Purple Player, Platform Purple, DRM, Leaping Brain, Brain Trust

gistfile1.txt

Audience: video content creators

It is alleged that:
* the initial DRM implementation simply XOR'd the first 13 bytes of the first 15 x 1K blocks of the video file;
* the 13 byte key was literally, "RANDOM STRING"
* reference: https://plus.google.com/+AsherLangton/posts/Yk71MgkvAXx

It was later observed that:
* the DRM implementation was changed to XOR the first 32 bytes of the first 16 x 1K blocks of the video file;
* the 32 byte key appears random;
* 6 bytes are appended to the end of the file (presumably to identify the original purchaser;
* trivially circumvented by modifying the BrainPlayer python script to save the decrypted file, e.g.,
```
*** ~/Library/Application Support/LeapingBrain/catalog/player/BrainPlayer.app/Contents/Resources/brainplayer.py.orig	2012-04-07 00:30:00.000000000 -0400
--- ~/Library/Application Support/LeapingBrain/catalog/player/BrainPlayer.app/Contents/Resources/brainplayer.py	2012-04-07 00:30:00.000000000 -0400
***************
*** 549,554 ****
--- 549,559 ----
      # Internal methods
      #
      def load(self, filename, start_time, enable_subtitles, window_state, vlc_args):
+         # HACK: make a copy of the "decrypted" file
+         import shutil
+         fakefilename = filename+"-decrypted.mp4"
+         shutil.copy(filename,fakefilename)
+         # END HACK
          """Load a file and set its starting time."""
          self.enable_media_controls(False)
          self.enabled_subtitles = enable_subtitles
```

Changes observed in Purple Player 3.2.3:
* the DRM implementation now XORs only the first 32 bytes of the video file;
* no additional bytes are appended to the end of the file;
* while the brain player python script is gone, circumvention may actually be easier because the .mp4 header is 28 to 32 bytes long, e.g.,
```
0000000   \0  \0  \0 034   f   t   y   p   m   p   4   2  \0  \0  \0  \0
0000020    m   p   4   2   i   s   o   m   a   v   c   1  ??  ??  ??  ??
```
or
```
0000000   \0  \0  \0       f   t   y   p   i   s   o   m  \0  \0 002  \0
0000020    i   s   o   m   i   s   o   2   a   v   c   1   m   p   4   1
```