Filter to Prevent Eavesdropping through Control Wiring
Filter to Prevent Eavesdropping through Control Wiring
(OP)
Request from client today:
"Do you know of a filter that can be installed on control cable to eliminate noise, not electrical noise but eavesdropping? Apparently there is a new government spec out there that certain conference rooms have to have eavesdropping filters installed on all wiring entering the room. Wireless is out of the question because of the way the rooms are constructed and the relationship to where equipment can be installed."
He's referring to typical HVAC control cable. Generally these are headed for thermistors, RTDs, 4-20 mA devices, 0-10V devices, and others. They may also be RS-485 or Ethernet lines. Others may be from 24 VDC or 24 VAC power supplies, to power controllers in the room. I have asked for clarification from the client as to whether this new spec refers to:
The use of the control wires to connect a microphone inside the room to a listening device outside the room;
The use of the control wires to power a wireless-listening or fixed-recording device inside the room;
Sensing actual acoustic vibration transmitted down the conductors or cable jacket from inside the room; or,
Listening to what goes on in the room through the other end of the conduit, or through the hole around the wall penetration.
Until I get answers (which I'll post here promptly), has anyone already run into this spec and found a way to meet it?
Many thanks.
"Do you know of a filter that can be installed on control cable to eliminate noise, not electrical noise but eavesdropping? Apparently there is a new government spec out there that certain conference rooms have to have eavesdropping filters installed on all wiring entering the room. Wireless is out of the question because of the way the rooms are constructed and the relationship to where equipment can be installed."
He's referring to typical HVAC control cable. Generally these are headed for thermistors, RTDs, 4-20 mA devices, 0-10V devices, and others. They may also be RS-485 or Ethernet lines. Others may be from 24 VDC or 24 VAC power supplies, to power controllers in the room. I have asked for clarification from the client as to whether this new spec refers to:
The use of the control wires to connect a microphone inside the room to a listening device outside the room;
The use of the control wires to power a wireless-listening or fixed-recording device inside the room;
Sensing actual acoustic vibration transmitted down the conductors or cable jacket from inside the room; or,
Listening to what goes on in the room through the other end of the conduit, or through the hole around the wall penetration.
Until I get answers (which I'll post here promptly), has anyone already run into this spec and found a way to meet it?
Many thanks.
Best to you,
Goober Dave
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RE: Filter to Prevent Eavesdropping through Control Wiring
http://www.protectivecountermeasures.com/security-...
AES256 encryption would be a reasonable minimum for encryption.
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RE: Filter to Prevent Eavesdropping through Control Wiring
RE: Filter to Prevent Eavesdropping through Control Wiring
RE: Filter to Prevent Eavesdropping through Control Wiring
A guy two layers up the technical chain has answered my clarification request with, "We think it's number 3, but number 4 may also be included."
So according to this guy, it's nothing to do with electricity. Vibrating wires and/or sounds coming thru a conduit or other wall penetration.
This is difficult. If spies can bounce some light off of a double-pane bulletproof glass window and record the sounds in the room via the acoustically induced vibration from across the street, how can we stop 'em from putting a stethoscope on a piece of wire?
By the way, the official spec calls the room: The Secure Dome of Silence
It's a serious problem for my client, though. How do you stop vibration from making it down a wire or pipe?
Best to you,
Goober Dave
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RE: Filter to Prevent Eavesdropping through Control Wiring
Run your cables in sand-filled ducts?
RE: Filter to Prevent Eavesdropping through Control Wiring
the answer is "noise generator" which are used in SCIFs built to TLA standards.
http://www.ebay.com/itm/Counter-Surveillance-Anti-...
http://www.microvideox.com/noise-generator.html
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RE: Filter to Prevent Eavesdropping through Control Wiring
My partner suggested hanging a heavy weight from the cable a few different places inside the room. I heard Scotty's clamp-it-down suggestion from another guy here. Fine strands is a new one on me, I can see how that would help.
One other suggestion was a terminal block screwed down tight to a piece of the structure.
I would be digging right now for the guy whe wrote the spec if I were the contractor. Unfortunately, he's probably a dozen requests-for-info removed from us, and he's probably simply specifying an end result with no idea what is on the market to accomplish it. Dang.
Best to you,
Goober Dave
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RE: Filter to Prevent Eavesdropping through Control Wiring
RE: Filter to Prevent Eavesdropping through Control Wiring
This would certainly block all sound what-so-ever from coming down the conduit, since sound is conducted via moving air. It also would block vibration of the wire itself by forcing the feeble vibrations that would come down the wire into wiggling the entire conduit and the structure its affixed to.
Example:
http://www.platt.com/CutSheets/Appleton/Vertical%2...
Keith Cress
kcress - http://www.flaminsystems.com
RE: Filter to Prevent Eavesdropping through Control Wiring
RE: Filter to Prevent Eavesdropping through Control Wiring
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Filter to Prevent Eavesdropping through Control Wiring
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RE: Filter to Prevent Eavesdropping through Control Wiring
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RE: Filter to Prevent Eavesdropping through Control Wiring
Start by requesting the specification number; then ask for a copy of it. If you're not permitted to see it, then ask what you need to do to become authorized. Ask if there's a related handbook that accompanies the spec.
There's likely to be official certification testing and officially certified products (if not now, eventually).
You'll know that you're there when it costs $100k and takes a year to replace the thermostat when it happens to fail.
RE: Filter to Prevent Eavesdropping through Control Wiring
Supplemental Guidance: Physical security safeguards applied to information system distribution and transmission lines help prevent accidental damage, disruption, and physical tampering. In addition, physical safeguards may be necessary to help prevent eavesdropping or in transit modification of unencrypted transmissions. Security safeguards to control physical access to system distribution and transmission lines include, for example: (i) locked wiring closets; (ii) disconnected or locked spare jacks; and/or (iii) protection of cabling by conduit or cable trays. Related controls: MP-2, MP-4, PE-2, PE-3, PE-5, SC-7, SC-8, SC-9.
Note that the cabling in question is transmission cabling, i.e., transmitting data over those cables. Note, also, the specific concern is unencrypted transmissions.
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RE: Filter to Prevent Eavesdropping through Control Wiring
I have submitted a request for the spec. If it's not classified, I'll share it.
Best to you,
Goober Dave
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RE: Filter to Prevent Eavesdropping through Control Wiring
"Will work for salami"
RE: Filter to Prevent Eavesdropping through Control Wiring
The goop that Keith showed is for explosion proof fittings, might be a bit overkill but the concept is right. The simpler and easier stuff is just called Duct Seal (Google it). It's a non-hardening clay-like putty designed for filling spaces and when used on wires, will not attack the insulation. There is also Fire Stopping material that is used to seal open spaces around wires and in conduits to prevent fire from propagating along the wire insulation, which may be necessary anyway.
"Will work for salami"
RE: Filter to Prevent Eavesdropping through Control Wiring
Dan - Owner
http://www.Hi-TecDesigns.com
RE: Filter to Prevent Eavesdropping through Control Wiring
Thanks for the conduit seal / duct seal / firestop suggestions, those might work too. Our client might combine most of the ideas above and make a submittal. The submittal rejecter (if rejected) will have to at least give us hints. I think we have some conduit seals and firestop in stock, will have to check with the product managers.
Still no word on if or when we'll see the spec. I don't even know which agency this thing is for, or in which hemisphere it's located. All I know is "Federal Government." They're probably reading this as I type and having a good laugh.
Best to you,
Goober Dave
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RE: Filter to Prevent Eavesdropping through Control Wiring
We usually call them "attendees".
There's a non-hardening goop sold in tubes that (in Canada) we often call "Acoustical Sealant". The intended purpose is to smear on studs before mounting the drywall so as to reduce sound transmission. It's also very commonly used to seal-up 6-mil ultra poly+ sheets to achieve a permanent air-tight vapour barrier. This sort of product could be useful.
If one was paranoid, one might wish to open up the cables and dampen the individual wires.
There's a concept of 'inspectable area'. If the adjacent rooms are under control (inspected and locked), then one shouldn't need to deal with the risk that an enemy agency sets up a rack of monitoring equipment in the next room.
RE: Filter to Prevent Eavesdropping through Control Wiring
That's another one to add to the list. Our client is submitting tomorrow, a combination of all the good suggestions here and some others they got from somewhere else. The good news is that none of the other subcontractors know what to do either. There's supposed to be some government lady coming to give them the requirements verbally.
Best to you,
Goober Dave
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RE: Filter to Prevent Eavesdropping through Control Wiring
That's sort-of ironic.
RE: Filter to Prevent Eavesdropping through Control Wiring
RE: Filter to Prevent Eavesdropping through Control Wiring
Remove or slit the jacket, bend the core a little, and detect the light that leaks out.
Mike Halloran
Pembroke Pines, FL, USA
RE: Filter to Prevent Eavesdropping through Control Wiring
That's interesting, Mike. Now you've got me wanting to experiment.
Best to you,
Goober Dave
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RE: Filter to Prevent Eavesdropping through Control Wiring
TTFN

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RE: Filter to Prevent Eavesdropping through Control Wiring
RE: Filter to Prevent Eavesdropping through Control Wiring
I hope I'll get to find out what the gummint wants...
Best to you,
Goober Dave
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RE: Filter to Prevent Eavesdropping through Control Wiring
RE: Filter to Prevent Eavesdropping through Control Wiring
How about no physical contact at all between the room and its surrounding structure? Make the secure room itself a self-contained self-supporting box, floating on magnets like a maglev train. The entrance door has an airlock that retracts in the surrounding room. The surrounding room is climate controlled so you need less fans in the isolated room. Or go the opposite route, and give the secure room self-contained atmosphere and evacuate the surrounding room. In space, no on can hear you share state secrets. Power (for lights, coffee maker, etc.) can be transmitted through inductive coils under the floor, picked up by secondary coils in the floor, like a flat air-gap transformer. Self-contained power is also an option; run the lights off batteries. If you need to send out/in any data signals, convert them to optical (laser LED) signals in one side of the wall, shining on receptors on the other side of the wall panel. Narrow beams with covers around them so that no one else can see the light except the intended target.
This is very sci-fi. Inefficient but you've got a government budget to spend.
STF
RE: Filter to Prevent Eavesdropping through Control Wiring
Mike Halloran
Pembroke Pines, FL, USA
RE: Filter to Prevent Eavesdropping through Control Wiring
Our client is stuck with running a twisted pair through the wall, different room construction is not on the table.
It would be interesting to make a soundproof room from scratch, though. Perhaps something super-heavy like a bank vault, surrounded by a larger concrete room, with IRstuff's noise generators in the interstice. Maybe the vault could have its own foundation, floating on water or an air cushion.
Add armed guards around the perimeter, and you're done. Stick a fork in it.
Note that I said soundproof -- not spyproof. If the bad guy is sitting at the conference table with you, you're toast.
You could also do it like the North Koreans are supposed to have done it. 30 stories underground, with soldiers everywhere above.
I'll keep trying to pry the info out of our client. They haven't said the word "classified" yet.
Best to you,
Goober Dave
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RE: Filter to Prevent Eavesdropping through Control Wiring
:D
RE: Filter to Prevent Eavesdropping through Control Wiring
RE: Filter to Prevent Eavesdropping through Control Wiring
RE: Filter to Prevent Eavesdropping through Control Wiring
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RE: Filter to Prevent Eavesdropping through Control Wiring
Best to you,
Goober Dave
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