This means that messages are end-to-end encrypted no matter whether they’re being sent, received, stored locally or in the cloud.
Mark Zuckerberg announced the milestone on his Facebook page, saying “We’re adding another layer of privacy and security to WhatsApp: an end-to-end encryption option for the backups people choose to store in Google Drive or iCloud. WhatsApp is the first global messaging service at this scale to offer end-to-end encrypted messaging and backups, and getting there was a really hard technical challenge that required an entirely new framework for key storage and cloud storage across operating systems.”
WhatsApp users will have to opt in to the new feature which will soon begin rolling out – it isn’t yet available to beta testers, but those will be the first users to be able try it out before it’s added to the app for what WhatsApp is calling “everyday users”.
The benefit of backing up your chat history with end-to-end encryption is that it will be accessible only to you, and no one will be able to unlock that backup, not WhatsApp not the service provider (Apple or Google).
WhatsApp was keen to point out that that no other messaging service at its scale (more than 2 billion users who send more than 100 billion messages a day) provides this level of security for messages.
Expect to see the option in the Backup section of Settings of both iOS and Android apps “in the coming weeks”.