X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=cipherbreak.py;h=120a89e4f82ec07561a0fa2ced9940344eafc60c;hb=ba7f680356ba1c48338814cd8164d667c82dc27d;hp=6f4d2aed7d037e509df96970891a7b9e1808c088;hpb=159c157fee78d4370a0e603de450bd8e2def305b;p=cipher-tools.git diff --git a/cipherbreak.py b/cipherbreak.py index 6f4d2ae..120a89e 100644 --- a/cipherbreak.py +++ b/cipherbreak.py @@ -416,6 +416,19 @@ def scytale_break_mp(message, max_key_length=20, scytale_break = scytale_break_mp +def railfence_break(message, max_key_length=20, + fitness=Pletters, chunksize=500): + """Breaks a hill cipher using a matrix of given rank and letter frequencies + + + """ + + sanitised_message = sanitise(message) + results = starmap(worker, [(sanitised_message, i, fitness) + for i in range(2, max_key_length+1)]) + return max(results, key=lambda k: k[1]) + + def railfence_break(message, max_key_length=20, fitness=Pbigrams, chunksize=500): """Breaks a railfence cipher using a range of lengths and @@ -445,24 +458,101 @@ def railfence_break(message, max_key_length=20, plaintext = railfence_decipher(message, height) fit = fitness(plaintext) return height, fit + sanitised_message = sanitise(message) results = starmap(worker, [(sanitised_message, i, fitness) for i in range(2, max_key_length+1)]) return max(results, key=lambda k: k[1]) +def amsco_break(message, translist=transpositions, patterns = [(1, 2), (2, 1)], + fillstyles = [AmscoFillStyle.continuous, + AmscoFillStyle.same_each_row, + AmscoFillStyle.reverse_each_row], + fitness=Pbigrams, + chunksize=500): + """Breaks an AMSCO transposition cipher using a dictionary and + n-gram frequency analysis + + >>> amsco_break(amsco_transposition_encipher(sanitise( \ + "It is a truth universally acknowledged, that a single man in \ + possession of a good fortune, must be in want of a wife. However \ + little known the feelings or views of such a man may be on his \ + first entering a neighbourhood, this truth is so well fixed in \ + the minds of the surrounding families, that he is considered the \ + rightful property of some one or other of their daughters."), \ + 'encipher'), \ + translist={(2, 0, 5, 3, 1, 4, 6): ['encipher'], \ + (5, 0, 6, 1, 3, 4, 2): ['fourteen'], \ + (6, 1, 0, 4, 5, 3, 2): ['keyword']}, \ + patterns=[(1, 2)]) # doctest: +ELLIPSIS + (((2, 0, 5, 3, 1, 4, 6), (1, 2)), -709.4646722...) + >>> amsco_break(amsco_transposition_encipher(sanitise( \ + "It is a truth universally acknowledged, that a single man in \ + possession of a good fortune, must be in want of a wife. However \ + little known the feelings or views of such a man may be on his \ + first entering a neighbourhood, this truth is so well fixed in \ + the minds of the surrounding families, that he is considered the \ + rightful property of some one or other of their daughters."), \ + 'encipher', fillpattern=(2, 1)), \ + translist={(2, 0, 5, 3, 1, 4, 6): ['encipher'], \ + (5, 0, 6, 1, 3, 4, 2): ['fourteen'], \ + (6, 1, 0, 4, 5, 3, 2): ['keyword']}, \ + patterns=[(1, 2), (2, 1)], fitness=Ptrigrams) # doctest: +ELLIPSIS + (((2, 0, 5, 3, 1, 4, 6), (2, 1)), -997.0129085...) + """ + with Pool() as pool: + helper_args = [(message, trans, pattern, fillstyle, fitness) + for trans in translist.keys() + for pattern in patterns + for fillstyle in fillstyles] + # Gotcha: the helper function here needs to be defined at the top level + # (limitation of Pool.starmap) + breaks = pool.starmap(amsco_break_worker, helper_args, chunksize) + return max(breaks, key=lambda k: k[1]) + +def amsco_break_worker(message, transposition, + pattern, fillstyle, fitness): + plaintext = amsco_transposition_decipher(message, transposition, + fillpattern=pattern, fillstyle=fillstyle) + fit = fitness(sanitise(plaintext)) + logger.debug('AMSCO transposition break attempt using key {0} and pattern' + '{1} ({2}) gives fit of {3} and decrypt starting: ' + '{4}'.format( + transposition, pattern, fillstyle, fit, + sanitise(plaintext)[:50])) + return (transposition, pattern, fillstyle), fit + +def hill_break(message, matrix_size=2, fitness=Pletters, + number_of_solutions=1, chunksize=500): + + all_matrices = [np.matrix(list(m)) + for m in itertools.product([list(r) + for r in itertools.product(range(26), repeat=matrix_size)], + repeat=matrix_size)] + valid_matrices = [m for m, d in + zip(all_matrices, (int(round(linalg.det(m))) for m in all_matrices)) + if d != 0 + if d % 2 != 0 + if d % 13 != 0 ] with Pool() as pool: - helper_args = [(message, trans, False, True, fitness) - for trans in - [[col for col in range(math.ceil(len(message)/rows))] - for rows in range(1,max_key_length+1)]] + helper_args = [(message, matrix, fitness) + for matrix in valid_matrices] # Gotcha: the helper function here needs to be defined at the top level # (limitation of Pool.starmap) - breaks = pool.starmap(column_transposition_break_worker, - helper_args, chunksize) - best = max(breaks, key=lambda k: k[1]) - return math.trunc(len(message) / len(best[0][0])), best[1] -scytale_break = scytale_break_mp + breaks = pool.starmap(hill_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 hill_break_worker(message, matrix, fitness): + plaintext = hill_decipher(matrix, message) + fit = fitness(plaintext) + logger.debug('Hill cipher break attempt using key {0} gives fit of ' + '{1} and decrypt starting: {2}'.format(matrix, + fit, sanitise(plaintext)[:50])) + return matrix, fit def pocket_enigma_break_by_crib(message, wheel_spec, crib, crib_position):