WhatsApp is now the largest IM provider to use end-to-end message encryption. Added to its Android app in a previous release, the encryption, provided by Open Whisper Systems, gives the decryption keys only to the two devices in the conversation, making it virtually impossible for WhatsApp to provide access to law enforcement agencies.
Most popular IM platforms, like Hangouts and Facebook Messenger, are not encrypted end-to-end, and WhatsApp was once accused of not taking security seriously enough, forgoing encryption altogether. While Telegram has come to be known as the de facto encrypted chat solution, and BBM another popular choice that, while not end-to-end encrypted does have strong consumer security, WhatsApp is setting an excellent precedent here.
The update hasn’t rolled out to iOS or Windows Phone just yet, but Android users will immediately be able to take advantage of this with no end-user changes.
WhatsApp also recently rolled out read receipts for Android users.