tests/test_playfair.py

   1 import pytest
   2 import string
   3
   4 from szyfrow.playfair import *
   5 from szyfrow.support.utilities import *
   6
   7 def test_wrap():
   8     assert playfair_wrap(3, 0, 4) == 3
   9     assert playfair_wrap(0, 0, 4) == 0
  10     assert playfair_wrap(4, 0, 4) == 4
  11     assert playfair_wrap(7, 0, 4) == 2
  12     assert playfair_wrap(-1, 0, 4) == 4
  13
  14 def test_encipher_bigram():
  15     grid = polybius_grid('playfairexample', list(range(5)), list(range(5)))
  16
  17     plain_pairs = 'hi de th eg ol di nt he tr ex es tu mp'.split()
  18     cipher_pairs = 'bm od zb xd na be ku dm ui xm mo uv if'.split()
  19
  20     for p, c in zip(plain_pairs, cipher_pairs):
  21         assert playfair_encipher_bigram(p, grid) == c
  22
  23 def test_decipher_bigram():
  24     grid = polybius_grid('playfairexample', list(range(5)), list(range(5)))
  25
  26     plain_pairs = 'hi de th eg ol di nt he tr ex es tu mp'.split()
  27     cipher_pairs = 'bm od zb xd na be ku dm ui xm mo uv if'.split()
  28
  29     for p, c in zip(plain_pairs, cipher_pairs):
  30         assert playfair_decipher_bigram(c, grid) == p
  31
  32 def test_playfair_bigrams():
  33     txt = sanitise('hide the gold in the tree stumps')
  34     f_bigrams = 'hi de th eg ol di nt he tr ex es tu mp sx'.split()
  35     t_bigrams = 'hi de th eg ol di nt he tr ex st um ps'.split()
  36     assert playfair_bigrams(txt, padding_replaces_repeat=True) == t_bigrams
  37     assert playfair_bigrams(txt, padding_replaces_repeat=False) == f_bigrams
  38
  39
  40
  41 def test_encipher_message():
  42     ct = playfair_encipher('hide the gold in the tree stump',
  43         'playfairexample', wrap_alphabet=KeywordWrapAlphabet.from_a)
  44     assert ct == 'bmodzbxdnabekudmuixmmouvif'
  45
  46     ct = playfair_encipher('this is a test message for the ' \
  47           'playfair decipherment', 'elephant')
  48     assert ct == 'clkrkrldhodghouhflovqbalhphzmerxnabkhapofatb'
  49
  50     ct = playfair_encipher('this is a test message for the ' \
  51           'playfair decipherment', 'elephant',
  52           wrap_alphabet=KeywordWrapAlphabet.from_last)
  53     assert ct == 'vlkrkrlwamnoamawdpolovalhplcklrhmnbkhahmentu'
  54
  55     ct = playfair_encipher('''Whoever has made a voyage up the Hudson must
  56         remember the Kaatskill mountains. They are a dismembered branch of
  57         the great''', 'hudson')
  58     assert ct == 'vuelznmscupnobnwszgpaoqmonudsohephortctnqnctmoclbwepcrkffthdembgchmoczcpnbbqhrntcntcbipcaeuhlmonkpnbqz'
  59
  60
  61 def test_decipher_message():
  62     plaintext = sanitise('''Whoever has made a voyage up the Hudson must
  63         remember the Kaatskill mountains. They are a dismembered branch of
  64         the great''')
  65
  66     trans_table = ''.maketrans('j', 'i')
  67
  68     for key in ['wink', 'elephant', 'swashbuckling']:
  69         for prp in [True, False]:
  70             expected = cat(playfair_bigrams(plaintext.translate(trans_table),
  71                 padding_replaces_repeat=prp))
  72             for wrap in KeywordWrapAlphabet:
  73                 enciphered = playfair_encipher(plaintext, key,
  74                     padding_replaces_repeat=prp, wrap_alphabet=wrap)
  75                 deciphered = playfair_decipher(enciphered, key,
  76                     padding_replaces_repeat=prp, wrap_alphabet=wrap)
  77                 assert deciphered == expected
  78
  79
  80 def test_playfair_break():
  81     plaintext = sanitise('''You will rejoice to hear that no disaster has accompanied the
  82         commencement of an enterprise which you have regarded with such evil
  83         forebodings.  I arrived here yesterday, and my first task is to assure
  84         my dear sister of my welfare and increasing confidence in the success
  85         of my undertaking.''')
  86     expected_key = 'swashbuckling'
  87     expected_wrap = KeywordWrapAlphabet.from_last
  88     expected_letters_to_merge = {'j': 'i'}
  89     expected_padding_letter = 'x'
  90     expected_padding_replaces_repeat = False
  91     ciphertext = playfair_encipher(plaintext, expected_key,
  92         padding_letter=expected_padding_letter,
  93         padding_replaces_repeat=expected_padding_replaces_repeat,
  94         letters_to_merge=expected_letters_to_merge,
  95         wrap_alphabet=expected_wrap)
  96
  97
  98     exptected_text = playfair_decipher(ciphertext, expected_key,
  99         padding_letter=expected_padding_letter,
 100         padding_replaces_repeat=expected_padding_replaces_repeat,
 101         letters_to_merge=expected_letters_to_merge,
 102         wrap_alphabet=expected_wrap)
 103
 104     expected_score = Ptrigrams(exptected_text)
 105
 106     dictionary = ['clearinghouse', 'computerising', 'counterclaims',
 107         'housewarmings',  'intravenously', 'liquefactions', 'somersaulting',
 108         'sportsmanlike', 'swashbuckling']
 109
 110     # dictionary = ['swashbuckling']
 111
 112     (key, wrap, letters_to_merge, padding_letter, padding_replaces_repeat), score = playfair_break(
 113         ciphertext,
 114         letters_to_merge=expected_letters_to_merge,
 115         padding_letter=expected_padding_letter,
 116         wordlist=dictionary, fitness=Ptrigrams)
 117
 118     assert key == expected_key
 119     assert wrap == expected_wrap
 120     assert letters_to_merge == expected_letters_to_merge
 121     assert padding_letter == expected_padding_letter
 122     assert padding_replaces_repeat == expected_padding_replaces_repeat
 123     assert score == pytest.approx(expected_score)