[FEATURE REQUEST] - Shred original files after importing

[hej2010]

From https://github.com/Arctosoft/Valv-Android/issues/23#issuecomment-1950223767:

The auto delete mechanism should use a shredder strategy to avoid data recovery. A random data overwrite + 0s overwrite would be enough (the last run should be using 0s, instead of random data, because random data usually means that some encrypted file is being hidden).

[ricassiocosta]

By the answer of this question here https://github.com/Arctosoft/Valv-Android/discussions/50, the app cache deletion should also be shredded on vault lock (if possible).

[hej2010]

It seems like it is difficult to permanently delete/shred files on Android: https://security.stackexchange.com/a/185627 https://stackoverflow.com/a/38518260/7232269

Maybe the best way is to not use the disk cache at all and only read directly from the encrypted files (and use the memory cache)

[clach04]

By the answer of this question here #50, the app cache deletion should also be shredded on vault lock (if possible).

I think a cache is a bad idea. Opened #95

[clach04]

From #23 (comment):

The auto delete mechanism should use a shredder strategy to avoid data recovery. A random data overwrite + 0s overwrite would be enough (the last run should be using 0s, instead of random data, because random data usually means that some encrypted file is being hidden).

Shredding / memory overwriting is definitely a good idea.

I'm not sure File shredding / over writing is worth doing on memory back storage like SD cards, MMC, etc. that Android uses for storage, due to wear leveling. I'm not sure you can overwrite those exact bytes in the same location "on disk". This is not my area of expertise though so this is definitely an armchair opinion 😆

Shredding is a great idea on spinning media 😀