Facebook doubles down on email encryption by Robert Hackett @FortuneMagazine September 22, 2015, 5:25 PM EDT E-mail Tweet Facebook Linkedin Share icons Facebook has begun supporting new encryption options, the company announced on Tuesday. The social network first began allowing users to receive encrypted email notifications in June. At that time, the company adopted OpenPGP, a decades-old encryption technology that helps keep messages between correspondents private. (The tech is secure, but infamously difficult to use.) Now Facebook FB has enabled support for elliptic curve cryptography, another flavor of message-scrambling tech. The ends are the same: This crypto—like OpenPGP—armors communications against prying eyes. Say, spies trying to intercept a “password reset” email. The difference? Elliptic curve crypto uses smaller keys—strings of code needed to lock and unlock messages—than the ones required by the RSA algorithm, which powers PGP encryption. Some people prefer it. MORE: “Facebook security chief Alex Stamos’ ambitious plan to connect the world—securely” Elliptic curve cryptography “is now supported in OpenPGP,” Facebook spokesperson Melanie Ensign wrote to Fortune, “and we want people to be able to share and use any valid OpenPGP key that they choose.” News of the update appeared on the social network’s security blog, a (you guessed it) Facebook page called “Protect the Graph.” Within the post, the company highlights an email service called ProtonMail, which offers a quick way to get up and running with encrypted email notifications from Facebook. The company has adopted other security measures as well. In 2013, Facebook began encrypting its Internet traffic by default. And last year, the company began supporting a version of its site on the dark web. For more on Facebook, watch this Fortune video: Subscribe to Data Sheet, Fortune’s daily business-tech newsletter.