Downloading DRM protected video and decrypt with a known key

[fvh78870]

I'm trying to download a demo video from https://bitmovin.com/demos/drm

and I found https://bitmovin-a.akamaihd.net/content/art-of-motion_drm/mpds/11331.mpd

The known key:

  kid: 'eb676abbcb345e96bbcf616630f1a3da',
  key: '100b6c20940f779a4589152b57d2dacb'

I've tried to download the video by using:

ffmpeg -i https://bitmovin-a.akamaihd.net/content/art-of-motion_drm/mpds/11331.mpd -codec copy e1.mp4
streamlink https://bitmovin-a.akamaihd.net/content/art-of-motion_drm/mpds/11331.mpd best -o e1.mp4

youtube-dl https://bitmovin-a.akamaihd.net/content/art-of-motion_drm/mpds/11331.mpd e1.mp4

youtube-dl download failed, showing:

[generic] 11331: Requesting header
WARNING: Falling back on generic information extractor.
[generic] 11331: Downloading webpage
[generic] 11331: Extracting information
ERROR: No video formats found; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type
youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

ffmpeg and streamlink successfully downloaded the file, but the decrypted video is wrong.
Here is what I've tried:

mp4decrypt --key eb676abbcb345e96bbcf616630f1a3da:100b6c20940f779a4589152b57d2dacb "e1.mp4" "d1.mp4"
mp4decrypt --key 100b6c20940f779a4589152b57d2dacb:eb676abbcb345e96bbcf616630f1a3da "e1.mp4" "d1.mp4"

ffmpeg -decryption_key 100b6c20940f779a4589152b57d2dacb -i e1.mp4 -codec copy d1.mp4

1. mp4decrypt decrypt streamlink download version produces 0 bytes video files.
2. mp4decrypt decrypt ffmpeg download version, didn't work as expected. Cannot watch video content.
3. ffmpeg decrypt showing "Option decryption_key not found."


Any idea how to download and decrypt the video, any help would be much appreciated

[lomero]

ffmpeg -decryption_key 100b6c20940f779a4589152b57d2dacb -i encrypted_media.mp4 -codec copy decrypted_media.mp4

[jagabo]

I think you just need a build of ffmpeg with the -decryption_key option enabled.

[fvh78870]

I think you just need a build of ffmpeg with the -decryption_key option enabled.

I'm using full build version of ffmpeg, please try to download the demo video from https://bitmovin.com/demos/drm and decrypt it with provided key. I have tried many times with different of method to decrypt the video content.

[hvq]

The key is correct and it decrypts the stream.

ffmpeg and streamlink successfully downloaded the file

No they didn't. That's where the error is. The file you download is corrupt.

Download this file and decrypt with: mp4decrypt --key 1:100b6c20940f779a4589152b57d2dacb 11331-11331.mp4 decrypted.mp4

[jagabo]

The file decrypted properly using mp4decrypt.exe. But using the latest build of ffmpeg (from VideoHelp.com) I got an error:

G:\Program Files\Bento4 Examples>"G:\Program Files\ffmpeg64\bin\ffmpeg" -decryption_key 100b6c20940f779a4589152b57d2dacb -i encrypted.mp4 -c copy ffmpeg_decrypted.mp4
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 10.2.1 (GCC) 20200726
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libsrt --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libgsm --disable-w32threads --enable-libmfx --enable-ffnvcodec --enable-cuda-llvm --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 000001fac494d680] Incorrect number of samples in encryption info
[mov,mp4,m4a,3gp,3g2,mj2 @ 000001fac494d680] Could not find codec parameters for stream 0 (Video: h264 (avc1 / 0x31637661), none, 1920x1080, 4851 kb/s): unspecified pixel format
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'encrypted.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: isomavc1iso5iso6
  Duration: 00:03:30.28, bitrate: 4860 kb/s
    Stream #0:0(und): Video: h264 (avc1 / 0x31637661), none, 1920x1080, 4851 kb/s, 25 fps, 25k tbr, 25k tbn, 50k tbc (default)
    Metadata:
      handler_name    : Bento4 Video Handler
    Side data:
      unknown side data type 24 (897 bytes)
Output #0, mp4, to 'ffmpeg_decrypted.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 1
    compatible_brands: isomavc1iso5iso6
    encoder         : Lavf58.45.100
    Stream #0:0(und): Video: h264 (avc1 / 0x31637661), none, 1920x1080, q=2-31, 4851 kb/s, 25 fps, 25k tbr, 25k tbn, 25k tbc (default)
    Metadata:
      handler_name    : Bento4 Video Handler
    Side data:
      unknown side data type 24 (897 bytes)
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
[mov,mp4,m4a,3gp,3g2,mj2 @ 000001fac494d680] Incorrect number of samples in encryption info
encrypted.mp4: Invalid data found when processing input
frame=    0 fps=0.0 q=-1.0 Lsize=       0kB time=00:00:00.00 bitrate=N/A speed=   0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

Any ideas?

[lomero]

try with ffmpeg full version from this site: https://www.gyan.dev/ffmpeg/builds/

[jagabo]

try with ffmpeg full version from this site: https://www.gyan.dev/ffmpeg/builds/

Will do. But I think I see what's wrong with the version I have -- it only supports aes 128 (16 byte key), not aes 256 (32 byte key).

<edit>
I get the same error with the latest gyan full build.
</edit>

[lomero]

ok. try with bento decrypt

[jagabo]

Yes, I already tried with bento4's mp4decrypt as mentioned in post #6 -- that worked as expected. But I'd prefer to use ffmpeg. Does your ffmpeg command line work for you with that particular video and key?

[freefall-sleek-endurance]

3. ffmpeg decrypt showing "Option decryption_key not found."

https://www.codesd.com/item/ffmpeg-how-to-produce-mp4-videos-cenc-common-encryption.html

These options and their values should be placed after all the inputs and before the output filename.

try

ffmpeg -i e1.mp4 -decryption_key 100b6c20940f779a4589152b57d2dacb -codec copy d1.mp4

[jagabo]

I've been experimenting with encrypting and decrypting videos with ffmpeg. Here's a batch file that encrypts a video file with ffmpeg, plays the encrypted video file with ffplay, then creates an unencrypted version of the file from the encrypted version:

ffmpeg -y -i Sample.mp4 -vcodec copy -acodec copy -encryption_scheme cenc-aes-ctr -encryption_key 76a6c65c5ea762046bd749a2e632ccbb -encryption_kid ffffffffffffffffffffffffffffffff Sample_encrypted.mp4

ffplay -decryption_key 76a6c65c5ea762046bd749a2e632ccbb Sample_encrypted.mp4

ffmpeg -y -decryption_key 76a6c65c5ea762046bd749a2e632ccbb -i Sample_encrypted.mp4 -codec copy Sample_decrypted.mp4

pause

Sample.mp4 is a normal mp4 file with no encryption. It only contains an AVC video stream. The encrypted file made by ffmpeg, Sample_encrypted.mp4, does not play with a normal player -- it has successfully been encrypted. Using ffplay.exe with the decryption key works, the video plays normally. The decrypted video created by ffmpeg, Sample_decrypted.mp4, plays normally in any player -- it has successfully been decrypted.

Notes:

The value of -encryption_key can be any valid 32 byte hexadecimal number.

ffplay accepts the -decryption_key both before and after the filename.

The ffmpeg decryption command line must have the -decryption key before the -i filename.


I still have not figured out why the same command line doesn't work for the encrypted sample in post #5. We know that the given key is valid because bento4's mp4decrypt works with that key.

<edit>

Another hint: mp4decrypt gave no complaints but it did not successfully decrypt the encrypted file created by ffmpeg.

mp4decrypt --key 1:76a6c65c5ea762046bd749a2e632ccbb Sample_encrypted.mp4 Sample_decrypted_by_mp4decrypt.mp4

A file is created that's the right size but it doesn't play properly (messed up image). So there appears to be some difference in the encryption.

</edit>

[fvh78870]

The key is correct and it decrypts the stream.

ffmpeg and streamlink successfully downloaded the file

No they didn't. That's where the error is. The file you download is corrupt.

Download this file and decrypt with: mp4decrypt --key 1:100b6c20940f779a4589152b57d2dacb 11331-11331.mp4 decrypted.mp4

oh, your file works perfectly, I think the problem should be my download method.

May I know how did you download the 11331.mpd file?

I using the following software and commands, which downloaded a corrupted file...

ffmpeg -i https://bitmovin-a.akamaihd.net/content/art-of-motion_drm/mpds/11331.mpd -codec copy e1.mp4
streamlink https://bitmovin-a.akamaihd.net/content/art-of-motion_drm/mpds/11331.mpd best -o e1.mp4
youtube-dl https://bitmovin-a.akamaihd.net/content/art-of-motion_drm/mpds/11331.mpd e1.mp4

[timucin]

I've managed to see DRM protected video keys with well known chrome extension. But don't know what to do next? How to download the protected video after finding keys (at least I think so)

It shows like this:


[Attachment 57207 - Click to enlarge]

I think it's done through ffmpeg but I don't have any experience or knowledge about this issue except I a few days ago learned about youtube-dl and I used it in non protected videos.

Please could you explain what to do next after finding these keys one by one.

[pedrothelion]

That video has been decrypted/downloaded yet.
See this thread: https://forum.videohelp.com/threads/400549-plz-help-me-to-decrypted-this-video-i-have-key

[Superuser2022]

There is a script that I came along in Github. It is called, Drm-Dash-stream-downloader. It can be used to retrieve Cenc Drm content.