82 SEFM03 Tutorial T6 Jorge Cuellar Brisbane, Sep 2003 Kerberos Single-Sign-On Obtaining additional tickets –Don't want to present user's password eac
{"Image DocumentName": "Complete Kerberos AS TGS Client Server KDC", "Image ImageDescription": "(from: B. C. Neuman + T. Ts\u2019o: IEEE Communications Magazine SEP. 1994) AS. TGS. Client. Server. KDC Protocol. < client communicate with AS to obtains a ticket for access to TGS > 1. Client requests AS of KDC to supply a ticket in order to. communicate with TGS. - request (C, TGS) C : client id. 2. AS returns a ticket encrypted with TGS key(Kt) along with a session. key Kct. - return = ( {ticket}Kt, {Kct}Kc Kct : TGS session key. - ticket = ( C, TGS, start-time, end-time, Kct ) Kc : client key. < client communicate with TGS to obtain a ticket for access to other server > 3. Client requests TGS of KDC to supply a ticket in order to communicate with order server. - request = ( {C, timestamp}Kct, {ticket}Kt, S ) S: server key. 4. TGS checks the ticket, If it is valid TGS generate a new random session key Kcs. TGS returns a ticket for S encrypted by Ks along with a session key Kcs. - return = ( {ticket}Ks, {Kcs}Kct ) ticket = ( C, S, start-time, end-time, Kcs ) < client communicate with the server to access an application > client decrypt {Kcs}Kct with Kct to get Kcs. client generate authenticator A with the information from ticket. - A = ( {C, S, start-time, end-time, address}Kcs ) 5 . Client sends the service request to the server along with the ticket and A. - ( {ticket}Ks, {C, S, start-time, end-time, address}Kcs, request. 6. The server decrypt ticket using Ks and check if C, S, start, end times are valid. If service request is valid, use Kcs in the ticket to decrypt authenticator. Server compares information in the ticket and in the authenticator. If agreement, the service request accepted. Brisbane, Sep 2003.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}