Developer Cannot Be Confirmed

I bought a new camera recently and decided I needed the "old" version of Photoshop I had lying around on my MacBook so I could salvage pics taken with my n00btastic photo skills. So as any reasonable person would do, I installed and then attempted to update Photoshop with the latest available patch from Adobe.

Finding the correct patch on Adobe's site wasn't exactly intuitive, which is surprising from a company that specializes in making software for the web, anyway I digress. Once the patch was downloaded, it wouldn't install. "AdobePhotoshop12-4-mul-AdobeUpdate.dmg can't be opened because the identity of the developer cannot be confirmed." Seems hard to believe, and I'm not sure who's to blame here, but after some searching it seems there are a number of rather large companies, i.e. Oracle, that have the same issue. (Either devs are signing their apps incorrectly or Apple released a patch/update breaking the previous verification mechanism.)

In any case, if you trust the developer, this can be overruled with a few clicks and your password:

System Preferences > Security & Privacy > General tab and you will see "App in question" was blocked from opening because the identity of the developer cannot be confirmed.

Click the button to allow anyway and enter your password, the app should start installing immediately.