WhatsApp has recently announced the launch of their end-to-end encrypted backups feature, even on cloud services. Earlier, despite having end-to-end encryption available by default, WhatsApp lacked a security feature for cloud backups.
WhatsApp End-to-End Encrypted Cloud Backups
As announced in the recent blog post, Facebook has introduced end-to-end encrypted cloud chat backups for WhatsApp users. The tech giant claims to be one of the first secure messaging apps to implement E2EE cloud backups.
WhatsApp already implements end-to-end encryption (powered by Signal’s protocol) for all users by default. This encryption applies to all chats, calls, and media exchanged on the platform, hence making the platform safe from interception.
However, users’ chats would become vulnerable upon backing up data to clouds, such as Google Drive or iCloud. Anyone accessing the drives could find the WhatsApp databases unencrypted there.
Nonetheless, with the recent move, WhatsApp users can securely backup their data to cloud services with E2E encryption.
This feature makes use of a newly implemented encryption key storage system. Users can enable E2EE backups managed by a securely generated encryption key. They can then store the key either manually or via a secure password to the Backup Key Vault.
Announcing this move in a Facebook post, Facebook’s CEO Mark Zuckerberg claimed WhatsApp to be the first to take such a step.
How WhatsApp E2EE Cloud Backup Works
Regarding how the key storage with the password would work, the post reads,
When someone opts for a password, the key is stored in a Backup Key Vault that is built based on a component called a hardware security module (HSM) — specialized, secure hardware that can be used to securely store encryption keys.
Whenever a user would require accessing backups (such as when installing WhatsApp to a new device), it would do so via the encryption key or the password.
In the latter case, the user would actually fetch the encryption key from the HSM via the password. At this point, the user needs to be careful about the password typed since multiple wrong attempts would render the key permanently inaccessible. WhatsApp implements this measure to curb brute-force attempts.
Explaining the mechanism further, the post reads,
WhatsApp’s front-end service, ChatD, handles client connections and client-server authentication, and will implement a protocol that sends the keys to the backups to and from WhatsApp’s servers. The client and HSM-based Backup Key Vault will exchange encrypted messages, the contents of which will not be accessible to ChatD itself.
The HSM-based Backup Key Vault will sit behind ChatD and provide highly available and secure storage for the encryption keys to the backups.
To implement this feature with reliability, the tech giant has distributed the HSM-based Backup Key Vault service across numerous data centers globally. With this step, the tech giant aims at preventing any issues due to potential data center outages.
The new feature will be available to all iOS and Android users in a few weeks.
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