Actually, in addition to these methods, there is another way:
Summary: We’re going to make a secure disk image that behaves like a password protected USB drive, using industry standard encryption and can only be accessed with a password you decide. Within this, you can store anything you need to keep safe – files, folders, applications etc.
1. Open Disk Utility (found in Applications > Utilities folder).
2. Click ‘New Disk Image’.
(Click here to see a screenshot of the screen I’m going to talk about)
Enter a name for your Disk Image.
Enter a ‘Volume name’ (kind of like a hard drive or USB drive name, for when it mounts).
*Choose a ‘Volume size’ *(this is like choosing the size of your protected drive, so make sure it’s big enough for what you need it to contain).
Skip the Voume Format – not important.
Choose ‘128-bit AES Encryption’ from the ‘Encryption’ list.
Skip the other bits.
Click OK.
Wait while it creates your disk image.
It will bring up a prompt screen for you to enter the password you want to use to access your protected disk image.
Enter a Password.
IMPORTANT! DO NOT have the ‘Remember password in my keychain’ box ticked. If you tick this, it renders most of this excercise pointless, because your computer (while you’re logged in) will remember that password for you, so anyone who gains access to your computer can mount the private drive and access its contents.
Click OK.
Wait while it creates the Disk Image Password.
Done.
Your new private Disk is mounted (like a USB drive would). You can drag files, etc into it and store them there. When you’re done, you eject the volume (ctrl+click and ‘eject’ or drag to dock eject icon).
To mount it again, find where you saved it and double-click, this will prompt you for your password. Again, do not allow the tick box saying ‘Remember in Keychain’ to be ticked, or your machine will remember the password which is much less secure.
What I then do is stash the .DMG file you’ve made somewhere else in your hard drive, and make an ‘Alias’ (shortcut) to it by doing Apple+L with the file selected. Put this shortcut on your desktop, dock or Apps folder, give it a funky icon, etc. Depending on how hidden you need the drive’s existence to be, of course.
Don’t forget the password, or there is very little chance you can recover the data that’s within the disk image.