1. (10 points) Alice and Bob share the same pair of asymmetric encryption algorithms, E and D. Alice have a pair of asymmetric keys: SA and PA, where SA is the private key and PA is the public key. Bob have a pair of asymmetric keys: SB and PB, where SB is the private key and PB is the public key. Suppose Alice wants to send a message M to Bob. Design an encryption scheme that will protect the confidentiality of M and prevent the message tampering during the transmission. (Hint: You may need to use cryptographic hash HASH to create a digest for some messages. For example, you can generate a digest for message D with HASH(D). You can concatenate two messages by using concatenate operator " ". For example, you can concatenate two message A and B with AB). a) (5 points) Write down the message format sent from Alice to Bob. b) (5 points) Describe how does Bob decrypt the received message and verify the authenticity of the message