[dm-devel] Another experimental dm target... an encryption target

[Christophe Saout]

Am Sa, 2003-07-26 um 18.54 schrieb jon+lvm at silicide.dk:
 
> > > Well this does kind of make my project redundant and moot :(
> > 
> > Not really. There are still things like storing the key on disk,
> > encrypted with an assymetric key (password) or something. And the LVM
> > part.
> 
> yeah, but arent you gonna make those?

No, I just wanted to play with the device mapper, the in-kernel part
only. I don't know why, but I find kernel programming much more
attractive. And the device-mapper is a very cleanly structured piece and
easy to understand.

> Besides, i'll at least have
> to talk this situation over with my fellow student and the professor.
> I would really like encryption to be a part of LVM, and i want keychange.
> I never really expected the dm-target to be the tough part, since it would
> just be sort of like dm-linear, and cryptoloop. The other stuff and
> performance tuning was where i expected to use time.

That's the point. It took me approx. 6 hours to write it (after I had
written or ported some other targets). There's nothing innovative in it.
 
> > > If it was so dog-slow, and an unneeded complexity, why did you make it?
> > 
> > Hmm, just for fun?
> 
> hehe, thats the spirit :)

Yes. The thing is, my semster at the university ended some days ago and
I really love programming but don't have too much time. I wanted to play
with the device-mapper for some time and now I got some ideas. I didn't
think it was so easy. I even barely had any oopses.

The interesting thing is that Joe said that the crypt target would be
easier than the file target (ok, if I have had to find out how to use
the filesystem it would have taken much more time, but I could simply
use the implementation of the loop driver). Actually my crypt target is
larger than the file target, and I used the worker thread I had
implemented there. Now it's 675 lines in size, a lot of comments, a lot
of copied code, really not complicated.

> Well, it's sort of both ways. I like encryption, and i want more support
> for that in linux. That part i am thrilled about. But i'm not too thrilled
> if i means the end of my university project, however, i guess that i better
> get used to other people doing the same things that i want to, it's not like
> i own the idea. You did catch me off guard, i didnt expect anyone to rush 
> out and do the same thing that i said i would try, but maybe thats common
> in the OS development world?

Yes, there is a lot of development in parallel. Normally this leads to
better and better implementations in the end.

The thing is, after my file backed target worked I wanted to try how you
could manipulate the data on its way through the target. The only useful
thing I could think of was using the cryptoapi because I had seen how it
was used in the loop driver - and it was very easy to use.

After it worked I was just too happy that it worked so I couldn't resist
to post it. Sorry.

--
Christophe Saout <christophe at saout.de>
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