1. An XML based Security Assertion Markup Language
SAML
An XML based Security Assertion Markup Language

2. Introduction
XML standard for exchanging authentication and authorization data between security domains, i.e. identity provider and service provider.
Solve the single sign-on (SSO) problem at intranet level using cookies.
SAML assumes principal (user) is enrolled at least with one identity provider.

3. Why is SAML required ? Limitations of Browser cookies
Cross-Domain SSO (CDSSO) problem
SSO Interoperability
SSO and CDSSO are completely proprietary
Web Services
Authentication/integrity services on an end-to-end basis
Federation
identity management across organizational boundaries to a
single (or at least a reduced set) Federated Identity

4. SAML Use Cases There are 3 use cases in SAML: - Single sign-on (SSO)
- Authorization service
- Back office transaction
Each use case have one or more scenarios
that provide a more detailed roadmap of interaction

5. SSO Use Case Adaptation

6. Authorization Service Use Case Adaptation

7. Back Office Transaction Use Case Adaptation

8. SAML Overview
Specification for exchanging authentication and authorization information using XML-based security
- XML schema and definition for security assertions
- XML schema and definition for a request/response protocol
- Rules on using assertions with standard transport and messaging frameworks. Bindings and Profiles
Emerging OASIS standard involving Vendors and Users
Codifies current system outputs rather than inventing new technology

9. SAML Assertions Declaration of facts (statements) about a subject
Contains multiple assertion statements
Can be digitally signed
3 kinds of assertion statements related to security:
1. Authentication
2. Attribute
3. Authorization Decision

10. Common Information in all Assertions
Issuer and issuance timestamp
Assertion ID
Subject
Name and security domain
Optional subject confirmation like public key
Conditions under which assertion is valid
Special conditions like – assertion validity period, audience restriction and target restriction
SAML clients must reject assertions containing unsupported conditions.

11. Authentication Assertion
The Issuing authority asserts that subject S,
was authenticated by means M, at time T.

12. Attribute Assertion The Issuing authority asserts that subject S, is
associated with attributes A, B,…, with values a, b, c.

13. Authorization Decision Assertion
The Issuing authority decides whether to grant the
request by subject S, for access type A, to resource R

14. Assertions - continued
Assertions without the rest of the structure may be provided for existing tightly coupled environments who may need their own protocol.
SAML is fully beneficial when parties with no direct knowledge of each other can interact via a third-party introduction

15. SAML Protocol simple request-response protocol
<samlp:Request xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" MajorVersion="1" MinorVersion="1“
RequestID="..." IssueInstant="...">
<!-- insert other SAML elements here -->
</samlp:Request>
<samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:1.0:protocol" MajorVersion="1" MinorVersion="1“
ResponseID="...“
InResponseTo="..."
IssueInstant="...">
<!-- insert other SAML elements here, including assertions --> </samlp:Response>

16. Authentication Assertion Request
What are the authentication assertions which are available for this subject
Successful responses are in the form of assertions containing an authentication statement
It is assumed that the requester and responder have a trust relationship and are talking about the same subject

17. Authentication Assertion Request - example

18. Attribute Assertion Request
The requested attribute is returned for this subject
Response is in the form of an assertion containing attribute statement
Requester can be denied access to some of the attributes and allowed access to a partial list of attributes

19. Attribute Assertion Request example

20. Authorization Decision Assertion Request
Given the evidence is this subject allowed access to the specified resource in the specified manner with the given evidence?
Response is in the form of an assertion containing an authorization decision statement

21. Authorization Decision Assertion Request example

22. Example Response

23. Protocol Binding and Profile
Binding – mapping of SAML request/response message exchanges into standard communication protocols.
SOAP-over-HTTP binding is the baseline
Profile – describes how SAML assertions are embedded into and extracted from a framework or protocol.
Web browser profile for SSO
SOAP profile for securing SOAP payloads

24. SOAP-over-HTTP Binding
SOAP is used as
SAML
request/response
protocol transport
mechanism

25. SOAP Profile SAML is used to provide assertions about a resource in
the SOAP Body of
the same document

26. Web Brower Profiles Assumptions
Standard commercial browser and HTTP(S)
User authenticated to local source site
Assertion’s subject refers to the user
What happens when user tries to access target site
Tiny authentication assertion reference travels with request so real assertion can be de-referenced
POST of real assertion can occur

27. SSO Pull Scenario Using Web Browser

28. SSO Pull Scenario Using Web Browser - explained
Step 1 : Access inter-site transfer URL:
User authenticated with
Clicks on a link that looks like it will take the user to
It really takes the user to inter-site transfer URL:
Step 2 : Redirect with artifact:
Reference to user’s authentication assertion generated as SAML “artifact” (8-byte base64 string)
User redirected to assertion consumer URL, with artifact and target attached:

29. Back Office Transaction Scenario

30. References