2. (20 points) Show that the Caesar, Vigenre ciphers are easy to break by doing a chosen-plaintext attack. How much plaintext is needed to recover the key for each of the ciphers? You might need to make some assumptions here, make sure to state them clearly. 3. (10 points) What is the effect of a single-bit error in the ciphertext when using the CBC, OFB, and CTR modes of operation