Is it possible to check if iOS application is signed by its developer at applications runtime? I tried to download .ipa of some apps and resigning them with my developer ID and almost all of them worked on my iOS device. But some of them didn't, so I guess they are somehow checking if signature has changed and forbidding them to run if it is.
I know, there is Code Signing Services for OSX, but I haven't found a way to do this in iOS.
Also I have read that after reviewing, apple signs application with their own signature. Are the _CodeSignature/CodeResources and embedded.mobileprovision files also changed during this process? Is it possible for me to check if it is signed with apples signature at runtime?
I wrote a small signature checker (using openssl). It is available here: https://github.com/elnormous/signature_check/blob/master/SignatureCheck/main.c
And the answer to the second question is no, _CodeSignature/CodeResources and embedded.mobileprovision are not being changed. Apple changes only the signature of the Mach-O file.