1. Kerberos Network Authentication Protocol A Team 1 Presentation: Les Beckford Joe DeCicco Vera Rhoads Than Lam Steve Parshley DCS835 June 24, 2000

2. Cerberus

3. Agenda What is Kerberos? What is the basic concept? How does it work? – Prerequisites – Conceptual implementation – Details in action Pros & Cons Summary

4. What is Kerberos? A network authentication protocol designed to provide strong authentication for client/server applications by using secret-key cryptography

5. What is the basic concept? Three entities authenticate each other, using private keys. 1. User ->Client 2. Kerberos Server 3. Application Server Client User Kerberos Server Application Server

6. How Does Kerberos Work? Prerequisites Principals list Authentication Server Ticket Granting Server Kerberos s/w Individual passwords Concept of Implementation Details in action

7. Kerberos Prerequisites Principals list Users Clients Application servers Authentication Server (AS) Ticket Granting Server (TGS) Kerberos s/w (V4 or V5) Individual passwords

8. Concept of Implementation Objective: secure network authentication to grant services to authorized users Authentication: Symmetric, two private keys Three two-way handshakes precede service Service: authorized services delivered from known to known

9. The Kerberos Model and Protocols

10. Start Client PW Username, PW -> AS < -AS returns TGT -> TGT, Kc, tgs <- Ticket, Kc S -> Ac <- Sc

11. Details in Action

12. Pros/Cons of Kerberos Pros: Free, flexible, open standards, key security, ticket expiration, widespread acceptance, enhanced versions Cons: prerequisites to set up, management intensive, third party security assumed, password security assumed.

13. Summary Kerberos is, for the correct environments, a superior alternative to public-key, certificate-based authentication systems, such as SSL. With a proper understanding of its strengths and weaknesses, one can implement the protocol with confidence, at low cost, and with high efficiency.

14. Questions? (If you dare)