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Comment by eridius | Hacker News Reader

Why is DV useless? DV asserts that you are securely talking to whomever controls that domain. That's very valuable. If they're confusing, that's on the browsers.

Edit: You also cannot just discard certificates and use HTTPS as an "I'm talking to the same server I was 5 seconds ago", because that does literally nothing to prevent MitM attacks. If you can't assert that you're talking securely to the domain owner, then there's nothing at all stopping someone in a privileged network position from intercepting and altering your traffic, because they could simply proxy it through their own server.

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This is the same argument as "self-signed certificates are useless". They aren't. Not all interception is MitM. With spy agencies operating passive taps on infrastructure, as a fraction of your intercepted traffic, virtually none of it us. Completely unsigned, unverified encryption is still a massive roadblock to dragnet surveillance.

>does literally nothing to prevent MitM attacks

It does more than nothing. Especially if you make the reasonable assumptions that 1) the user is not being MitMed most of the time and 2) the user is likely to have connected to the (small) set of sensitive sites before they experience their first MitM.

Example: my home internet is unadulterated. I check my mail. My computer saves the certificate. I go to a coffee shop. I check my mail again. Somone tries to MitM me. My computer instantly spots a changed certificate.

Obviously we should still use and verify certificates. But I notice a nasty trend of making the perfect the enemy of the good in security. There's a perception that if it's not perfect, it's worse than useless and should be shunned (probably due to historical bad experiences with false senses of security).

Your computer can't simply remember the certificate that was used for the last connection, because then sites can never change their certificates (which would be a huge issue).

Moxie mentioned before that using notaries would work, of course you have to worry about notaries being compromised but that's a much easier threat model.

https://en.wikipedia.org/wiki/Convergence_(SSL)

They could, for example, sign the new cert with the old one.

What if the certificate's private key is compromised? How would revocation work?

I think the parent post is saying that you'd know that you're talking to the "same server" in a very literal sense (ie. if you were MITM'd, you'd know you're talking to the same server that MITM'd you the entire session).

Not exactly sure what that'd buy...

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