WMP/iTunes Digital Copy/Disney File discs

[thepwrtank18]

Has anyone made anything to undo the PlaysForSure/FairPlay encryption on old Digital Copy discs?

In the one I have of Toy Story (from the 2010 Toy Box collection), there's a wmv folder that contains two files:
* a 338.4 MiB (presumably low quality) "ToyStory_PORT_EN.wmv" file
* a 1.2 GiB "ToyStory_PC_EN.wmv" file
There's also a DVDROM/Media folder, which contains a 1.1 GiB "FeatureMovie" MPEG-4 file with no extension. Likely what iTunes reads.

Parole Media Player recognizes they're encrypted and says that decryption is unsupported.

[spotter]

the wmv files might not even be playable with the normal protected playback as MS shutdown old licensing servers that those might need.

With that said, why? if one is willing to decrypt, the digital copy is highly inferior to other versions you can make yourself (i.e. just decrypt the bluray)

[thepwrtank18]

Curiosity, plus the rare case of something being different. Looking into it, it's a 56-bit key, and you can get it by bruteforcing what Microsoft does (https://github.com/MicrosoftDocs/PlayReady/blob/main/Docs/Specifications/playready-header-specification.md#5-key-checksum-algorithm) to validate the key; try every number until you get a good checksum. Computationally expensive, very impractical compared to bruteforcing CSS on DVDs, but possible. Also, the codename for the DRM is Cocktail apparently

[spotter]

pretty sure its a 64 bit key, not 56 bit (assuming cocktail, not AES). while 56 bit might be in the realm of consumer brute forcing, 64 bit is outside the realm

[spotter]

but to more answer your Q, there were multiple tools that enabled extraction of the keys and then decrypting the media (FairUse4WM was one of the most famous). But they are all pointless today as there's no keys to extract anymore from windows media player.

[thepwrtank18]

Says 56-bit here. https://learn.microsoft.com/en-us/dotnet/api/microsoft.media.drm.contentkeytype?view=playreadyserversdk-4.8

[spotter]

I believe cocktail uses 64 bit rc4 and 56 bit des in combination. but could always be wrong.

https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-drmcd/55bffa76-4742-4da6-864b-fd3ac470515b

see - https://www.eetimes.com/microsoft-details-drm-for-consumer-devices/

The DRM uses a set of encrypted digital keys to transfer licenses and policies securely between devices. Currently it employs on portable devices the so-called “cocktail” algorithm of 56-bit DES and 64-bit RC4 along with 160-bit Public Key Infrastructure (PKI) for storing keys. Networked devices such as set-tops use 128-bit AES and 2,048-bit PKI cryptography.

and https://en.wikipedia.org/wiki/Windows_Media_DRM

[kurkosdr]

I would be more interested if someone found a way to break Apple Vision Pro streaming DRM, so that archivists can archive those sweet 4K HDR stereoscopic movies (Blu-ray 3D only does 1080p SDR stereoscopic) than a 1.2 GiB WMV of Toy Story.

But anyway, as others have said, the authorization servers that served those PlaysForSure decryption keys have been shut down (thus making it DoesntPlayForSureOrAtAll), your best bet is to brute force them. A common shortcut when it comes to video files is to find a known bit pattern (usually some bitstream "sync word", which is usually dozens of zeros in a row) which can cut down the candidate keys substantially (that's how "uncrackable" 64-bit satellite encryption for MPEG-2 channels were cracked once at more or less real-time speeds using powerful home PCs of the era).

[coricopat]

I would be more interested if someone found a way to break Apple Vision Pro streaming DRM

A kingdom for that... would also mean Avatar in 4K, 3D and HFR 😍️