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I have a 3rd Gen Moto G that I just enabled encryption on. It showed the warning as usual, "make sure it's plugged in, this will take an hour or more", etc. However, after confirming this, the phone rebooted itself, asked me for my pin so it could "boot android" (even though the boot splash screen had already displayed), and then showed me my home screen.

The issue: this whole process took less than a minute. Now, granted, the phone has only 3 lightweight apps on it (aside from the not-very-bloatware-like stuff motorola put on there), plus android standard things. There's also a few albums of music on the 32GB SD card; perhaps under 2GbB.

Less than a minute is not an hour or more. Did the encryption actually happen? The device THINKS it is encrypted; it tells me so in the settings menu. If not, what next steps should I take?

This is android 5.1.1.

I just came across this right before I posted: Device encryption fails, but no error

My device IS plugged into a computer, but through a power-only cable. There is no data connection. Not sure if that matters; I'm not sure I can do anything about it anyway, because the phone says it is encrypted already.

Thanks!

migrated from superuser.com Sep 2 '15 at 11:50

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    AFAIK, the external SD card won't be encrypted, only the internal storage; encrypting only three small apps probably would only take a minute. – user43185 Sep 2 '15 at 12:00
  • In Android 6.0, the external sd card can be setup to include internal storage -- but even then it appears to not encrypt it (either that, or silently fail) -- I've got 50 GBs of data on this phone, and the SD is setup as internal storage, and it still encrypted in under a few minutes. -- The whole reason I wanted encryption was for the sd card. This feature is very misleading. – BrainSlugs83 Jul 27 '16 at 16:55
  • In my Xiaomi MI 5 (Marshmallow), it took me like 10 seconds, without even rebooting. I had Zenfone 5 (Lollipop) before, and the process would take around 10 to 15 minutes while the phone is rebooting. Granted, I encrypted my previous Zenfone 5 after 2 years of usage, while I encrypted MI 5 just right after I bought it. – Ghasan Feb 4 '17 at 5:53
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Android encryption is of two types:

  1. Device Encryption
  2. SD-card Encryption.

For Device encryption kernel DmCrypt layer is used and it encrypts "/data" part of the device.dm-crypt is a transparent disk encryption subsystem in Linux kernel versions 2.6 and later and in DragonFly BSD. (see https://en.wikipedia.org/wiki/Dm-crypt).

Prior to android Lollipop, android device encryption encrypts full "/data" partition. (Encryption is basically a mapping system , it maps all memory from real "/data" block to a virtual block device).

Prior to Lollipop, on some devices(like samsung devices) fast encryption was also supported. Fast encryption means it will encrypt only used partition of your "/data" partition. (i.e. it will map only used parttion). If you will copy any data after encryption, it will be encrypted on runtime and saved on the device.

From Lollipop, google uses default fast-encryption. that means , whenever you will trigger encryption, it will encrypt only your used "/data" partition.

You have mentioned that phone was almost blank, hence it was completed within one minute.

AFAIK google has also changed its encryption system in lollipop and it is much faster than kitkat.

Check this link for more information: https://source.android.com/devices/tech/security/encryption/

You can enter your SD-card on other device and check your files ( these will not be encrypted).If these were encrypted, you will not be able to play on different device.

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    It suddenly occurs to me that I may have moved 2 of those apps to the SD card before doing Encryption. If Android only encrypts the data partition, that makes sense....there was less than 10 MB to encrypt! Thanks for the clear answer! – Russell Uhl Sep 2 '15 at 14:04
  • In Android 6.0, if you setup the SD card as internal storage, you already can't use the SD card on another device -- so why doesn't encryption allow you to encrypt the SD card and give you a virtual block device like it does for /data? -- Is there any way to set this up for a rooted device? – BrainSlugs83 Jul 27 '16 at 16:58

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