deducing what tags are present until it has uniquely identified all tags in view. The algorithm is based on the idea that by sequential challenges of "0" or "1" then "00" or "01" etc. it can eventually get single responses from each tag. Tags are supposed to stay quiet when the challenge doesn't match their digits.

Therein lies the beauty of a blocking tag. It violates the algorithm. It always replies with a number, no matter what the challenge. Therefore, the reader is prevented from ever getting a "clean" return off any other tag you have on you. They always result in a collision, and the reader has to throw up its hands and give up. These are also called jamming tags.

See http://www.rsa.com/rsalabs/node.asp?id=2060 for more details.

[Still Thinking]

Hmm, if one blocker would be good, ten or thirty would be better. Then, even if the scanner managed to walk the tree down to the point that there would only be one legit response, rather than one out of two, it would be one voice among thirty. Good if the blockers, maybe higher quality at higher cost, could return a higher proportion of the received energy as well, so that their response would overwhelm the other not only by quantity but amplitude as well.