If I sign a JAR with a certificate from Comodo, will I still get warnings? I have written a piece of software in Java that I would like to sell, however it is currently unsigned. When I first wrote the software it didn't matter too much, but I think OS X has upgraded since then and has gotten more strict as have web browsers and I'm now getting lots of warnings to say the file "is not commonly downloaded and may be dangerous" and OS X will not allow the app to run without changing security settings.

From what I can gather the only way to address this is to sign the application, which is fine for Windows however on OS X I'm a bit confused. I've read online that now only certificates issued by Apple are valid, but some companies like DigiCert are still advertising that there code signing certificates work on Mac and pretty much all say that they work with Java. So, if I signed my JAR files with a code signing certificate from Comodo and then used JarBundler to create an app, would it be recognized as 'safe'?
After biting the bullet and purchasing a code signing certificate, I can now answer my own question with all certainty:

Short answer: No, the warnings don't go on OS X - although they do in web browsers.

Long(er) answer: Technically certificates from Comodo or any other certificate authority that is trusted do work on Mac and you can absolutely sign .apps with them, however how useful this is another matter. I suppose that for more advanced users it is still beneficial in that you can verify whether or not an application has been tampered with, but Apple still won't see it as being from a trusted developer - and that's where the confusion starts.

The warnings that I mentioned in my original question originate from Gatekeeper. Now, if I would have known that I wouldn't have needed to start this question but I guess if I didn't know other people won't either. Anyway Gatekeeper is something that Apple have designed to keep Mac's safe and to avoid unwanted, malicious software from entering the system. It does this by restricting what apps can be executed based upon their origin, and by default in OS X Mountain Lion and later Gatekeeper only allows the execution of Apps from the Mac App Store and trusted developers.

To become a trusted developer however, it takes more than just signing code with any old certificate. Trusted developers have Developer ID's, given to them by Apple, and their code signing certificate contains this Developer ID; again the only certificates to be able to hold a Developer ID are those issued by Apple.

So, when people tell you that Apple only trust themselves, that's not true. They trust certificates issued by most certificate authorities just not in the same way as Windows and signing you app does not mean you're a trusted developer. For that, you have to pay Apple $99/year.

In all fairness, you do get a lot for that $99 and it does make some sense for it to be this way. It's frustrating for developers, but  safer for users! Users can bypass Gatekeeper for individual apps, so if you're only planning on releasing one app for OS X or something then perhaps providing instructions on how to this might be a better option for you.

PS: After a lot of emails to the Comodo support team, I finally received this statement from them to confirm all of this:


  While our certificates work perfectly fine with signing .app files, it
  does not give you an Apple Developer ID to designate that you are an
  Identified Developer by Apple, as only Apple provides developer IDs
  for Mac and iOS applications.