WhatsApp said on Friday it will give its two billion users the option to encrypt their chat backups to the cloud, taking a significant step to put a lid on one of the tricky ways private communication between individuals on the app can be compromised.
The Facebook-owned service has had end-to-end encrypted chats between users for more than a decade. But users have had no option but to store their chat backup to their cloud — iCloud on iPhones and Google Drive on Android — in an unencrypted format.
Tapping these unencrypted WhatsApp chat backups on Google and Apple servers is one of the widely known ways law enforcement agencies across the globe have for years been able to access WhatsApp chats of suspect individuals.
“WhatsApp is the first global messaging service at this scale to offer end-to-end encrypted messaging and backups, and getting there was a tough technical challenge that required an entirely new framework for key storage and cloud storage across operating systems,” said Facebook’s chief executive Mark Zuckerberg in a post announcing the new feature.
Store your own encryption keys
The company said it has devised a system to enable WhatsApp users on Android and iOS to lock their chat backups with encryption keys. WhatsApp says it will offer users two ways to encrypt their cloud backups, and the feature is optional.
In the “coming weeks,” users on WhatsApp will see an option to generate a 64-digit encryption key to lock their chat backups in the cloud. Users can store the encryption key offline or in a password manager of their choice or create a password that backs up their encryption key in a cloud-based “backup key vault” that WhatsApp has developed. The cloud-stored encryption key can’t be used without the user’s password, which isn’t known by WhatsApp.
“We know that some will prefer the 64-digit encryption key whereas others want something they can easily remember, so we will be including both options. Once a user sets their backup password, it is not known to us. They can reset it on their original device if they forget it,” WhatsApp said.
“For the 64-digit key, we will notify users multiple times when they sign up for end-to-end encrypted backups that if they lose their 64-digit key, we will not be able to restore their backup and that they should write it down. Before the setup is complete, we’ll ask users to affirm that they’ve saved their password or 64-digit encryption key.”
A WhatsApp spokesperson told TechCrunch that previous copies of the backup will be deleted once an encrypted backup is created. “This will happen automatically, and there is no action that a user will need to take,” the spokesperson added.