I recently came across a link where a popular app that prevented itself from running on jailbroken devices was cracked to do so. The cracker highlighted that in the IDA tool they were looking for a string “jailbroken” or something like that and then trying to nail down the condition that caused the alert with “jailbroken” message to appear. I believe similarly any one can look for error messages in your app, find those message and hexedit the app using a tool like IDA and get to the condition that presented the error message and modify the condition to fail.
I already checked the following link for the methods for detecting cracked apps:
http://www.iphonedevsdk.com/forum/iphone-sdk-tutorials/36330-iphone-piracy-protection-code-2-another-tutorial.html
Is there any way we can make it difficult for the app to be cracked like by encrypting the error messages and not having them in plain text in the app?
Well, for one, don’t use plaintext “jailbroken” in your app. Another is to not throw up a dialog box, something that hackers could look for in your code and backtrace. The best is to just not allow certain features to be accessible, or better yet, randomly do weird things to make it harder for them to nail down a repro case.