I think an interesting approach would be to send secure email via programmatically generating the public string sequence within a domains TXT DNS record (short

I think an interesting approach would be to send secure email via programmatically generating the public string sequence within a domains TXT DNS record (short time to live expiry) you could even establish a very slow Diffie Hellman key exchange with two paired domains where their TXT records alterations reflect the key exchange. There are multiple dimensions of communication possible here too since you can have a near infinite number of TXT records per domain. You can even in theory transmit TCP packets (albeit slowly) over back and forth DNS modifications. If the encoded info were spread across multiple unrelated domains, it would require any interceptor to know which domains are the carriers of the information. This is pretty similar to blockchain transactions except as long as you have icanns authority to use that domain you control your own private part of the blockchain that is able to interact with any other as long as it operates on the same protocols.