1 from utilities
import *
2 from language_models
import *
5 from keyword_cipher
import KeywordWrapAlphabet
7 from logger
import logger
9 def polybius_grid(keyword
, column_order
, row_order
, letters_to_merge
=None,
10 wrap_alphabet
=KeywordWrapAlphabet
.from_a
):
11 """Grid for a Polybius cipher, using a keyword to rearrange the
15 >>> polybius_grid('a', 'abcde', 'abcde')['x'] == ('e', 'c')
17 >>> polybius_grid('elephant', 'abcde', 'abcde')['e'] == ('a', 'a')
19 >>> polybius_grid('elephant', 'abcde', 'abcde')['b'] == ('b', 'c')
22 alphabet
= keyword_cipher_alphabet_of(keyword
, wrap_alphabet
=wrap_alphabet
)
23 if letters_to_merge
is None:
24 letters_to_merge
= {'j': 'i'}
26 for k
, l
in zip([(c
, r
) for c
in column_order
for r
in row_order
],
27 [l
for l
in alphabet
if l
not in letters_to_merge
])}
28 for l
in letters_to_merge
:
29 grid
[l
] = grid
[letters_to_merge
[l
]]
32 def polybius_reverse_grid(keyword
, column_order
, row_order
, letters_to_merge
=None,
33 wrap_alphabet
=KeywordWrapAlphabet
.from_a
):
34 """Grid for decrypting using a Polybius cipher, using a keyword to
35 rearrange the alphabet.
37 >>> polybius_reverse_grid('a', 'abcde', 'abcde')['e', 'c'] == 'x'
39 >>> polybius_reverse_grid('elephant', 'abcde', 'abcde')['a', 'a'] == 'e'
41 >>> polybius_reverse_grid('elephant', 'abcde', 'abcde')['b', 'c'] == 'b'
44 alphabet
= keyword_cipher_alphabet_of(keyword
, wrap_alphabet
=wrap_alphabet
)
45 if letters_to_merge
is None:
46 letters_to_merge
= {'j': 'i'}
48 for k
, l
in zip([(c
, r
) for c
in column_order
for r
in row_order
],
49 [l
for l
in alphabet
if l
not in letters_to_merge
])}
53 def polybius_flatten(pair
, column_first
):
54 """Convert a series of pairs into a single list of characters"""
56 return str(pair
[1]) + str(pair
[0])
58 return str(pair
[0]) + str(pair
[1])
60 def polybius_encipher(message
, keyword
, column_order
, row_order
,
62 letters_to_merge
=None, wrap_alphabet
=KeywordWrapAlphabet
.from_a
):
63 """Encipher a message with Polybius cipher, using a keyword to rearrange
67 >>> polybius_encipher('this is a test message for the ' \
68 'polybius decipherment', 'elephant', \
69 [1, 2, 3, 4, 5], [1, 2, 3, 4, 5], \
70 wrap_alphabet=KeywordWrapAlphabet.from_last)
71 '2214445544551522115522511155551543114252542214111352123234442355411135441314115451112122'
72 >>> polybius_encipher('this is a test message for the ' \
73 'polybius decipherment', 'elephant', 'abcde', 'abcde', \
75 'bbadccddccddaebbaaddbbceaaddddaecbaacadadcbbadaaacdaabedbcccdeddbeaabdccacadaadcceaababb'
76 >>> polybius_encipher('this is a test message for the ' \
77 'polybius decipherment', 'elephant', 'abcde', 'abcde', \
79 'bbdaccddccddeabbaaddbbecaaddddeabcaaacadcdbbdaaacaadbadecbccedddebaadbcccadaaacdecaaabbb'
81 grid
= polybius_grid(keyword
, column_order
, row_order
, letters_to_merge
, wrap_alphabet
)
82 return cat(polybius_flatten(grid
[l
], column_first
)
87 def polybius_decipher(message
, keyword
, column_order
, row_order
,
89 letters_to_merge
=None, wrap_alphabet
=KeywordWrapAlphabet
.from_a
):
90 """Decipher a message with a Polybius cipher, using a keyword to rearrange
93 >>> polybius_decipher('bbdaccddccddeabbaaddbbecaaddddeabcaaacadcdbbdaaaca'\
94 'adbadecbccedddebaadbcccadaaacdecaaabbb', 'elephant', 'abcde', 'abcde', \
96 'toisisvtestxessvbephktoefhnugiysweqifoekxelt'
98 >>> polybius_decipher('bbdaccddccddeabbaaddbbecaaddddeabcaaacadcdbbdaaaca'\
99 'adbadecbccedddebaadbcccadaaacdecaaabbb', 'elephant', 'abcde', 'abcde', \
101 'thisisatestmessageforthepolybiusdecipherment'
103 grid
= polybius_reverse_grid(keyword
, column_order
, row_order
, letters_to_merge
, wrap_alphabet
)
104 column_index_type
= type(column_order
[0])
105 row_index_type
= type(row_order
[0])
107 pairs
= [(column_index_type(p
[1]), row_index_type(p
[0])) for p
in chunks(message
, 2)]
109 pairs
= [(row_index_type(p
[0]), column_index_type(p
[1])) for p
in chunks(message
, 2)]
110 return cat(grid
[p
] for p
in pairs
if p
in grid
)
113 def polybius_break_mp(message
, column_labels
, row_labels
,
114 letters_to_merge
=None,
115 wordlist
=keywords
, fitness
=Pletters
,
116 number_of_solutions
=1, chunksize
=500):
117 """Breaks a Polybius substitution cipher using a dictionary and
120 >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
121 'polybius decipherment', 'elephant', 'abcde', 'abcde'), \
123 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
124 (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'abcde', False), \
126 >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
127 'polybius decipherment', 'elephant', 'abcde', 'abcde', column_first=True), \
129 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
130 (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'abcde', True), \
132 >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
133 'polybius decipherment', 'elephant', 'abcde', 'abcde', column_first=False), \
135 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
136 (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'abcde', False), \
138 >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
139 'polybius decipherment', 'elephant', 'abcde', 'pqrst', column_first=True), \
141 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
142 (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'pqrst', True), \
145 if letters_to_merge
is None:
146 letters_to_merge
= {'j': 'i'}
147 with multiprocessing
.Pool() as pool
:
148 helper_args
= [(message
, word
, wrap
,
149 column_labels
, row_labels
, column_first
,
153 for wrap
in KeywordWrapAlphabet
154 for column_first
in [False, True]]
155 # Gotcha: the helper function here needs to be defined at the top level
156 # (limitation of Pool.starmap)
157 breaks
= pool
.starmap(polybius_break_worker
, helper_args
, chunksize
)
158 if number_of_solutions
== 1:
159 return max(breaks
, key
=lambda k
: k
[1])
161 return sorted(breaks
, key
=lambda k
: k
[1], reverse
=True)[:number_of_solutions
]
163 def polybius_break_worker(message
, keyword
, wrap_alphabet
,
164 column_order
, row_order
, column_first
,
167 plaintext
= polybius_decipher(message
, keyword
,
168 column_order
, row_order
,
169 column_first
=column_first
,
170 letters_to_merge
=letters_to_merge
,
171 wrap_alphabet
=wrap_alphabet
)
173 fit
= fitness(plaintext
)
176 logger
.debug('Polybius break attempt using key {0} (wrap={1}, merging {2}), '
177 'columns as {3}, rows as {4} (column_first={5}) '
178 'gives fit of {6} and decrypt starting: '
179 '{7}'.format(keyword
, wrap_alphabet
, letters_to_merge
,
180 column_order
, row_order
, column_first
,
181 fit
, sanitise(plaintext
)[:50]))
182 return (keyword
, wrap_alphabet
, column_order
, row_order
, column_first
), fit
184 if __name__
== "__main__":