What is the Diffie-Hellman key exchange?

A method for two parties to derive a shared secret key over a public channel without ever transmitting the secret itself.

It lets endpoints open confidential encrypted channels on an otherwise shared ledger, keeping sensitive on-chain communication private while everyone still maintains the same chain.

Go deeper:

• Diffie-Hellman key exchange — Wikipedia — the paint-mixing figure shows deriving a shared secret over a public channel.