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KX509: Leveraging Kerberos to Obtain Digital Certificates for Web Client Authentication University of Michigan Kevin Coffman Bill Doster.

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Presentation on theme: "KX509: Leveraging Kerberos to Obtain Digital Certificates for Web Client Authentication University of Michigan Kevin Coffman Bill Doster."— Presentation transcript:

1 KX509: Leveraging Kerberos to Obtain Digital Certificates for Web Client Authentication University of Michigan Kevin Coffman Bill Doster

2 April 11, 2000CIC TechForum 2000 Why X.509? An accepted international standard Application support out of the box –Web servers, web browsers, directory servers, IMAP servers, etc Allows the possibility for inter-institution authentication No need for N²-1 cross-realm trusts

3 April 11, 2000CIC TechForum 2000 Why Kerberos? We have been using Kerberos on campus since 1990 We have 200K+ principals defined in our Kerberos database It’s an integral part of our infrastructure It is currently used for authenticating to many services (AFS, dial-in, e-mail, login servers, web pages.)

4 April 11, 2000CIC TechForum 2000 Project History (Where We Started From) Started with MIT code for issuing certificates Shortcomings in the MIT code –Passwords passed to web server –User interaction required Obtain certificate Maintain and protect private key(s) –Long-term certificates, ignoring revocation –Only supported for Netscape Communicator

5 April 11, 2000CIC TechForum 2000 Project Goals (What We Are Doing) Eliminate password prompts for web access (actually use Kerberos) Transparent web authentication –Make certificate generation automatic at Kerberos login –Make certificate installation invisible to the user Browser-neutral, cross-platform Position for inter-institution authentication

6 April 11, 2000CIC TechForum 2000 Project Non-goals (What We Are NOT Doing) Not a complete PKI Not to be used for e-mail or document encryption Not to be used for e-mail or document signing (not yet, anyway) Not a complete replacement of the current cookie method of authentication (not yet, anyway)

7 April 11, 2000CIC TechForum 2000 KX509 Description Uses short-term (~1 day) certificates -- “junk keys” Obtains certificates securely from a kerberized certificate authority (KCA) server Used for authentication ONLY! Columbia PKCS#11 code

8 April 11, 2000CIC TechForum 2000 Why “Junk Keys” ? Revocation becomes a non-issue Private key storage is less an issue The directory isn’t the center of the universe (?) –Certificate management is less critical –Certificate publication for sharing is not necessary

9 April 11, 2000CIC TechForum 2000 The Cookie Trail

10 April 11, 2000CIC TechForum 2000 Unmodified Kerberos “Login” (kinit, klog, Kerb95,…) Standard Kerberos TGT Request Standard Kerberos Service Ticket Request Standard HTTPS (with X.509 Client Authentication) KX509 Overview Kerberos Authenticated Request With public-key to be certified X.509 v3 Certificate good for one day Unmodified Internet Explorer Kerberos Ticket File (plus registry on Windows) Unmodified Netscape Browser TGT Use TGT to get service ticket Store Generated RSA key-pair & One-day certificate Use RSA Key-pair & certificate Client Workstation Kerberized Certificate Authority (KCA) Unmodified Kerberos Server (KDC) Unmodified Kerberos Server (TGS) Enterprise-Wide Kerberos Servers    Unmodified Web Servers Copy ofKCA’s Published Certificate Enterprise & External Web Servers login password PKCS#11 module kx509

11 April 11, 2000CIC TechForum 2000 Demonstration...


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