WAYF in SAML? Was: First contact

Title: First contact

In Shibboleth there is a proprietary system for 
findng the authentication site,

the s.c. WAYF (Where Are You From) 
service.

 

In SAML I see no solutions at all for this.  
This is likely to affect SAML interoperability.

 

Question: Would the SAML-"community" be interested 
in defining a generic WAYF-service?

 

cheers

Anders Rundgren

  
----- Original Message ----- 

  
From: 
  Tim 
  Moses 

  
To: 'OASIS Security Services 
  group' 

  
Sent: Wednesday, July 25, 2001 
23:51

  
Subject: First contact

  

  
Colleagues - I've given consideration to the "first contact" 
  issue, and satisfied myself that the current browser profile satisfies the 
  requirement.

  
For those interested in the details ... 

  
Remember, the question is ... what will be the message flow if 
  the subject first goes to a site that has protected content, rather than first 
  going to an authentication site?

  
Push model 

  
Browser                   
  Content site         Authentication 
  site 
1 <----------- redirect---------- 
  
2 
  -------------redirect-----------------------------------> 
3 
  <-------------------------authenticate------------------> 
  
4                                  
  <-------assertion------- 
5                                  
  --------reference------> 
6 
  <-----------------------------------redirect(reference)-- 
7 --------redirect(reference)---> 

  
Pull model 
Browser                   
  Content site         Authentication 
  site 
1 <----------- redirect------------- 
  
2 
  -------------redirect-----------------------------------> 
3 
  <-------------------------authenticate------------------> 
  
4 
  <-----------------------------------redirect(reference)-- 
5 --------redirect(reference)------> 
6                                  
  --------reference------> 
7                                  
  <--------assertion------ 

  
The Push model leaves questions like ... 
How does the Authentication site know where to send the 
  assertion? 
How does the Authentication site know what 
  attributes to include in the assertion? 
Furthermore, 
  the authentication thread is occupied waiting for the reference to return from 
  the Content site. 

  
This might all just mean that the Push model becomes less 
  popular than the Pull model in this situation. 

  
In both cases, the Content site has no opportunity to indicate 
  its authentication requirements (one or two factor, for instance).  But, 
  perhaps, each Authentication site URL should be dedicated to a single 
  authentication policy.  Then the Content site chooses the policy by 
  redirecting the browser to the appropriate URL.

  
Step 6 in the Pull model is a SAML request for one or more 
  assertions.  The request must be able to carry the reference extracted 
  from the artifact in the redirection steps (4 and 5) as well as the list of 
  requested attributes.  So, I'll be checking the schema proposals to 
  ensure that this is possible.

  
Best regards.  Tim. 

  
------------------------------------------------------------------- 
  
Tim Moses 
Tel: 613.270.3183