The conventional wisdom suggests that WhatsApp provides 'fully encrypted' messaging between parties. I know that the Fediverse has a disproportionately high population of folk with a credible understanding of advanced cryptography... Can any of you tell me whether we can *prove* that the code running in the actual proprietary WhatsApp client is implementing uncompromised end-to-end encryption that only the sending & receiving part(y|ies) can decrypt? Or are we just taking Meta's word for it?