The drawing above shows one phase of Kerberos protocol. Answer the following questions by considering this drawing a) What is the purpose of above communication? When this communication happens? b) What is the purpose of using TS2 ? c) What is the purpose of KA,tgs in Tickettgs ?

rlogin 1-Request a Ticket Alice Alice's terminal TGS 2- A ticket 1- Alice TGS: ID8 || Tickettgs || Authenticators EKA,tgs [KAR || ID|| TS! || Tickete] 2- TGS Alice: Authenticatora = EKA, tgs ( IDA || ADA || TS3] Tickettgs = Ektes [Ka,tgs || IDA ADA I IDtgs || TS2 || Lifetimez] Ticketg = Ekg ( KAB || IDA || ADA || 1D || TS4 || Lifetime. ] IDA,IDB : Alice ve Bob sunucusunun kimlii, ADA: Alice'in adresi Kg : TGS ve Bob sunucusu arasndaki anahtar Ka,tgs: Alice ve TGS sunucusu arasndaki anahtar KAR: Alice ve Bob sunucusu arasndaki anahtar The drawing above shows one phase of Kerberos protocol. Answer the following questions by considering this drawing a) What is the purpose of above communication? When this communication happens? b) What is the purpose of using TS2? c) What is the purpose of Ka,tgs in Tickettgs