[kitten] Register too long SASL mechs?

[Simon Josefsson <[e-mail]>]

Hi!  There is a request to register the ECDH-X25519-CHALLENGE and
ECDSA-NIST256P-CHALLENGE mechanism names in the IANA SASL registry.  The
policy is First Come First Serve, so there is no real requirement of a
standard or anything, however the names are longer than the 20 character
limit imposed by RFC 4422.  Supposedly these are already deployed and
have been used in the wild for a couple of years already.

Some references:
  https://www.iana.org/assignments/sasl-mechanisms/sasl-mechanisms.xhtml
  https://github.com/atheme/atheme/blob/master/modules/saslserv/ecdh-x25519-challenge.c
  https://github.com/kaniini/ecdsatool#mechanism-spec

As far as I can see, we have some options:

1) Just let IANA register these names even if they are non-compliant.

2) Don't formally register them but mention them on the IANA page to
avoid any interop problems and allowing people to find out what these
are.

3) Refuse registration since tey are non-compliant.

I prefer 2) but could live with 1) as well.  I don't think it is in the
best interest of anybody that registration is refused on technicalities.
Maybe this post is sufficient to make relevant parties aware of what is
happening, and IANA can continue with 1).

Thoughts?

Pursuing standardization, or publishing a stable specification, of the
mechanisms is orthogonal to registration, but would be useful.

/Simon