[lbo-talk] Ubuntu stuff

Dwayne Monroe dwayne.monroe at gmail.com
Wed Aug 19 12:06:47 PDT 2009


Doug wrote:

Not so much anymore. There are no restrictions on freshly downloaded songs, at least in my recent experience.

....

There *are* restrictions but you haven't done anything to run against them because (I assume) you keep your media within the FairPlay compliant world. Also, if you're downloading media which isn't encrypted using FairPlay you enjoy total portability. As I wrote before, the cleverness of FairPlay/iTunes is its mixture of open and closed elements.

Information about FairPlay's architecture from the Wikipedia article:

<snip>

FairPlay-protected files are regular MP4 container files with an encrypted AAC audio stream. The audio stream is encrypted using the AES algorithm in combination with MD5 hashes. The master key required to decrypt the encrypted audio stream is also stored in encrypted form in the MP4 container file. The key required to decrypt the master key is called the "user key."

Each time a customer uses iTunes to buy a track a new random user key is generated and used to encrypt the master key. The random user key is stored, together with the account information, on Apple’s servers, and also sent to iTunes. iTunes stores these keys in its own encrypted key repository. Using this key repository, iTunes is able to retrieve the user key required to decrypt the master key. Using the master key, iTunes is able to decrypt the AAC audio stream and play it.

When a user authorizes a new computer, iTunes sends a unique machine identifier to Apple’s servers. In return it receives all the user keys that are stored with the account information. This ensures that Apple is able to limit the number of computers that are authorized and makes sure that each authorized computer has all the user keys that are needed to play the tracks that it bought.

[...]

full at --

<http://en.wikipedia.org/wiki/FairPlay>

In other words, so long as you only use devices which are able to participate in the key authorization system, you're fine. But once you try to play AAC encrypted audio on a non-compliant device, (which you might want to do at some point) you'll run against the restrictions I'm talking about.

Beyond that immediate concern, this platform is a tool-set Apple can use to create even greater restrictions in the future.

The Advanced Access Content initiative I've discussed before was (is still?) an effort to create a completely closed universe of 'premium content'.

.d.



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