Todd Vierling writes:
>: Well, for swap, you'd obviously want to use a random key, at very least.
>
>Which isn't really relevant to whether the implementation is at the block
>device level or swap level, of course.  Both could do this.

Right, you could add random/volatile keys to a block device cipher,
but doing it at the swap level gives you more control over how long
keys for pages that are no longer referenced stay around.

The approach described in the paper divides swap into some number 
of configurable size sections, with a random key generated on demand
for each section.  Each key also has associated with it a reference
count and an expiration time.

With a block device cipher, all they key(s) would have to persist as
long as the system is running, no?

>: A fresh implementation of a cipher block device should take all of an
>: evening or two to write.  Maybe I'll write one this week.
>
>You certainly have my personal enthusiasm.  Please feel free!  :)

Ditto!

:: Mike ::