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QUESTIONS

  1. How can you set different passwords for file-based encryption of different files in an Android version that allows file-based encryption?

  2. As a corollary,* how can you set a file-based encryption password that is different from the screen lock password?

*I am saying that the second question is corollary to the first because if you have two or more passwords for encryption then at least some of them would of necessity be different from the screen lock password.

I would like the answer to refer to (a) methods (for 1 or 2) generally available in any Android version, (b) if no such methods exist, any method available for a particular version (e.g. Lineage) or brand of manufacture, (c) if no such version or brand exists, any method through a third party app or command line hack, or finally (d) state that there is no method to achieve 1 or 2.

BACKGROUND

The questions amount to asking what the implementation of the following statement (from this android.com page) actually looks like.

Android 7.0 and later supports file-based encryption. File-based encryption allows different files to be encrypted with different keys that can be unlocked independently.

What I (perhaps naively) expected was to see handy Settings items for choosing groups of files and assigning them different passwords or at least a Settings item for assigning an encryption password different from the screen lock password.

What I instead found:

  • My Samsung phone running Android 11 has a Settings item called "Strong protection" (which I understand is the reference to the file-based encryption). It can only be turned on or off. The blurb for it goes, "Encrypt your phone using your secure lock type (pattern, PIN, or password)." I found nothing else in Settings relating to an encryption password.
  • The statement that setting an encryption password different from the screen lock password was "no longer possible" with file-based encryption, as found in this post.
  • No guide out there on the Internet on how to set different passwords for different files or an encryption password different from a screen lock password (other than what looked like a hack, used a third party app, or was three or four years old).

So it seems:

  • There is no practical way to separate encryption password from screen lock password in Android (as of version 11) to say nothing of setting different encryption passwords for different files.
  • The old complaint about having to strike a balance between security (from a long encryption password) and convenience (from a short screen lock) still remains.

LATER ADDED

As for the request appearing at the top of the post, i.e.

Your question has been identified as a possible duplicate of another question. If the answers there do not address your problem, please edit to explain in detail the parts of your question that are unique.

The linked post is about separate encryption vs. screen lock passwords. This post is about multiple encryption passwords (the encryption vs. screen lock part of it arising only as a corollary). I don't see how the two questions could be conflated, but there it is.

Thanks for the comments tending to say that multiple passwords are either not possible or not to be encouraged.

If so, how should I square away the apparent contradiction with the statement from android.com, i.e.:

Android 7.0 and later supports file-based encryption. File-based encryption allows different files to be encrypted with different keys that can be unlocked independently.

Maybe comments might suffice on this contradiction. If this must be a separate question, please advise. I am willing to remove the 'contradiction' bit to a new post.

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  • Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer.
    – Community Bot
    Nov 7, 2021 at 10:26
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    That's not possible. Storage encryption is cryptographically bound to screen lock code. You can use file manager's vault to further encrypt your personal files with different vault PIN.
    – defalt
    Nov 7, 2021 at 11:00
  • @alecxs Because you shouldn't believe everything you see on a random page? Because the statement from android.com patently contradicts it? Because things might have changed?
    – Catomic
    Nov 7, 2021 at 11:03
  • @Community Can you explain what is not "specific" about the question? "How can you set different passwords for different files?" Maybe there is no way to do it, but that does not mean the question is not "specific." I think you must have some other request in mind. If you express it, I will consider it.
    – Catomic
    Nov 7, 2021 at 11:14
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    Android file-based encryption only knows two types of files: Those that are encrypted by a key bound to the user login password and those that are not bound to this password (but still encrypted by a key in the Gatekeeper). On a rooted device you may be able to apply custom Linux encryption to other partitions but I would not try to do this with the user data partition as this would interfere with the standard Android encryption.
    – Robert
    Nov 7, 2021 at 11:19

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