Problem 4 (15 POINTS): The following ciphertext was produced from a 63-letter English text using a Vigenre cipher. TILLF SUXPM OVWZD SUIMQ TIRQD WIRKZ KFWFD BFVRN UURDS HFZYX TILLFSUXPM OVW (a) Use the Kasiski test to obtain a list of possible keyword lengths (b) Use the Friedman test to estimate the length of the keyword. One should start by computing the number of occurrences of the letters from the ciphertext. The first values have already been computed below. A BCDEFGHIJK L MNO PQ R S TUV W X Y Z 0 1 0 4 0 6 0 1 5 0 2 4 3 1 2 2 2 4 e) What value for the length of the keyword did you obtain after running both tests? (d) Suppose you know that the cipher block UXPMMOvW is an encoding for TURNOUT Decode the message and write it in the space indicated below. Hint: The Vigenre cipher is a succession of shift ciphers. Decode each of them! cipher TILLF SUXPM OVWZD SUIMQ TIRQD WIRKZ KFWFD pli cipher BFVRN UURDS HFZYX TILLF SUXPM OVW