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USB "Condom" Allows You To Practice Safe Charging 208

Posted by samzenpus
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."
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USB "Condom" Allows You To Practice Safe Charging

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  • by PhrostyMcByte (589271) <phrosty@gmail.com> on Monday September 16, 2013 @02:06AM (#44860799) Homepage

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

    • by tjohns (657821) on Monday September 16, 2013 @02:36AM (#44860953) Homepage

      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.

      • by aXis100 (690904) on Monday September 16, 2013 @02:41AM (#44860995)

        "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.

        • by viperidaenz (2515578) on Monday September 16, 2013 @03:04AM (#44861061)

          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.

        • by 3247 (161794) on Monday September 16, 2013 @03:45AM (#44861183) Homepage

          "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.

          For dump power supplies, it's "just some fixed resistances" between data pins. That's a shortcut for chargers that don't want to implement the USB protocol.
          Computers, however, do use the data lines for the intended purpose. With computers, the amount of power that can be drawn is negotiated between the computer and the devices.

        • by SuricouRaven (1897204) on Monday September 16, 2013 @04:31AM (#44861341)

          Depends upon device/manufacturer. Some use fixed-resistance, but there's no agreement upon which resistance indicates which current. Others use a true computerized negotiation, but again there is no common protocol - and some manufacturers use that negotiation as a means to lock-out third party chargers by deliberately not disclosing the protocol, or even using cryptographic authentication.

          • by FatLittleMonkey (1341387) on Monday September 16, 2013 @05:26AM (#44861485)

            [sigh] So much for "Universal".

          • The "official" way is for the charger to short the data pins and then go into current limit if the device tries to draw more power than it can supply.

            Which could cause problems for a charge only cable if it's used with a host port that shuts down rather than current limiting when overloaded.

            • by cdrudge (68377)

              The "official" way is for the charger to short the data pins and then go into current limit if the device tries to draw more power than it can supply.

              I'll admit that I'm not an electrical engineer, but why would a charger need to current limit the power if the device tries to draw more than it can provide?

              That's like putting a restrictor plate on my car so that I can go faster then it allows me to go.

              • would a charger need to current limit the power if the device tries to draw more than it can provide?

                Because many chargers are connected to devices or power lines (110VAC etc) that can supply MUCH more power than the cable can handle. The wires inside a USB cable used for power are often 24 gauge which can only handle a relatively modest amount of power before they overheat. You need a charger that is smart enough to not exceed the limits of a USB cable even if the device is dumb enough to "request" that much power. Otherwise you could end up with a molten wire rather easily.

          • by AmiMoJo (196126) * <(mojo) (at) (world3.net)> on Monday September 16, 2013 @07:30AM (#44861807) Homepage

            Actually there is a standard, laid out in the USB Battery Charging Specification [usb.org]. 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.

        • by ThePhilips (752041) on Monday September 16, 2013 @05:18AM (#44861457) Homepage Journal

          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.

          Samsung's charger for the Galaxies simply shorts the data pins. (No, not the cable. The charger.) They do it as a way to recognize that it is a charger connected and allow drawing more power.

        • "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.

          Sometimes a device/cable combination can work in either way. They'll have some goofy resistances-between-pins coding scheme for dumb chargers; but they'll also do the official USB SIG power negotiation dance if plugged into an actual USB host. Of course, so long as you only want to charge the device, it just has to wor
      • by mcgrew (92797) *

        Is it even necessary? When I plug my phone into the wall (USB cable plugs into the wall plug) it just charges but when I plug it into a computer it asks me what I want it to do.

    • by Psyborgue (699890) on Monday September 16, 2013 @04:38AM (#44861357) Homepage Journal
      Also there are many phones that will refuse to charge *at all* without these pins.
      • by timeOday (582209) on Monday September 16, 2013 @10:01AM (#44862799)
        Wow, I got something useful out of slashdot today. I have always wondered why my wife's phone won't charge from the cigarette lighter -> USB converter in our car. Is there some term that is used to distinguish connectors with / without this functionality, so I can buy the right kind?
        • by JesseMcDonald (536341) on Monday September 16, 2013 @01:44PM (#44865025) Homepage

          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 [amazon.com], 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.

  • by _merlin (160982) on Monday September 16, 2013 @02:11AM (#44860819) Homepage Journal

    This wouldn't allow devices to detect fast charge capability, as that depends on resistances between data pins and power pins, or high-level protocol negotiation if it's an intelligent host with this capability. Devices will only charge slowly (100mA) if at all.

    • They can still try to draw 500mA and let the host cry. I don't know if they will, but wall chargers don't seem to have a complex protocol setup, I don't know how the do it.
      • by _merlin (160982) on Monday September 16, 2013 @02:27AM (#44860899) Homepage Journal

        All PowerPC Macs will current limit if they try to draw more than 100mA without negotiating, not sure what other PCs will or won't do (yeah, I'm out of date on that front). If a device is properly USB compliant it won't draw more than it knows it's allowed to. My Galaxy S3 is pretty quick to go into slow charge mode if it isn't sure it's allowed to go for more. Other reputable devices do the same - don't want to lose your USB logo certification.

      • by jamesh (87723) on Monday September 16, 2013 @02:34AM (#44860945)

        They can still try to draw 500mA and let the host cry. I don't know if they will, but wall chargers don't seem to have a complex protocol setup, I don't know how the do it.

        I had an aftermarket iPhone charger for my car that was a cigarette lighter adapter with a USB socket on it and then a USB to iPhone cable. One day I was in the office and needed to charge my iPhone and didn't have a charger so I grabbed the USB cable from my car. The moment I plugged it into my laptop, even before plugging the iPhone in, the laptop turned off. No damage. Being naturally curious I tried it again and it was repeatable.

        I'd go as far to say that some are basically brain dead

    • by inasity_rules (1110095) on Monday September 16, 2013 @02:30AM (#44860915) Journal

      Make the condom intelligent enough to pretend to be a phone, on one side and a charger on the other with no connection in between. I can't believe I just typed that sentence... Anyhow, I am sure you can get PICs with dual USB which would do that.

      • Some people have done this with programmable microcontrollers (ATTiny in USB host mode) for PS3 controller charging (they require negotiation to charge). Lost the link, but its pretty trivial to do.
    • by tjohns (657821) on Monday September 16, 2013 @02:31AM (#44860937) Homepage

      These boards have quite a bit of logic on them. If they were just cutting the data pins, that would all be unnecessary.

      The product page is light on details, but I'd be surprised if that logic wasn't there precisely to negotiate charge rate.

    • by Kjella (173770)

      Well why then is this a whole PCB with chips and not just a double plug with the data pins leading to nothing? I'd hope this one is smart enough to do the power negotiation in both ends, but without the physical capability to transfer data. But hey, lets be armchair quarterbacks and assume that whoever came up with this knows nothing about USB charging...

    • by TavisJohn (961472)

      Most phones do not care about resistance across the data pins. Just short them out and BAM fast charge!
      That is how I was able to trick my Epic 4g to work with my palm pre touchstone charger.

      There is no need for all the circuits and such... I made my own a while back out of a spare cable. I just opened the cable, cut the data wires. Than I shorted the data wires on the side that went to the phone. I sealed it all up and I can plug my phone into any usb port and it charges at the maximum output of the U

      • Why do these solutions need to be soo complex?

        Consistency? Not needing to have a specific cable for a specific phone? The USB spec with respect to charging is not incredibly complex, but it is there to give some consistency and assurance you're not going to destroy your device or computer, and still be able to charge at the maximum rate available.

        On a computer connected device, the client being well behaved is important- if every port draws the maximum available (before the on-board fuse triggers), there won't be enough current to go around, and can ca

      • Why do these solutions need to be soo complex?

        Corner cases usually. The power requirements [wikipedia.org] of devices plugged into USB are a bit unpredictable so it's more complex than many realize. I agree with you though. It seems like they are adding a bunch of needless complexity to make up for some poor initial design choices.

        As an example of poor design choices, it has always mystified me why they made USB a keyed connection instead of a reversible one. I'm not overly impressed with Lightning cables from Apple but one of the things Apple did right was to mak

    • by sjames (1099)

      I don't know if they do, but the condom could negotiate the charging current itself, then provide it to the protected device. Since the condom has no other function, it can be kept simple enough to not be exploited itself while keeping the device safe.

    • Actually, all the condom needs is a switch that when open, leaves D+ and D- connected to nothing at all, and when closed, shorts D+ and D- with each other. By definition, if the phone sees that the D+ and D- pins are shorted together, the device is entitled to draw 1.7A from the power supply.

      Officially, if D+ and D- are neither shorted nor able to negotiate for higher current, the device is only supposed to draw 100mA. In reality, everything I've ever seen besides Motorola's annoying phones ignores that rul

      • Very few computers actually have a switch to cut off current and can actively say 'no' - it is usually done with a thermal fuse- too much current, the fuse gets hot, goes up in resistance, limits the current to the device. The thermal fuses aren't meant to trigger as a matter of course- trigger it too often, and you have to replace it. For most people, that means replacing the motherboard.

    • by AmiMoJo (196126) * <(mojo) (at) (world3.net)> on Monday September 16, 2013 @03:27AM (#44861127) Homepage

      Actually you have been able to get "charge only" USB cables for years, and they fully support fast charging too. To enable 1000mA charging you just tie the D+ and D- lines together, so the charge only cables simple cross the over. Data comms fail but charging works fine.

      I bought a couple last time I was in Japan, and assume they will become available in the west eventually.

    • by CastrTroy (595695)
      That isn't even enough to keep my phone from discharging itself, although it will discharge slower. I've had this happen a couple times, where I had a faulty cable, or a plugged it into the wrong port on my laptop. My laptop isn't that old, and it still has unpowered USB ports.
  • Damn... I wanted something that would take all kinds of measurements and then later plug into my usb port.That would be real marketing brilliance. Speed, power, duration, ect. correlated with attractiveness.. that sounds like some useful data.

  • by chaboud (231590) on Monday September 16, 2013 @02:14AM (#44860841) Homepage Journal

    I've made my own, but you can buy them inexpensively. They're really convenient if you're, say, trying to keep devices from popping the VMWare Fusion Mac/Linux selection dialog or complaining about ejection.

    So, yeah, this guy made a board, but a cut-line extension cable has been the answer to this problem for a while. Some devices may fuss or trickle charge, but it generally works.

  • by Anonymous Coward
    An entire PCB filled with parts? This looks like an example of someone too smart for their own good. I just bought a dedicated USB charger wall-wart on eBay for 2$ and an octopus adapter cable so anyone who comes to my place can charge anything at all.

    This over-engineered nonsense in the article is ridiculous.

    • by Ford Prefect (8777) on Monday September 16, 2013 @04:34AM (#44861351) Homepage

      An entire PCB filled with parts? This looks like an example of someone too smart for their own good.

      The photo seems to be of this thing [int3.cc], which is an entirely different device which apparently 'allows a computer (or "host") to masquerade as a USB "device" to communicate with other USB devices or USB Hosts.'

      In other words, exactly the kind of device you wouldn't want to unknowingly connect things to.

  • Huh? (Score:4, Interesting)

    by juventasone (517959) on Monday September 16, 2013 @02:18AM (#44860863)

    Why does this require a big PCB with three ICs? Why not just simply remove pins 2 & 3?

    • Re: (Score:2, Funny)

      by Anonymous Coward

      Why does this require a big PCB with three ICs?

      Obviously for the circuitry to inject its own malware into the devices connected to it.

    • Power negotiation between host and device can be active. USB is only supposed to grant 100mA without proper negotiation.

      • Re:Huh? (Score:4, Interesting)

        by Darinbob (1142669) on Monday September 16, 2013 @03:12AM (#44861079)

        I don't have specs handy, but there's power management to consider. A port can be put into a low power or suspend state, where the device is expected to put itself into lower power mode and consume less than the 100ma that's on the power pins. So a two wire cable would not be able to handle this power management and would consume the whole 100ma when charging (not very nice if on a battery powered laptop).

        Additionally, I think some devices would need to actually enumerate correctly before they start charging normally. Ie, they won't consume 100ma to charge without being active. Most devices I think keep it as simple as possible so this won't matter for them.

        But I think the real reason for the condom is to negotiate basic info so that it can request 500ma for devices that want it.

        • Re: (Score:2, Informative)

          by snowgirl (978879)

          I had a boyfriend with a motorola phone... it absolutely REFUSED to charge if connected into an intelligent host, unless their special software were installed. It was a total pain in the butt...

  • After all, we've had power extensions for years!

  • by irp (260932) on Monday September 16, 2013 @02:22AM (#44860883)

    I've apparently made 'USB condoms' myself. A male and female usb connector soldered end-to-end, the data pins shorted together.

    This enables my ancient HTC Desire to recognize any usb charger as a dedicated charger, and charge with up to 1 A (in reality significantly less). It is a low tech solution that works.

    So why so much electronics on the board??

    • Re: (Score:3, Interesting)

      by phantomfive (622387)

      So why so much electronics on the board??

      Wow, you're not kidding. I just clicked on the link, and there is a LOT. With that much stuff, I'd be afraid it'd connect to the phone itself and send the data off to a remote server. It's definitely doing more than just cutting the data lines.

    • by thegarbz (1787294)

      So that when you plug your DIY USB condom into a port that was assembled with all the care that chinese typically apply to circuit protection you don't set your house on fire.

      You have a specific solution that works in a specific scenario. Can't blame you I actually did the same here to get my phone to charge faster. But your solution wouldn't work with all devices and the reasons that power negotiation is such a retarded clusterfuck in the USB spec is because of the great variety of different USB ports whic

    • Shorting together data pins prevents iDevices from charging properly. A 10nF capacitor between them is a better choice.
  • by enoz (1181117) on Monday September 16, 2013 @02:30AM (#44860919)

    In the standard A and B plugs the data pins are recessed compared to the power pins. Grab any standard cable and you can slide it in until the power makes contact, giving you charging without any data connection.

    I've been doing this for years to charge a MP3 device without it being mounted by the host computer.

  • Could inductive chargers be considered a diaphragm?
  • by ericfitz (59316) on Monday September 16, 2013 @02:37AM (#44860967)
    There's a current KickStarter project called LockedUSB [kickstarter.com] 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)
  • ...so that it doesn't automatically execute/autoplay/file-connect/whatever when the hardware is plugged in?

    • by seebs (15766)

      Except that "automatically connect" is a primary requirement for a sync cable. And sure, in theory that doesn't mean automatically executing, but software has bugs.

      The current behavior of phones is probably right for 99% of their users. Makes more sense to solve the special case specially and get the default case right, I think.

    • by smash (1351)

      May be more difficult than that. You'd need to guarantee that the implementation of the protocol it talks to a host PC by is defect free. Which may be difficult to do.

      It's probably easier and more provably secure to just "firewall" it in hardware.

  • When I first got a Playstation Vita (What? Why is everyone laughing?), I had a USB battery to charge it on the go - but it wouldn't work! Of course, Sony said that it would only charge from their own Vita power bricks, but that was obviously just PR - it was just a USB A connector on the business end, after all. After some investigating, I found out that the Vita checks for shorted data pins, and if it doesn't find them, it won't charge (unless it's connected to a PS3 or computer.) Other products use dif
  • by TuringCheck (1989202) on Monday September 16, 2013 @04:07AM (#44861265)
    A capacitor connected between D+ and D- lines will block any USB negotiation and data transfer without interferring with the DC levels used to "negotiate" charger capacity.
  • From the "Same same, but (very) different" Dept. there is this little Kickstarter project:
    http://www.kickstarter.com/projects/david-toledo/the-practical-meter-know-your-power [kickstarter.com]

    Actually, it is twofold, there's the "Practical meter", which shows how much power is drawn, and then there's the three tipped charging cable with built in circuits enabling a device to draw more power from sources that supports it.

  • Hmm, if that's a USB condom, then I guess some of my devices came with a USB ePeen enlargement.

    I can't remember which ones that came with the "changing only" cable, anyhow, I also remember some of them wanting to change more for a "data cable".

    I'm pretty sure one was my Garmin GPS device. It will not charge without the cable it came with: The "charging" cable has a resistor from a voltage line to one of the data lines, and refuses to charge without it (even when connected to a PC and transferring data

  • I've built workstations intended for connection to library systems, and one of the airgap security measures I've employed was to cut the data conductors behind the USB port*. OK, it's permanent unless you're really handy with a soldering iron, but you'd have to get around the keybolts holding the case together first...

    *Recent innovations in workstation motherboard design have done away with PS/2 ports for keyboard/mouse, the way around that is to use a quality keyboard/mouse and hardwire those suckers.

    And t

  • by oneiros27 (46144) on Monday September 16, 2013 @07:05AM (#44861745) Homepage

    I've been in airports, and had people w/ just a USB cable ask me if they could plug into my laptop to charge ...

    Luckily, as I usually fly southwest, the two times it's happened I was able to point out that there was USB charging available from their power points.

    (when people think I'm mean for not sharing power in other situations, I'll break out the 'It's not how many USB sticks you plug into your laptop' PSA reference) ... I'd love for USB sticks to bring back the hardware write-only switch.

    Personally, I wouldn't need one of these 'til my current phone dies -- WebOS will assume charging only unless you specifically enter your passcode to allow it to function as a USB disk when you plug it in.

    • by Lumpy (12016)

      My response is, "my battery is almost dead, I cant." it usually shuts them up. and honestly if they are travelling and too stupid to carry their charger, their own fault for draining the phone to dead in such a short amount of time.

  • Blocking the data pins means it will not charge at anything more than the 100ma trickle. you NEED the resistance devider on the data pins to tell the phone/tablet that it is a high current charger and kick it into high gear.

    Note: you have been able to buy a $1.99 device like this that DOES enable high power charging for well over 4 years now. IT's an iphone USB charger adapter adapter. little usb plug or 6 inch cable that adds the resistor network to fool the phone to charge at full speed.

    Nothing new he

  • My N900 requires confirmation on the screen to grant data access to USB host devices, so this thing isn't useful for it or any device which has this important feature (like even a Blackberry). What it will do is prevent the charging power from being negotiated.

    • Yes but these days nobody trusts science so even if your phone says it locks out data access through the USB and sets your phone to charge only on the USB cable most people still think the High Wizards of NSA have some way of overriding that the instant they detect your phone plugged into a data port.

      Remember, the NSA has unlimited resources to force every phone manufacturer and OS vendor to provide back-doors so they can monitor billions of devices in real-time on the off chance a stupid terrorist is trans

  • I am sure there are situations where someone might need to plug in their phone in a random place for that important call, but I mean, someone leaving their home with a 1/4 charged phone before heading out on a business trip is probably going to forget their condoms too.

    No glove, no love, period.

  • "It's one of those simple solutions that seems so obvious once someone came up with it"
    Also it already exists and I've had one for years. It's called a "power-only" USB cable. There are many manufacturers of them in the world.
  • So now the arms race escalates to USB ports that cut holes in the USB Condom so the contacts work again, and they can go back to sucking down all your data.
  • by dido (9125) <dido@@@imperium...ph> on Monday September 16, 2013 @10:33AM (#44863119)

    Their domain int3.cc is an allusion to the one-byte software interrupt instruction [wikipedia.org] on 16-bit x86 systems. Opcode 0xCC disassembles to int 3, and it's most frequently used by debuggers, which patch a single byte of code with it to make a breakpoint.

  • This won't work for devices that insist on using the USB charger protocol to negotiate higher currents from the power supply. For those that will still work without the data pins present you'll be charging much slower with the 500mA default limit.

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