>>> vigenere_keyword_break_mp(vigenere_encipher(sanitise('this is a test ' \
'message for the vigenere decipherment'), 'cat'), \
wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
- ('cat', -52.947271216...)
+ ('cat', -52.9472712...)
"""
with Pool() as pool:
helper_args = [(message, word, fitness)
"certain that the theft has been discovered and that I will " \
"be caught. The SS officer visits less often now that he is " \
"sure"), 'florence')) # doctest: +ELLIPSIS
- ('florence', -307.5473096791...)
+ ('florence', -307.5473096...)
"""
def worker(message, key_length, fitness):
splits = every_nth(sanitised_message, key_length)
return max(results, key=lambda k: k[1])
+def polybius_break_mp(message, column_labels, row_labels,
+ letters_to_merge=None,
+ wordlist=keywords, fitness=Pletters,
+ number_of_solutions=1, chunksize=500):
+ """Breaks a Polybius substitution cipher using a dictionary and
+ frequency analysis
+
+ >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
+ 'polybius decipherment', 'elephant', 'abcde', 'abcde'), \
+ 'abcde', 'abcde', \
+ wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
+ (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'abcde', False), \
+ -54.53880...)
+ >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
+ 'polybius decipherment', 'elephant', 'abcde', 'abcde', column_first=True), \
+ 'abcde', 'abcde', \
+ wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
+ (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'abcde', True), \
+ -54.53880...)
+ >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
+ 'polybius decipherment', 'elephant', 'abcde', 'abcde', column_first=False), \
+ 'abcde', 'abcde', \
+ wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
+ (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'abcde', False), \
+ -54.53880...)
+ >>> polybius_break_mp(polybius_encipher('this is a test message for the ' \
+ 'polybius decipherment', 'elephant', 'abcde', 'pqrst', column_first=True), \
+ 'abcde', 'pqrst', \
+ wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
+ (('elephant', <KeywordWrapAlphabet.from_a: 1>, 'abcde', 'pqrst', True), \
+ -54.53880...)
+ """
+ if letters_to_merge is None:
+ letters_to_merge = {'j': 'i'}
+ with Pool() as pool:
+ helper_args = [(message, word, wrap,
+ column_labels, row_labels, column_first,
+ letters_to_merge,
+ fitness)
+ for word in wordlist
+ for wrap in KeywordWrapAlphabet
+ for column_first in [False, True]]
+ # Gotcha: the helper function here needs to be defined at the top level
+ # (limitation of Pool.starmap)
+ breaks = pool.starmap(polybius_break_worker, helper_args, chunksize)
+ if number_of_solutions == 1:
+ return max(breaks, key=lambda k: k[1])
+ else:
+ return sorted(breaks, key=lambda k: k[1], reverse=True)[:number_of_solutions]
+
+def polybius_break_worker(message, keyword, wrap_alphabet,
+ column_order, row_order, column_first,
+ letters_to_merge,
+ fitness):
+ plaintext = polybius_decipher(message, keyword,
+ column_order, row_order,
+ column_first=column_first,
+ letters_to_merge=letters_to_merge,
+ wrap_alphabet=wrap_alphabet)
+ if plaintext:
+ fit = fitness(plaintext)
+ else:
+ fit = float('-inf')
+ logger.debug('Polybius break attempt using key {0} (wrap={1}, merging {2}), '
+ 'columns as {3}, rows as {4} (column_first={5}) '
+ 'gives fit of {6} and decrypt starting: '
+ '{7}'.format(keyword, wrap_alphabet, letters_to_merge,
+ column_order, row_order, column_first,
+ fit, sanitise(plaintext)[:50]))
+ return (keyword, wrap_alphabet, column_order, row_order, column_first), fit
+
+
def column_transposition_break_mp(message, translist=transpositions,
fitness=Pbigrams, chunksize=500):
"""Breaks a column transposition cipher using a dictionary and