Last month, Facebook CEO Mark Zuckerberg announced that alongside chats, WhatsApp’s end-to-end encryption will be used for its backups as well. Today, that has materialized and we have collected all the details for you.

WhatsApp’s end-to-end encryption technology for backups could come in handy if you store the backup on a cloud service like iCloud or Google Drive. It is a huge plus because, by default, iCloud does not encrypt backups and this new feature can help fix just that. The feature is optional and is gradually rolling out to 2 billion users on iOS and Android. Facebook said that the rollout would deliberately be “slow” to ensure a “consistent and reliable user experience for people on iOS and Android around the world.”

Zuckerberg noted that WhatsApp is now the first worldwide messaging service to offer end-to-end encrypted chats and backups. He praised the team’s effort for the feature implementation in a post on Facebook.

According to the social media giant’s blog post, end-to-end encrypted backups will be secured with a password you can define or an automatically-generated 64-digit encryption key that Facebook would only provide to you. The company claims that neither WhatsApp nor other third parties would be able to ready your backed-up data.

There is one caveat, though. If you accidentally forget the password or misplace the encryption key for the backup, you will not be able to restore the backup. This is because WhatsApp itself won’t be able to decrypt your file.

That said, you can check if you have access to the feature by navigating to Settings > Chats > Chat Backups > End-to-End Encrypted Backup. If you have access, follow the on-screen prompts to enable encryption. Facebook didn’t specify how slow the rollout would be and when all WhatsApp users would certainly have access to the encryption feature.

To better understand how end-to-end encryption works, here are links to a whitepaper and an engineering blog about the technology.