Encrypted Files

Okay, I'm in a situation where I have a file (specifically, a pages document) that I want to encrypt with a password, and in the best of cases, hide it from spotlight searches and such.Any ideas on how to achieve this? Please consider that I have to constantly open, view and edit the archive at times, so a disk image, zip or rar file won't work for me.

I thought FileVault, but I don't really want all of my files with password, and it gave me the "not enough space on disk error" when I tried to do it anyways.I'm assuming this service is available in the OS itself, but I haven't been able to find it just yet. Or can anyone tell me of a program that allows that option without having to leave Finder?

 

yeah but doesn't that make it uneditable until i get it out of the dmg again?