2021/2021-challenge4.md

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  14 ---
  15
  16 ```python Collapsed="false"
  17 from szyfrow.caesar import *
  18 from szyfrow.affine import *
  19 from szyfrow.keyword_cipher import *
  20 from szyfrow.support.text_prettify import *
  21 ```
  22
  23 ```python Collapsed="false"
  24 challenge_number = 4
  25 plaintext_a_filename = f'plaintext.{challenge_number}a.txt'
  26 plaintext_b_filename = f'plaintext.{challenge_number}b.txt'
  27 ciphertext_a_filename = f'ciphertext.{challenge_number}a.txt'
  28 ciphertext_b_filename = f'ciphertext.{challenge_number}b.txt'
  29 ```
  30
  31 ```python Collapsed="false"
  32 ca = open(ciphertext_a_filename).read()
  33 cb = open(ciphertext_b_filename).read()
  34
  35 sca = sanitise(ca)
  36 scb = sanitise(cb)
  37 ```
  38
  39 ```python
  40 (word_a, wrap_a), score_a = keyword_break(sca)
  41 print(word_a, wrap_a, '\n')
  42 pa = keyword_decipher(ca, word_a, wrap_a)
  43 print(pa)
  44 ```
  45
  46 ```python
  47 pa = keyword_decipher(sca, word_a, wrap_a)
  48 print(prettify(pa))
  49 ```
  50
  51 ```python Collapsed="false"
  52 open(plaintext_a_filename, 'w').write(prettify(pa))
  53 ```
  54
  55 ```python
  56 morse_chars = 'a b c d e f g h i j k l m n o p q r s t u v w x y z 0 1 2 3 4 5 6 7 8 9'.split()
  57 # morse_chars
  58 ```
  59
  60 ```python
  61 morse_codes = '.- / -... / -.-. / -.. / . / ..-. / --. / .... / .. / .--- / -.- / .-.. / -- / -. / --- / .--. / --.- / .-. / ... / - / ..- / ...- / .-- / -..- / -.-- / --.. / ----- / .---- / ..--- / ...-- / ....- / ..... / -.... / --... / ---.. / ----.'.split(' / ')
  62 ```
  63
  64 ```python
  65 char_to_morse = {l: c for l, c in zip(morse_chars, morse_codes)}
  66 morse_to_char = {c: l for l, c in zip(morse_chars, morse_codes)}
  67 [char_to_morse[l] for l in 'abc']
  68 ```
  69
  70 ```python
  71 morse_table = ''.maketrans('AD', '.-')
  72 cb_dd = cb.translate(morse_table)
  73 cb_words = cb_dd.split(' / ')
  74 cb_letters = cat(cat(morse_to_char[l] for l in w.split()) for w in cb_words)
  75 cb_letters
  76 ```
  77
  78 ```python
  79 (word_b, wrap_b), score_a = keyword_break(cb_letters, fitness=Ptrigrams)
  80 print(word_b, wrap_b, '\n')
  81 pb = keyword_decipher(cb_letters, word_b, wrap_b)
  82 print(prettify(pb))
  83 ```
  84
  85 ```python Collapsed="false"
  86 open(plaintext_b_filename, 'w').write(prettify(pb))
  87 ```
  88
  89 ```python Collapsed="false"
  90
  91 ```