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So I want to encrypt my phone and my SD card. What are the precautions should I have?

What if my phone doesn't work anymore. Can I restore the data again? What should I do in order to make sure that if the phone doesn't work or anything goes wrong I can decrypt the data and not lose it?

I have samsung galaxy note 3.

Thank you.

The Quantum Physicist
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2 Answers2

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Before encrypting you should:

  • Ensure all your contacts are associated with, and synced to, your Google account. This can be verified by viewing your contacts online at https://www.google.com/contacts.
  • Your photos and other media are backed up. Photos and videos can be automatically saved with the Google+ app. Any other files/data can be saved to your computer by connecting the Android device via USB and copying them over.
  • Make note of all installed apps.

You can’t reverse encryption on Android devices. If you decide you want a decrypted device you will have to perform a factory reset at which time all your data will be removed and lost. In addition, if the encryption fails or doesn't complete partial or full data loss will occur (the most common reason for this is power loss during the encryption process).

  • Thanks for the response! So there's no way I could use a key to decrypt the SD Card, for example? Isn't this crazy? – The Quantum Physicist Sep 27 '14 at 10:31
  • @TheQuantumPhysicist It is crazy from a practical standpoint, but the encryption alters the data and phone process flow in such a way that it makes it hard to simply roll back. It is also an additional security measure to not allow total decryption. As for a key; you would have one that needs to be entered every time you use your device (an annoyance for me personally). –  Sep 27 '14 at 15:25
  • Entering the password every time for the SD card is not a problem. But the problem is if I would like to decrypt the SD card in some other device... You're saying that is impossible... This is just crazy... For example, in Linux, you get a key that you can use to decrypt your HDD from any other device ... I wonder why Android doesn't do the same!!!!! – The Quantum Physicist Sep 27 '14 at 15:39
  • Actually you probably can do that; I will make it clearer my answer. Most devices now have two options for encryption (internal and external). The external can be turned off for moving to another device –  Sep 27 '14 at 15:53
  • Actually turning off encryption doesn't provide a universal solution. What if my phone broke and it doesn't work anymore? A decryption code, like linux does, solves this problem. But the way Android does it is so stupid! Don't you think? – The Quantum Physicist Sep 27 '14 at 16:12
  • It certainly has its challenges! –  Sep 27 '14 at 16:17
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Based on the comments from the accepted answer, it looks like you're wanting to backup the key used to encrypt the internal and/or external storage. It is likely possible that you can backup both of the encryption key(s) if you can get root using dmsetup. If you have backups of the encrypted block devices and have the key, you can access the decrypted files on a linux system supporting dm-crypt.

In order to do a backup of the internal storage block device, you'll need to have the bootloader unlocked to use TWRP or be rooted. If you relock the bootloader, userdata will be wiped, and I suspect a new encryption key generated, so be careful of that.

There's also an alternative method for getting the encryption key for the external storage, root needed as well.

crass
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