updated 07:50 pm EST, Thu January 6, 2011
Could lead to changes from Apple
(Updated with further information and clarification) Mere hours after the opening of the Mac App Store, software crackers have already found a method that could lead to pirating of Mac App Store software. The method involves copying some package resources from a free app and implanting them into a copy of a paid app obtained from some other source (such as the developer's own web site) where the app does not do any receipt checking.
"Cracking" or creating an unlicensed copy of a restricted app is nothing new, but developers who didn't implement Apple's suggested method of ensuring that only authorized machines run purchased apps may suffer as unethical users help themselves to "free" versions of normally-paid applications that have no other license-checking schema. The specific technique is detailed in a post on Pastebin.com (specific post not linked), and Apple is aware of the breach.
MacNN strongly condemns software piracy as illegal and damaging to the entire Mac community.
Update: Developer Sean Christmann has explained the flaw and how to correct it in more detail. He calls it a "massive failure in the implementation of Apple's receipt system," but suggests the problem is limited in scope (falling mainly on apps that did not fully implement Apple's suggested receipt checking) and that other apps would prove less vulnerable to the technique.