March 5, 2002
Practical Aspects of Modern Cryptography
13
The Basic Kerberos Protocol (2)
nPhase 1: C gets a Ticket-Granting Ticket
2.KDC responds with two items
nThe ticket-granting ticket
nA ticket for C to talk to TGS
nA copy of the session key to use to talk to TGS, encrypted in C’s shared key
nKDC è C: {TC,TGS}KTGS , {KC,TGS}KC
nwhere Tc,s = s, {c, c-addr, lifetime, Kc,s}Ks
nOnly the TGS can decrypt the ticket
nC can unlock the second part to retrieve KC,TGS