https://www.digitalinformationworld.com/2020/03/whatsapp-tes...
But even if, WhatsApp remains a closed source app, owned by Facebook. I really see no reason to trust them. Zuckerbergs privacy policy seems unchanged, since he called his user dumb fucs for trusting him with their data, while at the same time, buying the surrounding houses of his Villa, to protect his own privacy.
The only thing holding them back is a bit public image, but the general population do not care much and maybe breaking of privacy laws. But since the governments also really do not want real encryption for everyone, I would rather imagine "gentlements agreement" behind doors, than real investigations, in case for example WhatsApp would secretly send also the key for the backup to someone else.
I bet this is also why the intelligence agencies aren't pounding on them for having E2E encryption, obviously Google is an open book to them. And Google has access to all your history for their own purposes.
Of course you can choose to turn off the backups, but you can't be sure all your contacts are doing the same.
And while there is definitely no hope for binary blob consumer software to ever have real end-to-end encryption, there is hope that it could happen for open source software, distribution of which is not controlled by software vendors with many competing parties that package and ship it and an incentive not to sneak anything in because of that.
Note that the client side apps are available for researchers to study. If they find a back door, it will be a big publicity issue for the app vendor.
Your concern is still valid though. Both Whatsapp and Signal could announce tomorrow that they drop E2EE or add some feature (like a default on non-disable-able cloud based spellchecker) and there is nothing you could do to protect your correspondence.
Matrix is different here that it encourages independent implementations as well as end to end encryption.
If you use Google’s backup for WhatsApp, it is NOT encrypted. Your local backup IS encrypted. It’s not your data - you can’t have it except through the app. But google can (and does) have that data for likely 95% of android WhatsApp users; E2E with this state of affairs is not very useful. (I assume the iOS situation is similar, but don’t know for sure)
Also, a copy of your phone book, continuous IP (and likely location) and all your conversation metadata is stored on Facebook’s servers even if you don’t use the google drive backup.
Yes, WhatsApp is useful and works well, But the E2E aspect is false safety. For many practical purposes, you should assume there’s No encryption. For the purposes that inconvenience you, it’s obviously there.