1.1.1.1: Fast, privacy-first consumer DNS service

Re:1.1.1.1: Fast, privacy-first consumer DNS service by dfox on Sunday April 01, 2018 @07:23PM (#16731123)

It is hard because of the TLS's pre-PFS legacy and to some extent also because of (very meaningful) intention to reduce roundtrips. The way to do SNI-like stuff is obvious: negotiate unauthenticated encrypted channel (by means of some EDH variant, you need one roundtrip for that) and perform any endpoint authentication steps inside that channel. This is what SSH2 does and AFAIK Microsoft's implementation of encrypted ISO-on-TCP (eg. rdesktop) does something similar.

Edit: in SSH2 the server authentication happens in the first cryptographic message from server (for the obvious efficiency reasons), and thus for doing SNI-style certificate selection there would have to be some plaintext server-ID in first clients message, but the security of the protocol does not require that as long as the in-tunnel authentication is mutual (it is for things like kerberos).

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Re:1.1.1.1: Fast, privacy-first consumer DNS service by tialaramex on Monday April 02, 2018 @06:57AM (#16733572)

So, it feels like you're saying this is how SSH2 and rdesktop work, and then you caveat that by saying well, no, they actually don't offer this capability at all it turns out.

You are correct that you can do this if you spend one round trip first to set up the channel, and both the proposals for how we might encrypt SNI in that Draft do pay a round trip. Which is why I said they're slow and ugly. And as you noticed, SSH2 and rdesktop do not, in fact, spend an extra round trip to buy this capability they just go without.

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