Rockbox General > Rockbox General Discussion

DRM - Seriously, Why Not?

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AlexP:
It is simple.  Creative, Sandisk etc. know the secret code in order to be able to use the licence.  If rockbox were to be able to use the code, because of the rockbox licence, we would have to publish the code.  Therefore it is no longer secret and therefore we will not be given the code, leaving aside any philosophical things.

(In common with many here, I am philosophically opposed to DRM).

Yotto:
You aren't thinking of it correctly, Hef.  It's not like you have a song that says "I won't play unless you give me a password.  Give me the password, and I'll play."  You have a song that's encrypted with a hidden algorithm and needs a key.

You need, to listen to the song, have both the key (Your license code) AND the algorithm.

AND THE ALGORITHM IS SECRET.

It *MUST* be secret.  If it's not secret, DRM DOES NOT WORK.  If all you needed was the license code, then everybody would post valid license codes on usenet, irc, or whatever people use these days, and Rhapsody would cry and the RIAA would cry and we'd never get any free music and we'd all lose the ability to detect sarcasm and, well, you get the idea.

Essentially, if Rockbox can decode the license key, then *anybody* can. The *only* way a player (Rockbox included) could decode the license key is if Rhapsody told the developers how to do it, or provided them with the code (Which is the same thing), OR gave them a black-box sort of plug-in, which Rockbox, being Open Source, cannot accept.

Not that Rhapsody would ever give this kind of thing to an open source media player. It'd be like Exxon giving away drilling rights.

Llorean:
There are three parts to encryption:
The key (your license), the algorithm (the secret math) and the encrypted file.

If they shared the secret math, anyone could take a valid license, use that secret math, and decrypt the files permanently. So they have to keep the math hidden, so that only their programs can do it and the files stay encrypted.

This means that while they tell Sandisk and  Creative how to do that math, they do it by making them sign an agreement saying "We won't share it." Rockbox is open source. By its very license, code in it must be shareable. That means that if we were told the secret math, that encryption would not longer work as intended anymore, because someone could easily take our code to play the encrypted files, and instead make it write the file back onto the disk as an unencrypted file: Basically, you could get songs from Rhapsody, and save them as songs you can use anywhere, forever, and then cancel your Rhapsody subscription.

This is not something they want.

So this is what prevents it: To do it, the encryption would necessarily need to be reverse engineered, or hacked.

So even philosophical limitations aside, it's not as simple as just "using" the license, because there's a step you seem to be overlooking, or assuming is far, far simpler than it is.

Bagder:
Just a minor point here: The e200 Rhapsody firmware, or at least the relevant parts of it, is in fact written by Real and not by SanDisk...

So they didn't even have to reveal their secrets in this case, they can keep it to themselves!

LambdaCalculus:

--- Quote from: Hef on November 21, 2007, 06:05:12 PM ---As for Lamba - telling me WE will never support is - that's a great stance- as for those articles, talking about people that bought movies that are DRM encoded - I would never do that, and that's not what we are talking about.

--- End quote ---

I'm LambdaCalculus.

I showed you that article because it explains why DRM is not a good idea. Movies or not, the principle is still the same.

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