2021/2021-challenge6.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.support.text_prettify import *
  23
  24 import numpy as np
  25 import pandas as pd
  26 import matplotlib.pyplot as plt
  27
  28 import collections
  29 %matplotlib inline
  30 ```
  31
  32 ```python Collapsed="false"
  33 challenge_number = 6
  34 plaintext_a_filename = f'plaintext.{challenge_number}a.txt'
  35 plaintext_b_filename = f'plaintext.{challenge_number}b.txt'
  36 ciphertext_a_filename = f'ciphertext.{challenge_number}a.txt'
  37 ciphertext_b_filename = f'ciphertext.{challenge_number}b.txt'
  38 ```
  39
  40 ```python Collapsed="false"
  41 ca = open(ciphertext_a_filename).read()
  42 cb = open(ciphertext_b_filename).read()
  43
  44 sca = sanitise(ca)
  45 rsca = cat(reversed(sca))
  46 scb = sanitise(cb)
  47 rscb = cat(reversed(scb))
  48 ```
  49
  50 ```python
  51 sca_counts = collections.Counter(sca)
  52 sca_counts
  53 ```
  54
  55 ```python
  56 pd.Series(sca_counts).sort_index().plot.bar()
  57 ```
  58
  59 ```python
  60 key_a, score_a = railfence_break(sca, fitness=Ptrigrams)
  61 print(key_a, '\n')
  62 pa = railfence_decipher(sca, key_a)
  63 print(pa)
  64 ```
  65
  66 ```python
  67 (word_a, fill_a, empty_a), score_a = column_transposition_break(sca, fitness=Ptrigrams)
  68 print(word_a, fill_a, empty_a, '\n')
  69 pa = column_transposition_decipher(sca, word_a, fillcolumnwise=fill_a, emptycolumnwise=empty_a)
  70 print(pa)
  71 ```
  72
  73 ```python
  74 transpositions_of('deacb')
  75 ```
  76
  77 ```python
  78 transpositions[word_a]
  79 ```
  80
  81 ```python
  82 print(prettify(pa))
  83 ```
  84
  85 ```python Collapsed="false"
  86 open(plaintext_a_filename, 'w').write(prettify(pa))
  87 ```
  88
  89 ```python
  90 word_b, score_b = vigenere_frequency_break(scb, fitness=Ptrigrams)
  91 print(word_b, '\n')
  92 pb = vigenere_decipher(scb, word_b)
  93 print(pb)
  94 ```
  95
  96 ```python
  97 word_b, score_b = vigenere_frequency_break(rscb, fitness=Ptrigrams)
  98 print(word_b, '\n')
  99 pb = vigenere_decipher(rscb, word_b)
 100 print(pb)
 101 ```
 102
 103 ```python
 104 pb = vigenere_decipher(rscb, word_b)
 105 print(prettify(pb))
 106 ```
 107
 108 ```python Collapsed="false"
 109 open(plaintext_b_filename, 'w').write(prettify(pb))
 110 ```
 111
 112 ```python Collapsed="false"
 113
 114 ```