DRM is not so terrible as it is painted

When Esher Langton of Livermore National Laboratory bought a film in one online store that required a proprietary video downloader from Leaping Brain , he had difficulty installing the player on the iPhone. Trying to deal with the problem, he found that the video was downloaded to a hidden folder as a set of regular .mov files. True, none of them could not be reproduced.

The proprietary DRM-protected player turned out to be a Python wrapper script around several libraries from the VLC project. Python code did some conversion on the file before feeding it to VLC. The FAQ on the Leaping Brain website said that their player uses an incredibly cool cryptographic algorithm to implement DRM:

“We use the BrainTrust proprietary encryption algorithm when uploading videos to our servers. Even if someone can access your content, the files will not play and will be completely useless, because they are stored in encrypted form. After downloading to the user's device, only the legal user can play the files and only through MOD Machine Player. We do not know a more reliable scheme than this. Windows Media DRM is easy to crack and works only on Windows, while BrainTrust is almost impossible to crack, and this technology works fine on Windows 8, Vista, XP and Mac. ”

Scratching away a wrapper script, Escher Langton saved the processed file and compared it to "encrypted". It turned out that the inaccessible algorithm consisted in the fact that in the first 15 kilobytes of the file several initial bytes of each kilobyte block were XOR-ed with a “secret key”, which was the string “RANDOM_STRING”.

Source: Asher Langton blog .
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PS The old version of the FAQ has already disappeared from the official site Leaping Brain. But Google's cache remembers !