One of the lesser known functions of the Keychain on OS X is its ability to add Secure Notes, notes that require you to enter your Keychain login password to view them.
There are a ton of third-party apps out there that allow you to password protect your notes, but Keychain is built right in to Mac OS X, and has been for a while; it’s a pretty nifty thing to have when you need it.
Better yet? The current version of Keychain will let you put images and video into your notes, making it a snap to secure your media files to your password.
Launch Keychain Access, an app found in your Utilities folder (which is itself inside your Applications folder).
Once launched, click on the Secure Notes title in the left-hand column. Click on the Plus button in the lower left, and title your new note in the resulting dialog.
Next, drag and drop any images or video you want to secure to the notes field below the title field. A little green bubble with a plus sign in it will appear, just like it does when you copy files in the Finder.
When adding a video file, you may get a warning that the file is really big; OS X will offer you the option to just add an Alias to the file, or let you click the Add button to actually place the video inside the note. The latter is the more secure option.
When you’ve finished adding all the images and videos you want, hit the Add button in the lower right corner of the Note dialog, and your new Secure Note will list itself in the right-hand column. To view any of your Secure Notes, double click on them in the Keychain Access app and then enter your Keychain password to view.
Via: Macworld Hints