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join our online communityThe process of removing
encryption will wipe your
device, so you need to back up
fi rst, ideally using an encryption-
compatible recovery image such
as TWRP. Custom recoveries
back up the content of a
partition rather than the binary
image, and this means that they
can be restored later to an
unencrypted partition.Nexus factory images
are normally updated
around the same time as OTA
updates fi rst become available.
They are available to download
from https://developers.google.
com/android/nexus/images- take care to download the
correct image, particularly where
Wi-Fi and mobile variants of a
device are both available.
Device encryption in
Lollipop happens
immediately on fi rst boot on a
wiped device and is confi gured
using a fl ag in the boot image.
Custom boot images are
available for download in
forums such as XDA-
Developers.com that change
this fl ag and are fl ashed using
the fastboot tool.The factory images are
in a tar.gz format and
these will contain the images
themselves (in a ZIP format) as
well as the fl ashing scripts. As
you will be fl ashing manually
without using the scripts, you
will need to extract the ZIP fi le
as well as the main archive in
order to fully access the bare
images for your Nexus.Be aware that on an
unencrypted device, if
you accidentally fl ash a normal
boot image (either manually
fl ashing an update or by applying
an OTA), then the device will
automatically re-encrypt itself
when booting up and you will
have to repeat the process! Only
fl ash updates with similarly
patched images.Now that you have your
device in bootloader
mode, you should fl ash each
partition in turn as detailed in
the fl ashall script. The only step
you want to skip here is the
‘fastboot format userdata’ step
because this is the part that will
end up wiping your device!
Reboot with ‘fastboot reboot’
when you are done.Back up with a
custom recoveryDownload the
factory imageFlash a custom
boot imageExtract the fi les
from the imageAvoid accidentally
re-encryptingManually fl ash the
partitionsA
ndroid devices have supported full
device encryption for a number of
releases now, protecting user data
from even the most concerted of thieves.
Android Lollipop, however, takes this a step
further with full automatic encr y ption for all
users (much to the chagrin of law
enforcement). It even includes a PIN unlock
prompt as soon as the device powers on. The
downside of this is that the extra processing
power required to encrypt/decrypt data
when the dev ice is in use slows the read and
write speed, meaning there is an overall
performance hit. Different Nexus dev ices
seem to be impacted in varying degrees by
the change, but generally if you do disable
the encryption there will be some benefi t.O
ne of the key benefi ts of a Nexus
device is that they are normally the
fi rst to receive new operating system
versions. There is a catch though – as w ith
Play store downloads, Google employ a
staged rollout for the updates, meaning that if
you are unfortunate enough to be in a late
batch, you could end up getting the update
weeks later than other Nexus users.
Frustrating to say the least! Don’t worr y
though; there is invariably a way to update
your device manually, either by manually
using ADB and the OTA update fi le itself or by
using the latest factor y images. This approach
normally wipes the dev ice, but you can
prevent this happening by slightly tweaking
the fl ash process.NexusupdateswithoutOTA
Boost performance in Lollipop
The Lollipop version of
Android encrypts
dev ices by default, but it
does this at the expense
of performanceGoogle employs
staggered rollouts for
OS updates which can
be frustrating, but
there is a faster way1
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