to actually tackle this (on the off chance you're serious, I'm assuming not) - this doesn't work.
The payload that implements your crypto cannot be delivered over http, because any intermediate party can just modify your implementation and trivially compromise it.
If you don't trust TLS, you have to pre-share something. In the case of TLS and modern browser security, the "pre-shared" part is the crypto implementation running in the browser, and the default trusted store of root CAs (which lives in the browser or OS, depending).
If you want to avoid trusting that, you've got to distribute your algorithm through an alternative channel you do trust.
You are right presharing is a requirement, unless you hash the keys used to encrypt the secret into the secret itself, but that can only be prooven later on a channel where the same MITM is not present.
Work in progress, that said presharing solve(d/s) enough for the world to dump DNS and HTTPS in a bin and light it on fire now, because nobody has the power to implement all the MITM needed if everyone "makes their own crypto" on top of allready shared secrets!
Circular arguments, wishful thinking and all...