> The privacy concern DPRIV is trying to address is to prevent an adversary 
> seeing the contents 
> of DNS traffic or being able to deduce them from packet sizes, timing etc.
>
> That is a very different problem from stopping the attacker from being able 
> to distinguish 
> DNS traffic from HTTP. At the extreme, any client connecting to 8.8.8.8 is 
> doing DNS...

OK. So, we have clarified that you do not have an issue with leaking SNI while 
using TLS for DPRIVE. You are looking at ways to plug the SNI leak in TLS, and 
also the clear text certificate leak. You are concerned that even if make DNS 
traffic opaque, adversaries will still be able to retrieve the same information 
by harvesting SNI and certificate. That's certainly a valid concern, but why 
not fight one battle at a time? Let's first make DNS traffic opaque. That's the 
DPRIVE charter. Then plug the holes in TLS. That ought to be the TLS charter.

The circular dependency that you hypothesize is only an issue if SNI+CERT 
disclosure mitigations (1) need to be applied to the DNS resolver connection 
and (2) require finding data in DNS. I am not sure at all about (1) since as 
you wrote, "at the extreme, any client connecting to 8.8.8.8 is doing DNS..." 
And I would rather not assume that the data comes from the DNS as in (2), 
before seeing actual designs...

-- Christian Huitema



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