Question: 1. Prof. Maladroit, the esteemed Ineptitude Professor of Computer Science at Wikipedia University, is developing a new terminal program (and associated service) to log into the servers in his lab. Although he is aware of ssh, he refuses to use it because he doesn't like being hushed.1 Instead, he decides to construct his own novel protocol. Like telnet and ssh, his remote console/terminal program should allow a remote user to type commands and execute them on a remote machine. Since Prof. Maladroit doesn't trust anyone- particularly the students in his network security class - he decides that all communication should be encrypted. Hoping to become the next dotcom millionaire, Prof. Maladroit decides to create an online money payment service similar to PayPal. His service, PayDroit, allows users to transfer money to other users of the system. To ensure that no fraudulent activity takes places, the PayDroit service issues a key pair to each user. If Alice("A") wishes to give X dollars to Bob ("B"), she sends the following message to the PayDroit service ("S"):A ? S : A, B, X, n, {X|n}A-where n is a nonce, A- is Alice's private key, and {M}K- denotes a digital signature over M computed using the private key K-.Is Prof. Maladroit scheme secure? To what attack is it vulnerable? And if it is vulnerable, how can it be fixed?