My Nexus 4 screen met a tragic end due to violent contact with flooring tiles. Everything works except the touchscreen (which displays fine but does not react to touch any more).

I would like to get a full copy of my data partition, but my device uses Full Disk Encryption, with a lock pattern. I can easily get image files of my partitions from CWM recovery through adb:

adb pull /dev/block/mmcblk0p23 ./userdata.img

which gives me a nice 6GB file, but mounting this image is another story since it is encrypted. My PC uses XUbuntu (I also have Windows at hand if necessary, but I guess a linux system is more useful here). My phone is rooted.

I know my unlock pattern of course, so there should be some way to mount/read my userdata.img file. Any pointers ?

Thanks !

I can confirm with 100% certainty that the numbers are indeed 1-9 for the pattern unlock.

My Nexus 4 met the same unfortunate end (except on concrete) and after some Googling, I found this post and was able to follow personne3000's answer in order to mount my pattern-encrypted userdata partition.

I'm running Ubuntu 15.04 x64 and had to apt-get install android-tools-adb android-tools-fastboot in order to continue the procedure.

My pattern is this (3x3 in order from 1-6):

[_   1   2]
[3   5   6]
[_   4   _]

Booted my phone to recovery from bootloader by running fastboot boot twrp-2.8.7.0-mako.img, and then when TWRP loaded, ran adb shell twrp decrypt 234856 and it successfully mounted my encrypted userdata to /dev/block/dm-0.

My 234856 decrypt password, ordered from 1-6 starting on the left, correlates to the positions on the above pattern grid, where '2' in the password correlates to '1' in the grid.

@Rhaegar Android sees the pattern as 0-8, because those are the bytes it uses when generating the SHA-1 hash for storing the pattern (http://www.cclgroupltd.com/a-rainbow-table-for-android-pattern-locks/), but TWRP sees the pattern as 1-9 when decrypting the userdata partition from the command line.

Huge +1 to personne3000 as without him providing that highly valuable information straight from TWRP devs I would not have my Android data right now.

I <3 Stack Exchange :)

  • While this would work for 3x3 pattern, it wouldn't work for more complext patterns> Please see the following link if you are trying to decrypt a 4x4 or higher pattern twrp.me/faq/openrecoveryscript.html – Ramast Jun 22 at 22:06
up vote 3 down vote accepted

Apparently there is no tool on PC to decrypt Android's encryption at the moment, but the TWRP recovery can be used on the device to decrypt everything... Even with a broken touchscreen, as long as your device is supported by TWRP recovery:

  • Download the TWRP image (2.8.7 worked for me)
  • Boot into fastboot (power + vol. down on Nexus 4)
  • Start the recovery, from your PC:

    fastboot boot twrp-2.8.7.0-mako.img

  • Once you are in the recovery, you can decrypt your data from the command line:

    adb shell twrp decrypt yourpassword

where yourpassword is your encryption password. In case of schema, translate it to numbers:

1 2 3
4 5 6
7 8 9

if you go through the same point twice, it is ignored after the first time.

Then it will tell you that your decrypted data is available in a block device, I think this was /dev/block/dm-0 for me (not sure). You can back it up to your PC with:

adb pull /dev/block/dm-0 ./decrypted-data.img

And finally, mount the image as ext4 on your Linux PC ! (or use some program that can read ext4 partitions on Windows).

HUGE thanks to the TWRP folks on IRC who told me about the twrp decrypt command !

  • I think the pattern starts with 0 and ends with 7. – Rhaegar Oct 6 '15 at 16:55

A much simpler version: Connect a USB mouse (or keyboard, but that didn’t work in my case), using a standard USB-OTG (OnTheGo) cable, and use the appearing pointer like a finger, to tap in things.

This even worked inside of TWRP for me!

From there on, the whole endeavor should be much easier. :)
(Like just copying the files over, the regular way, and syncing PIM data to your hopefully existing personal “cloud”.)

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