Crypto as I know it doesn&#x27;t allow performing an authenticated key exchange between two entities without neither a pre-shared secret nor a trusted third party (CA) [1]. Anyone who promises anything like that is either selling snake-oil or hiding some requirement. DANE still requires trusted third parties, I&#x27;m not sure why it&#x27;s better than the current model.<p>[1] There&#x27;s <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Merkle%27s_Puzzles" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Merkle%27s_Puzzles</a>, but it&#x27;s not really practical when you make it secure and not secure when you make it practical.