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USB "Condom" Allows You To Practice Safe Charging

Posted by samzenpus on from the plugging-it-in dept.

MojoKid writes "Yep, a USB condom. That term is mostly a dose of marketing brilliance, which is to say that grabs your attention while also serving as an apt description of the product. A little company called int3.cc has developed a product—a USB condom—that blocks the data pins in your USB device while leaving the power pins free. Thus, any time you need to plug a device such as a smartphones into a USB port to charge it—let's say at a public charging kiosk or a coworker's computer--you don't have to worry about compromising any data or contracting some nasty malware. It's one of those simple solutions that seems so obvious once someone came up with it."

13 of 208 comments (clear)

  1. *yawn* these have around for years? by PhrostyMcByte · · Score: 5, Interesting

    My MP3 player, the nearly 10 years old Cowon D2, actually came with a power-only USB cable. Maybe their goal was to save money on copper.

    1. Re:*yawn* these have around for years? by tjohns · · Score: 5, Interesting

      If you plug your power-only USB cable into a modern charger, you'll find that your phone charges quite a bit slower than you'd expect. Modern chargers use the data pins to negotiate whether a charger supports higher currents.

      You don't want a phone to try drawing 2A from a charger that's only designed for 500mA.

    2. Re:*yawn* these have around for years? by aXis100 · · Score: 5, Insightful

      "Negotiate" is a loose term - really it's just some fixed resistances across the data pins that set USB charging mode. This can be built into the plug without any extra copper in the cable.

      That said for the portable device on the other end to recognise charging mode it also needs to see some fixed resistance, which would need to be build into the far end plug too.

    3. Re:*yawn* these have around for years? by viperidaenz · · Score: 5, Insightful

      and if you don't connect the data pins, the port, if it obeys the USB standards strictly, may shut down if more than 100ma is drawn without negotiation.

    4. Re:*yawn* these have around for years? by fuzzyfuzzyfungus · · Score: 5, Funny

      [sigh] So much for "Universal".

      Hey, man, not my problem if two passengers don't get along, I just drive the bus.

      -USB Implementors' Forum, Inc.

    5. Re:*yawn* these have around for years? by Anonymous Coward · · Score: 5, Informative

      The host power lines are usually protected by a "polyfuse" (aka self-resetting fuse), sometimes just one for all lines combined if the total current is no danger to the traces should it be drawn from one port. A polyfuse is a (normally small) resistance which is designed to go into thermal runaway when the current limit is exceeded. After a few minutes without current, the fuse "resets", i.e. it cools down sufficiently for the resistance to drop far enough that the normal current won't trigger the thermal runaway.

    6. Re:*yawn* these have around for years? by AmiMoJo · · Score: 5, Informative

      Actually there is a standard, laid out in the USB Battery Charging Specification. It clearly states that a dumb charger should short D+ and D- directly to indicate that it can supply up to 1.5A.

      The only company that uses resistors is Apple. The USB spec was released in 2007 so maybe their early devices pre-dated that. In any case, any properly designed USB device from the past 5 years should fast charge from a dumb charger simply by having the D+ and D- lines shorted.

      --
      const int one = 65536; (Silvermoon, Texture.cs)
      SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
    7. Re:*yawn* these have around for years? by JesseMcDonald · · Score: 5, Informative

      Is there some term that is used to distinguish connectors with / without this functionality, so I can buy the right kind?

      I gave up on finding USB Charging Specification-compatible chargers a while ago and just picked up a "charge-only" USB cable, which does the same thing as the adapter in this article: short the D+ and D- pins on the device side. This lets any standards-compliant (i.e. non-Apple) device know that it's safe to charge at full speed, so it should fix the problem so long as your charger can handle the current.

      You can tell whether an Android device is charging properly by looking at the Battery pages in Settings. It should say "Charging (AC)" to indicate a full-speed charge, or "Charging (USB)" to indicate that it's limiting itself to 100mA.

      --
      "The state is that great fiction by which everyone tries to live at the expense of everyone else." - Bastiat
  2. Re:Not Completely Safe by smash · · Score: 5, Insightful

    If someone has physical access to your phone unsupervised, ALL BETS ARE OFF.

    --
    I run: Windows, OS X, Linux, FreeBSD. Just because you have a hammer, doesn't mean everything is a nail.
  3. Re:So, if I manufacture chargers.... by jamesh · · Score: 5, Funny

    You could do that. I could also not buy your broken charger.

    But you know what you're doing. Social engineering will always work on some people though:

    "My phone is flat and I really need to take a photo of my big mac to show my friends, can I borrow your charger?"

    "Sure, here you go"

    "It's not working"

    "Try taking that adapter thing off, it's probably mucking up the charging"

    Faced with the horror of eating their big mac without it first being photographed, I think you can guess how this story ends...

  4. Not the only one out there by ericfitz · · Score: 5, Interesting

    There's a current KickStarter project called LockedUSB which does something similar, but which also includes a power management chip in order to negotiate higher power charging levels that normally require data connectivity. LockedUSB doesn't appear as big or ugly as the one in TFA. (Full disclosure: I'm a backer)

  5. Re:Condom. You keep using that word... by jamesh · · Score: 5, Insightful

    A little company called int3.cc has developed a product—a USB condom—that blocks the data pins in your USB device while leaving the power pins free.

    If you consider something that blocks the middle of the male end but leaves the sides open to be a "condom," you might want to see a doctor. Soon.

    If you consider that it allows for insertion without allowing the flow of information, the comparison might be more correct than you think.

  6. Re:Not Completely Safe by robthebloke · · Score: 5, Funny

    That's why I tamper-proof my phone with Windows 8, and a picture of Justin Bieber for the locked screen.