Lamport Hash Question...

-Suppose we are using Lamport's hash, and Bob crashes before receiving Alice's reply. Suppose an intruder, Trudy, can eavesdrop and detect that Bob crashed (maybe Trudy can even cause Bob to crash). Then Trudy has a quantity (whatever Alice replied that Bob did not receive) which Trudy can use to impersonate Alice, if Trudy logs in before A ice attempts to log into Bob again. How can we modify Bob's behavior to prevent this threat? (Exactly when do we overwrite Bob's database, and with what)? -Suppose we are using Lamport's hash, and Bob crashes before receiving Alice's reply. Suppose an intruder, Trudy, can eavesdrop and detect that Bob crashed (maybe Trudy can even cause Bob to crash). Then Trudy has a quantity (whatever Alice replied that Bob did not receive) which Trudy can use to impersonate Alice, if Trudy logs in before A ice attempts to log into Bob again. How can we modify Bob's behavior to prevent this threat? (Exactly when do we overwrite Bob's database, and with what)