Matthew Stevens, Ruotger Skupin, Apple, Dave Carlton, Fraser Hess, anlumo, yene, David Keegan, Alessandro Segala.
At the end of October 2010 Apple announced the App Store for Mac. The App Store will put a receipt into your app bundle, but won't implement any copy protection scheme. For details see Validating App Store Receipts (Developer membership needed)
Unfortunately this document doesn't tell you how to process this receipt in detail, quote:
The payload of the PKCS7 container is encoded using ASN.1, as described by ITU-T X.690.This validator parses and validates the payload and the PKCS7 container itself.
Thanks to Matthew Stevens for coming up with the parser code. Thanks to Dave Carlton for polishing it a bit. Thanks to Fraser Hess for more polish and correcting my non-native English. Thanks to anlumo for the certificate checking code. Thanks to Alessandro Segala for the In-App purchasing code.
Missing from this project:
If you have an app that is more or less ready for the App Store, I think you will be able figure it out. Important is that you link with the dependencies listed in validatereceipt.m.
Be aware that there will be people trying to crack your app. So cover your tracks. I won't go into details but Blocks and Grand Central Dispatch seem to be good tools for that.
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