Sdcard encrypted on rooted phone, is there a way to copy encryption key from the system

[Shadow7107]

As I stated, my sdcard is encrypted on a rooted phone, is there a way to copy encryption key from the system files, so I can just paste the key into the device after factory reset, so I can use it again? Encryption key is random, and not fixed to a device. So where is it stored? In /data ? In /system ? Or in any other location.
The point is that I have a backup of the key, so if my phone decides to die on me, I could factory reset it, paste the encrypt key with root, and use SDcard without decrypting and re-encrypting it?
Os: Android 8.0 Oreo
Phone: Galaxy Note8 SM-N950F

 

[rmpbklyn]

It depends on the source of the app that you saved from might need to save to folder or use share to email.

try esfile manager app, i was able to even copy files to desktop by using the wifi network transfer (note must be on same wifi account example like home wifi)

As I stated, my sdcard is encrypted on a rooted phone, is there a way to copy encryption key from the system files, so I can just paste the key into the device after factory reset, so I can use it again? Encryption key is random, and not fixed to a device. So where is it stored? In /data ? In /system ? Or in any other location.
The point is that I have a backup of the key, so if my phone decides to die on me, I could factory reset it, paste the encrypt key with root, and use SDcard without decrypting and re-encrypting it?
Os: Android 8.0 Oreo
Phone: Galaxy Note8 SM-N950F

 

[Rukbat]

The key depends, in part, on the hardware of the phone (the motherboard, mainly). Even if you knew the key, using a new phone, or even replacing he motherboard on the original phone, would require a different key, and the files are encrypted using the old motherboard's key.

SD Card encryption keys aren't transferable. It's part of making sure that if someone steals your card, even if he has a total debug dump of your phone, unless he's an encryption expert and knows the encryption method used (and I'm sure that disclosing that, if you work for Google, is an offense that only starts with being fired immediately), it's impossible to decrypt the card.

So great plan, but it can't work. You'd have to duplicate the motherboard.

 

[Shadow7107]

But then, how do you lose all data on sdcard after encrypting it, and then factory resetting it?
That would not be the case if it was a hardware thing.
I encrypted my sdcard, put it on my pc, scanned md5 of a file, DIDN'T EDIT IT IN ANY WAY, and then decrypted my sdcard, and encrypted it again. Scanned md5 and it was different.