Suppose a user employs one-time passwords as above (or, for that matter, reusable passwords), but that the password is transmitted sufficiently slowly. (a) Show that an eavesdropper can gain access to the remote server with a relatively modest number of guesses. (Hint: The eavesdropper starts guessing after the original user has typed all but one character of the password.) (b) To what other attacks might a user of one-time passwords be subject?

When an attack is being carried out, what purpose does it serve to employ poison packets? Could you illustrate your point with a few specific instances?

Is a MAC (message authentication code) capable of modifying the Tag and the ciphertext while they are in transit? This attack will fail because the recipient will always be able to identify a changed Tag/ciphertext.

Consider the following scenario: you get a message from your company's mail server informing you that the password for your account has been changed and that you must confirm the change. According to what you know, you have not altered the password! What may have motivated the password change, and how did it happen? Was it a virus, and if so, on which computers, that may have given an attacker with the information they needed to successfully reset the password?