Comment by ale42
15 hours ago
It's not just Let's Encrypt, right? CT is a requirement for all Certificate Authorities nowadays. You can just look at the certificate of www.google.com and see that it has been published to two CT logs (Google's and Sectigo's)
Now I get why they want to reduce certificate validity to 20 minutes. The logs will become so spammy then that the bad guys won't be able to scan all hosts in them any more...
Technically logging certificates is not a Requirement of the trust stores, but most web browsers won't accept a certificate which isn't presented with a proof of logging, typically (but not always) baked inside the certificates.
The reason for this distinction is that failing to meet a Requirement for issued certificates would mean the trust stores might remove your CA, but several CAs today do issue unlogged certificates - and if you wanted to use those on a web server you would need to go log them and staple the proofs to your certs in the server configuration.
Most of the rules (the "Baseline Requirements" or BRs) are requirements and must be followed for all issued certificates, but the rule about logging deliberately doesn't work that way. The BRs do require that a CA can show us - if asked - everything about the certificates they issued, and these days for most CAs that's easiest accomplished by just providing links to the logs e.g. via crt.sh -- but that requirement could also be fulfilled by handing over a PDF or an Excel sheet or something.