A helper class for verifying App Store receipts under iOS.
Rick Maddy, Matthew Stevens, Ruotger Skupin, Apple, Dave Carlton, Fraser Hess, anlumo, yene, David Keegan, Alessandro Segala.
These files are based off of the roddi/ValidateStoreReceipt project.
For details on iOS receipt validation from Apple, see Receipt Validation Programming Guide (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 VerifyStoreReceipt.m.
This class depends on OpenSSL being statically linked into your project. Please see https://github.com/x2on/OpenSSL-for-iPhone for one approach to getting that done.
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.
The sample project shows one possible way to make use of this receipt verifier. Please note that the sample app requires that you use the OpenSSL-for-iPhone project. Put both projects in a common parent directory. There are plenty of tasks that need to be completed to make the sample code complete but it is a framework to get you started. Like the notes in the VerifyStoreReceipt.m file, the code in the sample app should not be used as-is. If everyone uses the same code, it will be easy for hackers to work around the code making the receipt checking worthless.
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