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Comment by x0x0 | Hacker News Reader

(I'm not an engineer). I a similar article; iirc android phones could be owned by plugging them into a hostile usb connection. I wonder, though, if you couldn't produce a simple adapter that just drops some of the pins? Maybe I don't know enough about usb.

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You can buy just such an adapter from the link below; Version 2 is in the works, which will include a microprocessor to allow for full-power charging.

http://int3.cc/products/usbcondoms

thank you jdietrich

Speaking as someone who writes embedded software using USB stacks for a living, there are a number of solutions to this. Your solution is possible, and is how many iPhone USB charging cables are designed. If limited communication is required, the device being charged can also contain a separate processor for the interface. The ideal solution is for the device to contain some security measures, to prevent these issues; this solution is also the least versatile or most costly depending on implementation, and may not be achievable.

You can make a power-pin-only USB connector, but I believe that precludes requesting high-current mode (i.e. you are stuck in 100mA mode)

Most hosts will provide at least 500mA without any signal from a device. Hosts and chargers vary in their current capability; those capable of providing more than standard USB spec vary in their implementation. In general, high current hosts always provide their full capability, and the devices are the ones which require some signal to indicate maximum current available. Other devices increase their current draw until the host's voltage drops, and hold at that level (or less).

Ok, so maybe I had it backwards which way the communication goes.

I wouldn't say you got it backwards, the communication is bilateral, but the device is the unit which controls current flow; the effect is the same.

Yep they make charging only cables and I THINK adapters as well, I quit looking after the first find: http://www.amazon.com/Retractable-Micro-Charging-Cables-FUNC...

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