Facebook just finished rolling out its Secret Conversations—which are Messenger chats protected by end-to-end encryption—but it's only secure from prying eyes in limited circumstances. So, for those who are freaked out by the revelation that Yahoo may have allowed the government to scan all of its users' email, take heed. As 9to5Mac notes:
• Both parties have to have the latest version of the app for it to work.
• There is no cross-device support, so you "can't start a Secret Conversation on one device and continue it on another."
• There is no support for GIFs or video (though images and stickers can be used). MB