[FFmpeg-devel] Patch libavformat/crypto to add seek when reading

[Simon H]

hmm...  not sure i understand fate, even after a quick look.  Is there an
explanation more complete than on the website?

I'm guessing that the ideal test for this would be to exercise the url
functions directly from code; e.g.:
1. write some known data through crypto:, compare with pre-prepared output
of openssl.
2. read the same data linearly through crypto: , and check it's the same as
it should be.
3. read the same data non-linearly through crypto: , and check it's the
same as it should be.
4. try to write some known data with seek, and expect failure?

Seems fate has some dedicated test programs; libavformat/tests/aes.c may be
a good example to start with?
Seems to just return 0 if OK, and 1 if fail?

s

On Tue, Aug 30, 2016 at 4:17 PM, Michael Niedermayer <michael at niedermayer.cc
> wrote:

> On Tue, Aug 30, 2016 at 09:47:12AM +0100, Simon H wrote:
> >
>
> >  crypto.c |  116 ++++++++++++++++++++++++++++++
> +++++++++++++++++++++++++++++++--
> >  1 file changed, 114 insertions(+), 2 deletions(-)
> > a8d9d6638d0be86896de1cb2fa5f9a9f60d7b3c3  libavformat-crypto-add-seek.
> patch
> > From a0c4d274b2b1712e6ca26a18083edccb55032b94 Mon Sep 17 00:00:00 2001
> > From: Simon Hailes <btsimonh at googlemail.com>
> > Date: Tue, 30 Aug 2016 09:40:14 +0100
> > Subject: [PATCH] cyrpto allows reading of data which has been aes-128-cbc
> >  encrypted given a key and an iv. But it did not handle filetypes which
> >  require seeking...  e.g. it failed on an encrypted .mp4 file.
> >
> > example:
> > take 25.mp4 created with:
> > ffmpeg -f lavfi -i sine=frequency=1000:beep_
> factor=2:r=48000:duration=720.0 -f lavfi -i
> testsrc=duration=720.0:rate=25 -vcodec libx264 -cmp 22 -timecode
> 10:00:00:00 -r 25 -y out\25.mp4
> >
> > encrypt with:
> > openssl enc -aes-128-cbc -K 12345678901234567890123456789012 -iv
> 12345678901234567890123456789012 -in 25.mp4 -out 25.enc
> > then to transcode in ffmpeg:
> > ffmpeg -key 12345678901234567890123456789012 -iv
> 12345678901234567890123456789012 -i crypto:25.enc -vcodec mpeg4 -r 25 -y
> 25dec.mp4
> >
> > prior to this modification, the transcode would fail.
> >
> > Note also:  crypto previously maked both reads and writes as streamed,
> which caused the whole file
> > to be read before the transcode started.  Now, for read only, if the
> underlying layer is not marked as streamed,
> > then crypto is not.  This should enable efficient reading of encrypted
> containers which require seeking.
> > ---
> >  libavformat/crypto.c | 116 ++++++++++++++++++++++++++++++
> ++++++++++++++++++++-
> >  1 file changed, 114 insertions(+), 2 deletions(-)
>
> applied
>
> can you add a fate test for this case ?
>
> thanks
>
> [...]
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> When you are offended at any man's fault, turn to yourself and study your
> own failings. Then you will forget your anger. -- Epictetus
>
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