USB Condom: charge your devices without allowing sneaky data-transfers


Originally published at:


I have a beef with the mentioned item: How do I pocket it without damaging it? It's a raw PCB!

Fortunately, there's competition, producing something more pocket friendly in Apple and non-Apple versions:


What are the extraneous components ((R1, 2, 3) for? The product description says it's just a USB passthrough with the data lines clipped - so why are those resistors there?


Newer Apple devices require a voltage level on the data pins or the device wont charge. I just modified an old iPod docking station to accommodate my iPhone 4 for that reason.


I have these, they seem to work very well, and do speed up charging of a computer and the like (computers may be too smart for your own good, and cut your phone down to the 2.5w spec of usb 2.0, when it could handle 10+w).


Voltage divider for Apple stuff -- they expect a certain voltage on the data pins. Makes DIY chargers a pain.

Edit: didn't notice that @vector had responded to ya... I need to quit posting from my phone.


You aren't likely to damage it by carrying it around with your pocket change, but you'd probably tear a hole in your pocket lining. Corners of PCBs are hell on fabric.


Why is this a circuit board?

Wouldn't a little flat piece of plastic, custom-cut to block the data pins, be far more elegant, affordable, and a better fit for the condom comparison?

ETA: ohhh, Apple crap. I'm little inclined to design accessories around the whims of devices that refuse to play nicely with others.


Xipiter, the security consultancy who created it, has already done one production run and shaken out the bugs, so it seems likely that they'll be able to fulfill orders again -- but as with all crowdfunded projects, caveat emptor.

It looks simple enough. I would probably play it safe and put in $5k as a starting point, even if you know what you're doing for a small batch electronics production run.


As far as I've followed the issue it's actually Apple that plays nicely by following the USB spec by not simply drawing beyond 100 mA without negotiation.


The final product has a clear shrink wrap over the printed circuit board for protection and to prevent snags.


There is no negotiation for a device that only charges stuff...
From what I recall when making a DIY voltage supply/charging station, the charging standard just requires shorting the data pins with a resistor -- Apple has a completely different scheme for supplying a certain voltage to each data pin (the voltage on the data pins tells the iPhone/etc what sort of current the charger can supply).


Yes, but that is a relatively recent addition to the standard as a reaction to non-compliant dumb devices.


Not that much malware is targeting these devices, but it's baked into the new builds of WP8.1 I guess:

It's not hardware though.

[Insert Obligatory Anti-Microsoft Verbiage Below Here]


A new cased version of the USB Condom is coming out soon. An official announcement in a few days ...


At least you're keeping it charged. :smiley:


So how is this different from the $8.99 "fast charging" no-data cable in Cory's link, or the $6.99 tiny "fast charging" no-data dongle in @kpkpkp's post?

Why Kickstart something that already exists, for more money? Do people think it's different because it's marketed as a "condom?"


A few other bits and pieces (I know that I have this problem with an older Motorola dumbphone, and that it isn't terribly rare; but I don't know of a comprehensive list of device behaviors) expect various fiddly oddness on the data lines when connected to a charger.

Sometimes it's pure lock-in, or an attempt, some times I think it tells the device something about the current capabilities of the charger. Inelegant; but cheaper than throwing a whole USB host into a wall wart I suppose.


This reminds me of a post I made quite some time ago:

plus ça change!


Well, if you're extra-vigilant about protection, you can both visually inspect the entire circuit, and test the broken-out pins to confirm nothing dodgy is happening. Not possible with devices encased in (likely Chinese, with its implications) plastic.