Suppose you suspect that your session with a server has been intercepted in a man-in-the-middle attack. You have a key, K, that you think you share with the server, but you might be only sharing it with an attacker. But the server also has a public key, KP , which is widely known, and a private secret key, KS , that goes with it. Describe how you can either confirm you share K with the server or discover that you share it only with a man-in-the-middle.

There has been session among user and server as per the query. The user has a key K that he feels it is shared by the user, however he actually shares it with a hacker, which is why the session was intercepted.  

The Server has a commonly known public key P, and also has a private key S, which is normally sent with P.

ACK technique may be used to check that the user's key has been shared with MAN IN MIDDLE. ARP spoofing. ARP(Address Resolution Protocol) is widely used to evaluate the MAC address connected with such a specific IP address.

The recipient also sends acknowledgment when the user shares his key with the server and therefore does not receive acknowledgement with the intended attached information as it will be very clear for the user to realize that the server was intercepted.

answer is c. complication