X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=cipherbreak.py;h=669d1330b898e888890f4cdd6e74f41cac98dcc4;hb=f1a99f2d70045b6fd19ded876c9a7584099b0e18;hp=0ca46062ddf4db5244f63402c60f91deb043c6f0;hpb=4e49d9a8c3379d16d1d721a14b072396568ecbcc;p=cipher-tools.git diff --git a/cipherbreak.py b/cipherbreak.py index 0ca4606..669d133 100644 --- a/cipherbreak.py +++ b/cipherbreak.py @@ -266,7 +266,7 @@ def vigenere_keyword_break_mp(message, wordlist=keywords, fitness=Pletters, >>> 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) @@ -297,7 +297,7 @@ def vigenere_frequency_break(message, max_key_length=20, fitness=Pletters): "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) @@ -336,6 +336,78 @@ def beaufort_frequency_break(message, max_key_length=20, fitness=Pletters): 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', , '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', , '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', , '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', , '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 @@ -569,7 +641,7 @@ def hill_break_worker(message, matrix, fitness): fit, sanitise(plaintext)[:50])) return matrix, fit -def bifid_break_mp(message, wordlist=keywords, fitness=Pletters, +def bifid_break_mp(message, wordlist=keywords, fitness=Pletters, max_period=10, number_of_solutions=1, chunksize=500): """Breaks a keyword substitution cipher using a dictionary and frequency analysis @@ -577,18 +649,19 @@ def bifid_break_mp(message, wordlist=keywords, fitness=Pletters, >>> bifid_break_mp(bifid_encipher('this is a test message for the ' \ 'keyword decipherment', 'elephant', wrap_alphabet=KeywordWrapAlphabet.from_last), \ wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS - (('elephant', ), -52.834575011...) + (('elephant', , 0), -52.834575011...) >>> bifid_break_mp(bifid_encipher('this is a test message for the ' \ 'keyword decipherment', 'elephant', wrap_alphabet=KeywordWrapAlphabet.from_last), \ wordlist=['cat', 'elephant', 'kangaroo'], \ number_of_solutions=2) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE - [(('elephant', ), -52.834575011...), - (('elephant', ), -52.834575011...)] + [(('elephant', , 0), -52.834575011...), + (('elephant', , 0), -52.834575011...)] """ with Pool() as pool: - helper_args = [(message, word, wrap, fitness) + helper_args = [(message, word, wrap, period, fitness) for word in wordlist - for wrap in KeywordWrapAlphabet] + for wrap in KeywordWrapAlphabet + for period in range(max_period+1)] # Gotcha: the helper function here needs to be defined at the top level # (limitation of Pool.starmap) breaks = pool.starmap(bifid_break_worker, helper_args, chunksize) @@ -597,13 +670,13 @@ def bifid_break_mp(message, wordlist=keywords, fitness=Pletters, else: return sorted(breaks, key=lambda k: k[1], reverse=True)[:number_of_solutions] -def bifid_break_worker(message, keyword, wrap_alphabet, fitness): - plaintext = bifid_decipher(message, keyword, wrap_alphabet) +def bifid_break_worker(message, keyword, wrap_alphabet, period, fitness): + plaintext = bifid_decipher(message, keyword, wrap_alphabet, period=period) fit = fitness(plaintext) logger.debug('Keyword break attempt using key {0} (wrap={1}) gives fit of ' '{2} and decrypt starting: {3}'.format(keyword, wrap_alphabet, fit, sanitise(plaintext)[:50])) - return (keyword, wrap_alphabet), fit + return (keyword, wrap_alphabet, period), fit def pocket_enigma_break_by_crib(message, wheel_spec, crib, crib_position):