[ Thanks to David for this link.
“A loopback device is a very special device that allows you to
mount a normal file as it was a physical device. Loopbacks can be
encrypted: this becomes very useful sometimes.
“Consider, as [an] example, that you need to encypt a few files,
nothing big, let’s say 100 MB or so. Encrypting an entire partition
could be too much. Then a cryptoloop could be the right solution to