[agwa]

> In principle, everybody who sees the log could agree that they see the same Merkle Tree head, thus the certificate really is logged. In practice the mechanisms to ensure this works, a Gossip protocol, do not exist and have never been deployed in practical use.

It has been - the commercial instance of Cert Spotter gossips STHs with Chrome's SCT auditing infrastructure.

Edit: here's the gossip feed of STHs observed by Chrome's SCT auditing infrastructure: https://www.gstatic.com/ct/gossip/ct/v1/sth-pollination

And here's the gossip feed of STHs observed by Cert Spotter: https://certspotter.com/.well-known/ct/v1/sth-pollination

[tialaramex]

Ooh interesting, when did that start?

[agwa]

2017, but it only started having real value once SCT auditing rolled out in 2022.