2021/2021-challenge9.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.hill import *
  25 from szyfrow.support.text_prettify import *
  26
  27 import numpy as np
  28 import pandas as pd
  29 import matplotlib.pyplot as plt
  30
  31 import collections
  32 %matplotlib inline
  33 ```
  34
  35 ```python Collapsed="false"
  36 challenge_number = 9
  37 plaintext_a_filename = f'plaintext.{challenge_number}a.txt'
  38 plaintext_b_filename = f'plaintext.{challenge_number}b.txt'
  39 ciphertext_a_filename = f'ciphertext.{challenge_number}a.txt'
  40 ciphertext_b_filename = f'ciphertext.{challenge_number}b.txt'
  41 ```
  42
  43 ```python Collapsed="false"
  44 ca = open(ciphertext_a_filename).read()
  45 cb = open(ciphertext_b_filename).read()
  46
  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 tags=[]
  60 pd.Series(sca_counts).sort_index().plot.bar()
  61 ```
  62
  63 ```python
  64 import itertools
  65 ```
  66
  67 ```python
  68 permutes = [transpositions_of(cat(t)) for t in itertools.permutations('abcdefghi')]
  69 len(permutes)
  70 ```
  71
  72 ```python
  73 key_a, _ = column_transposition_break(sca, translist=permutes, fitness=Ptrigrams)
  74 word_a, fill_a, empty_a = key_a
  75 word_a, fill_a, empty_a
  76 ```
  77
  78 ```python
  79 # mod_word_a = (1, 3, 6, 4, 5, 7, 0, 2, 8)
  80 pa = column_transposition_decipher(sca, word_a,
  81         fillcolumnwise=fill_a, emptycolumnwise=empty_a)
  82 pa
  83 ```
  84
  85 ```python
  86 print(prettify(pa))
  87 ```
  88
  89 ```python Collapsed="false" tags=[]
  90 open(plaintext_a_filename, 'w').write(prettify(pa))
  91 ```
  92
  93 ```python
  94 scb_counts = collections.Counter(scb)
  95 scb_counts
  96 ```
  97
  98 ```python tags=[]
  99 pd.Series(scb_counts).sort_index().plot.bar()
 100 ```
 101
 102 ```python
 103 key_b, _ = hill_break(scb, fitness=Ptrigrams)
 104 ```
 105
 106 ```python
 107 key_b
 108 ```
 109
 110 ```python
 111 pb = hill_decipher(key_b, scb)
 112 pb
 113 ```
 114
 115 ```python
 116 print(prettify(pb))
 117 ```
 118
 119 ```python Collapsed="false"
 120 open(plaintext_b_filename, 'w').write(prettify(pb))
 121 ```
 122
 123 ```python Collapsed="false"
 124
 125 ```