Edward Snowden: Can a refrigerator function as a Faraday Cage?

MAKE's Michael Colombo says:

In today’s New York Times article by Heather Murphy, a story was related where a group of lawyers were ordered by NSA whistleblower Edward Snowden to put their cell phones in the refrigerator before sitting down for dinner. The idea was that the metal-clad fridge would act as a Faraday cage, blocking any electromagnetic signals and preventing the group from being surveilled.

This sounded a bit dubious, since a refrigerator is not completely sealed in metal. A counter surveillance designer by the name of Adam Harvey suggested that a cocktail shaker is a much better alternative. Curiosity got the best of me, so I decided to test out both. See the video above for the results.

Edward Snowden: Can a Refrigerator Function as a Faraday Cage?


      1. Deus ex refrigerator, cf. ISBN 978-0-330-30955-4, p. 245. (Anybody ever named that one, btw?)

        Not the best place for a phone. You’ve got to seal it with a strand of your hair to be sure nobody used the fridge to get into your android device…

  1. He should have left room for other explanations. He didn’t.

    I prefer to think he asked for it just to see them do it.

  2. I approve of his choice of booze.

    A microwave oven will have more attenuation than a refrigerator, since it’s designed to keep 1 kW of RF energy at 2.45 GHz (close to the 2 GHz of cell phones) inside rather than outside the box. I’d hope it has at least 60 dB of attenuation, which is a million times reduction in signal power.

    But cell phones these days are amazingly good at working in high-attenuation conditions, so he’d be better off putting the phones in a holiday cookie tin and placing that in the microwave oven. The cookie tin should add another 30-40 dB of attenuation.

    1. In original NYT article doesn’t make it clear whether they were told or were just inferring that the refrigerator was suppose to act as a faraday cage. From what I understand, fridges have decent sound proofing as a side benefit of keeping the cold in.Maybe he should have put the phones in the tin sitting in a microwave stuffed in the fridge.

      1. This is more likely. A listening device would be next to useless inside of a refrigerator. There’s really no point in blocking RF transmissions- a bug hidden in a cellular phone could easily just record instead of transmit.

      2. Yup, was just about to post this.  Inside the fridge there would be very little audio, and no video able to be recorded.

  3. Fun video… but….

    Ok, this is getting kind of stupid…  all this is based on rampant speculation from an inane article instead of anything Snowden has actually said.

    Does anyone really believe that Snowden was trying to use the fridge for anything besides protecting the sound waves of his own voice?
    Also, did they observe inside the fridge and see if he put the phones inside something else in there?

    This is ALL the orginal article about Snowden says about this:

    Snowden wore a cap and sunglasses and insisted that the assembled lawyers hide their cellphones in the refrigerator of the home where he was staying, to block any eavesdropping.

    It says nothing of him saying it’s a “faraday cage”, nothing of blocking “signals”, etc.
    It’s obvious to me he put the phones in the fridge to guarantee the microphones weren’t exposed to his voice.  To me, the only people that look stupid right now is the media and the dolts that uncritically listen to them.The End.

    1. Good point.

      We might infer a few other things, then. Any attempt at all means he doesn’t think they are intentionally recording him… or he’d have to check for other more single-purpose technology. Not to mention the room itself.

      So if he thinks the phones are likely to be used to listen in on their conversation without the cooperation of the owners, does this imply that he believes (or knows) that cell phones are being remotely activated to act as listening devices? 

      We all know that it’s possible, and most of us assume it’s likely, but it’s interesting to see that presumption play out through someone who is actually in a position to know how our electronic devices are being used by surveillance interests.

      1. It’s more than possible. When Toby Studebaker was caught, UK police said in a press conference that they had known his location from his cellphone at all times, *even when it was turned off.* 

        The only gaps, according to police, were when it was either out of power or he’d pulled the battery out (likely the former, as it came back online).

        This doesn’t show remote microphone activation, but it’s confirmation that a switched-off phone can indeed be remotely accessed. 

        Pretty sure that logical next step wouldn’t trouble the NSA.

        1. People fundamentally misunderstand “off” in modern electronics.  Off doesn’t mean off — it means the display is off and the computer is in standby mode, perhaps doing maintenance tasks — or spying on you.  The only way to ensure it is “off” in the sense of a blender being off, is to disconnect it from power.  The same is true of any modern computing device, TV you can turn on w/ an infrared remote, etc. etc.

          1. We’ll get to that as soon as we solve the mystery of the rotating Egyptian statue.

      2. does this imply that he believes (or knows) that cell phones are being remotely activated to act as listening devices?

        I’m sure he knows just as I do.  They’ve already been doing that even while the phones are “turned off”.  The Feds do this all the time.

        The technique is called a “roving bug”.  There’s ways to workaround it, but I don’t think this is the appropriate place to discuss it. [cow waves to NSA]

        1. It’s public knowledge since the FBI used it against the Mafia in 2006: http://news.cnet.com/2100-1029_3-6140191.html

    2.  I like that you used the term “dolts”.  I’m going to have to resurrect that in my vocabulary list. 

    3.  What is the point of worrying about people listening to you while you are talking to reporters?  Don’t they supposedly take notes and put anything interesting in a news article….  Is he protecting their scoops from their own phones?

      1. I think those are good questions.

        If there wasn’t another container within the fridge that acted as a faraday cage…

        He was likely attempting to thwart audio intelligence to locate his position. The CIA, etc. might not have access to Hong Kong’s cell towers to triangulate his position directly, but they could manage simple audio access through other types of attacks.

        If one of the journalists mentioned his location verbally inadvertently or otherwise, his position could be compromised in real-time to whomever was listening.

        Also, once again, there’s no mention of what was inside the fridge and for all we know he also had something in there that was also acting as a faraday cage to block radio signals to/from the phones as well.

        When dealing with a vast, corrupt military-industrial complex, you should probably cover all your bases if you want to escape to Mexico.

        Whoops… did I say Mexico? Please… corporatist journalists, don’t rush to depart Moscow, Russia on every first class flight that leaves on June 30th from 3am to 5am to fly to Metlatónoc, Mexico…. Don’t do it.

  4. For those who don’t want to watch the video to find out: no, the fridge doesn’t work but the metal cocktail shaker does.

  5. egad, that was an ungrounded (Britishish: unearthed)  cocktail shaker as well.  yer classic Faraday-cage is at least grounded; s’why i keep all my cocktail shakers chained to a water pipe… lest they talk.

    1. Grounding doesn’t matter one whit. It’s a cage.

      You might need the chain to keep the phone from vibrating itself off the table, though.

      1. there’s a surprising amount of nerdly controversy on the issue (to earth one’s cage or not).   many folks believe that leaving a Faraday cage ungrounded might cause electrostatic transmission (similar to a capacitor) through the cage, (one need only consult the Wikipedia page).  i can tell which side of this particular issue you’re on; but, at least, we could acknowledge this thrilling controversy thrives.

        1.  The thing in the cage has no way to sense the potential of the cage relative to ground, so it’s a silly idea. But people will argue about anything.

  6. Snowden never said it would, that’s a stupid leap by the journo. In reality, it’s just for the soundproofing.

    Any phone can be a bugging device, whether it looks powered on or not. Battery pull is the only answer – but you can’t take the battery out of plenty of phones.

    Much to the joy of the security services…

    1. It was clear from the video that the phone in the fridge couldn’t be heard, so it seems it would be pretty effective.

      The cocktail shaker is interesting, though I think it could be improved by soldering on a connector so a wire between it and the faucet could be attached — plumbing is grounded, or at least supposed to be.

    1. of course -his- was clearly marked as “lead lined” (occasionally wonder if that was a ‘thing’).   but then, Dr Jones’s gunpowder is magnetic…

  7. I wonder if a stainless steel fridge vs non-stainless makes a difference.  I don’t know anything about fridge construction so I’m not sure if there’s a more than cosmetic difference.

    1. I think all metals attenuate wireless signals quite a bit… but Paget’s Shmoocon paper says woven stainless wallets can’t protect your contactless credit cards, so without a seamless metal box it might not make any useful difference, and no fridge is a seamless metal box because metal transfers temperature far too well.

      If the fridge has an entirely non-metallic shell, like the cheap white fridges made under conditions some call slave labor, it would probably be almost entirely transparent to wireless signals.  By way of contrast, an old Norge with a thick painted steel case would only leak signal at the door gasket.

      I don’t like stainless kitchen appliances because stainless steel is generally very friendly to microbial growth (unlike glass, wood, or copper) and I don’t like the idea of lining my food preparation area with large sheets of randomly colonized biofilm.

  8. While traveling in Beijing, I learned to turn my phone on, send/receive texts real quick, and then pull the battery.  I forgot a few times and “somebody” tried to image my phone.

    I also was only able to used it during the People’s Security Bureau’s normal working hours for some reason. 

    My mother in law is a PSB retiree, and my father in law had a distinguished military and civil career.  Yet we have never been able to make a non-monitored to them from the States. 

    So yes, when you’re traveling in a Police State, no matter how charming,  keeping a little metal box might not be too paranoid.

  9. It could have been a clever ploy to get a gaggle of Chinese lawyers to give him their full attention. He probably wasn’t in any mood to have their discussion surreptitiously recorded and sold to the highest bidder.

    1.  Wait about 4 more hours, then wake him up. Unless his phone’s in the fridge, in which case he won’t hear it.

  10. Richard Stallman was right, mobile phones are tracking devices and bugs.  This is a horrible government run by horrible people.  If we don’t collectively do something about this masses of regular people will one day find themselves swept up in prison camps for no other reason other than being on the wrong list.

    1.  Don’t worry, they’ll come for the irregular people first.  That’s what things like PRISM are all about – finding the nails that stick up – for example women who own ferrets, men who don’t watch pro sports, and those nuts who put bergamot oil in tea.  Likely to be terrorists, every one (certainly Earl Grey terrifies my taste buds).

      By the time the regular people are on a list, there won’t be any part of the country left that isn’t a prison camp in everything but name, so the normals don’t have so much to worry about in that regard.  I recommend investing in law enforcement suppliers and drug companies in the short term, and marrying into the hereditary ruling classes in the long run.

  11. I strongly suspect that Snowden was more concerned with voices than electromagnetic radiation.

  12. Put the phone in the cocktail shaker, then put that in the fridge.  Bam, best of both worlds.

  13. Unless Snowden left a low-power cell phone signal jammer inside the fridge… Dealextreme sells one for less than US$30 http://tinyurl.com/bavae3s

  14. That guy’s hands sure were shaking a lot! I wonder what he’s trying to hide? NSA DESCEND!

      1. I have a tremor, too. A cocktail usually fixes it. Propanolol does, as well, but the cocktail is more fun.

        1.  In all seriousness: this is a known fix for Parkinson’s disease tremors.  A family friend followed his doctor’s advice to the letter: one shot of vodka per hour.

  15. I have no idea what type of person Snowden really is.  He could be a terrible person that is only partially accurate about the NSA or the government.  I am glad he has got everyone talking about privacy, and people have the choice to determine an open society, or a constantly monitored state of security.  Also, I have a gateway style router that can broadcast to appliances not just my cellphone/laptop etc.  Is there something common and affordable I can use to block my wireless signal from my router?  I thought about a microwave but I was worried it might cause the router to overheat.  Does anyone have any thoughts? 

    1. Turn off the wireless feature, or buy one without a wifi subsystem. Or cut off the antenna and connect the center conductor of the coax cable to the outer shield.

  16. The rule of thumb is that any holes in the shielding should be smaller than any wavelength you care about. Cocktail shaker good. Foil bag good. Pouch made from metal screen pretty good. Microwave oven good. Refrigerator with gaps around the door not so good.

    That said, you make do with what you’ve got.

  17. Don’t ever do this.
    Seriously, you have no idea what kind of forces you’re dealing with.

  18. It doesn’t matter if it does act like a Faraday cage or not. Having the lawyers put their phones in the refrigerator separated them. They couldn’t hear the phones if they range and the lawyers couldn’t use them to get outside info. The lawyers were effectively cut off from their biggest resource.

    And, no interruptions.

  19. I think the issue is the fridge. Mine blocked the call, but mine is stainless steel and likely better made than the typical apartment fridge.

  20. I see no reason why you couldn’t put a phone in a cocktail shaker inside a microwave inside a refrigerator. After pulling out the SIM and battery of course.

    1. Makes sense to me.  And then set the whole thing on fire, take off and nuke it from orbit.

  21. If it can protect Indiana Jones from a nuclear blast it can sure as shit block electronic signals!

  22. If the intent was to keep any recording from happening, then it worked. But even if a fridge in Red China can work like a Faraday cage and the intent was to keep from being tracked? Not so good. Once the lawyer’s identities are known the location of the clandestine meeting is known. Just look to where all the phones converge and disappear for several hours. Not sure of Snowden’s intent. A lawyer could still have had a recording device on him or her.

  23. I tried with my microwave, and was surprised that my phone could still receive calls while inside.

  24. What if the phone was put in the metal freezer portion of a fridge, of the tiny kind that is in many hotel rooms? That is much more Faraday cage-like.

  25. If you don’t have a cocktail shaker a stainless steel saucepan with the lid on blocks signals effectively.

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