Using a blockchain for secure communication I've recently heard of the idea of using a blockchain for secure communication. No details were given so it's a little hard for me to say that it can't be done. But as far as I know:


Secure communication doesn't need blockchains. We have AES, MACs,
digital signatures, etc. for that.
Blockchains are only useful for documentation. Not for securing
anything.


Am I missing something here?
Secure communication doesn't need blockchains. We have AES and digital signatures for that.
  


Correct, though we also require tools other than block ciphers and digital signatures. But that is besides the point, as "blockchain" is not on that list.


  
  Blockchains are only useful for documentation. Not for securing anything.
  


Blockchain is a distributed, append-only ledger. That in itself does not provide confidentiality, integrity, or authenticity. However, availability is one of the pillars of information security, and it is arguable that blockchain could be used towards that end.


  Am I missing something here?


Probably not. It has become trendy to try and attach blockchain to everything:


  Long Island Iced Tea Corp., now called Long Blockchain Corp., received an ultimatum from Nasdaq in October, when the exchange threatened to delist it unless the market value rose above $35 million for 10 business days in a row. It achieved that on Friday, flaunting one of the hottest buzzwords of the year to get there.


Often times by people who don't/barely know what cryptography is, how it works, or what is is useful for.