[FFmpeg-devel] [PATCH] support encrypted asf

[Michael Niedermayer]

Hi

On Wed, Oct 10, 2007 at 08:52:40AM +0200, Reimar D?ffinger wrote:
> Hello,
> On Wed, Oct 10, 2007 at 12:28:21AM +0100, M?ns Rullg?rd wrote:
> > Michael Niedermayer <michaelni at gmx.at> writes:
> > > On Wed, Oct 10, 2007 at 12:05:23AM +0200, Reimar D?ffinger wrote:
> > > [...]
> > >> [... DES code ...]
> > >> > hmm, this doesnt look remotely optimal, maybe you should look at 
> > >> > john the ripper IIRC it contains quite fast DES code. though surely far too
> > >> > messy for us to use directly but i guess the ideas used in it could be
> > >> > applied to our code as well
> > >> 
> > >> DES is a mess as it is, it seems unlikely it well ever get any new use,
> > >
> > > then why is it used in asf DRM?
> > 
> > Because asf is a mess?
> 
> Also because it is quite old (encryption seems to have stayed the same
> since v1 of the DRM) and because (since it is DRM) it has to rely on
> obscurity anyway, so using more secure encryption is not that helpful.
> Concerning simplicity of the versions using tables: replacing code by
> mysterious and unexplained tables is not my idea of simplification ;-)

you can always explain them in comments ...


> I'll try to find the DES implementation you mentioned and see if it is
> less horrible...

i dont think you will like that implementation as is, its a huge #ifdef hell
but if you pick one of these #ifdef cases it might be interresting, i suspect
every of the case is much faster than your code ;)

and to see the source try
apt-get source john (assuming you use the wrong;) distro ...)

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

While the State exists there can be no freedom; when there is freedom there
will be no State. -- Vladimir Lenin
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