I can confirm that you don't know.

I can count 3 mistakes here:

1- The client isn't the only thing that matters (There's servers)

2- The client doesn't follow a spec in WhatsApp, there is no spec as it's a private non-interoperable system.

3- Browsers and HTTPS work with an entirely different encryption model, TLS is asymmetric, certificate based and domain based. TLS may be used in Whatsapp to some extent, but it's not the main encryption tool.