On the Mac App Store

I’ve just come off iDeveloper.TV Live with Scotty and John, where we were talking about the Mac app store. I had some material prepared about the security side of the app store that we didn’t get on to – here’s a quick write up.

There’s a lot of discussion on twitter and the macsb mailing list, and doubtless elsewhere, about the encryption paperwork that Apple are making us fill in. It’s not Apple’s fault, it’s the U.S. Department of Commerce. You see, back in the cold war (and, frankly, ever since) the government have been of the opinion that encryption is a weapon (because it hides data from their agents) and so are powerful computers (because they can do encryption that’s expensive to crack). So the Bureau of Industry and Security developed the Export Administration Regulations to control the flow of such heinous weapons through the commercial sector.

Section 5, part 2 covers computer equipment and software. Specific provision is made for encryption, in the documentation we find that Items may be controlled as encryption items even if the encryption is actually performed by the operating system, an external library, a third-party product or a cryptographic processor. If an item uses encryption functionality, whether or not the code that performs the encryption is included with the item, then BIS evaluates the item based on the encryption functionality it uses.

So there you go. If you’re exporting software from the U.S. (and you are, if you’re selling via Apple’s app store) then you need to fill in the export notification.

Other Mac App Store security things, in “oh God is it that late already” format:

  • Receipt validation. No different really from existing licensing frameworks. All you can do is make it hard to find the tests from the binary. I had an idea about a specific way to do that, but want to test it before I release it. As you’ve no doubt found, anti-cracking measures aren’t easy.
  • Users. The user base for the MAS will be wider, and less tech-savvy, than the users existing micro-ISVs are selling to. Make sure your intent with regard to user data, particularly the consequences of your app’s workflow, are clear.
  • Similarly, be clear about the content of updates. Clearer than Apple are: “contains various fixes and improvements” WTF?
  • As we’ve found with the iOS store, it’s harder to push an update out than when you host the download yourself. Getting security right (or, pragmatically, not too wrong) the first time avoids emergency update submissions.
  • Permissions. Your app needs to run entirely as the current user, who may not be an admin. If you’re a developer, you’re probably running as an admin. Test with a non-admin account. Better, do all of your development in a non-admin account. Add yourself to the _developer group so you can still use gdb/Instruments properly.

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