I have transitioned to zpMasonry 1.4.1 from zpGalleriffic 1.0, having tried out 1.4.1 of zpGalleriffic.
Thanks for the theme! It's beautiful and very fast.
When I was using zpGalleriffic 1.0, there were no problems with controlling access to the full-size images. I used the corresponding fields under Options: Image to password protect those files.
When my shoot subjects needed to access the full resolution file, they needed to enter a common username and password which I gave to them.
This seems to have changed under zpMasonry 1.4.1.
Firstly, I set the Options: Theme: 09 Final Image Link Option to Standard ZenPhoto.
When I tested on another browser (not logged in to my admin account), I could, as a public user, access the full-size image without being accosted by a username/password dialogue.
Past threads such as http://www.zenphoto.org/support/topic.php?id=9307 seem to imply that the core protection of full-size images only applies to "protect script access to the images". This statement, along with the fact that nothing has changed in my configuration but the theme, leads me to suspect a different access method to the images used by zpMasonry is bypassing that protection process.