[mdlug] Curious - Phone Tapping Tech

[Michael Mol]

On Thu, Jun 21, 2012 at 8:19 PM, Aaron Kulkis <akulkis00 at gmail.com> wrote:
> Michael Mol wrote:
>> On Thu, Jun 21, 2012 at 7:02 PM, Aaron Kulkis <akulkis00 at gmail.com> wrote:
>>> Michael Mol wrote:
>>>> On Thu, Jun 21, 2012 at 1:53 PM, Aaron Kulkis <akulkis00 at gmail.com> wrote:
>>>>> Michael Mol wrote:
>>
>> [snip]
>>
>>>>> You couldn't detect a signal even if it was only 1 copper pair.
>>>>> Don't believe me?  Try it.
>>>>
>>>> Hall effect sensors would do it easily, in the single-pair case. And
>>>> if that isn't enough, you could use the signal propagation detection
>>>> and lock-on technique I wrote about last week to do it. I came up with
>>>> that in response to the 'thermal noise' encryption thing that was
>>>> making the rounds last week. It requires three measuring points, and
>>>> then applies triangulation in a time+distance space to figure out
>>>> where a signal is coming from and when, and uses that to lock on for
>>>> pass/block filtering purposes. The hardest part is timecode
>>>> synchronization between the three measuring points.
>>>>
>>>
>>> That's significantly more sophisticated, and entirely different
>>> geometry than wrapping a wire around a bundle of cables, which
>>> is what Robert asked about.
>>
>> It sounded to me like Robert was asking a question about a real-world
>> situation where someone was claiming to be able to sniff signal. I was
>> giving real-world answers. You challenged me on the case of a single
>> pair. I described how it could be done. I then extended into an
>> explanation of how one could do it with far more difficult
>> measurements.
>>
>> And you tell me my response to you is inapplicable to a misquote of
>> Robert's case. Perhaps it is...but I wasn't responding to him, there;
>> I was responding to you.
>>
>> My first response to Robert sums up my opinion of the situation. Ask
>> for a demonstration, control the setup; if the guy's a charlatan,
>> he'll back out. If he's not, he's either going to demo and succeed (in
>> which case there's something interesting there), or he's going to demo
>> and be embarrassed. The worst that could happen is a waste of time and
>> some bruised egos.
>>
>> If you want to get _really_ sophisticated, take this "band" the guy
>> was talking about, and build it out of a line of hall effect sensors.
>> Wrap it around the bundle of cable, and you have something that's
>> effectively a passive MRI; you've got measurements at the edge of a 2D
>> space sufficient to build a cross-sectional map of currents going back
>> and forth within the circle via triangulation. But now we're talking
>> about something extraordinarily expensive.
>
> Precisely.
>
> The answer to Robert's original question...is there anything
> like what Hollywood portrays to tap a phone cable.. .no

I don't even know how you see Hollywood portraying phone taps. I've
seen it portrayed as attaching butt sets, I've seen it portrayed as
attaching a voice recorder at the dmarc, and I've seen it not
portrayed at all--it all happens offscreen. I don't think I've ever
even seen inductive coupling portrayed in Hollywood, though it's
definitely possible.

There was a story a couple years back about an American sub that'd
squat on a Russian underseas communications cable. I don't know the
exact technique they used to pick up the signal in that copper, but I
doubt they risked exposing it to seawater.

>
> On the other hand, there ARE bugs similar what were portrayed
> in the movie "Enemy of the State"... looking very similar to
> the props used in the movie (which I believe were just very
> large capacitors).

As it happens, I haven't seen that one.

>
> Do a google search:  Theremin Moscow Embassy Bug
>
> Amazingingly simple and no power supply required -- the other
> half of the system activates powers the bug with radio waves
> which are also used as a carrier for the bug's own broadcast.

So, effectively how RFID chips operate; the chip modulates its
reflection of the incoming RF.

-- 
:wq