Unified AppSync dynamic library.
AppSync Unified and jailbreaking are NOT for piracy.
AppSync Unified and jailbreaking are for freedom of your iOS device.
AppSync Unified is a tweak that patches installd to allow for the installation of fakesigned IPA packages on an iOS device.
AppSync Unified can be used to downgrade or clone installed apps, to download fakesigned IPAs (often emulators), and also to assist in the development of iOS applications using Xcode 6 or below.
AppSync Unified should not be used to pirate iOS apps. Please support iOS developers and do not pirate!
I explain the problem with AppSync Unified and iOS piracy rather thoroughly in this reddit post. Please give it a read.