Re: [dane] Need better opportunistic terminology

Michael Richardson <mcr+ietf@sandelman.ca> Fri, 07 March 2014 09:35 UTC

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Date: Fri, 07 Mar 2014 04:35:06 -0500
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Subject: Re: [dane] Need better opportunistic terminology
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Viktor Dukhovni <viktor1dane@dukhovni.org> wrote:
    > So you might ask what was the word "opportunistic" doing in our
    > avant-garde use of the term "opportunistic DANE TLS"?  The answer is
    > that as with (pre-DANE) opportunistic TLS, the client is willing to
    > send in the clear to any server for which no "secure" TLSA records are
    > available.

    > Thus, until the happy future when a significant fraction of domains are
    > DNSSEC signed, and their MX hosts are accompanied by DNSSEC-validated
    > "secure" TLSA records, in practice the protocol is essentially the same
    > as with (pre-DANE) opportunistic TLS.  The client employs the best
    > security level available (including cleartext).

And, in particular, I think that "opportunistics TLS" interoperates with
"opportunistics DANE TLS".  The two sides don't have to have to known each
other's policies.

    > So Phillip is quite right that DANE gets us stronger semantics, but I
    > would argue, that because the actual security posture is *conditional*
    > on published receiving system capabilities, from the perspective of the
    > sending system, this is just a "hardened" version of opportunistic TLS
    > where, for just some destinations not known to the sender in advance,
    > MITM attacks cannot trivially downgrade senders to plaintext or
    > compromise transport integrity or confidentiality.

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]               Never tell me the odds!                 | ipv6 mesh networks [
]   Michael Richardson, Sandelman Software Works        | network architect  [
]     mcr@sandelman.ca  http://www.sandelman.ca/        |   ruby on rails    [


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Michael Richardson <mcr+IETF@sandelman.ca>ca>, Sandelman Software Works
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