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 xca = polybius_decipher(sca, keyword='a', column_order=col_a, row_order=row_a,
  77                   column_first=col_first_a, wrap_alphabet=wrap_a)
  78 xca
  79 ```
  80
  81 ```python
  82 word_a, _ = monoalphabetic_sa_break(xca)
  83 word_a
  84 ```
  85
  86 ```python
  87 pa = keyword_decipher(xca, word_a)
  88 pa
  89 ```
  90
  91 ```python
  92 print(prettify(pa))
  93 ```
  94
  95 ```python Collapsed="false"
  96 open(plaintext_a_filename, 'w').write(prettify(pa))
  97 ```
  98
  99 ```python
 100 cb[:11]
 101 ```
 102
 103 ```python
 104 int('10101', 2)
 105 ```
 106
 107 ```python
 108 scb = cat(c for c in cb if c in '01')
 109 len(scb)
 110 ```
 111
 112 ```python
 113 ncb = [int(g, 2) for g in cb.split()]
 114 min(ncb), max(ncb)
 115 ```
 116
 117 ```python
 118 tcb = cat(unpos(n) for n in ncb)
 119 tcb
 120 ```
 121
 122 ```python
 123 word_b, score_b = monoalphabetic_sa_break(tcb)
 124 word_b
 125 ```
 126
 127 ```python
 128 word_b, score_b = vigenere_frequency_break(tcb, fitness=Ptrigrams)
 129 print(word_b, '\n')
 130 pb = vigenere_decipher(tcb, word_b)
 131 print(pb)
 132 ```
 133
 134 ```python
 135 print(prettify(pb))
 136 ```
 137
 138 ```python Collapsed="false"
 139 open(plaintext_b_filename, 'w').write(prettify(pb))
 140 ```
 141
 142 ```python Collapsed="false"
 143
 144 ```