I'm part of the apple developer program so I can code sign and install on my device.
Is it possible to take an application from Cydia (it doesn't appear to use mobilesubstrate, it's packaged as a .deb) and re-sign it so I can install it on my non-jailbroken iPhone?
Thanks!
If the full source code for that app is provided in the .deb (which you can extract and see) then you could probably resign the code and put it on your device. However, you would need everything that the actual developer had, which as I understand does not happen. (If you compile an iPhone app and look at the .app package contents, you'll notice all your resources, but no .h /. files, just a data.momd file.
If you do some tricky decompiling, perhaps you could get all the files you need, but that's a different story.
Probably. Depending on the app. Some applications are just App Store applications (or similar), that were or would be rejected. If it is one of those, extracting the .app file then codesign-ing the binary inside there should get it to work.
However, many Cydia apps require themselves to be installed to the "system" directory (/Applications), so won't work in the App Store/Developer directories, and also may require root access or access to other files that Apple would deny.
Your best bet, if you want to run one of these apps, is to jailbreak.