WhatsApp is rolling out an option for users to encrypt their message backups, and that is a big win for user privacy and security. The new feature is expected to be available for both iOS and Android “in the coming weeks.” EFF has pointed out unencrypted backups as a huge weakness for WhatsApp and for any messenger that claims to offer end-to-end encryption, and we applaud this improvement. Next, encryption for backups should become the default for all users, not just an option.
Currently, users can choose to periodically back up their WhatsApp message history on iCloud (for iOS phones) or Google Drive (for Android phones), or to never back them up at all. Backing up your messages means that you can still access them if, for example, your phone is lost or destroyed.
WhatsApp does not have access to these backups, but backup service providers Apple and Google sure do. Unencrypted backups are vulnerable to government requests, third-party hacking, and disclosure by Apple or Google employees. That’s why EFF has consistently recommended that users not back up their messages to the cloud, and further that you encourage your friends and contacts to skip it too. Backing up secure messenger conversations to the cloud unencrypted (or encrypted in a way that allows the company running the backup to access message contents) means exposing the plaintext to third parties, and introduces a significant hole in the protection the messenger can offer.
When encrypted WhatsApp backups arrive, that will change. With fully encrypted backups, Apple and Google will no longer be able to access backed up WhatsApp content. Instead, WhatsApp backups will be encrypted with a very long (64-digit) encryption key generated on the user’s device. Users in need of a high level of security can directly save this key in their preferred password manager. All others can rely on WhatsApp’s recovery system, which will store the encryption key in a way that WhatsApp cannot access, protected by a password of the user’s choosing.
This privacy win from Facebook-owned WhatsApp is striking in its contrast to Apple, which has been under fire recently for its plans for on-device scanning of photos that minors send on Messages, as well as of every photo that any Apple user uploads to iCloud. While Apple has paused to consider more feedback on its plans, there’s still no sign that they will include fixing one of its longstanding privacy pitfalls: no effective encryption across iCloud backups. WhatsApp is raising the bar, and Apple and others should follow suit.