6 from itertools
import zip_longest
, cycle
, permutations
, starmap
7 from segment
import segment
8 from multiprocessing
import Pool
11 import matplotlib
.pyplot
as plt
13 logger
= logging
.getLogger(__name__
)
14 logger
.addHandler(logging
.FileHandler('cipher.log'))
15 logger
.setLevel(logging
.WARNING
)
16 #logger.setLevel(logging.INFO)
17 #logger.setLevel(logging.DEBUG)
20 from language_models
import *
25 # c5a = open('2012/5a.ciphertext', 'r').read()
26 # timeit.timeit('keyword_break(c5a)', setup='gc.enable() ; from __main__ import c5a ; from cipher import keyword_break', number=1)
27 # timeit.repeat('keyword_break_mp(c5a, chunksize=500)', setup='gc.enable() ; from __main__ import c5a ; from cipher import keyword_break_mp', repeat=5, number=1)
29 transpositions
= collections
.defaultdict(list)
31 transpositions
[transpositions_of(word
)] += [word
]
33 def frequencies(text
):
34 """Count the number of occurrences of each character in text
36 >>> sorted(frequencies('abcdefabc').items())
37 [('a', 2), ('b', 2), ('c', 2), ('d', 1), ('e', 1), ('f', 1)]
38 >>> sorted(frequencies('the quick brown fox jumped over the lazy ' \
39 'dog').items()) # doctest: +NORMALIZE_WHITESPACE
40 [(' ', 8), ('a', 1), ('b', 1), ('c', 1), ('d', 2), ('e', 4), ('f', 1),
41 ('g', 1), ('h', 2), ('i', 1), ('j', 1), ('k', 1), ('l', 1), ('m', 1),
42 ('n', 1), ('o', 4), ('p', 1), ('q', 1), ('r', 2), ('t', 2), ('u', 2),
43 ('v', 1), ('w', 1), ('x', 1), ('y', 1), ('z', 1)]
44 >>> sorted(frequencies('The Quick BROWN fox jumped! over... the ' \
45 '(9lazy) DOG').items()) # doctest: +NORMALIZE_WHITESPACE
46 [(' ', 8), ('!', 1), ('(', 1), (')', 1), ('.', 3), ('9', 1), ('B', 1),
47 ('D', 1), ('G', 1), ('N', 1), ('O', 2), ('Q', 1), ('R', 1), ('T', 1),
48 ('W', 1), ('a', 1), ('c', 1), ('d', 1), ('e', 4), ('f', 1), ('h', 2),
49 ('i', 1), ('j', 1), ('k', 1), ('l', 1), ('m', 1), ('o', 2), ('p', 1),
50 ('r', 1), ('t', 1), ('u', 2), ('v', 1), ('x', 1), ('y', 1), ('z', 1)]
51 >>> sorted(frequencies(sanitise('The Quick BROWN fox jumped! over... ' \
52 'the (9lazy) DOG')).items()) # doctest: +NORMALIZE_WHITESPACE
53 [('a', 1), ('b', 1), ('c', 1), ('d', 2), ('e', 4), ('f', 1), ('g', 1),
54 ('h', 2), ('i', 1), ('j', 1), ('k', 1), ('l', 1), ('m', 1), ('n', 1),
55 ('o', 4), ('p', 1), ('q', 1), ('r', 2), ('t', 2), ('u', 2), ('v', 1),
56 ('w', 1), ('x', 1), ('y', 1), ('z', 1)]
57 >>> frequencies('abcdefabcdef')['x']
60 return collections
.Counter(c
for c
in text
)
63 def caesar_break(message
, fitness
=Pletters
):
64 """Breaks a Caesar cipher using frequency analysis
66 >>> caesar_break('ibxcsyorsaqcheyklxivoexlevmrimwxsfiqevvmihrsasrxliwyrh' \
67 'ecjsppsamrkwleppfmergefifvmhixscsymjcsyqeoixlm') # doctest: +ELLIPSIS
68 (4, -130.849989015...)
69 >>> caesar_break('wxwmaxdgheetgwuxztgptedbgznitgwwhpguxyhkxbmhvvtlbhgtee' \
70 'raxlmhiixweblmxgxwmhmaxybkbgztgwztsxwbgmxgmert') # doctest: +ELLIPSIS
71 (19, -128.82410410...)
72 >>> caesar_break('yltbbqnqnzvguvaxurorgenafsbezqvagbnornfgsbevpnaabjurer' \
73 'svaquvzyvxrnznazlybequrvfohgriraabjtbaruraprur') # doctest: +ELLIPSIS
74 (13, -126.25403935...)
76 sanitised_message
= sanitise(message
)
78 best_fit
= float('-inf')
79 for shift
in range(26):
80 plaintext
= caesar_decipher(sanitised_message
, shift
)
81 fit
= fitness(plaintext
)
82 logger
.debug('Caesar break attempt using key {0} gives fit of {1} '
83 'and decrypt starting: {2}'.format(shift
, fit
, plaintext
[:50]))
87 logger
.info('Caesar break best fit: key {0} gives fit of {1} and '
88 'decrypt starting: {2}'.format(best_shift
, best_fit
,
89 caesar_decipher(sanitised_message
, best_shift
)[:50]))
90 return best_shift
, best_fit
92 def affine_break(message
, fitness
=Pletters
):
93 """Breaks an affine cipher using frequency analysis
95 >>> affine_break('lmyfu bkuusd dyfaxw claol psfaom jfasd snsfg jfaoe ls ' \
96 'omytd jlaxe mh jm bfmibj umis hfsul axubafkjamx. ls kffkxwsd jls ' \
97 'ofgbjmwfkiu olfmxmtmwaokttg jlsx ls kffkxwsd jlsi zg tsxwjl. jlsx ' \
98 'ls umfjsd jlsi zg hfsqysxog. ls dmmdtsd mx jls bats mh bkbsf. ls ' \
99 'bfmctsd kfmyxd jls lyj, mztanamyu xmc jm clm cku tmmeaxw kj lai ' \
100 'kxd clm ckuxj.') # doctest: +ELLIPSIS
101 ((15, 22, True), -340.601181913...)
103 sanitised_message
= sanitise(message
)
106 best_one_based
= True
107 best_fit
= float("-inf")
108 for one_based
in [True, False]:
109 for multiplier
in [x
for x
in range(1, 26, 2) if x
!= 13]:
110 for adder
in range(26):
111 plaintext
= affine_decipher(sanitised_message
,
112 multiplier
, adder
, one_based
)
113 fit
= fitness(plaintext
)
114 logger
.debug('Affine break attempt using key {0}x+{1} ({2}) '
115 'gives fit of {3} and decrypt starting: {4}'.
116 format(multiplier
, adder
, one_based
, fit
,
120 best_multiplier
= multiplier
122 best_one_based
= one_based
123 logger
.info('Affine break best fit with key {0}x+{1} ({2}) gives fit of {3} '
124 'and decrypt starting: {4}'.format(
125 best_multiplier
, best_adder
, best_one_based
, best_fit
,
126 affine_decipher(sanitised_message
, best_multiplier
,
127 best_adder
, best_one_based
)[:50]))
128 return (best_multiplier
, best_adder
, best_one_based
), best_fit
130 def keyword_break(message
, wordlist
=keywords
, fitness
=Pletters
):
131 """Breaks a keyword substitution cipher using a dictionary and
134 >>> keyword_break(keyword_encipher('this is a test message for the ' \
135 'keyword decipherment', 'elephant', Keyword_wrap_alphabet.from_last), \
136 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
137 (('elephant', <Keyword_wrap_alphabet.from_last: 2>), -52.834575011...)
140 best_wrap_alphabet
= True
141 best_fit
= float("-inf")
142 for wrap_alphabet
in Keyword_wrap_alphabet
:
143 for keyword
in wordlist
:
144 plaintext
= keyword_decipher(message
, keyword
, wrap_alphabet
)
145 fit
= fitness(plaintext
)
146 logger
.debug('Keyword break attempt using key {0} (wrap={1}) '
147 'gives fit of {2} and decrypt starting: {3}'.format(
148 keyword
, wrap_alphabet
, fit
,
149 sanitise(plaintext
)[:50]))
152 best_keyword
= keyword
153 best_wrap_alphabet
= wrap_alphabet
154 logger
.info('Keyword break best fit with key {0} (wrap={1}) gives fit of '
155 '{2} and decrypt starting: {3}'.format(best_keyword
,
156 best_wrap_alphabet
, best_fit
, sanitise(
157 keyword_decipher(message
, best_keyword
,
158 best_wrap_alphabet
))[:50]))
159 return (best_keyword
, best_wrap_alphabet
), best_fit
161 def keyword_break_mp(message
, wordlist
=keywords
, fitness
=Pletters
, chunksize
=500):
162 """Breaks a keyword substitution cipher using a dictionary and
165 >>> keyword_break_mp(keyword_encipher('this is a test message for the ' \
166 'keyword decipherment', 'elephant', Keyword_wrap_alphabet.from_last), \
167 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
168 (('elephant', <Keyword_wrap_alphabet.from_last: 2>), -52.834575011...)
171 helper_args
= [(message
, word
, wrap
, fitness
)
173 for wrap
in Keyword_wrap_alphabet
]
174 # Gotcha: the helper function here needs to be defined at the top level
175 # (limitation of Pool.starmap)
176 breaks
= pool
.starmap(keyword_break_worker
, helper_args
, chunksize
)
177 return max(breaks
, key
=lambda k
: k
[1])
179 def keyword_break_worker(message
, keyword
, wrap_alphabet
, fitness
):
180 plaintext
= keyword_decipher(message
, keyword
, wrap_alphabet
)
181 fit
= fitness(plaintext
)
182 logger
.debug('Keyword break attempt using key {0} (wrap={1}) gives fit of '
183 '{2} and decrypt starting: {3}'.format(keyword
,
184 wrap_alphabet
, fit
, sanitise(plaintext
)[:50]))
185 return (keyword
, wrap_alphabet
), fit
188 def column_transposition_break_mp(message
, translist
=transpositions
,
189 fitness
=Pbigrams
, chunksize
=500):
190 """Breaks a column transposition cipher using a dictionary and
191 n-gram frequency analysis
193 >>> column_transposition_break_mp(column_transposition_encipher(sanitise( \
194 "It is a truth universally acknowledged, that a single man in \
195 possession of a good fortune, must be in want of a wife. However \
196 little known the feelings or views of such a man may be on his \
197 first entering a neighbourhood, this truth is so well fixed in the \
198 minds of the surrounding families, that he is considered the \
199 rightful property of some one or other of their daughters."), \
201 translist={(2, 0, 5, 3, 1, 4, 6): ['encipher'], \
202 (5, 0, 6, 1, 3, 4, 2): ['fourteen'], \
203 (6, 1, 0, 4, 5, 3, 2): ['keyword']}) # doctest: +ELLIPSIS
204 (((2, 0, 5, 3, 1, 4, 6), False, False), -709.4646722...)
205 >>> column_transposition_break_mp(column_transposition_encipher(sanitise( \
206 "It is a truth universally acknowledged, that a single man in \
207 possession of a good fortune, must be in want of a wife. However \
208 little known the feelings or views of such a man may be on his \
209 first entering a neighbourhood, this truth is so well fixed in the \
210 minds of the surrounding families, that he is considered the \
211 rightful property of some one or other of their daughters."), \
213 translist={(2, 0, 5, 3, 1, 4, 6): ['encipher'], \
214 (5, 0, 6, 1, 3, 4, 2): ['fourteen'], \
215 (6, 1, 0, 4, 5, 3, 2): ['keyword']}, \
216 fitness=Ptrigrams) # doctest: +ELLIPSIS
217 (((2, 0, 5, 3, 1, 4, 6), False, False), -997.0129085...)
220 helper_args
= [(message
, trans
, fillcolumnwise
, emptycolumnwise
,
222 for trans
in translist
.keys()
223 for fillcolumnwise
in [True, False]
224 for emptycolumnwise
in [True, False]]
225 # Gotcha: the helper function here needs to be defined at the top level
226 # (limitation of Pool.starmap)
227 breaks
= pool
.starmap(column_transposition_break_worker
,
228 helper_args
, chunksize
)
229 return max(breaks
, key
=lambda k
: k
[1])
230 column_transposition_break
= column_transposition_break_mp
232 def monoalphabetic_break_hillclimbing(message
, max_iterations
= 10000000,
234 ciphertext
= unaccent(message
).lower()
235 alphabet
= list(string
.ascii_lowercase
)
236 random
.shuffle(alphabet
)
237 alphabet
= ''.join(alphabet
)
238 return monoalphabetic_break_hillclimbing_worker(ciphertext
, alphabet
,
239 max_iterations
, fitness
)
241 def monoalphabetic_break_hillclimbing_mp(message
, workers
=100,
242 max_iterations
= 10000000, fitness
=Pletters
, chunksize
=1):
244 ciphertext
= unaccent(message
).lower()
245 for i
in range(workers
):
246 alphabet
= list(string
.ascii_lowercase
)
247 random
.shuffle(alphabet
)
248 alphabet
= ''.join(alphabet
)
249 worker_args
.append((ciphertext
, alphabet
, max_iterations
, fitness
))
251 breaks
= pool
.starmap(monoalphabetic_break_hillclimbing_worker
,
252 worker_args
, chunksize
)
253 return max(breaks
, key
=lambda k
: k
[1])
255 def monoalphabetic_break_hillclimbing_worker(message
, alphabet
,
256 max_iterations
, fitness
):
257 def swap(letters
, i
, j
):
263 return letters
[:i
] + letters
[j
] + letters
[i
+1:j
] + letters
[i
] + letters
[j
+1:]
264 best_alphabet
= alphabet
265 best_fitness
= float('-inf')
266 for i
in range(max_iterations
):
267 alphabet
= swap(alphabet
, random
.randrange(26), random
.randrange(26))
268 cipher_translation
= ''.maketrans(string
.ascii_lowercase
, alphabet
)
269 plaintext
= message
.translate(cipher_translation
)
270 if fitness(plaintext
) > best_fitness
:
271 best_fitness
= fitness(plaintext
)
272 best_alphabet
= alphabet
273 print(i
, best_alphabet
, best_fitness
, plaintext
)
274 return best_alphabet
, best_fitness
277 def column_transposition_break_worker(message
, transposition
,
278 fillcolumnwise
, emptycolumnwise
, fitness
):
279 plaintext
= column_transposition_decipher(message
, transposition
,
280 fillcolumnwise
=fillcolumnwise
, emptycolumnwise
=emptycolumnwise
)
281 fit
= fitness(sanitise(plaintext
))
282 logger
.debug('Column transposition break attempt using key {0} '
283 'gives fit of {1} and decrypt starting: {2}'.format(
285 sanitise(plaintext
)[:50]))
286 return (transposition
, fillcolumnwise
, emptycolumnwise
), fit
289 def scytale_break_mp(message
, max_key_length
=20,
290 fitness
=Pbigrams
, chunksize
=500):
291 """Breaks a scytale cipher using a range of lengths and
292 n-gram frequency analysis
294 >>> scytale_break_mp(scytale_encipher(sanitise( \
295 "It is a truth universally acknowledged, that a single man in \
296 possession of a good fortune, must be in want of a wife. However \
297 little known the feelings or views of such a man may be on his \
298 first entering a neighbourhood, this truth is so well fixed in the \
299 minds of the surrounding families, that he is considered the \
300 rightful property of some one or other of their daughters."), \
301 5)) # doctest: +ELLIPSIS
303 >>> scytale_break_mp(scytale_encipher(sanitise( \
304 "It is a truth universally acknowledged, that a single man in \
305 possession of a good fortune, must be in want of a wife. However \
306 little known the feelings or views of such a man may be on his \
307 first entering a neighbourhood, this truth is so well fixed in the \
308 minds of the surrounding families, that he is considered the \
309 rightful property of some one or other of their daughters."), \
311 fitness=Ptrigrams) # doctest: +ELLIPSIS
315 helper_args
= [(message
, trans
, False, True, fitness
)
317 [[col
for col
in range(math
.ceil(len(message
)/rows
))]
318 for rows
in range(1,max_key_length
+1)]]
319 # Gotcha: the helper function here needs to be defined at the top level
320 # (limitation of Pool.starmap)
321 breaks
= pool
.starmap(column_transposition_break_worker
,
322 helper_args
, chunksize
)
323 best
= max(breaks
, key
=lambda k
: k
[1])
324 return math
.trunc(len(message
) / len(best
[0][0])), best
[1]
325 scytale_break
= scytale_break_mp
328 def vigenere_keyword_break_mp(message
, wordlist
=keywords
, fitness
=Pletters
,
330 """Breaks a vigenere cipher using a dictionary and
333 >>> vigenere_keyword_break_mp(vigenere_encipher(sanitise('this is a test ' \
334 'message for the vigenere decipherment'), 'cat'), \
335 wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
336 ('cat', -52.947271216...)
339 helper_args
= [(message
, word
, fitness
)
340 for word
in wordlist
]
341 # Gotcha: the helper function here needs to be defined at the top level
342 # (limitation of Pool.starmap)
343 breaks
= pool
.starmap(vigenere_keyword_break_worker
, helper_args
, chunksize
)
344 return max(breaks
, key
=lambda k
: k
[1])
345 vigenere_keyword_break
= vigenere_keyword_break_mp
347 def vigenere_keyword_break_worker(message
, keyword
, fitness
):
348 plaintext
= vigenere_decipher(message
, keyword
)
349 fit
= fitness(plaintext
)
350 logger
.debug('Vigenere keyword break attempt using key {0} gives fit of '
351 '{1} and decrypt starting: {2}'.format(keyword
,
352 fit
, sanitise(plaintext
)[:50]))
357 def vigenere_frequency_break(message
, max_key_length
=20, fitness
=Pletters
):
358 """Breaks a Vigenere cipher with frequency analysis
360 >>> vigenere_frequency_break(vigenere_encipher(sanitise("It is time to " \
361 "run. She is ready and so am I. I stole Daniel's pocketbook this " \
362 "afternoon when he left his jacket hanging on the easel in the " \
363 "attic. I jump every time I hear a footstep on the stairs, " \
364 "certain that the theft has been discovered and that I will " \
365 "be caught. The SS officer visits less often now that he is " \
366 "sure"), 'florence')) # doctest: +ELLIPSIS
367 ('florence', -307.5473096791...)
369 def worker(message
, key_length
, fitness
):
370 splits
= every_nth(sanitised_message
, key_length
)
371 key
= ''.join([chr(caesar_break(s
)[0] + ord('a')) for s
in splits
])
372 plaintext
= vigenere_decipher(message
, key
)
373 fit
= fitness(plaintext
)
375 sanitised_message
= sanitise(message
)
376 results
= starmap(worker
, [(sanitised_message
, i
, fitness
)
377 for i
in range(1, max_key_length
+1)])
378 return max(results
, key
=lambda k
: k
[1])
381 def beaufort_frequency_break(message
, max_key_length
=20, fitness
=Pletters
):
382 """Breaks a Beaufort cipher with frequency analysis
384 >>> beaufort_frequency_break(beaufort_encipher(sanitise("It is time to " \
385 "run. She is ready and so am I. I stole Daniel's pocketbook this " \
386 "afternoon when he left his jacket hanging on the easel in the " \
387 "attic. I jump every time I hear a footstep on the stairs, " \
388 "certain that the theft has been discovered and that I will " \
389 "be caught. The SS officer visits less often now " \
390 "that he is sure"), 'florence')) # doctest: +ELLIPSIS
391 ('florence', -307.5473096791...)
393 def worker(message
, key_length
, fitness
):
394 splits
= every_nth(sanitised_message
, key_length
)
395 key
= ''.join([chr(-caesar_break(s
)[0] % 26 + ord('a')) for s
in splits
])
396 plaintext
= beaufort_decipher(message
, key
)
397 fit
= fitness(plaintext
)
399 sanitised_message
= sanitise(message
)
400 results
= starmap(worker
, [(sanitised_message
, i
, fitness
)
401 for i
in range(1, max_key_length
+1)])
402 return max(results
, key
=lambda k
: k
[1])
405 def plot_frequency_histogram(freqs
, sort_key
=None):
406 x
= range(len(freqs
.keys()))
407 y
= [freqs
[l
] for l
in sorted(freqs
.keys(), key
=sort_key
)]
409 ax
= f
.add_axes([0.1, 0.1, 0.9, 0.9])
410 ax
.bar(x
, y
, align
='center')
412 ax
.set_xticklabels(sorted(freqs
.keys(), key
=sort_key
))
416 if __name__
== "__main__":