WASHINGTON — When Facebook informs you that you’ve been tagged in a photo, the social media giant can do it by a secret notification even the National Security Agency can’t decipher.

Facebook has announced users can add an OpenPGP key to a Facebook profile.

Here’s how it can improve your privacy: next time you get an email notification for a new tag, friend request, or password reset, the message will be encrypted, reports pcworld.com.

Facebook doesn’t help you generate your own security key, but if you have one it can be added to your profile, which will provide an extra layer of security when the social network notifies you of activity on your account.

While most people have never heard of, much less know how to use, OpenPGP keys, this is the second security upgrade in recent months. In October, Facebook created a site on the Tor network which allows users to connect to the network more anonymously.

Basically, here’s how email encryption works: To use OpenPGP, you generate two keys — one private, one public.

When someone sends you an encrypted message, their email program uses your public encryption key to scramble the message. To unscramble the message, you enter your private key.

PCworld.com has step-by-step instructions on how to set up a Facebook account, using OpenPGP.