Recovery chances for SD card - used as android internal memory - which got formatted by another mobile?

  1. I used a micro SD card in a Nokia Smartphone for years as internal storage.
  2. I ejected it to test if another phone detects this type of SD card.
  3. Although we planned to just see if it is detected, certain off-topic factors led to the acceptance of Google's suggestion to 'format it as internal storage'.

As long as my phone still remembers the decryption, is there a way to recover my Photos, GPS-tracks, Text-Notes and other data, despite being encrypted with the known key and formatted by another phone?


My assumptions:

a) data from a non-encrypted card can often be retrieved mainly because the raw data still 'looks like' photos, mp3 etc.

b) encrypted data doesn't 'look like' anything, so recovery tools won't find anything - and even if, my phone doesn't care about data parts but about some 'yes I am your encrypted storage do not format me'-File

c) a recovery tool would need the decryption information to look for the original content (-> how to extract it from the phone + tell the tool?)


Side note/non-duplicate: Similar questions that I found always have sb. loosing the decryption key and I agree that recovery should be impossible in those cases.

Answers 1

  • Accessibility of the data on a storage volume that has been adopted by Android Marshmallow or higher as "internal storage" is well documented and has requirements of root at an absolute minimum... So I won't go into that in my answer, the details are here: https://nelenkov.blogspot.com/2015/06/decrypting-android-m-adopted-storage.html

    You stated you do not have root on your device so the encryption key is not accessible, and rooting the device at this time will wipe the encryption key. So it is not recoverable.

    Unfortunately, when the card was inserted into the other device, it was "formatted" as internal storage on the that device, not only erasing the existing data making it virtually impossible to recover even without taking encryption into account, but also changed it's identity to Android and setup a new encryption key pair between the new device and the storage card. This last step also made the card unrecognizable in the previous device as the other "half" of the key on the device no longer matches the storage volumes key.

    Sadly, the end result here is that any data on the card initially is now lost permanently and is not recoverable. It is best at this time just to allow the device to format the card again, and consider that formatting the card as "external" or removable storage may be a more appropriate use of the storage card.


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