Re: [dns-privacy] Possible use case: Opportunistic encryption for recursive to authoritative

Ben Schwartz <> Thu, 06 August 2020 15:18 UTC

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From: Ben Schwartz <>
Date: Thu, 06 Aug 2020 11:18:25 -0400
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To: Paul Hoffman <>
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Subject: Re: [dns-privacy] Possible use case: Opportunistic encryption for recursive to authoritative
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I think opportunistic or unauthenticated encryption is worth pursuing.
However, your quote also says "use authentication when possible", and I
agree.  I would like to avoid selecting an opportunistic encryption design
that doesn't match well with our authenticated encryption design, so I
think that means we need to develop them together.

On Thu, Aug 6, 2020 at 10:59 AM Paul Hoffman <> wrote:

> Greetings again. The following is a short text-based version of my slides
> from last week's WG meeting. I'd like to find out if this is one of the use
> cases that the WG would be interested in dealing with.
> Use case: Opportunistic encryption for recursive to authoritative
> In this use case, a resolver operator says “I’m happy to use encryption
> with the authoritative servers if it doesn’t slow down getting answers by
> much”, and an authoritative server says “I’m happy to use encryption with
> the recursive resolvers if it doesn’t cost me much”.
> Opportunistic encryption is defined in RFC 7535. From the abstract:
> "Protocol designs based on Opportunistic Security use encryption even when
> authentication is not available, and use authentication when possible,
> thereby removing barriers to the widespread use of encryption on the
> Internet."
> The assumptions behind the use case are:
> • More encryption is good for the Internet
> • Resolver vendors are smart and motivated
> • Most resolvers don’t validate with DNSSEC and may never want to
> • Authoritative operators don’t care much about encryption, but some would
> turn it on because more encryption is good for the Internet
> • Other use cases for authentication stronger than opportunistic may
> appear and would co-exist with this one
> The other slides had thoughts about possible solutions that implement this
> use case, but before we go there, I wanted to find out if more than a
> handful of people here are interested in this use case. If so, I could turn
> the above into a draft with some possible solutions for us to bang on.
> --Paul Hoffman
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