3. a. Assume an attacker knows that a user's password is either mnop or byce. Say the user encrypts his password using the shift cipher, and the attacker sees the resulting ciphertext. Show how the attacker can determine the user's password, or explain why this is not possible. b. Repeat part (a) for the Vigenre cipher using period 2, using period 3, and using period 4. Latawafoto 12 3. a. Assume an attacker knows that a user's password is either mnop or byce. Say the user encrypts his password using the shift cipher, and the attacker sees the resulting ciphertext. Show how the attacker can determine the user's password, or explain why this is not possible. b. Repeat part (a) for the Vigenre cipher using period 2, using period 3, and using period 4. Latawafoto 12