Question

1. Encrypt the message howareyou using the affine cipher using the key (7,3). (a) What is the resulting ciphertext? (b) What is the decryption function you can use to decipher each ciphertext character? (c) Use your decryption function to decrypt the message to confirm you get the ciphertext back. 2. Use the ADFGX cipher using the grid below and the keyword "place" to encrypt the plaintext "brandenburggate". FREE GX (a) (b) What is the resulting ciphertext? How does the ADFGC cipher fare in satisfying the properties of confusion and diffusion? 3. You intercept an enemy transmission that you believe was encrypted using the Vigenère cipher: ULEFIZBCXFICBWRDVRUMSUABPJGIIZBVREINE (a) You believe that the key length used to encrypt the message was either 1, 2, 3, or 4. Using displacement coincidences, find the number of coincidences corresponding to each of the possible key lengths. Based on this, what do you suspect is the key length?

Answer 1

Answer Since the question is asking us to do both the ciphering and deciphring, Thurpre the fastest way to da that would be to find the cuptos tent of eich alphabet from a-z Solution given Rey = (7,3) ic (72+3) for the cipher teat, plain tent A | B C D E F G H I J K L Bildelf/G/H I J K kinantop/s/R/S/Tlu v w x y z 16 cieho texto K RY IFMTA/HOV KJ / 8 /X/ELLIS/2/4 Wu, В la p o o 1 2 3 4 6 WSK 17 18 19 20 21 22 23 24 25 5 6 7 8 9 10 11 R IS IM IS KG 17 18 7.0+3 = 3=D 7.1+3 = 10ak 2, 7.2+3 = 17 =R we absorve that, the cipher tent starts from D. skips of alphapte, then gills to rent ciphu teal, thirup ble fall in the ciphu tent, by ways of counting

using the table above we can easily cushes & diciphes any plain text with to Affine apher with the key (73) Ola) - Plain tent = HOW ARE YOU ciphu tent = AX BD SFP XN Q(bls we use the sustem of manually calculating each ciphu teat of all the alphabets. ak) - AX BD S F PX N - Plain text = HOW ARE YOU
HOMEWORKLIB POLICY - answer the first question only when there are multiple questions