56090 2020/2021 summer sem. Surname & Name ID number group acad. year Cryptology Homework nr 1 Initial data: Student's ID number 5 6 0 9 0 Sum of ID digits Last ID digit range 0-1 2-3 Select the proper word from the table beside that fits to the last digit of ID number for further use. It will be denoted as initial text IT. Permutations will be used later. word perseverance exasperation felicitation abbreviation voluminosity permutation 34125 52413 41523 25134 53142 4-5 6-7 8-9 The table of correspondence between alphabetic characters and modulo 26 residues. Preparatory work: Select 5 letters from your IT text pointed by the subsequent ID digits. It will be treated as the plaintext T (looking rather as 'having-no-sens' set of letters) used in the next tasks. Plaintext T = selected 5 letters from IT text Task 1. Perform encryption of plaintext T using Caesar's cipher. key: k= sum of ID digits (modulo 26) Ciphertext C: = result of T encryption Task 2. Encrypt the same plaintext T as in Task 1 by means of substitution cipher using the encryption function: ep(x) = p(x) given in the table below. ep(x) = p(x) encryption function. np. ep(a) = F, eb) = N,... etc. p = 0, 1,... 25 a b c d fgh ilj p FNWGOVA PHX BOI g s n Y u V Z v z M R J S D I Ciphertext C = result of T encryption Task 3. Encrypt the initial IT text (full word) by means of substitution method using the encryption function based on the little changed English sentence known that contains all letters of alphabet: The quick fox jumps over the brown lazy dog. As the keyword use the name of your university. ab d e Plaintext T = initial text IT (full word) Ciphertext C = result of IT encryption Task 4. Encrypt the initial plaintext IT with Vigenere cipher. As the keyword use the name of the university where you are currently studying. The keyword k = name of the university. Equivalent representation in the way of rest of (mod 26) Initial plaintext IT Sequence of keyword Addition of IT and keywords (mod 26) Ciphertext Task 5. Encrypt the given plaintext T with a permutation cipher. The permutation p should be selected in the same way as the initial IT text, i.e., depending on the last digit of the ID. Plaintext T = cryptology 1 2 Permutation p = 3 4 5 Plaintext T Ciphertext C