Consider the SSH protocol in Figure 10.1. a. Explain precisely how and where Alice is authenticated. What prevents a replay attack? b. If Trudy is a passive attacker (i.e., she can only observe...

Consider the SSH protocol in Figure 10.1.

a. Explain precisely how and where Alice is authenticated. What prevents a replay attack?

b. If Trudy is a passive attacker (i.e., she can only observe messages), she cannot determine the key K. Why?

c. Show that if Trudy is an active attacker (i.e., she can actively send messages) and she can impersonate Bob, then she can determine the key K that Alice uses in the last message. Explain why this does not break the protocol.

d. What is the purpose of the encrypting the final message with the key if?