On feasibility

Omar Shahine writes

It seems that Paul Thurrott is astonished that Apple would apply DRM to purchased music on the client (iTunes) rather than the server. Seems like a really bad design decision and a good way to open the door for two programmers to crack it...

...I guess hindsight is 20/20 (that goes for everyone)...

In hindsight, I don't think this was a poor design decision, but rather the only feasible option for Apple.

The iTunes Music Store, as it stands, is already an amazing database feat. They have terabytes of digital music selections, and everyday they serve tens of thousands of song downloads and song previews on demand. It's amazing that they can handle that many database queries in the first place -- now imagine that in addition to all of that, they added on the computational overhead of encrypting each song on the server-side. (Whereas with a software update, you only need to encrypt the file once, but iTunes downloads need to be encrypted separately for each specific user.) Encrypting on the client-side is a clever way to let the servers focus on database queries and file serving without crashing... unfortunately, it really leaves Apple open to clever hackers.