Re: [dns-privacy] Intermediate proposal (what I was saying at the mic)

[Christian Huitema <[e-mail]>]

On 8/1/2021 9:21 PM, Martin Thomson wrote:
> On Fri, Jul 30, 2021, at 06:08, Eric Rescorla wrote:
>> - Recursives can attempt to connect to any authoritative by probing
>>    with DoT/DoQ [0]. In this case, they should cleanly fall back to
>>    Do53 on connect failure and not validate the credential (whether
>>    WebPKI or DANE) This allows authoritatives to just turn on TLS
>>    without risk.
> I assume that your MUST NOT validate here only exists because of the combination of:
>
> 1.  Us not being able to decide between Web PKI and DANE; and
>
> 2.  The potential for an unauthenticated mode.
>
> If we decided on a single answer for the first and in the negative for the second, would that make authentication viable?  Or is the opportunism a feature?

I am torn on the PKI vs DANE issue. I understand the simplicity of using 
Let's encrypt or similar and getting an X.509 certificate backed by 
proof of ownership of the domain name. But I am also very concerned that 
this introduces a circular dependency. Allowing for DANE breaks that 
dependency when DNSSEC is available, which is why I would like 
authentication to allow both. If the server can prove its identity using 
either DANE or PKI, the client is probably fine.

And given the simplicity of getting PKI, I don't quite see the point of 
an unauthenticated mode. It does not ease the deployment much, and it 
paints a thick MITM target. I would rather fall back to Do53 than to 
unauthenticated DoT or DoQ.

-- Christian Huitema