WhatsApp Messenger allows people to exchange messages (including chats, group chats, images, videos, voice messages and files) and make WhatsApp calls around the world . WhatsApp messages and calls between a sender and receiver that use WhatsApp client software released after March 31, 2016 are end-to-end encrypted .

The Signal protocol, designed by Open Whisper Systems, is the basis for WhatsApp’s end-to-end encryption . This end-to-end encryption protocol is designed to prevent third parties and WhatsApp from having plaintext access to messages or calls. What’s more, even if encryption keys from a user’s device are ever physically compromised, they cannot be used to go back in time to decrypt previously transmitted messages.

This document gives an overview of the Signal protocol and its use in WhatsApp .