Yes, it is a waste of your time unless you are VERY proficient at reverse engineering.
Decryption key? man. You have the right idea, but the decryption key is different on EVERY SINGLE activation attempt. Even on the same computer, and the same beta key. So even if you do get the decryption key, it won't work on a different computer, let alone the next time you try to activate. And whats the only known way to get one? Its to actually have a beta key. Now, if you can't use that decryption key on another computer, that kinda makes it pointless right? Good job. You've gottent he decryption key... But you already had a legit beta key. That gets you nowhere.
Unlock Request Algorithm is the only solution if you follow this path.
The easier path however is to Crack the EXE. Not a No-CD patch. That is a 3 on a scale of 1-10 here. Think about it, there isn't even a real CD for this game yet as its not even released. not even considering the fact that the game boots up just fine without a cd as long as its activated. The 'no cd inserted' error is only a generic error for failing activation.