Bug#371135: [Pkg-cryptsetup-devel] Bug#371135: encrypted swap with variable key fails

[Jonas Meurer]

On 21/06/2006 Andrew Pimlott wrote:
> > first, LUKS devices with random key are possible, you just need to store
> > the random key after luksFormat, to reuse it for luksOpen. afterwards
> > you can shred/wipe the key.
> 
> True, but this can't be configured in crypttab, which makes it
> effectively unavailable.  Moreover, it wouldn't provide much additional
> safety.  Presumably, a hypothetical "luksrandom" keyword in crypttab
> would mean: check that it's a luks partition, than re-luksFormat and
> luksOpen with the same random key.  The problem is, this would happily
> trash any normal (non-randomly-keyed) luks partition.  So you really
> want an explicit marker that says "I am disposable".

do you see any advantages in providing this? i don't like the idea of
invoking luksFormat automatically in any case.

> > > However it may still be overkill.  I would be happy enough if there were
> > > a check for randomly keyed swap partitions that verifies that the source
> > > device is 1) not a formatted, unencrypted volume and 2) not Luks.
> > > That's still a good measure of safety.
> > 
> > yes, that's exactly what i suggested as well. in my opinion, up to now all
> > other proposed checks are compromises which have disadvantages as well.
> 
> Cool.  So you would special case a key of /dev/*random, and perform only
> those two checks?  In other words, would my existing configuration
> 
>     swap    /dev/hda2 /dev/urandom  swap
> 
> start working again?  That sounds like a nice resolution.

that's the plan.

...
 jonas