Facebook has started testing one-to-one secret conversation in Messenger that will be end-to-end encrypted that means the person who will receive the message can only read the message and not anyone else including Facebook. Users can also choose to set a timer to control the duration of time each message you send remains visible within the conversation. According to Facebook, their technology uses signal protocol developed by Open Whisper Systems.
Facebook has already introduced end-to-end encryption feature in WhatsApp and that works great. But there are some differences as in WhatsApp end-to-end encryption is set default and everything you send like videos, photos, messages and other rich content to other person are end-to-end encrypted. But in Messenger, rich content like GIFs or videos in secret conversation is not currently supported including making payments and other popular messenger features.
Messages you send within a secret conversation can only be read on one device, that’s why Facebook has kept the feature optional as users may wanna use messenger on other devices.
Right now, secret conversation feature is only available on a limited test basis but Facebook will be making this feature more widely available this summer. Before rolling it out to everyone using Messenger, Facebook would like to gather some feedback regarding its functionality.