Why unity3d on file to do so strict check

For example, the development on the IOS platform I on my DLL file some confusion or encrypted operation. Then the MD5 value of the DLL file certainly changes. I copied the DLL files back into the *.ipa file after this program can not be run on the device.

Similarly, if I copy this file to 'Managed' the unity3d generate xcode project under xcode project can not be correct debug

I can only be understood as a resource file md5 checksum: Unity3D he veto any modified files or: as long as you modify your dll, and then he put it back, so this project can not run.

I know that this will bring some security. But so it goes, I will not be able to confuse my code.

But, I build windows version when there is no distress.