OS X Mountain Lion: Application Signing

By default, Mac OS X Mountain Lion disables the ability to run applications which are not signed, the idea being to prevent hackers from persuading you to run a nefarious application.

This is an excellent security precaution, but also a headache until all apps are signed (and some never will be).

When an application is not signed as per the system preferences (see below), you will see a dialog like the following:

Mac OS X Mountain Lion unidentified developer application

There are two ways to allow an application to run—

Allowing an application to run — context menu

Right-click or control click on the application, choosing Open:

Right-click / control-click to choose “Open”

A dialog then appears to confirm that you want to open the app:

Dialog to confirm opening an application that is not signed

Allowing an application to run — system prefs

Use some care here— be certain of the origin of the application!

The quick way is to use a contextual menu: right-click (control-click) the application.

To allow the application to run:

1. Temporarily choose “Anywhere”.
2. Run the application.
3. Change security back to previous setting.

Once the application has run, it is “approved” and these steps will not be necessary again for that particular application.

Mac OS X Mountain Lion system preferences for application signing