Diffie-Hellman Key Exchange

Eve, an attacker, can alter messages that Alice and Bob send to each other without their knowing. To do this she intercepts (and makes some changes to) the exchanges Alice and Bob make with each other. Discover this method and describe it to me. Hint: You should be attacking the key-exchange. Find a method so that Alice and Eve have shared keys and Eve and Bob have shared keys (even though Alice thinks she is communicating with Bob and Bob thinks he is communicating with Alice). And remember that Eve can intercept any message Alice sends to Bob and vice versa. This means that she can stop the message from reaching its destination and send another in its place.