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A Secure Off Switch for Cell Phones

Please don't use my cell as a covert listening device
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Most people don't realize it, but even when cell phone are turned off- they're often not fully off. If some hacker (or 3-letter agency) decides to listen to you, they can remotely program your cell to transmit the sound to some designated number without you being aware, even when it seems to be turned off [see links]. For this reason, in high-security locations it's standard policy to require removing your cell-phone battery before you enter.

This always struck me as a rather crude solution. I'd like to see some brave cell manufacturer (or self-assembly kit) that installs a simple on/off switch to the battery of your cell phone (or to the mike if you still want to text). This secure switch will physically disconnect the wires when it's switched off, just like normal switches used to do. This seems like a trivial solution to get privacy, and have a longer lasting battery to boot.

Notes: * Even an amateur can verify that such a switch is really hooked up to the battery pack.. * Oh ya. And all this is equally applicable for your cell phone camera and laptop/PDA too.

imho, Jun 16 2009

Wikipedia: Covert listening device http://en.wikipedia...rt_listening_device
[imho, Jun 16 2009]

Schneier on Security http://www.schneier...otely_eavesd_1.html
[imho, Jun 16 2009]

[link]






       If you're that paranoid, just take the battery out. [-]   

       BTW, the cell-phone I'm looking at right now is switched off, and drawing around 200uA. If anyone knows how to power a GSM RF section off 200uA ('cos that's what you'd need to remotely switch this sucker on), I'd be happy to discuss an employment contract.
coprocephalous, Jun 16 2009
  

       ... if the switch was just at the microphone you'd even be able to still get messages (apart from the ones beamed directly into your head...)
loonquawl, Jun 16 2009
  

       //('cos that's what you'd need to remotely switch this sucker on)//   

       Unless a resident malicious piece of software woke the device up at specific, scheduled times, and then put it back to sleep (all the while without starting the display and keyboard locked?).   

       Can I have a job please?
Jinbish, Jun 16 2009
  

       //Unless a resident malicious piece of software //
Well, I could explain why that wouldn't work, but then I'd have to be jolly beastly to you.
coprocephalous, Jun 16 2009
  

       Firmware update then? Or at least, not so malicious software.   

       Dammit, shove a cron job on a Nokia N810... despite it having neither a cellular interface, nor analagous 'off' state (?).   

       (Any closer to that contract yet?)
Jinbish, Jun 16 2009
  

       I just wrap the whole phone in tinfoil. I always keep a large supply around, just in case.
miasere, Jun 16 2009
  

       If you regulary wrap youself in tinfoil, and keep the phone inside, then this is simply not a problem. [marked-for-irony] Solved with Tinfoil.
Aristotle, Jun 16 2009
  

       The whole point of this idea is that you can still use your phone when you need it. But conveniently disable it when you're at some critical strategy meeting, or making HR decisions, etc. To paraphrase the famous quote: "Just because you're paranoid, doesn't mean they're no listening in". And listening in to cell phones is incredibly easy for professionals.
imho, Jun 16 2009
  

       Um, a custom-sized sound-insulated plastic box to put the cellphone in, with a little white-noise speaker inside would keep any useful sound from being picked up. The phone could still get RF signals, and could activate an LED as a "ringer".   

       Cool, the Samsung 900 series of phones are most vulnerable. Mine is retired to playing audiobook MP3s under my pillow at night. Somebody is getting an earful of Jeeves and Wooster, slobbering snores and the occasional obscene grunting.   

       Which gets back to the anti-eavesdropping. Switch a music-player phone over to playing Bon Jovi's _It's_My_Life or just random noise--and damn anyone trying to listen in.
baconbrain, Jun 17 2009
  

       I also would like an appallingly stone-aged "Off" setting.   

       For a DIY solution a foil-insulator-foil sandwich could be placed between one battery terminal and its corresponding terminal in the handset, and the outer foil layers connected by a switch.   

       On a stupid Sony-Ericson 'phone I keep as a backup I take out the battery, place a small piece of plastic film over its terminals, and replace it, so that it doesn't drain the battery or activate the alarm (which cannot be deactivated without a SIM card. Aaagh!). <rant> It is useless without a SIM card anyway, so there's no reason not to be able to turn it off. I hate phones that lock you out entirely when you don't have a SIM. I never consider buying handset+plan packages because they encourage such artificial stupidity </rant>.
spidermother, Jun 17 2009
  

       I knew a guy who was sure the CIA collected every photograph ever taken from a cell phone.   

       After a few days, I managed to convince him that they were actually recording video, and that new phones had the cameras because older phones had them hidden in the speaker or earpiece, and somebody found one.   

       Paranoids are fun to screw with. I'll have to tell him about the tinfoil trick if I see him again.
ye_river_xiv, Jun 17 2009
  

       Just because the battery is disconnected, doesn't mean it can't eavesdrop. There may be a capacitor or spare battery on the circuit board somewhere, with enough capacity to keep the phone going for a few hours after someone switches it off.   

       Therefore, I think the best solution is indeed to wrap it in your spare tin foil hat. Yet another way this brilliant garment protects us from evil shadowy government surveillance types.
Bad Jim, Jun 17 2009
  

       [21 Quest] The Sony Ericsson is a free hand-me-down and came without a SIM. I use it as a backup when a charger for my main handset is not available. It's not really worth spending even 25 bucks on.   

       I stand by my dislike of the bundling of innately separate products such as phone handsets with plans, and computers with proprietory operating systems. I think such things disempower consumers.
spidermother, Jun 18 2009
  

       *approves*
spidermother, Jun 18 2009
  

       "I just wrap the whole phone in tinfoil. I always keep a large supply around, just in case" I just use emergency blanket material (plastic stuff, we call it space blanket in the UK), it's less crinkly.   

       Also you could print adverts on the emergency blanket for anti-tracking device companies, or therapists.   

       // the alarm (which cannot be deactivated without a SIM card //   

       Why not put in the SIM card from your main phone for long enough to disable the alarm? Also, if this phone does nothing useful without a SIM card, are you just using it as a pocketwatch?
notexactly, Jun 22 2019
  

       Things have moved on a bit now and many home devices listen constantly. Whenever I get a bit paranoid, I turn on a device that should not be listening and have an artificial conversation about e.g. penguins and then wait until social media starts pushing penguin related content. Its a fun tinfoil game for the whole family.
bigsleep, Jun 25 2019
  

       Hackaday had a post years ago (back in the days of no capital letters, green links, and scrapbook corners on the pictures) about how somebody had modded their phone with a switch so that the microphone was only connected when they wanted it to be. I feel like it might have been either a manual switch or a reed switch with a magnet to detect the screen being opened (because this was also back in the days of flip phones being common outside Japan).
notexactly, Jul 01 2019
  
      
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