2 from support
.utilities
import *
3 from support
.language_models
import *
4 from cipher
.keyword_cipher
import KeywordWrapAlphabet
, keyword_cipher_alphabet_of
6 from logger
import logger
8 def polybius_grid(keyword
, column_order
, row_order
, letters_to_merge
=None,
9 wrap_alphabet
=KeywordWrapAlphabet
.from_a
):
10 """Grid for a Polybius cipher, using a keyword to rearrange the
14 >>> polybius_grid('a', 'abcde', 'abcde')['x'] == ('e', 'c')
16 >>> polybius_grid('elephant', 'abcde', 'abcde')['e'] == ('a', 'a')
18 >>> polybius_grid('elephant', 'abcde', 'abcde')['b'] == ('b', 'c')
21 alphabet
= keyword_cipher_alphabet_of(keyword
, wrap_alphabet
=wrap_alphabet
)
22 if letters_to_merge
is None:
23 letters_to_merge
= {'j': 'i'}
25 for k
, l
in zip([(c
, r
) for c
in column_order
for r
in row_order
],
26 [l
for l
in alphabet
if l
not in letters_to_merge
])}
27 for l
in letters_to_merge
:
28 grid
[l
] = grid
[letters_to_merge
[l
]]
31 def polybius_reverse_grid(keyword
, column_order
, row_order
, letters_to_merge
=None,
32 wrap_alphabet
=KeywordWrapAlphabet
.from_a
):
33 """Grid for decrypting using a Polybius cipher, using a keyword to
34 rearrange the alphabet.
36 >>> polybius_reverse_grid('a', 'abcde', 'abcde')['e', 'c'] == 'x'
38 >>> polybius_reverse_grid('elephant', 'abcde', 'abcde')['a', 'a'] == 'e'
40 >>> polybius_reverse_grid('elephant', 'abcde', 'abcde')['b', 'c'] == 'b'
43 alphabet
= keyword_cipher_alphabet_of(keyword
, wrap_alphabet
=wrap_alphabet
)
44 if letters_to_merge
is None:
45 letters_to_merge
= {'j': 'i'}
47 for k
, l
in zip([(c
, r
) for c
in column_order
for r
in row_order
],
48 [l
for l
in alphabet
if l
not in letters_to_merge
])}
52 def polybius_flatten(pair
, column_first
):
53 """Convert a series of pairs into a single list of characters"""
55 return str(pair
[1]) + str(pair
[0])
57 return str(pair
[0]) + str(pair
[1])
59 def polybius_encipher(message
, keyword
, column_order
, row_order
,
61 letters_to_merge
=None, wrap_alphabet
=KeywordWrapAlphabet
.from_a
):
62 """Encipher a message with Polybius cipher, using a keyword to rearrange
66 >>> polybius_encipher('this is a test message for the ' \
67 'polybius decipherment', 'elephant', \
68 [1, 2, 3, 4, 5], [1, 2, 3, 4, 5], \
69 wrap_alphabet=KeywordWrapAlphabet.from_last)
70 '2214445544551522115522511155551543114252542214111352123234442355411135441314115451112122'
71 >>> polybius_encipher('this is a test message for the ' \
72 'polybius decipherment', 'elephant', 'abcde', 'abcde', \
74 'bbadccddccddaebbaaddbbceaaddddaecbaacadadcbbadaaacdaabedbcccdeddbeaabdccacadaadcceaababb'
75 >>> polybius_encipher('this is a test message for the ' \
76 'polybius decipherment', 'elephant', 'abcde', 'abcde', \
78 'bbdaccddccddeabbaaddbbecaaddddeabcaaacadcdbbdaaacaadbadecbccedddebaadbcccadaaacdecaaabbb'
80 grid
= polybius_grid(keyword
, column_order
, row_order
, letters_to_merge
, wrap_alphabet
)
81 return cat(polybius_flatten(grid
[l
], column_first
)
86 def polybius_decipher(message
, keyword
, column_order
, row_order
,
88 letters_to_merge
=None, wrap_alphabet
=KeywordWrapAlphabet
.from_a
):
89 """Decipher a message with a Polybius cipher, using a keyword to rearrange
92 >>> polybius_decipher('bbdaccddccddeabbaaddbbecaaddddeabcaaacadcdbbdaaaca'\
93 'adbadecbccedddebaadbcccadaaacdecaaabbb', 'elephant', 'abcde', 'abcde', \
95 'toisisvtestxessvbephktoefhnugiysweqifoekxelt'
97 >>> polybius_decipher('bbdaccddccddeabbaaddbbecaaddddeabcaaacadcdbbdaaaca'\
98 'adbadecbccedddebaadbcccadaaacdecaaabbb', 'elephant', 'abcde', 'abcde', \
100 'thisisatestmessageforthepolybiusdecipherment'
102 grid
= polybius_reverse_grid(keyword
, column_order
, row_order
, letters_to_merge
, wrap_alphabet
)
103 column_index_type
= type(column_order
[0])
104 row_index_type
= type(row_order
[0])
106 pairs
= [(column_index_type(p
[1]), row_index_type(p
[0])) for p
in chunks(message
, 2)]
108 pairs
= [(row_index_type(p
[0]), column_index_type(p
[1])) for p
in chunks(message
, 2)]
109 return cat(grid
[p
] for p
in pairs
if p
in grid
)
112 def polybius_break_mp(message
, column_labels
, row_labels
,
113 letters_to_merge
=None,
114 wordlist
=keywords
, fitness
=Pletters
,
115 number_of_solutions
=1, chunksize
=500):
116 """Breaks a Polybius substitution cipher using a dictionary and
119 >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
120 'polybius decipherment', 'elephant', 'abcde', 'abcde'), \
122 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
123 (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'abcde', False), \
125 >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
126 'polybius decipherment', 'elephant', 'abcde', 'abcde', column_first=True), \
128 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
129 (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'abcde', True), \
131 >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
132 'polybius decipherment', 'elephant', 'abcde', 'abcde', column_first=False), \
134 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
135 (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'abcde', False), \
137 >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
138 'polybius decipherment', 'elephant', 'abcde', 'pqrst', column_first=True), \
140 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
141 (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'pqrst', True), \
144 if letters_to_merge
is None:
145 letters_to_merge
= {'j': 'i'}
146 with multiprocessing
.Pool() as pool
:
147 helper_args
= [(message
, word
, wrap
,
148 column_labels
, row_labels
, column_first
,
152 for wrap
in KeywordWrapAlphabet
153 for column_first
in [False, True]]
154 # Gotcha: the helper function here needs to be defined at the top level
155 # (limitation of Pool.starmap)
156 breaks
= pool
.starmap(polybius_break_worker
, helper_args
, chunksize
)
157 if number_of_solutions
== 1:
158 return max(breaks
, key
=lambda k
: k
[1])
160 return sorted(breaks
, key
=lambda k
: k
[1], reverse
=True)[:number_of_solutions
]
162 def polybius_break_worker(message
, keyword
, wrap_alphabet
,
163 column_order
, row_order
, column_first
,
166 plaintext
= polybius_decipher(message
, keyword
,
167 column_order
, row_order
,
168 column_first
=column_first
,
169 letters_to_merge
=letters_to_merge
,
170 wrap_alphabet
=wrap_alphabet
)
172 fit
= fitness(plaintext
)
175 logger
.debug('Polybius break attempt using key {0} (wrap={1}, merging {2}), '
176 'columns as {3}, rows as {4} (column_first={5}) '
177 'gives fit of {6} and decrypt starting: '
178 '{7}'.format(keyword
, wrap_alphabet
, letters_to_merge
,
179 column_order
, row_order
, column_first
,
180 fit
, sanitise(plaintext
)[:50]))
181 return (keyword
, wrap_alphabet
, column_order
, row_order
, column_first
), fit
183 if __name__
== "__main__":