[Ffmpeg-devel] [RFC] MXF AES decryption

Michael Niedermayer michaelni
Fri Feb 9 00:30:57 CET 2007


Hi

On Thu, Feb 08, 2007 at 10:15:51PM +0100, Reimar D?ffinger wrote:
> Hello,
> On Sun, Jan 14, 2007 at 09:00:59PM +0100, Baptiste Coudurier wrote:
> > Reimar D?ffinger wrote:
> > > [...]
> > >>> @@ -768,9 +913,16 @@
> > >>>              av_log(mxf->fc, AV_LOG_INFO, "source track %d: stream %d, no descriptor found\n", source_track->track_id, st->index);
> > >>>              continue;
> > >>>          }
> > >>> +        essence_container_ul = descriptor->essence_container_ul;
> > >>> +        if (IS_KLV_KEY(essence_container_ul, mxf_encrypted_essence_container)) {
> > >>> +           MXFCryptoContext *cc = mxf_find_track_cryptocontext(mxf, descriptor->linked_track_id);
> > >>> +           if (cc)
> > >>> +               essence_container_ul = cc->source_ul;
> > >>> +           mxf->sync_key = mxf_encrypted_triplet_key;
> > >>> +        }
> > >> That's wrong. descriptor essence container should be original source
> > >> coutainer. That file is broken. Working 100% solution must be
> > >> implemented, also linked track id is optional in S377M. Yes it is
> > >> complicated but a working 100% solution exists.
> > > 
> > > I moved the sync_key setting someplace else, so the remaining code is
> > > only a hack. I hope you don't expect my to improve a hack without any
> > > samples that would need it (since it's a hack I'm actually tempted to
> > > just remove the linked_track_id check and DMSegment and CryptoFramework
> > > parsing and just grab the source_ul from the first best CryptoContext
> > > found).
> > > 
> > 
> > Well if track count is only one, I agree that would be more convenient.
> 
> Since the problems are probably caused by an old version of the spec and
> the code is needed for later per-track encryption key (if it will ever
> be implemented *g*) I decided to keep it.
> I fixed it to use source_track->track_id instead of
> descriptor->linked_track_id though.
> Does this version look again to be applied?

iam fine with the changes to avformat.h, and iam not mxf maintaier so no
comment about that

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When the tyrant has disposed of foreign enemies by conquest or treaty, and
there is nothing more to fear from them, then he is always stirring up
some war or other, in order that the people may require a leader. -- Plato
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