1.Alice uses one of the two protocols given below to send a message to Bob. Both of the protocols take a message as input and generate an output which is subsequently send to Bob. These are the details of the protocols;
Protocol 1: O=Ek1( M || H(k2||M) )
Protocol 2: O=Ek1( M || E'eA(M) )
In the above formulation M denotes the message of Alice, O is the output message sent to Bob, E denotes encryption with a symmetric (private key) cipher, || denotes concatenation, H is a hash function, k1and k2are two secret keys only known to Alice and Bob, E' is encryption with an asymmetric (public key) cipher, and eAis Alice's private key.
Think about what Protocols 1 and 2 are designed to achieve and answer the following questions.
a.. For each protocol, provide a step-by-step description of what Bob needs to do upon receiving O. Be concise when giving your steps.
b. State whether the goals of confidentiality, integrity, and non-repudiation can be achieved by the two protocols.
C.. Compare and contrast the two protocols in terms of advantages and disadvantages they have over each other.
2. Consider PKI explain why and how compromise of a certificate authority yields to the failure of a system. Can compromise a certificate of authority effect other certificate authority ( or other PKI domain) If so how