Tighten Pro - Secure Mac App Store Receipt Validation
Getting your Mac OS X App ready for the App Store is simple. Until you start thinking about verifying the store receipt, checking the certificate chain used to sign your application and checking the integrity of the application bundle. Implementing all of the WWDR recommendations for the App Store could take up to a month (that's the voice of experience speaking), even for experienced developers!
Tighten Pro changes all that. With a built-in code generator that reads directly from your codesign-ed app bundle, you can add a complete, robust App Store implementation to your own application in under 30 minutes. And since the code generator creates customized security code, your app will be more secure than if you simply reused sample code from the internet.
I use it myself. I wouldn't have it any other way. Enjoy.