Problem 1 (50 points) Alice wants to send a message m to the server, and the server wants to respond with a message m'. The communication should be confidential, and no man-in-the-middle should be able to tamper with the communication. The server chooses a public-private key pair (PKs, SKs) and keeps SKs secret. Alice and the server then communicate as below: Server (Bob) SKs, PKs Client (Alice) I am Alice I am server (Bob) Public Key: PKs z EncpKs(k1, k2) Choose random symmetric keys: k1, k2 c, t t MACk2 c) c, t' c' Encki(m) 1. Write down the algorithm the server uses to recover m