2021/2021-challenge8.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.railfence import *
  24 from szyfrow.support.text_prettify import *
  25
  26 import numpy as np
  27 import pandas as pd
  28 import matplotlib.pyplot as plt
  29
  30 import collections
  31 %matplotlib inline
  32 ```
  33
  34 ```python Collapsed="false"
  35 challenge_number = 8
  36 plaintext_a_filename = f'plaintext.{challenge_number}a.txt'
  37 plaintext_b_filename = f'plaintext.{challenge_number}b.txt'
  38 ciphertext_a_filename = f'ciphertext.{challenge_number}a.txt'
  39 ciphertext_b_filename = f'ciphertext.{challenge_number}b.txt'
  40 ```
  41
  42 ```python Collapsed="false"
  43 ca = open(ciphertext_a_filename).read()
  44 ncb = open(ciphertext_b_filename).read()
  45
  46 numtrans = ''.maketrans('12345', 'abcde')
  47 cb = ncb.translate(numtrans)
  48
  49 sca = sanitise(ca)
  50 rsca = cat(reversed(sca))
  51 scb = sanitise(cb)
  52 rscb = cat(reversed(scb))
  53 ```
  54
  55 ```python
  56 sca_counts = collections.Counter(sca)
  57 sca_counts
  58 ```
  59
  60 ```python tags=[]
  61 pd.Series(sca_counts).sort_index().plot.bar()
  62 ```
  63
  64 ```python
  65 key_a, score_a = vigenere_frequency_break(sca, fitness=Ptrigrams)
  66 key_a, score_a
  67 ```
  68
  69 ```python
  70 pa = vigenere_decipher(sca, key_a)
  71 pa
  72 ```
  73
  74 ```python
  75 print(prettify(pa))
  76 ```
  77
  78 ```python Collapsed="false" tags=[]
  79 open(plaintext_a_filename, 'w').write(prettify(pa))
  80 ```
  81
  82 ```python
  83 word_a, wrap_a, col_a, row_a, col_first_a = key_a
  84 polybius_decipher(sca, keyword=word_a, column_order=col_a, row_order=row_a,
  85                   column_first=col_first_a, wrap_alphabet=wrap_a)
  86 ```
  87
  88 ```python
  89 xcb = polybius_decipher(scb, keyword='a', column_order='abcde', row_order='abcde',
  90                   column_first=False, wrap_alphabet=KeywordWrapAlphabet.from_a,
  91                   letters_to_merge={'z': 'y'})
  92 xcb
  93 ```
  94
  95 ```python
  96 sncb = cat(l for l in ncb if l in '12345')
  97 xcb = polybius_decipher(sncb, keyword='a', column_order='12345', row_order='12345',
  98                   column_first=False, wrap_alphabet=KeywordWrapAlphabet.from_a,
  99                   letters_to_merge={'z': 'y'})
 100 xcb
 101 ```
 102
 103 ```python
 104 scb_counts = collections.Counter(xcb)
 105 scb_counts
 106 ```
 107
 108 ```python tags=[]
 109 pd.Series(scb_counts).sort_index().plot.bar()
 110 ```
 111
 112 ```python tags=[]
 113 pd.Series(english_counts).sort_index().plot.bar()
 114 ```
 115
 116 ```python
 117 len(set(xcb))
 118 ```
 119
 120 ```python
 121 key_b, _ = column_transposition_break(xcb, fitness=Ptrigrams)
 122 word_b, fill_b, empty_b = key_b
 123 word_b, fill_b, empty_b
 124 ```
 125
 126 ```python
 127 pb = column_transposition_decipher(xcb, word_b,
 128         fillcolumnwise=fill_b, emptycolumnwise=empty_b)
 129 pb
 130 ```
 131
 132 ```python
 133 print(prettify(pb))
 134 ```
 135
 136 ```python Collapsed="false" tags=[]
 137 open(plaintext_a_filename, 'w').write(prettify(pa))
 138 ```
 139
 140 ```python
 141 cb[:11]
 142 ```
 143
 144 ```python
 145 int('10101', 2)
 146 ```
 147
 148 ```python
 149 scb = cat(c for c in cb if c in '01')
 150 len(scb)
 151 ```
 152
 153 ```python
 154 ncb = [int(g, 2) for g in cb.split()]
 155 min(ncb), max(ncb)
 156 ```
 157
 158 ```python
 159 tcb = cat(unpos(n) for n in ncb)
 160 tcb
 161 ```
 162
 163 ```python
 164 word_b, score_b = monoalphabetic_sa_break(tcb)
 165 word_b
 166 ```
 167
 168 ```python
 169 word_b, score_b = vigenere_frequency_break(tcb, fitness=Ptrigrams)
 170 print(word_b, '\n')
 171 pb = vigenere_decipher(tcb, word_b)
 172 print(pb)
 173 ```
 174
 175 ```python
 176 print(prettify(pb))
 177 ```
 178
 179 ```python Collapsed="false"
 180 open(plaintext_b_filename, 'w').write(prettify(pb))
 181 ```
 182
 183 ```python Collapsed="false"
 184
 185 ```