[Cryptography] Shredding a file on a flash-based file system?

[Theodore Ts'o]

The eMMC specification does have something called "secure discard"
which is supposed to guarantee the data does get erased --- that is,
those sectors not effected by the erase block get moved elsewhere, and
then the entire erase block is erased.

Of course, you have to trust that the eMMC device correctly
implemented secure erase, but that's true in general whenever you
delegate to a closed source implementation.  There is always the risk
that some security function will be incomptently or maliciously
implemented.

						- Ted