Innocent
September 21st, 2004, 18:14
Quote:
But on the other hand, is there really any DRM system that's stupid enough to only put an encryption envelope around the whole file, and then decrypt pure sound data in memory? The ones I've seen have been much more "intertwined" than that... |
Actually, I think there is. It is called eLicense.

Getting an elicense DRM'd file unpacked is as easy as any program that is packed with elicense. While on the subject... wouldn't there be a way to capture the data somehow as it gets sent to the player anyway? (in the case of other DRM protections like M$ DRM) I mean, the player needs to be passed unencrypted data so can't we find where it is passed to the player and progressively dump it?

The only workaround I can see would be to have a player that "reads" encrypted files. In this case the player would have it's own encryption system. Here is an example:
Say M$ created a new file format. Call it .wme for windows media encrypted (file). Only windows media player can play it. This system would consist of 2 layers of encryption:
1. Take an existing mp3 file and encrypt it in the new .wme standard. The file is now encrypted in a scheme that only windows media player can handle.
Suppose the original mp3 had the data: 10D3D092BD34AA99
Now that it is in .wme it looks like: 2659274501374855
Have the .wme extension trigger the wme reading mode:
Now when playing the file media player sees: 2659274501374855 but recognizes that it is really 10D3D092BD34AA99 and plays that. I suppose this could be done through simple substitution. i.e. the player sees 26h (the first byte of the example string) and knows that it really means 10h by using a substitution table. The key to this is that the "real" bytes are never passed in a buffer so someone can dump it.
Expanding on this: now that you have a working substitution table why not have say, 256 different ones and include which one you want media player to use for this file. (the one that the file is encoded for)
2. Now that you have working .wme files, add the DRM layer. A person buys and downloads the .wme, receives the license key, and can now play the file.
The DRM layer is decrypted on the fly and media player never puts the original bytes of the file in memory.
Call me crazy or whatever.

I don't know if all this would work or not; it was just my crazy tangent to your post dELTA.
