nPhase 3: C communicates with S
5.C sends the ticket to S along with an authenticator to
establish a shared secret
nC è S: {AC,S}KC,S , {TC,S}KS
nwhere Ac,s = {c, timestamp, opt. subkey}Kc,s
nS decrypts the ticket TC,S to get the shared secret KC,S needed
to communicate securely with C