Bugged Canadian Coins?

tundra_man writes "CBC has an article about RFID type devices in Canadian coins found on US Contractors. From the article: 'Canadian coins containing tiny transmitters have mysteriously turned up in the pockets of at least three American contractors who visited Canada, says a branch of the U.S. Department of Defense.' The report did not indicate what kinds of coins were involved."

Comments

Re:Motive???

[LiquidCoooled]

I also read the article and thought WTF.

I seriously doubt anyone managed to mung currency and insert a real RFID unit.
What I do think however is that in a small percentage of coins they resonate at the same frequency as an RFID which would appear as though they were magical.

If you did infact hollow out a bit of a coin and replace some of the metal with an electronic bug the weight and bounce (striking against a piezo sensor) would cause such a difference any coin mech you inserted it into would reject it.

NOT an RFID is my bet.

[Ungrounded Lightning]

For the life of me, I can't figure a reason that somebody would do this. Coins change hands quickly and RFID has a pretty limited range.

If you RTFA article closely you'll see that the souce told the press that transmitters were found in coins.

Then (in paragraph 11) reporter notes that the type of transmitter was not disclosed. In paragraph 12 he starts speculating about RFID. The rest of the article (and possibly part of the preceeding section - along with the Slashdot headline) is based on the unfounded assumption that the transmitter IS an RFID-type device.

Which strikes me as totally bogus.

IMHO it's more likely that the "transmitter" found is a remotely-powered area audio bug, like "The Great Seal Bug", the martini fake olive bug, or the "diodes in the wall" bugs. Planted on a person it would bug his conversations and those around him until he spent it - hours or days later. (As you can imagine from the martini-olive bug, which is only useful while the spy is toting the martini, in some situations long-term bugging is an unnecessary bonus.)

Such bugs can be simple: A shaped cavity with a flexible membrane over it is one way to do it - the cavity resonates, giving a strong reflection, while the sound modulates the cavity's effectiveness, AMing the reflection. Another is just to fasten a diode to something that can be vibrated by sound. The diode frequency-doubles the reflected signal or mixes two of them to produce the sum and difference frequencies (sorting the diode's reflection from most ordinary reflections) and the vibration of it along the line between the bug and the monitor phase-modulates the return with the local audio. No fancy circuitry or local power supplies necessary.

I presume this one did involve at least a diode, or some semiconductor circuitry, since it was found in a radio scan - which is often done by looking for the frequency-multiplying and/or frequency mixing effect of diodes / semiconductor junctions. Finding a pure cavity resonator bug - or even identifying what it is when you have it - is a bitch.

Bugging the audio at a conference, or the conversations of a contractor at work on classified projects, would be worth planting a bug on him and having it there for only a few hours. After that, if he "spends" it, so what? (At least until they are noticed and a way found to identify them BEFORE the conversations to be monitored.)