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Secure Web Systems Authentication and Authorization Overview

Learn about terminology, cryptography, REST, and social networks in web security systems. Explore authentication, authorization, and challenges with HTTP, SSL, and OpenID. Discover access control methods, including Grid Security Infrastructure and OAuth. Improve your understanding of single sign-on, identity federation, and attribute exchange.

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Secure Web Systems Authentication and Authorization Overview

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  1. Authentication and Authorization in Web Systems Zhenhua Guo Jun-30-2009

  2. Outline • Background • Terminology • Cryptography • REST, Web 2.0, Social Network • Authentication • Authorization • Conclusion

  3. Terminology • Authentication • Authorization • Confidentiality • Integrity • Non-repudiation • Single Sign-On • Delegation

  4. Cryptography encrypt decrypt clear text encrypted text clear text • Shared-key cryptography • DES, 3DES, AES • Public-key cryptography • RSA, DSA • Digital Certificate • Bind an entity’s identity with a public key • Certificate Authority • Public Key Infrastructure

  5. REST - REpresentational State Transfer • Each resource is identified by a unique ID. • Stateless communication • Link resources together • Resources have multiple representations • Based on HTTP

  6. Web 2.0 • Read-write collaborative web • Participatory nature • Cooperate, not control • … Cooperate, Participate, Collaborate  Social Network

  7. Social Network • Science collaboration • OpenSocial • APIs for web-based social network apps • MySpace, Orkut, Ning…

  8. Security Challenges in WWW • Loosely coupled components • Separation of security policies and security mechanisms. • No single, isolated trusted base • Domain-specific policies • …

  9. Outline • Background • Authentication • Identity Federation • HTTP Auth, SSL • Central Authentication Service • OpenID • Authorization • Conclusion

  10. HTTP Basic Auth • Allow browser to provide credential when making a request. WWW-Authenticate: Basic realm="Secure Area“ Username: Aladdin Password: open sesame Aladdin:open sesame Base64 Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ== Drawback: Clear text HTTP Digest Access Auth

  11. SSL/TLS End-to-End message protection protocol Features • Use both shared-key cryptography and public-key cryptography. • Authentication • Key exchange • Confidentiality • Integrity • Non-repudiation • Prevention of replay attack

  12. Identity Federation • Data across multiple identity management systems can be joined.

  13. Central Authentication Service https://cas.iu.edu/cas/login?cassvc=ANY&casurl=https://onestart.iu.edu/my2-prd/Login.do?__p_dispatch__=login https://onestart.iu.edu/my2-prd/Login.do?__p_dispatch__=login&casticket=ST-26434-krE7MK7qkv1CcXrfBPLT-wsa453.uits.indiana.edu

  14. CAS • Use HTTPS to guarantee confidentiality and integrity. • Advantages • Simplicity • Single Sign-On (ticket-granting cookie) • Drawbacks • Single point of failure • ID federation

  15. discovery OpenID relying party Association

  16. OpenID • How to discover Identity Providers? • The Relying Party uses the Identifier to look up the necessary information for initiating requests • Solution • XRI • Yadis • HTTP-Based discovery • How to share user attributes beyond authentication? • Solution • Simple Registration Extension • Attribute Exchange

  17. OpenID – Drawbacks • If username and password of a user are stolen or phished, then all of the registered sites then become targets. • Quality of OpenID providers varies.

  18. Kerberos vs. CAS vs. OpenID

  19. Outline • Background • Authentication • Authorization • Access Control • Grid Security Infrastructure • Shibboleth • OAuth • Conclusion

  20. Access Control • Access Control List • A list of permissions are attached to an object. • Role-Based Access Control • permissions → roles • roles → users • Access Control Matrix • characterizes the rights of each subject with respect to every object in the system • …

  21. Architecture (local site) VS: validation servicePEP: policy enforcement pointPDP: policy decision pointAR: attribute repository

  22. Architecture - Push mode (in distributed systems) VS: validation servicePEP: policy enforcement pointPDP: policy decision pointAR: attribute repository AA: attribute authority

  23. Architecture - Pull mode(in distributed systems) VS: validation servicePEP: policy enforcement pointPDP: policy decision pointAR: attribute repository AA: attribute authority

  24. GSI (Grid Security Infrastructure)

  25. GSI • Based on X.509 PKI • Every entity involved in the Grid has an X.509 certificate • Each site trusts the CAs it wants • Each Grid transaction is mutually authenticated • Authorization is enforced using local policies. • Global ID (certificate DN) is mapped to local ID

  26. GSI Features • Proxy Certificate (rfc3820) and Delegation • A temporary credential is generated for the user proxy • Delegation is indicated by user signing the temporary certificate with a secret. • Single Sign-On • Identity Mapping and Authorization • Global identity is mapped to a local identity before local identity is used to enforce policies "/C=US/O=Globus/O=ANL/OU=MCS/CN=Ben Clifford” benc "/C=US/O=Globus/O=ANL/OU=MCS/CN=MikeWilde” wilde

  27. GSI - Drawbacks • Granularity of delegation • All or none • Infrastructure cost

  28. Shibboleth - Flow Assertions Attribute Query

  29. the user is an IU student Shibboleth - Example • InCommon “more than 3 million end-users” Authentication

  30. OAuth - Features • A third party app can access user’s data stored at service provider without requiring username and password. • Delegated authorization protocol • Explicit user consent is mandatory. • Light-weight

  31. Third-party application OAuth - Flow

  32. Your google calendar data is: Would you like the third party app to access your Google Calender data??? Google Calendar Third-party application

  33. OAuth - Drawbacks • Delegation granularity • Error handling • Token expiration and revocation

  34. GSI vs. CAS* vs. Shibboleth vs. OAuth CAS: Community Authorization Service

  35. Research Opportunities • Authorization granularity • Trust management

  36. Questions?

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