I. Figure below shows the operations that Alice must perform to provide

confidentiality, authentication, and integrity. Diagram the corresponding

operations that Bob must perform on the package received from Alice.

Protocol design for sender authentication and message confidentiality. Suppose Alice

wants to send an e$-$mail to Bob. Bob has a public$-$private

key pair: $Kb\frac{+}{K}b,$ and Alice has Bob's certificate for his public key. But Alice does not

have a public, private key pair for herself. Alice and Bob $($and the entire world$)$ share

the same hash function $H(*).$

a$.$ Is it possible to design a scheme so that Bob can verify that it is Alice who created

and sent the message to Bob? If yes, show how with a block diagram for Alice

and Bob; if no$,$ explain why.