In order to remove the encryption from an iOS binary on the App Store, it first has to be executed on a ARM capable device. Is there a way to do this without access to a device?
In order to remove the iOS app encryption (called FairPlay), you'd need to do one of the following:
- Run the app on a physical ARM device and dynamically decrypt it.
- Run the app on a virtual ARM device and dynamically decrypt it.
- Statically decrypt the app.
Number 1 is the most common approach used, but it's out of the question since you're asking how to decrypt the app without access to a physical device.
Number 2 seems to currently be out of the question since the only emulator I was able to find that supposedly "supported" iOS is iEmu, which is now defunct.
Number 3 is theoretically possible, but based on my Googling, nobody has yet written a static decrypter for FairPlay.
N.B. iOS-based reverse engineering is definitely not my area of expertise, so perhaps someone can provide a better answer and/or correct any incorrect assumptions I've made above.
My answer What you can actually do is to look for "cracked IPA apps", which basically mean they are decrypted (FairPlay encryption removed). There are many sites like this one (AppAddict).
I had to do that since I upgraded my jailbroken device to iOS 8.4 (Pangu jailbreak). The iOS8.4 jailbreak disabled debugger tools like Clutch, which I used to decrypt binaries. Maybe the iOS 9.0 jailbreak allows them to work again.
I couldn't even get to decrypt some older versions of Facebook or Tinder. That's when you really rely on the community to have uploaded their cracked binaries.
Please note that I am not supporting piracy. Linking cracked IPA resources is meant for reverse engineering and research purpose. In this point of view I find it helpful to provide decrypted ("cracked") binaries of free apps to the community (via AppAddict for instance).