Only one person has to hack the key. Then he/she can distribute either the key or the decrypted content to everyone else. This is exactly why DRM will never work.
Have you noticed that XBox 360 is not cracked (short of one batch that had leaky DVD drives)?
It's not a problem to create a real pain in the ass for the pirates. The problem is to avoid creating real pain in the ass for normal users and your own developers at the same time.
