The problem is that if that is your threat model, then the VPS provider, ISP, and literally everything between you and letsencrypt can pull a conpromised key fro letsencrypt.
This actually happened btw, an xmpp server was attacked this way, they compromised not the server itself, but the VPS provider MITMed their traffic: www.devever.net/~hl/xmpp-incident
If your threat model involves this, then the only solution is Tor, which eliminates these requirements of trust.
WhyJiffie@sh.itjust.works 2 hours ago
which is still there if you are not using lets encrypt, because they can strongarm them to make a fake cert for your domain, and install a proxy repackaging HTTPS traffic with the fake certificate. all browsers trust the lets encrypt root certificate, so they won’t see anything suspicious.
the only thing there today to detect this (but not avoid) is certificate transparency logs. all modern certificates are required to be added to this log, for the CA to remain compliant. but browsers are not checking the logs, that would be a lot of additional traffic and how do they decide if a certificate was created maliciously? also, lets encrypt could afford being noncompliant, browser vendors can’t realistically just distrust their root certificate, many sites would become inaccessible.
IpsumLauren@lemmy.world 2 hours ago
Oh snap! That definitely sounds possible. Found more info about it.
tl;dr: Either the attack is ineffective against some browsers that check the certificate transparency logs (like Chrome), or the attack is visible and the CA will lose all its credibility (hopefully being removed from the browsers).
WhyJiffie@sh.itjust.works 1 hour ago
and details: wiki.mozilla.org/…/Certificate_Transparency
this sounds important:
this also means, it can’t truly verify SCT’s that were issued since the last browser update?
WhyJiffie@sh.itjust.works 1 hour ago
it seems Firefox started doing the CT validation too, without needing to contact the CT log service: developer.mozilla.org/…/Certificate_Transparency#…
possiblylinux127@lemmy.zip 1 hour ago
Maybe I’m mistaken but aren’t the logs cryptography verifiable? (As in you can’t create a rouge cert without it creating a trace)
WhyJiffie@sh.itjust.works 1 hour ago
apparently certs can have a cryptographic proof of having been included in the CT logs. but what do browsers do if the letsencrypt cert has no such proof?