Answer the following in relation to a scenario where Bob and Alice use Kerberos for mutual authentication:
a. When Bob receives a ticket from Alice, how does he know it is genuine?
b. When Bob receives a ticket from Alice, how does he know it came from Alice?
c. Alice receives a reply, how does she know it came from Bob (that it is not a reply of an earlier message from Bob)?
d. What does the ticket contain that allows Alice and Bob to talk securely?