CSIS 5857: Encoding and Encryption Assignment 1: Traditional Ciphers Due Feb. 1 1. Despite the advice given in this course, Alice and Bob have decided to try to hide the encryption algorithm they have used. Assume that they send a ciphertext message, which is intercepted by Darth. How can Darth determine whether a monoalphabetic substitution cipher or a transposition cipher was used just by examining the message? 2. Suppose there is a language that has only the letters a and b. The frequency of the letter a is 10% and the frequency of the letter b is 90%. A message is encrypted using a Vigenere cipher (with a keyword of size 2). The ciphertext is BABABAAABA. Determine the most likely key and decrypt the message. 3. Caesar wants to arrange a secret meeting with Marc Antony either at the river or the arena. He sends the ciphertext EVIRE, created using an additive Caesar cipher. However, Antony has forgotten the key, so he tries all possibilities. Where will he meet Ceasar? (Hint: this is a trick question!) 4. The encryption key in a transposition cipher is the following. Give the decryption key. 3 6 2 4 5 1 Please turn these in using a word processor (such as Word), instead of hand-written form.