My Oneplus 5 got softbricked (touch input completely stopped working some time after an update and nothing could be done about it). This happened soon (a couple of weeks) after it was updated to stable OxygenOS 9.0.3 (first Pie-based ROM for my device), bootloader was locked.
It was not easy, but I managed to get images of all the phone's partitions via Qualcomm EDL mode. Then I factory reset ("unbricked") it using "MSMDownloadTool" provided by Oneplus (which uses EDL as well).
Needless to say, most of the extracted userdata partition (which should contain all my files, e.g. photos) is encrypted. The encryption method is FBE. I also used a PIN lock (which I know).
What I am trying to understand if it possible to decrypt the files. My very basic understanding is that this involves some keys specific to my unit (so can only be done on the device itself?) and also some keys found on the userdata image in a "unencrypted" directory and some further keys which are encrypted using the former.
In some initial attempts to decrypt the data I have since unlocked the bootloader and rooted the phone.
So my questions are:
1) Is this theoretically possible? Could the modifications to the phone's firmware I have already done wiped something necessary for decryption, which was not stored on disk (in userdata or another partition)?
2) Can anyone provide any manual as to how this could be approached? I have found a manual for Huawei Mate 9 on xda-developers but could not
follow it (
vold directory missing in
misc, probably encrypted).
3) If not, what documentation / source code would you recommend studying?