Re: [Cfrg] Adoption call for draft-harkins-pkex-05

[Dan Brown <[e-mail]>]

I'm seeing two minor issues to be resolved before adoption:
1. "Public key exchange" is a totally non-specific name, so much so, that I
oppose adoption under this name.  Public key exchange could mean
Diffie-Hellman key agreement, for example.  If PKEX has been deployed in
some places, the name should be updated retroactively.  (Sorry that this is
merely a terminology issue (as in the color of bikeshed, not the bikeshed
itself.)
2. What is the problem being solved here?  For example, I think that TLS
will or does offer PSK authentication.  So, why not just do an out-of-band
PAKE to establish a PSK, then use PSK-authenticated TLS.  So, to rephrase my
question: is there some security defect with PSK-authenticated TLS that PKEX
solves?  Maybe this was discussed already, sorry if I missed it (and am out
of order).
Otherwise, I do not have much of an opinion in either direction.

-----Original Message-----
From: Cfrg [mailto:[e-mail]] On Behalf Of Alexey Melnikov
Sent: Sunday, April 8, 2018 7:42 AM
To: [e-mail]
Subject: [Cfrg] Adoption call for draft-harkins-pkex-05

Dear CFRG participants,
This message is starting a 2 weeks adoption call for
draft-harkins-pkex-05 (Public Key Exchange). From the document's
Introduction:

   [RFC7250] further states that "the main security challenge [to using
   'raw' public keys] is how to associate the public key with a specific
   entity.  Without a secure binding between identifier and key, the
   protocol will be vulnerable to man-in-the- middle attacks."

   The Public Key Exchange (PKEX) is designed to fill that gap: it
   establishes a secure binding between exchanged public keys and
   identifiers, it provides proof-of-possession of the exchanged public
   keys to each peer, and it enables the establishment of trust in
   public keys that can subsequently be used to facilitate
   authentication in other authentication and key exchange protocols.
   At the end of a successful run of PKEX the two peers will have trust
   in each others exchanged public keys and also share an authenticated
   symmetric key which may be discarded or used for another purpose.

The adoption call will last for 2 weeks and will end on April 22nd.

Thank you,
Kenny and Alexey

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