Is it possible to save data from an encrypted SD card with original phone after factory reset?

[little_owl]

Hello

I have factory reset my phone (Samsung Galaxy A405) and forgot that I have my SD card encrypted. I have read a lot of posts on this topic on this (and other) forums and generally I dont see my chances high about getting the data back. Especially, if I understand the Android encryption system (from the last few hours of reading), the master key used to encrypt the data is generated randomly after each factory reset. The key generated using the PIN only encrypts this master key.

But I am posting this question anyways, because usually the issue described online is the original phone is not available/broken or the PIN is lost. My situation is different in that I have the card, the phone fully operational and I remember the pin. The card in PC shows the complete file structure including file names, but the phone says the card has been encrypted by a different device. Also worthy of note, Smart Switch backup was not used.

I would like to ask if there is a possibility to somehow to mount the card back into the phone for it to recognize it is the card from the phone and access it without loosing the data?

I have found one guide that suggests encrypting an empty card (either original encrypted after backup into PC or a new one) with the same PIN in the same phone and then manualy copying the files in the PC onto it and choosing decrypt could work. I also found a lot of software (like easyus) clayming they can save it, but I am really suspicious of such claims made by companies and dont want to infest my PC with malware or corrupt the card.

Thank you in advance for any piece of advice that could lead me to solving this issue.

Final disclaimer: Its a friends phone and the story of how this happened is rather long and its not relevant to the problem so for the purpose of simplification its "my" phone...

 

[B. Diddy]

Welcome to Android Central! I'm not a security expert, but I think it's still not going to be possible, since the encryption key would have been randomly generated. Let's see if anyone else has any insight into it.

 

[smvim]

When you encrypted the microSD card previously, that created an encryption key that essentially linked the card directly to your phone. But when you did that Factory Reset, that particular encryption key was wiped. Keep in mind that encryption keys are very, very specific, they are not in any way generic and universally switchable between devices. It's not a matter where you can just put that encrypted card back into your phone now to access whatever data is stored on it, the encryption key is relied upon is gone. The card isn't trashed however, it's just that the data on it is locked. You can reformat the card to reset it, from scratch, and just keep using it normally as is. Or if you opt to encrypt it again, just be sure to back up the data you store on it.

 

[little_owl]

Welcome to Android Central! I'm not a security expert, but I think it's still not going to be possible, since the encryption key would have been randomly generated. Let's see if anyone else has any insight into it.

Thank you for the welcome

When you encrypted the microSD card previously, that created an encryption key that essentially linked the card directly to your phone. But when you did that Factory Reset, that particular encryption key was wiped. Keep in mind that encryption keys are very, very specific, they are not in any way generic and universally switchable between devices. It's not a matter where you can just put that encrypted card back into your phone now to access whatever data is stored on it, the encryption key is relied upon is gone. The card isn't trashed however, it's just that the data on it is locked. You can reformat the card to reset it, from scratch, and just keep using it normally as is. Or if you opt to encrypt it again, just be sure to back up the data you store on it.

I was both afraid and expecting this answer. Yet if I did not ask, I would not be able to claim I did everything I could. Thanks for your quick reply.