I want to know how to protect a specific Mac OS X 10.7 partition which is installed on a dual-boot machine.
I do not need anything too powerful or secure, but I have two Mac partitions on the same machine, one of which I would prefer had some kind of security layer/protection. More specifically, if I wanted to protect "partition A", I want to prevent logging into "partition B" and browsing through and/or modifying the contents of "partition A".
I do not know if some kind of password protection would suffice or if I actually need encryption of some or all of the contents of "partition A" (or perhaps complete encryption of the entire hard drive, "partition A" + "partition B"). If it would simplify my configuration, I would not require that "partition A" were protected from the scenario in which some external drive were used to boot into some other OS (ex. Linux) in order to snoop around "partition A". I am mainly concerned about protecting "partition A" from "partition B".
According to my brief research, there seems to be multiple approaches to solving this general problem. Encryption apparently adds performance overhead, unfortunately, so I will almost certainly avoid that, even if it is my only option. I am looking for a convenient, light security solution. Again, my security demands are pretty lax.