--- /dev/null
+from utilities import *
+from language_models import *
+import multiprocessing
+
+from keyword_cipher import KeywordWrapAlphabet
+
+from logger import logger
+
+def polybius_grid(keyword, column_order, row_order, letters_to_merge=None,
+ wrap_alphabet=KeywordWrapAlphabet.from_a):
+ """Grid for a Polybius cipher, using a keyword to rearrange the
+ alphabet.
+
+
+ >>> polybius_grid('a', 'abcde', 'abcde')['x'] == ('e', 'c')
+ True
+ >>> polybius_grid('elephant', 'abcde', 'abcde')['e'] == ('a', 'a')
+ True
+ >>> polybius_grid('elephant', 'abcde', 'abcde')['b'] == ('b', 'c')
+ True
+ """
+ alphabet = keyword_cipher_alphabet_of(keyword, wrap_alphabet=wrap_alphabet)
+ if letters_to_merge is None:
+ letters_to_merge = {'j': 'i'}
+ grid = {l: k
+ for k, l in zip([(c, r) for c in column_order for r in row_order],
+ [l for l in alphabet if l not in letters_to_merge])}
+ for l in letters_to_merge:
+ grid[l] = grid[letters_to_merge[l]]
+ return grid
+
+def polybius_reverse_grid(keyword, column_order, row_order, letters_to_merge=None,
+ wrap_alphabet=KeywordWrapAlphabet.from_a):
+ """Grid for decrypting using a Polybius cipher, using a keyword to
+ rearrange the alphabet.
+
+ >>> polybius_reverse_grid('a', 'abcde', 'abcde')['e', 'c'] == 'x'
+ True
+ >>> polybius_reverse_grid('elephant', 'abcde', 'abcde')['a', 'a'] == 'e'
+ True
+ >>> polybius_reverse_grid('elephant', 'abcde', 'abcde')['b', 'c'] == 'b'
+ True
+ """
+ alphabet = keyword_cipher_alphabet_of(keyword, wrap_alphabet=wrap_alphabet)
+ if letters_to_merge is None:
+ letters_to_merge = {'j': 'i'}
+ grid = {k: l
+ for k, l in zip([(c, r) for c in column_order for r in row_order],
+ [l for l in alphabet if l not in letters_to_merge])}
+ return grid
+
+
+def polybius_flatten(pair, column_first):
+ """Convert a series of pairs into a single list of characters"""
+ if column_first:
+ return str(pair[1]) + str(pair[0])
+ else:
+ return str(pair[0]) + str(pair[1])
+
+def polybius_encipher(message, keyword, column_order, row_order,
+ column_first=False,
+ letters_to_merge=None, wrap_alphabet=KeywordWrapAlphabet.from_a):
+ """Encipher a message with Polybius cipher, using a keyword to rearrange
+ the alphabet
+
+
+ >>> polybius_encipher('this is a test message for the ' \
+ 'polybius decipherment', 'elephant', \
+ [1, 2, 3, 4, 5], [1, 2, 3, 4, 5], \
+ wrap_alphabet=KeywordWrapAlphabet.from_last)
+ '2214445544551522115522511155551543114252542214111352123234442355411135441314115451112122'
+ >>> polybius_encipher('this is a test message for the ' \
+ 'polybius decipherment', 'elephant', 'abcde', 'abcde', \
+ column_first=False)
+ 'bbadccddccddaebbaaddbbceaaddddaecbaacadadcbbadaaacdaabedbcccdeddbeaabdccacadaadcceaababb'
+ >>> polybius_encipher('this is a test message for the ' \
+ 'polybius decipherment', 'elephant', 'abcde', 'abcde', \
+ column_first=True)
+ 'bbdaccddccddeabbaaddbbecaaddddeabcaaacadcdbbdaaacaadbadecbccedddebaadbcccadaaacdecaaabbb'
+ """
+ grid = polybius_grid(keyword, column_order, row_order, letters_to_merge, wrap_alphabet)
+ return cat(polybius_flatten(grid[l], column_first)
+ for l in message
+ if l in grid)
+
+
+def polybius_decipher(message, keyword, column_order, row_order,
+ column_first=False,
+ letters_to_merge=None, wrap_alphabet=KeywordWrapAlphabet.from_a):
+ """Decipher a message with a Polybius cipher, using a keyword to rearrange
+ the alphabet
+
+ >>> polybius_decipher('bbdaccddccddeabbaaddbbecaaddddeabcaaacadcdbbdaaaca'\
+ 'adbadecbccedddebaadbcccadaaacdecaaabbb', 'elephant', 'abcde', 'abcde', \
+ column_first=False)
+ 'toisisvtestxessvbephktoefhnugiysweqifoekxelt'
+
+ >>> polybius_decipher('bbdaccddccddeabbaaddbbecaaddddeabcaaacadcdbbdaaaca'\
+ 'adbadecbccedddebaadbcccadaaacdecaaabbb', 'elephant', 'abcde', 'abcde', \
+ column_first=True)
+ 'thisisatestmessageforthepolybiusdecipherment'
+ """
+ grid = polybius_reverse_grid(keyword, column_order, row_order, letters_to_merge, wrap_alphabet)
+ column_index_type = type(column_order[0])
+ row_index_type = type(row_order[0])
+ if column_first:
+ pairs = [(column_index_type(p[1]), row_index_type(p[0])) for p in chunks(message, 2)]
+ else:
+ pairs = [(row_index_type(p[0]), column_index_type(p[1])) for p in chunks(message, 2)]
+ return cat(grid[p] for p in pairs if p in grid)
+
+
+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 multiprocessing.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
+
+if __name__ == "__main__":
+ import doctest
\ No newline at end of file
projects / cipher-tools.git / blobdiff