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I'm looking for a solution that would allow to encrypt external microSD card with the following conditions:

  • external microSD card is not merged with the internal storage;
  • encrypted external microSD is mounted upon booting automatically;
  • content of an encrypted microSD card can be viewed in another Android device and Windows/Linux PC if the smartphone where this card has been used was physically destroyed beyond repair.

The motivation behind these criteria stems from my workflow on a desktop computers. All of them have both system and storage drives fully encrypted with VeraCrypt. I set them up in a way that I enter a password upon booting once, and all the favorite volumes are automatically mounted and I boot into fully functioning system. On the other hand, if for some reason I cannot boot anymore (e.g. missing or corrupted system drive), I can take off the encrypted data drive, plug it into any other machine running Windows/Linux/MacOS with installed VeraCrypt and decrypt my files in no time.

However, I cannot achieve the same with the default encryption offered by Android. To encrypt the SD card, one must merge it with the internal memory, and if the device fails to start, there is no easy way to recover/decrypt my data from the external card.

I searched Google Play and couldn't find any third-party app similar to VeraCrypt.

There are related topics, but I couldn't find an answer in any of these either:

I'm using a rooted Moto G5s running Android 8.1, but a vendor-independent answer would be more preferable.

  • Are you looking for a non-root solution or just for rooted devices? – alecxs May 20 at 13:02
  • maybe here is what you looking for? alternativeto.net/software/luks/?platform=android android is basically linux. you can compile your own static binaries for arm architecture with Linux Deploy google.com/search?q=cryptsetup+android – alecxs May 20 at 13:28
  • @alecxs Personally, I all the devices I use are rooted. If the there is a solution for the non-rooted smartphones the community can benefit from, this would be ideal. – andselisk May 20 at 13:42
  • @alecxs I've been thinking about LUKS and I even used an app called LUKS Manager (or something similar) around 2012-2013, but then the development was seized. I'm also not sure how robust using LUKS on Android would be, e.g. I suspect a lot of things might break if I decide to upgrade to the next Android version, or flash another ROM; feel free to correct me if I'm wrong. – andselisk May 20 at 13:47
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    If you have a rooted phone, EncFS is a simple solution that I have been using on my K and L devices for years to use (physically) external SD card as public external storage (/sdcard) by Disabling Internal Memory (DIM). Also it's quite easy to do incremental backup of some encrypted directories like DCIM to cloud (such as with rclone). It does have multi-platform support. All you need is a kernel with FUSE support, an encfs binary and an init.d script. – Irfan Latif May 26 at 12:20

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