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Your USB charged devices can be attacked through the USB port while charging. This has been demonstrated at Blackhat 2013 (https://www.blackhat.com/us-13/briefings.html#Lau,http://www.extremetech.com/extreme/157207-black-hat-hackers-break-into-any-iphone-in-under-a-minute-using-a-malicious-charger) and documented on the web under the general term "Juice Jacking". See for example: http://www.zdziarski.com/blog/?p=2345.

How can we protect ourselves against malicious public charging stations or cheap iphone chargers sold on chinese websites? One of the answers is to make a USB cable which can only feed power to the USB device without any ability to transfer data. This is suprisingly easy to do so let's get starting!

Step 1: Shopping List and Tools

We will need:

  • a micro USB cable which has a micro USB plug at one end and a micro USB socket at the other end. Purchase at your favorite chinese vendor.
  • duct tape

Tools & skills:

  • paper cutter
  • l33t cable surgery skills :)

Step 2: The Incision

We need to make a short incision along the length of the USB cable using the paper cutter. It can be a bit tricky as you need to be careful not to cut the USB wires and at the same time cut through the whole insulation which can be thick.

One way I found that works is to first make a shallow cut and make it gradually deeper until you can feel the knife moving smoothly when it's tip gets to the empty space between the insulation and the wires. In case you are not sure you can do this properly take some old keyboard or mouse cable and practice.

Also, it's good to buy two USB cables so that you won't have to wait for a new one when you make a mistake. They are dirt cheap so it's a good idea to have a backup.

Step 3: Open and Inspect

Open and inspect the cut to see if the USB wires that we care about are not damaged. We have to leave the red and black wires as they provide the power. The other wires (white and green) are the data lines.

Step 4: Cut the Data Wires

Simply cut the data wires leaving the power wires intact.

Step 5: Finish Up

Seal the incision with a bit of duct tape.

Step 6: Test

Connect the device to your PC using the cable you've made. If the device starts to charge but the operating system doesn't see the new device plugged in your cable works! How to check if your operating system detects the device or not?

<p>&quot;White and purple&quot;? I have to ask, and without meaning any offense, <br>does the author of this post suffer from any sort of colorblindness <br>issues? The fourth wire in a standard USB cable is <strong><em>green</em></strong>, not purple, and in fact the image right above that text clearly shows a green wire sticking out of the sliced-open cable.</p><p>Perhaps it was merely a mistake, but regardless &mdash; for anyone following this guide, &quot;purple&quot; should be &quot;green&quot;.</p>
I do suffer from colorblindness. Already fixed the guide, wikipedia also mentions the standard data cable colors as being green and white https://en.wikipedia.org/wiki/USB#Pinouts<br>Thanks for the heads up :).
<p>I thought that might be it. :-) My dad dealt with that. &quot;Are these socks black or brown?&quot; &quot;...They're navy blue.&quot; &quot;Oh.&quot; Happy to help! (I can't believe nobody mentioned it for 2 years...)</p>
<p>The USB standard provides for notifying the device that it can fast charge if it sees that the data pins on the device end of the cable are shorted together. Apple is non-standard in this respect, but rewiring cables this way has worked with all my Android devices (4 Samsung phones and 2 Amazon Kindle Fires).</p><p>Yes, the Fire is an Android, just stripped of Google Play - which can be added back in on 5th generation and later Fires - go to XDA Forums at <a href="http://forum.xda-developers.com/amazon-fire/general/how-to-install-google-play-store-fire-t3486603" rel="nofollow"> http://forum.xda-developers.com/amazon-fire/gener...</a> and download and run the four apk installation files there - a tip of the hat to the eBook Reader Blog for that link).</p>
<p>I followed these steps, but my Garmin devices (GPS and dash cam) still somehow go into 'mass storage' mode. I also tried insulating the two central contacts on the large USB socket, which also failed to work. One thing that did work is a hack attached as a pic - problem is that it's really fiddly and is unsuitable if you plug the device in/out often because the wire 'jumper' gets lost.</p>
<p>Very cool and props on the l33t skills :-) will apple products give the stupid &quot;not certified&quot; error - any idea?</p>
<p>I thought &quot;certified&quot; was only for Lightning cables, or Lightning-to-USB adapter cables? You definitely don't want to try this hack with a Lightning cable, even if it's USB on one end.</p>
<p>I do not know, I don't own any Apple hardware. If I will meet someone who has though I will try to remember to check.</p>
<p>The four resistor thing is for apple devices. The direct connection of data wires was the chinese makers who started this whole fast charge thing off so the europeans had to change it and added a 200 ohm resistor. A 200 ohm resistor should be ok for the early chinese standard, the direct connection would probably be ok to charge on most set ups, but perhaps not all. As an aside some phones switch wifi off when charging but you can fool your phone by using the 200 ohm resistor cable and it will still work. <em>Important- the resistor (200 ohm) is phone side of the cable, the matching two wires on the supply side should *not* be connected together. Only connect the resistor side of the cable to a phone, never to the USB supply.</em></p>
<p>useless info</p>
it took 3 months to decide the information is too technical for you? Just move on and buy a 50 cent cable off ali without understanding if that's what you want.
Apple phones will need some array of resistors.
Samsung Galaxy S2 requires D+ and D- to be shorted in order to charge at full power (battery usage should show AC)
<p>Interesting comments about the additional components needed.</p><p>A few years back, I bought a couple of those multi-purpose power supplies which have the changeable power connectors to suit most laptops. They also have a USB power out as well, with a range of power connectors, which meant I had a couple of micro-USB plugs. I recycled an old Palm charger and a 5 volt power supply from some long gone device into phone chargers. They just have the two wires for +5 V and 0 V.</p><p>They work fine with all our phones which are Samsung, HTC and Nokia, which range from a year or two old to about four or five years.</p><p>The Palm charger seen below has been &quot;double&quot; adapted: It has a Euro adapter super-glued over the US pins and a micro-USB plug on the cable. The Palm fell apart about two years ago.</p>
<p>Proste a zarazem genialne w swojej prostocie ;)</p><p>To jeden z powod&oacute;w dla ktorych uzywam mojego power banku kiedy jadę gdzieś. Lepiej nie ufać darmowemu ładowaniu smartfona w galerii czy innym miejscu</p>
<p>good looking hack.</p><p>connecting D+ and D- of device side may enable highspeed charge.</p><p>some device requires appropriate pullup/pulldown of shorted D+ and D-.</p><p>for galaxy tab, 33k ohm to Vcc and 10k ohm to GND, resulting D+ and D- at 1.16V.</p><p>but be aware: power source without appropriate current limit circuit may burn.</p>
very good way for protection..if i rememver correctly..some mobiles do need a voltage at data pins also ..so we use a 100ohm resistor on data pins
most android phones need this
My phone (Samsung Galaxy Nexus) doesn't seem to require that and charges OK.
<p>Do you have the values of R1..R4?</p>
R1=75k ,R2=R4=51k,R3=43k
<p>I love this! Simple soluition to a complex problem. </p>
<p>Nice little trick! Thanks for sharing this. </p>

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