1. Kerberos Short presentation Protocol run Ressources By Artur Hecker, ENST Paris, 11/01/2002

2. Kerberos: general information Based on Needham-Schroeder protocol Introduced by the MIT Uses only symmetric cryptography Shared secrets, session keys, timestamps, limited validity Purposes: Authentication Session key distribution Preconditions: Existence of a central instance with common keys for each party All keys are pre-installed respectively (  shared secrets)

3. 1 2 3 4 Alice Notary Bob Problem: synchronized clocks Kerberos: typical protocol run time stamp validity period Bob knows K Alice knows K

4. Kerberos: Ressources Jennifer G. Steiner, Clifford Neuman, Jeffrey I. Schiller. "Kerberos: An Authentication Service for Open Network Systems", USENIX Mar 1988. [athena-dist.mit.edu:pub/kerberos/doc/usenix.PS] R. M. Needham and M. D. Schroeder, "Using Encryption for Authentication in Large Networks of Computers", Communications of the ACM, Vol. 21(12), pp. 993-999 (December, 1978). Li Gong, "A Security Risk of Depending on Synchronized Clocks", Operating Systems Review, Vol 26, #1, pp 49--53. S.M. Bellovin and M. Merritt, "Limitations of the Kerberos Authentication System," USENIX Jan 1991. [research.att.com:dist/internet_security/kerblimit.usenix.ps] C. Neuman and J. Kohl, "The Kerberos Network Authentication Service (V5)", RFC 1510, September 1993. Kerberos Reference Page, [http://www.contrib.andrew.cmu.edu/usr/shadow/kerberos.html]http://www.contrib.andrew.cmu.edu/usr/shadow/kerberos.html MIT Kerberos Ressources, [http://web.mit.edu/kerberos/www/]http://web.mit.edu/kerberos/www/