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. Also, be sure your solution will not be discovered by a packet sniffer.

What will be an ideal response?

Ask the server to digitally sign your shared key, K, using his private key, KS,
and encrypt the result with K, so no one with a packet sniffer can read this. Then ask the
server to send you the result. You can decrypt the package with K and verify the servers
signature using his public key, KP . If this was done correctly, you can verify everything. If
you have a man-in-the-middle, however, the message you get will either be garbled, or the
signed shared key will not be the same.