To provide a better user experience to existing WhatsApp user, WhatsApp is now testing and adding several features which includes end to end encrypted backup. This feature now rolls on Android and iOS platform.
With this feature enabled, you can store the backup at Google Drive or Apple iCloud. WhatsApp claim even them nor Facebook is able to read the content stored. Since 2016, message encryption has been in place and now WhatsApp finally added end-to-end encrypted backup.
Facebook call this Physical Hardware Security Module (HSM) to be used to decrypted the encrypted file uploaded to Google Drive or iCloud. More features of this will be introduced later after it has been rigorously tested.