If possible, how can I encrypt a folder with a password on OS X Mavericks?
OS X doesn't ship with a folder by folder encryption. You can create an encrypted sparse bundle which acts as a folder that is decrypted once it mounts and stores all contents in an encrypted form on disk.
Enable advanced image options in Disk Utility:
defaults write com.apple.DiskUtility advanced-image-options 1
Open Disk Utility (found in
Select File → New → Disk Image from Folder… or press ⌘ cmd+⇧ shift+N.
Select the folder that contains your files and press Image.
Choose sparsebundle as the Image Format, and choose the level of encryption you require.
Choose a password to encrypt the image. Make sure to uncheck the Remember password in my Keychain box if you want to be prompted each time you attempt to mount the disk.
Click OK. Disk Utility will create a sparse bundle to hold your files. Don't forget to delete the original folder.
You can make an alias (or a symbolic link, symlink for short) to folders in the encrypted folder to hide much of the difference between a disk image and the actual encrypted folder if desired. Alternatively, you can mount this disk image in a custom folder (instead of /Volumes) for even smoother access.