What about <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Supersingular_Isogeny_Key_Exchange" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Supersingular_Isogeny_Key_Exch...</a>, which seems to have reasonably small key sizes and fewer of the problems associated with lattices?