Connecting IMS LTI and SAML (Draft)

IMS LTI and SAML / SSO
DRAFT - 01
Charles Severance, Ph.D.
IMS Global Learning Consortium (IMS GLC)

http://www.imsglobal.org/
http://www.dr-chuck.com/

© Copyright 2012 IMS Global Learning Consortium
All Rights Reserved. 1

Thanks to

• Keith Hazelton, University of Wisconsin
• Scott Fullerton, University of Wisconsin


Problem Statement

• We need a way to align IMS Learning Tools
Interoperability and (SAML)


Use Cases

• When a LMS is protected using an SSO and launches an
external tool using LTI, we to communicate the SSO
identity to the external tool
• This enables the external tool to connect the user_id
value from LTI with an SSO identity
• This allows the user to connect directly to the
external tool and log in using their SSO


Scenario

• We have three LMS's at three schools, one
protected using SAML, one protected using CAS,
and one that has no SSO
• They all connect to an external tool that is
capable of LTI, CAS, and SAML and has
relationships with the appropriate SAMLE IDP and
CAS Server

mod_saml mod_cas
saml.edu nada.edu cas.edu

saml.edu Scenario cas.edu
IDP Server

mod_saml /launch mod_cas
hyperlti.com


Essential Design Concept

• The LTI Launch is completely normal providing the
normal within-LMS data like user_id, role,
context_id, etc.
• If the LMS is protected using an SSO and the
current user is logged in through the SSO, we add
the type of SSO (SAML, CAS, etc) and the identity
provider for the SSO.

Essential Design Concept (cont)

• The LTI launch does *not* include the SSO identity
as there is no way to do this reliably.


Design For External Tool

• The external tool has an unprotected LTI launch
URL to receive LTI requests (/launch)
• The external tool has SSO-protected URLs for all
the identity providers and SSO types it has a
relationship with (/cas_edu, /saml_edu)


Design for External Tool

• If the LTI launch code receives a launch with an SSO
type and Identity provider that it is capable of
handling, it sets up the LTI data (user, course, role,
etc) in the session and forwards to the appropriate
SSO-protected url on its own server
• Since the user is already signed on via the SSO, they
simply fall through with REMOTE_USER properly set


Design for External Tool

• Under the SSO-protected URL, the code knows the
LTI user course, and role as well as the Identity
provider and enterprise identity.
• The tool can link all of these together within its
data structures.


External Tool Design

• From that point forward, the tool can identify the
user either via an LTI launch through user_id or
through a direct login to an SSO-protected URL
that provides REMOTE_USER


B mod_saml lms.saml.edu
r 2
o 1 (1) User accesses
w
LMS, (2) redirected
s
to SSO, (3) SSO
e saml.edu displays login page.
r IDP
3

/launch
hyperlti.com
mod_saml


2
r
o
3 (1) User enters
w
login submits to
s
IDP, (2) IDP sets
e saml.edu cookie and
r IDP
1 redirects to LMS,
(3) LMS displays
screen

/launch
hyperlti.com
saml_cookie mod_saml


2
r
o
1 (1) User selects LTI
w
tool. (2) LMS sends
s
signed LTI data
e saml.edu form to browser (3)
r IDP browser submits
data to LTI launch
user_id=12
url
sso_type=saml
sso_idp=saml.edu 3 /launch
hyperlti.com


r
o
(1) Tool stores the
w
LTI launch data in
s
a session for the
e saml.edu browser and then
r IDP (2) redirects to the
mod_saml URL
user_id=12 1
sso_type=saml
2 /launch sso_idp=saml.edu
hyperlti.com


r
o
(4) The user's browser
w
follows the redirect,
s
adding the SAML cookie,
e saml.edu (5) the mod passes the
r IDP request through setting
SAML identity
user_id=12 1
sso_type=saml
2 /launch sso_idp=saml.edu
hyperlti.com
saml_cookie 4 mod_saml remote_user=csev

5

r
o
(6)The mod requests
w
and receives an
s
attribute from the IDP
e saml.edu and (7) adds it to the
r IDP user data

6
user_id=12
sso_type=saml
/launch sso_idp=saml.edu
hyperlti.com
saml_cookie mod_saml remote_user=csev
phone=763-0300
7

r
o User has new browser.
w (1) Access the tool
s directly at SSO-
e 3 saml.edu protected URL. (2)
r IDP mod redirects to IDP,
(3) IDP produces login
page
1

/launch
hyperlti.com
2 mod_saml


r
o
(1) User enters login
w
submits to IDP, (2) IDP
s 1 sets cookie and
e saml.edu redirects to tool. (3)
r IDP Tool looks up user
2 data based on SAML id
user_id=12
sso_type=saml
/launch sso_idp=saml.edu
hyperlti.com
saml_cookie mod_saml remote_user=csev
phone=763-0300
3

Notes

• This extends easily to multiple types of SSO
providers and multiple identity providers per SSO.
• This carefully avoids the LMS forwarding the SSO
identity, but instead provides a mechanism for the
tool to "add" the SSO identity to a session through
a redirect


Questions / Comments

• This is a draft – comments welcome


Connecting IMS LTI and SAML (Draft)

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