Thanks for your review, Hannes.  Replies are inline...

-----Original Message-----
From: OAuth [mailto:oauth-boun...@ietf.org] On Behalf Of Hannes Tschofenig
Sent: Wednesday, August 3, 2016 12:51 AM
To: oauth@ietf.org
Subject: [OAUTH-WG] Review of draft-ietf-oauth-amr-values-01

Hi Mike, Phil, Tony,

I have read through draft-ietf-oauth-amr-values-01. My earlier comments have 
been addressed.

As a shepherd I nevertheless have a few questions/remarks:

1) The term 'multiple-channel authentication' is unfamiliar to me.
Could you give me an example or a reference to a specification?

https://www.ldapwiki.com/wiki/Multiple-channel%20Authentication has a clear 
explanation.  However, I'm reluctant to reference a wiki page that may be 
transient from an RFC.  If anyone out there has a more stable reference to 
suggest, please do so.  Instead, I've added this example text for -02:

            For instance, a multiple-channel authentication might involve both 
entering information into
            a workstation's browser and providing information on a telephone 
call to a pre-registered number.

2) PIN: The use of RFC 2119 language appears to be inappropriate.

Thanks, will be fixed in -02.

3) Could you explain me what 'risk-based authentication' is? While you provided 
a reference

https://en.wikipedia.org/wiki/Risk-based_authentication has a clear 
explanation.  Bruce Schneier writes about it in a blog post here 
https://www.schneier.com/blog/archives/2013/11/risk-based_auth.html.  Deloitte 
has a primer at 
http://deloitte.wsj.com/cio/2013/10/30/risk-based-authentication-a-primer/.  
There's lots of material on the web and the term is pretty widely known in 
authentication/identity circles.  Unfortunately, as with "mca", I don't know of 
a great authoritative reference to cite.  Any suggestions out there?

4) Could we generalize the term 'wia' to operating systems other than Windows 
as well?

I don't think so.  It consists of a particular set of documented protocol 
interactions, as describe at 
http://blogs.msdn.com/b/benjaminperkins/archive/2011/09/14/iis-integrated-windows-authentication-with-negotiate.aspx.
  That said, because these protocols are publicly documented, other systems 
(maybe SAMBA?) may have also implemented it.

5) I am not sure whether all normative references indeed need to be declared as 
such.
For example, 'otp' is defined in a very generic fashion but you list HTOP, and 
TOTP as normative references.
I would rather see HTOP and TOTP as a standardized examples of 
one-time-passwords. IMHO the story would be different if you indeed want to 
differentiate between the different technical mechanisms itself. This is a 
reasonable approach as well if the security differences between the mechanisms 
is important for the given application.

If use cases arise in which applications want to define additional "amr" values 
"hotp" and/or "totp", they can use the registry established by this application 
to do so.  It's explicitly not a goal of this specification to define all 
practical values.  Rather, it defines a few values that are actually in 
production use and even more importantly, establishes the registry for defining 
more, as needed in practice.

Ciao
Hannes


                                Thanks again,
                                -- Mike



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