Most purchased tracks include Digital Rights Management information, called FairPlay by Apple. A computer must be registered with Apple by the track purchaser before the tracks can play. Currently, each user is allowed to have up to five registered computers. Any number of iPods may also be used (these do not need to be registered), and each playlist containing protected tracks may be burned to CDs a maximum of seven times (with no limit on burning individual tracks).
In April 2007, Apple and EMI announced that EMI's music would be available in a DRM-free version at twice the sound quality for $1.29 USD per track, in addition to the traditional DRM tracks for $0.99. Albums and music videos were made available without DRM with no change in price
Apple only allows the purchaser to download a track once, so it is very important to make backup copies. If you lose a song you purchased, you will need to purchase the song again.
Why Apple Cares About DRM?
The real impetus behind blocking FairPlay cracks is that Apple has to answer to the labels it licenses its music from; if Apple allows crackers to break the DRM system and recover songs, it has to pay damages to the RIAA.
 Apple obviously doesn't want to pay for damages, nor does it really want to continue developing an increasingly sophisticated DRM system under constant attack from smart crackers armed with financial incentives to exploit it.
The only reason Apple maintains FairPlay is to preserve access to licensed content from the music labels for the iPod and the Mac, QuickTime, and iTunes platforms.
How does Apple's FairPlay work?
When a user buys a song from the iTunes Store, a user key is created for the purchased file. The AAC song itself is scrambled using a separate master key, which is then included into the protected AAC song file. The master key is locked using the user key, which is both held by iTunes and also sent to Apple’s servers.
Protected, purchased content is locked within iTunes; songs are not scrambled on Apple's server. This speeds and simplifies the transaction by delegating that work to iTunes on the local computer.
The result is an authorization system that does not require iTunes to verify each song with Apple as it plays. Instead, iTunes maintains a collection of user keys for all the purchased tracks in its library, it is hard to remove DRM from iTunes music.
To play a protected AAC song, iTunes uses the matching user key to unlock the master key stored within the song file, when is then used to unscramble the song data.
Every time a new track is purchased, a new user key may be created; those keys are all encrypted and stored on the authorized iTunes computer, as well as being copied to Apple's servers.
When a new computer is authorized, it also generates a globally unique ID number for itself and sends it to Apple, which stores it as one of the five authorizations in the user account.
Apple's server sends the newly authorized machine the entire set of user keys for all the tracks purchased under the account, so all authorized systems will be able to play all purchased songs.
An iTunes computer can be authorized by multiple iTunes user accounts; for each account, iTunes maintains a set of user keys.
|
Home
Products
