An idea: If one does it, then one Should at Least try to do it Well

I understand the difference between symmetric and asymmetric cryptography, and that is the reason for my question. OTR is the most difficult option in terms of key management. Not only do you need to keep the key secret during the exchange between involved parties (in contrast to asymmetric crypto), but is also going to have to be as long as the message itself, and must never be re-used again.

That is what confuses me: you are talking about web programming as the application area for your character-based OTR combination operator, but in web programming I see no way on how to realistically do the key management for anything remotely OTR-like (hence most/all claims of OTR for web applications are snake oil).

If you intend to reject asymmetric crypto, then I'd love to hear a better option for it (as we have known for quite a while that e.g. DH and RSA will be susceptible to quantum algorithms once we get a sufficient number of qbits in a stable configuration).

Btw, asymmetric crypto is not inherently less secure than symmetric crypto, as the decryption operation is always the inverse of encryption (we are talking about lossless encryption, I assume ;-) ). It has just been studied a lot longer.

Rene