That sounds like secure scuttlebutt.

Secure Scuttlebutt is a database protocol for unforgeable append-only message feeds.

"Unforgeable" means that only the owner of a feed can update that feed, as enforced by digital signing (see Security properties). This property makes Secure Scuttlebutt useful for peer-to-peer applications. Secure Scuttlebutt also makes it easy to encrypt messages.

https://scuttlebot.io/more/protocols/secure-scuttlebutt.html