How to encrypt or obfuscate objective c code? [duplicate]

Answer 1

It's a lot more complicated than it might seem initially. Any tool that mangles method names has the potential to fudge up:

1. KVC compliance
2. The use of dynamically generated selectors
3. Nib file compatibility
4. Protocol conformance
5. Method inheritance

Obfuscation is just another layer to deal with; often obfuscation is easily reversed. It is not really possible to “encrypt” your classes because the Objective-C runtime and Cocoa framework won't know how to decrypt it. Anyone determined enough will eventually figure out how your program works.

Answer 2

Apparently, according to this answer Apple encrypts iPhone binaries as a matter of course for all iPhone apps.

I'd stop worrying about it.

Answer 3

Actually you can provide some obfuscation and tamper protection with specialist 3rd party tools. There are 2 companies, I know of, that provide tools or services to do this : Arxan and irDato.

Neither are cheap or accessible to small developers but if you are developing for a large corporation then you should consider them.

Obfuscation is done by mangling code paths and adding redundant instructions so as to confuse anybody trying to reverse engineer the code. Tamper protection is done by adding checksums to the code and embedding checksum checks within functions. You can create a network of interdependent checksums that makes it extremely difficult to bypass them. There are a few other things that can be done but you really need to talk to specialists in this area.

Further to the earlier answer, Apple does not encrypt the binaries but just signs them. It is fairly easy to reverse engineer and modify app binaries on a jailbroken device.