WhatsApp is the most popular messaging app on the planet with 600 million monthly active users as of August 2014. It's also owned by Facebook, which doesn't exactly have the best track record when it comes to protecting your privacy, but today WhatsApp announced plans to make its service as secure as possible.

Working with the privacy-focused Open Whisper Systems, WhatsApp is implementing end-to-end encryption for every device using the app. The new system works by jumbling each new message with a cryptographic key saved on your device. That means not even WhatsApp (and by association Facebook) will be able to snoop on your activity.

"WhatsApp deserves enormous praise for devoting considerable time and effort to this project," Open Whisper Systems, which powers the encryption using its open-sourced technology, noted in a blog post announcing the news. "Even though we're still at the beginning of the rollout, we believe this already represents the largest deployment of end-to-end encrypted communication in history."

The full encryption rollout won't happen overnight. Part of WhatsApp's strategy has been to run on every device and operating system out there, and that means updating every single version of the app will take a while. For example, the company's Android client already encrypts some messages, but there are plans to add protection for group chats and multimedia next week. Meanwhile, encryption for the iPhone app is coming soon, though it's unclear exactly when that update will hit.