Facebook Messenger end to end encryption is now available to all 900 million users. In order to use the end to end encryption feature on your iOS or Android device, you must be using the most current version of Messenger. Be sure to update the app.
When you turn on “Secret Conversation” for conversation it will really be private. Facebook can’t read the message, hackers and law enforcement won’t be able to spy on you.
If you want to start a new encrypted conversation:
1 Tap the new conversation icon at the top right.
2 Tap “Secret” in the top right.
3 Choose your recipient and begin messaging.
If you want to turn an ongoing conversation into an encrypted Secret Conversation:
1 Open the message thread.
2 Tap their name at the top of your screen.
3 Tap “Secret Conversation” to switch it over.
Unfortunately, there’s no way to set “Secret Conversation” as the default so you’ll need to enable it every time you start a new conversation. If you don’t see the Secret Conversation option that means the person you want to start a conversation with doesn’t have the current version of Messenger.