Currently a method that works is to use a popular open-source cracking software "Clutch". Some of the tools (gdb in my base) are not working reliably on the iPhone 5S / iOS7. Signing with ldid (since the original signature is made invalid after editing) See Dustin Howett's theos if you would like to try this method. When you are patching functions, an easier way to work (if you know Objective-C) is to use MobileSubstrate to hook the relevant functions. It may still be quite messy since much of iOS's code works with objc_sendMsg().
#What are ipa files pro
One possible tool is IDA Pro (Free version does not support ARM). You can begin reverse engineering the code when you have access to an unencrypted copy of the binary. There are many tools of dubious purposes (piracy) which automates the process, however the above is the gist of how the process is done.
#What are ipa files install
Install the IPA on an authorized device.The typical method in brief (with a jailbroken iOS device) is to Otherwise, you will need to decrypt the app. If cryptid is 0, you can proceed on to the Post Decryption section.
(where thebinary is the executable binary - see the app's ist, CFBundleExecutable key) otool -arch armv7 -l thebinary | grep crypt If you are unsure, you can check whether the cryptid bit is set with otool (see this page). If the IPA file is straight from iTunes/iPhone (without any modification), the code section in the binary (as indicated by the ist) is encrypted with FairPlay (Apple's proprietary DRM).