All chats use the same Signal protocol outlined in this whitepaper, regardless
of their end-to-end encryption status. The WhatsApp server has no access to
the client’s private keys, though if a business user delegates operation of their
Business API client to a vendor, that vendor will have access to their private
keys - including if that vendor is Facebook.
All chats use the same Signal protocol outlined in this whitepaper, regardless of their end-to-end encryption status. The WhatsApp server has no access to the client’s private keys, though if a business user delegates operation of their Business API client to a vendor, that vendor will have access to their private keys - including if that vendor is Facebook.
(https://scontent.whatsapp.net/v/t39.8562-34/122249142_469857..., p. 13)