Consider the OSI protocol stack shown on the right. What is the unit of the link layer? Bit Packet Datagram None of the other options 3 Consider the OSI protocol stack. What is the unit of the network layer? Bit Frame Packet None of the other options Consider the binary plaintext consisting of the binary bits 1101 1011, if these bits are encrypted with a OTP 01100111 , what is the resulting ciphertext? 10010011 10111100 00101110 None of the other options 5 Consider Alice and Bob share a common symmetric key, "Kab". Alice wants to make sure she is talking to Bob. The figure below shows, the corresponding exchange of the first two messages. What should Bob send back to prove to Alice she is indeed talking to him? {rB}Kab {rA}Kab rA None of the other options Suppose Alice wants to send Bob a message and make sure that Bob can check the message was not altered in transit. Alice first sends the message in plaintext as shown below. After that, she is also going to send some information to Bob to enable him to check if the message was modified in transit or no. To achieve this, what is a possible algorithm that she can use in the block labeled "1"? None of the other options Suppose Alice wants to sign a plaintext message. The diagram below shows the plaintext block and the process to generate her digital signature. What cryptographic function should be used in the block labeled "1"? Symmetric encryption Asymmetric encryption Hashing None of the other options