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RE: [TLS] TLS WG Chair Comments on draft-ietf-tls-authz-07

2009-02-14 15:59:01
Hi Sam, 

I am aware of some of the authorization mechanisms used in Kerberos (e.g.,
those introduced by Microsoft). 

The issue here is a bit different, particularly on the Internet (in
comparison to the pure enterprise space). 

We see a good deal of SSO solutions being deployed. To provide incremental
deployment the protocol designers have written their specs in such a way
that they do not require end host modifications. It turned out that this is
a fairly good idea to find excitement in the industry. It seems that end
host changes (even if they are only in the browser) aren't so easy. Many
other solutions are theoretically possible to solve the WebSSO problem when
you assume end host modifications are possible. 

Now, the question (for me) is why someone should deploy a new technique that
requires end host modifications when they can get a similar result with
already widely deployed mechanisms. (Not speaking about the OpenID being
fairly popular on the Internet due to it's simple deployment model.) To
answer this question, I believe, one has to start with a particular problem
/ usage scenario. 

I don't want to prevent anyone from standardizing (or even implementing) new
authorization extensions for TLS but all the discussions we see about the
IPRs are IMHO a bit over the top. I have a hard time seeing the widespread
deployment in front of me. I could be wrong -- we will see in a few years.  

Ciao
Hannes

-----Original Message-----
From: ietf-bounces(_at_)ietf(_dot_)org 
[mailto:ietf-bounces(_at_)ietf(_dot_)org] On 
Behalf Of Sam Hartman
Sent: 13 February, 2009 00:40
To: Josh Howlett
Cc: Melinda Shore; Hannes Tschofenig; tls(_at_)ietf(_dot_)org; 
ietf(_at_)ietf(_dot_)org
Subject: Re: [TLS] TLS WG Chair Comments on draft-ietf-tls-authz-07

"Josh" == Josh Howlett <Josh(_dot_)Howlett(_at_)ja(_dot_)net> writes:

   Josh> I have a long list of applications, collected from within
   Josh> this community, with which they would like to use SAML-based
   Josh> authorisation; and it seems to me that the ability for
   Josh> application protocols to share a common mechanism for
   Josh> expressing authorisation would mitigate or perhaps even
   Josh> avoid the need to make application-specific authorisation
   Josh> extensions.


The Kerberos community has many years of experience that 
within an infrastructure, carrying authorizations in-band has 
been useful and has reduced the effort required to fit an 
application into a larger infrastructure.  Sometimes it 
reduces implementation cost in that sometimes libraries can 
automatically handle some aspects of authorization.  Mor 
often, it reduces the cost of specifying a protocol or 
adapting a protocol that was not intended to work within a 
given infrastructure to working within the infrastructure.  In 
many cases, authorization handling becomes a matter for client 
libraries and the server implementation, requiring little if 
any effort from the client application or any changes to the 
client->server protocol.

As a result, it becomes significantly easier to expand the 
authorization system. To a large extent, it becomes a matter 
of updating the infrastructure, and updating only one side of 
the application.  That is a huge savings in deployment and 
software engineering complexity.



I would expect that SAML infrastructures could see similar benefits.

For these reasons I support the publication of a standard in 
this space.  I don't object to this work going to the TLS 
working group provided that
1) it is within their current charter
2) They commit to do the work and have sufficient energy  to 
move it forward quickly.

I do object to moving the discussion of whether to solve this 
problem to the TLS working group.  I don't think that is the 
right forum: the TLS working group does not collect the people 
who would benefit from this work.

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