Comment # 14 on bug 1184069 from Klaus Mueller

(In reply to Andreas Stieger from comment #12)
> It is true that the key strengthening function is tuned to take about 1000ms
> for a single run to generate the key from the passphrase. The underlying
> problem is that the single-threaded performance for this operation has
> diverged so much from the running system to grub, so that strengthening
> parameters picked will make it run slower in grub.

This means: grub should urgently implement multi threaded operations to cope
with the system capabilities. It's usual since years to parallelize work.

> You can use different
> parameters, it is not fundamentally less secure.

The high number of iterations compensates for the poor entropy of probably most
passphrases / passwords in the wild. That's how I understood it so far.
Therefore it would be fatal to reduce the number of iterations to derive the
key. If you have a big enough key initially derived from /dev/(u)random, it's
surly possible to massively reduce the amount of iterations without reducing
security at all most probably. Unfortunately, my passphrases don't reach this
high entropy.