permissionSecurity
I'm trying to figure out the best place for me to backup my Lastpass CSV and it seems like the best place to put it would be on my full-disk-encrypted macbook, but I would like to be able to require a password before someone is actually able to read it.
I know I can password protect a folder with a chosen password but that's likely something that will be forgotten.
Is there a way to set the permissions of a file to require the Admin password before viewing the contents?
Your friend has no idea what he's talking about. You don't even need to use a Linux disc - you can use single user mode or a Mac OS X install disc to copy things or make changes to the filesystem.
To prevent someone from booting into single user mode or from an unauthorized disc or external drive, your friend can set a firmware password. However, this, too, is easily bypassed if you can open the computer and remove the drive, or alter the memory configuration. Simply put, if someone has physical access to a computer, encryption is the only way to protect your data.
In System Preferences you go to Security and Privacy.
Code signing is a component of this. Choosing Mac App Store and Identified developers requires the use of Code Signing certificate. If you want to be able to install anything unsigned, you will have to select "Anywhere." This allows you to install anything, but it allows you to install anything :) See this pic:
Best Answer
You can always use Disk Image to mount an encrypted partition that you can write files to. You choose the password, so you could set it to be the same as the password for admin. It's pretty simple to do:
https://support.apple.com/en-us/HT201599