Open-source chat-encryption tool Cryptocat announced its latest update, which includes full encryption for Facebook private messages, in a blog post Monday.

Cryptocat’s mission is to make encrypted chat accessible and easy to use. With Cryptocat celebrating its third birthday (already!), we’re happy to announce the new Encrypted Facebook Chat feature in the latest Cryptocat 2.2 update.

Facebook Chat as a Cryptocat Buddy List

Cryptocat can now log into your Facebook account for you, fetch your Facebook contacts, and if another contact is also using Cryptocat, you’ll be able to automatically set up an end-to-end encrypted chat. If a Facebook friend later logs in via Cryptocat, your chat will be immediately upgraded to an encrypted Cryptocat chat:

Effectively, what Cryptocat is doing is benefitting from your Facebook Chat contact list as a readily available buddy list. As a compliment to Cryptocat’s ephemeral group chat feature, Encrypted Facebook Chat lets you view which of your friends are online and allows you to immediately set up encrypted chat with them

With Cryptocat offering free, easy encryption for everyone with its browser add-on, its user base is likely to grow pretty substantially. The tool works by reading users’ Facebook contact lists and turning them into Cryptocat buddy lists, and it requires both users in conversations to have the add-on installed. This isn’t a complicated process.

Cryptocat launched three years ago, and it allows users to encrypt their online chat-room exchanges by means of a browser extension. It also offers a free iPhone application, enabling the encryption of messages sent via iOS, with an Android version on its way. Now users can enjoy genuine privacy while communicating via Facebook chat.