Update on status of draft-irtf-cfrg-spake2.

The authors of the IETF SPAKE2 draft have published a new version which
expires on April 5, 2020:

https://tools.ietf.org/html/draft-irtf-cfrg-spake2-09

If you are curious here is a diff between drafts 8 and 9:

https://tools.ietf.org/rfcdiff?url2=draft-irtf-cfrg-spake2-09.txt

The new draft:

   - Removes references to a MHF (scypt)
   - Removes SPAKE2+
   - Explains the key exchange protocol in more detail

I don't believe this requires updating our protocol, but we should make
sure our spec language reflects the current draft.  Filed Issue #235 to
track this work item.

In terms of the future roadmap, Benjamin Kaduk believes that there should
be a path to publishing SPAKE2 as an RFC within the CFRG in the future
(regardless of the outcome of the PAKE competition).

m.