Comment 35 for bug 423608

Can we add a "can_hibernate" option to /etc/crypttab, and have upower accept swap devices marked as "can_hibernate"? A setup tool such as the Debian installier should add this option when using decrypt_derived; changing it is up to the user.
This allows users to use their own scripts for decrypt_derived.

IMHO this is cleaner than checking for /dev/random and /dev/urandom; although it requires current users of encrypted swap to modify their crypttab.