WhatsApp updates its messaging app so that every text message and voice call will be encrypted for the company’s one billion users. Facebook partnered with Open Whisper System, company behind Signal and TextSecure encryption apps, to integrate the Signal’s Open source strong encryption protocol into WhatsApp messaging app. The latest version of WhatsApp mobile app offers you an option to verify the keys of the other users with whom you are communicating, ensuring prevention from the man-in-the-middle attack. However, there is one point to be noted that if several users are sending texts in a group chat and one of the users doesn’t support encrypted messages, all the conversation going through that group chat will remain unencrypted.
Source: https://thehackernews.com/2016/04/whatsapp-end-to-end-encryption.html