2021/2021-challenge7.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.column_transposition import *
  21 from szyfrow.vigenere import *
  22 from szyfrow.polybius import *
  23 from szyfrow.support.text_prettify import *
  24
  25 import numpy as np
  26 import pandas as pd
  27 import matplotlib.pyplot as plt
  28
  29 import collections
  30 %matplotlib inline
  31 ```
  32
  33 ```python Collapsed="false"
  34 challenge_number = 7
  35 plaintext_a_filename = f'plaintext.{challenge_number}a.txt'
  36 plaintext_b_filename = f'plaintext.{challenge_number}b.txt'
  37 ciphertext_a_filename = f'ciphertext.{challenge_number}a.txt'
  38 ciphertext_b_filename = f'ciphertext.{challenge_number}b.txt'
  39 ```
  40
  41 ```python Collapsed="false"
  42 nca = open(ciphertext_a_filename).read()
  43 cb = open(ciphertext_b_filename).read()
  44
  45 numtrans = ''.maketrans('12345', 'abcde')
  46 ca = nca.translate(numtrans)
  47
  48 sca = sanitise(ca)
  49 rsca = cat(reversed(sca))
  50 scb = sanitise(cb)
  51 rscb = cat(reversed(scb))
  52 ```
  53
  54 ```python
  55 sca_counts = collections.Counter(sca)
  56 sca_counts
  57 ```
  58
  59 ```python
  60 pd.Series(sca_counts).sort_index().plot.bar()
  61 ```
  62
  63 ```python
  64 key_a, score_a = polybius_break(sca, column_labels='abcde', row_labels='abcde',
  65                       fitness=Ptrigrams)
  66 key_a, score_a
  67 ```
  68
  69 ```python
  70 word_a, wrap_a, col_a, row_a, col_first_a = key_a
  71 polybius_decipher(sca, keyword=word_a, column_order=col_a, row_order=row_a,
  72                   column_first=col_first_a, wrap_alphabet=wrap_a)
  73 ```
  74
  75 ```python
  76 pa = polybius_decipher(sca, keyword='a', column_order=col_a, row_order=row_a,
  77                   column_first=col_first_a, wrap_alphabet=wrap_a,
  78                   letters_to_merge={'z': 'y'})
  79 pa
  80 ```
  81
  82 ```python
  83 # word_a, _ = monoalphabetic_sa_break(xca)
  84 # word_a
  85 ```
  86
  87 ```python
  88 # pa = keyword_decipher(xca, word_a)
  89 # pa
  90 ```
  91
  92 ```python
  93 print(prettify(pa))
  94 ```
  95
  96 ```python Collapsed="false"
  97 open(plaintext_a_filename, 'w').write(prettify(pa))
  98 ```
  99
 100 ```python
 101 cb[:11]
 102 ```
 103
 104 ```python
 105 int('10101', 2)
 106 ```
 107
 108 ```python
 109 scb = cat(c for c in cb if c in '01')
 110 len(scb)
 111 ```
 112
 113 ```python
 114 ncb = [int(g, 2) for g in cb.split()]
 115 min(ncb), max(ncb)
 116 ```
 117
 118 ```python
 119 tcb = cat(unpos(n) for n in ncb)
 120 tcb
 121 ```
 122
 123 ```python
 124 word_b, score_b = monoalphabetic_sa_break(tcb)
 125 word_b
 126 ```
 127
 128 ```python
 129 word_b, score_b = vigenere_frequency_break(tcb, fitness=Ptrigrams)
 130 print(word_b, '\n')
 131 pb = vigenere_decipher(tcb, word_b)
 132 print(pb)
 133 ```
 134
 135 ```python
 136 print(prettify(pb))
 137 ```
 138
 139 ```python Collapsed="false"
 140 open(plaintext_b_filename, 'w').write(prettify(pb))
 141 ```
 142
 143 ```python Collapsed="false"
 144
 145 ```