Possible to encrypt external SD card without using it as "internal"

I read @siltaar’s guide to making an encrypted image on an external SD card.

I’m wondering if there’s a way to make the whole sd-card encrypted and the android system recognizing it as an external sd card? The purpose being that data is safe if the phone would get lost/stolen.

I’ve been looking into this guide using cryptsetup, but it works similarly as the first guide, with an image and only part of the SD card.

That happens (except for the external aspect) when you configure the SD card as an expansion of internal storage.

However, this method is known to cause a lot of problems and is not recommended at all on this forum.

I think there are two ways to go, which can be used in combination.

  • Set up a high-security cloud storage facility with a company like Proton.me and push your data there regularly. It’s possible to make certain cloud folders accessible off-line (locally). You’ll be paying for this of course, which frankly I find normal.
  • Use an app like DroidFS (available on F-Droid). This app will let you encrypt local data on the SD card, and even, I’m told, provides a camera app that can save photos directly to the encrypted storage. However, Android (and other apps therefore) would not have direct access to these encrypted data.

Thanks for the ideas @OldRoutard, however they don’t cover what I’m looking for. I’m wondering about a whole-partition encryption method for the SD-card so that it is accessible (when decrypted and mounted) as a regular external SD-card.

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You want a full encryption that is readable via Andoid and Windows for example ?

Not necessarily by Windows/Mac (I use Mac) but by android, yes.

I mean, does it have to be multi platform or would just Android do?

Just android is fine!

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Ok I will have a look.

But a simple solution is use Amdroid’s built-in encryption on rooted device and keep a backup of encryption key so that SD card can be decrypted later on a PC
external sd - How to encrypt an SD card for android so that it can also be used on other devices? - Android Enthusiasts Stack Exchange

Samsung seem to have it built in

Yea looks like a perfect option, but it’s not available on Lineageos 19.1…

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