WhatsApp will begin rolling out the end-to-end encryption for chat backups it announced in September for its users globally on Android and iOS devices.

       The Facebook-owned messaging service has more than 2 billion users globally and over 400 million in India. These users send more than 100 billion messages a day.

       With this update, if someone chooses to back up his chat history with end-to-end encryption, it will be accessible only to him, and no one will be able to unlock the backup, not even WhatsApp. Neither WhatsApp nor the backup service provider (like Apple) will be able to access their end-to-end encryption key or their end-to-end encrypted backup.

       "Starting today, we are making available an extra, optional layer of security to protect backups stored on Google Drive or iCloud with end-to-end encryption. No other global messaging service at this scale provides this level of security for their users’ messages, media, voice messages, video calls, and chat backups," WhatsApp said in a blog post explaining how this extra layer of security will work.

       Users can now secure their end-to-end encrypted backup with either a password of their choice or a 64-digit encryption key that only they would know. Neither WhatsApp nor its backup service provider will be able to read their backups or access the key required to unlock it.

       Encryption is the practice of scrambling data to make it unintelligible for even the service providers. It keeps conversations private, and end-to-end encryption means only the intended sender and receiver can see the messages being sent.

       A major issue and question with WhatsApp's chat backups was that these are stored with third party cloud providers like Google (Drive) or iCloud.

       "Prior to the introduction of end-to-end encrypted backups, backups stored on Apple iCloud and Google Drive were not protected by WhatsApp’s end-to-end encryption. Now we are offering the ability to secure your backups with end-to-end encryption before they are uploaded to these cloud services," WhatsApp said earlier in a whitepaper explaining the technology behind this new update.