+++ /dev/null
-"""A set of functions to break the ciphers give in ciphers.py.
-"""
-
-import string
-import collections
-import norms
-import logging
-import random
-import math
-from itertools import starmap
-from segment import segment
-from multiprocessing import Pool
-
-import matplotlib.pyplot as plt
-
-logger = logging.getLogger(__name__)
-logger.addHandler(logging.FileHandler('cipher.log'))
-logger.setLevel(logging.WARNING)
-#logger.setLevel(logging.INFO)
-#logger.setLevel(logging.DEBUG)
-
-from cipher import *
-from language_models import *
-
-# To time a run:
-#
-# import timeit
-# c5a = open('2012/5a.ciphertext', 'r').read()
-# timeit.timeit('keyword_break(c5a)', setup='gc.enable() ; from __main__ import c5a ; from cipher import keyword_break', number=1)
-# 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)
-
-transpositions = collections.defaultdict(list)
-for word in keywords:
- transpositions[transpositions_of(word)] += [word]
-
-def frequencies(text):
- """Count the number of occurrences of each character in text
-
- >>> sorted(frequencies('abcdefabc').items())
- [('a', 2), ('b', 2), ('c', 2), ('d', 1), ('e', 1), ('f', 1)]
- >>> sorted(frequencies('the quick brown fox jumped over the lazy ' \
- 'dog').items()) # doctest: +NORMALIZE_WHITESPACE
- [(' ', 8), ('a', 1), ('b', 1), ('c', 1), ('d', 2), ('e', 4), ('f', 1),
- ('g', 1), ('h', 2), ('i', 1), ('j', 1), ('k', 1), ('l', 1), ('m', 1),
- ('n', 1), ('o', 4), ('p', 1), ('q', 1), ('r', 2), ('t', 2), ('u', 2),
- ('v', 1), ('w', 1), ('x', 1), ('y', 1), ('z', 1)]
- >>> sorted(frequencies('The Quick BROWN fox jumped! over... the ' \
- '(9lazy) DOG').items()) # doctest: +NORMALIZE_WHITESPACE
- [(' ', 8), ('!', 1), ('(', 1), (')', 1), ('.', 3), ('9', 1), ('B', 1),
- ('D', 1), ('G', 1), ('N', 1), ('O', 2), ('Q', 1), ('R', 1), ('T', 1),
- ('W', 1), ('a', 1), ('c', 1), ('d', 1), ('e', 4), ('f', 1), ('h', 2),
- ('i', 1), ('j', 1), ('k', 1), ('l', 1), ('m', 1), ('o', 2), ('p', 1),
- ('r', 1), ('t', 1), ('u', 2), ('v', 1), ('x', 1), ('y', 1), ('z', 1)]
- >>> sorted(frequencies(sanitise('The Quick BROWN fox jumped! over... '\
- 'the (9lazy) DOG')).items()) # doctest: +NORMALIZE_WHITESPACE
- [('a', 1), ('b', 1), ('c', 1), ('d', 2), ('e', 4), ('f', 1), ('g', 1),
- ('h', 2), ('i', 1), ('j', 1), ('k', 1), ('l', 1), ('m', 1), ('n', 1),
- ('o', 4), ('p', 1), ('q', 1), ('r', 2), ('t', 2), ('u', 2), ('v', 1),
- ('w', 1), ('x', 1), ('y', 1), ('z', 1)]
- >>> frequencies('abcdefabcdef')['x']
- 0
- """
- return collections.Counter(c for c in text)
-
-
-def caesar_break(message, fitness=Pletters):
- """Breaks a Caesar cipher using frequency analysis
-
- >>> caesar_break('ibxcsyorsaqcheyklxivoexlevmrimwxsfiqevvmihrsasrxliwyrh' \
- 'ecjsppsamrkwleppfmergefifvmhixscsymjcsyqeoixlm') # doctest: +ELLIPSIS
- (4, -130.849989015...)
- >>> caesar_break('wxwmaxdgheetgwuxztgptedbgznitgwwhpguxyhkxbmhvvtlbhgtee' \
- 'raxlmhiixweblmxgxwmhmaxybkbgztgwztsxwbgmxgmert') # doctest: +ELLIPSIS
- (19, -128.82410410...)
- >>> caesar_break('yltbbqnqnzvguvaxurorgenafsbezqvagbnornfgsbevpnaabjurer' \
- 'svaquvzyvxrnznazlybequrvfohgriraabjtbaruraprur') # doctest: +ELLIPSIS
- (13, -126.25403935...)
- """
- sanitised_message = sanitise(message)
- best_shift = 0
- best_fit = float('-inf')
- for shift in range(26):
- plaintext = caesar_decipher(sanitised_message, shift)
- fit = fitness(plaintext)
- logger.debug('Caesar break attempt using key {0} gives fit of {1} '
- 'and decrypt starting: {2}'.format(shift, fit,
- plaintext[:50]))
- if fit > best_fit:
- best_fit = fit
- best_shift = shift
- logger.info('Caesar break best fit: key {0} gives fit of {1} and '
- 'decrypt starting: {2}'.format(best_shift, best_fit,
- caesar_decipher(sanitised_message, best_shift)[:50]))
- return best_shift, best_fit
-
-def affine_break(message, fitness=Pletters):
- """Breaks an affine cipher using frequency analysis
-
- >>> affine_break('lmyfu bkuusd dyfaxw claol psfaom jfasd snsfg jfaoe ls ' \
- 'omytd jlaxe mh jm bfmibj umis hfsul axubafkjamx. ls kffkxwsd jls ' \
- 'ofgbjmwfkiu olfmxmtmwaokttg jlsx ls kffkxwsd jlsi zg tsxwjl. jlsx ' \
- 'ls umfjsd jlsi zg hfsqysxog. ls dmmdtsd mx jls bats mh bkbsf. ls ' \
- 'bfmctsd kfmyxd jls lyj, mztanamyu xmc jm clm cku tmmeaxw kj lai ' \
- 'kxd clm ckuxj.') # doctest: +ELLIPSIS
- ((15, 22, True), -340.601181913...)
- """
- sanitised_message = sanitise(message)
- best_multiplier = 0
- best_adder = 0
- best_one_based = True
- best_fit = float("-inf")
- for one_based in [True, False]:
- for multiplier in [x for x in range(1, 26, 2) if x != 13]:
- for adder in range(26):
- plaintext = affine_decipher(sanitised_message,
- multiplier, adder, one_based)
- fit = fitness(plaintext)
- logger.debug('Affine break attempt using key {0}x+{1} ({2}) '
- 'gives fit of {3} and decrypt starting: {4}'.
- format(multiplier, adder, one_based, fit,
- plaintext[:50]))
- if fit > best_fit:
- best_fit = fit
- best_multiplier = multiplier
- best_adder = adder
- best_one_based = one_based
- logger.info('Affine break best fit with key {0}x+{1} ({2}) gives fit of '
- '{3} and decrypt starting: {4}'.format(
- best_multiplier, best_adder, best_one_based, best_fit,
- affine_decipher(sanitised_message, best_multiplier,
- best_adder, best_one_based)[:50]))
- return (best_multiplier, best_adder, best_one_based), best_fit
-
-def keyword_break(message, wordlist=keywords, fitness=Pletters):
- """Breaks a keyword substitution cipher using a dictionary and
- frequency analysis.
-
- >>> keyword_break(keyword_encipher('this is a test message for the ' \
- 'keyword decipherment', 'elephant', KeywordWrapAlphabet.from_last), \
- wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
- (('elephant', <KeywordWrapAlphabet.from_last: 2>), -52.834575011...)
- """
- best_keyword = ''
- best_wrap_alphabet = True
- best_fit = float("-inf")
- for wrap_alphabet in KeywordWrapAlphabet:
- for keyword in wordlist:
- plaintext = keyword_decipher(message, keyword, wrap_alphabet)
- 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]))
- if fit > best_fit:
- best_fit = fit
- best_keyword = keyword
- best_wrap_alphabet = wrap_alphabet
- logger.info('Keyword break best fit with key {0} (wrap={1}) gives fit of '
- '{2} and decrypt starting: {3}'.format(best_keyword,
- best_wrap_alphabet, best_fit, sanitise(
- keyword_decipher(message, best_keyword,
- best_wrap_alphabet))[:50]))
- return (best_keyword, best_wrap_alphabet), best_fit
-
-def keyword_break_mp(message, wordlist=keywords, fitness=Pletters,
- number_of_solutions=1, chunksize=500):
- """Breaks a keyword substitution cipher using a dictionary and
- frequency analysis
-
- >>> keyword_break_mp(keyword_encipher('this is a test message for the ' \
- 'keyword decipherment', 'elephant', KeywordWrapAlphabet.from_last), \
- wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
- (('elephant', <KeywordWrapAlphabet.from_last: 2>), -52.834575011...)
- >>> keyword_break_mp(keyword_encipher('this is a test message for the ' \
- 'keyword decipherment', 'elephant', KeywordWrapAlphabet.from_last), \
- wordlist=['cat', 'elephant', 'kangaroo'], \
- number_of_solutions=2) # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
- [(('elephant', <KeywordWrapAlphabet.from_last: 2>), -52.834575011...),
- (('elephant', <KeywordWrapAlphabet.from_largest: 3>), -52.834575011...)]
- """
- with Pool() as pool:
- helper_args = [(message, word, wrap, fitness)
- for word in wordlist
- for wrap in KeywordWrapAlphabet]
- # Gotcha: the helper function here needs to be defined at the top level
- # (limitation of Pool.starmap)
- breaks = pool.starmap(keyword_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 keyword_break_worker(message, keyword, wrap_alphabet, fitness):
- plaintext = keyword_decipher(message, keyword, wrap_alphabet)
- 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
-
-def monoalphabetic_break_hillclimbing(message, max_iterations=10000000,
- alphabet=None, fitness=Pletters):
- ciphertext = unaccent(message).lower()
- if not alphabet:
- alphabet = list(string.ascii_lowercase)
- random.shuffle(alphabet)
- alphabet = ''.join(alphabet)
- return monoalphabetic_break_hillclimbing_worker(ciphertext, alphabet,
- max_iterations, fitness)
-
-def monoalphabetic_break_hillclimbing_mp(message, workers=10,
- max_iterations = 10000000, alphabet=None, fitness=Pletters, chunksize=1):
- worker_args = []
- ciphertext = unaccent(message).lower()
- for i in range(workers):
- if alphabet:
- this_alphabet = alphabet
- else:
- this_alphabet = list(string.ascii_lowercase)
- random.shuffle(this_alphabet)
- this_alphabet = ''.join(this_alphabet)
- worker_args.append((ciphertext, this_alphabet, max_iterations, fitness))
- with Pool() as pool:
- breaks = pool.starmap(monoalphabetic_break_hillclimbing_worker,
- worker_args, chunksize)
- return max(breaks, key=lambda k: k[1])
-
-def monoalphabetic_break_hillclimbing_worker(message, alphabet,
- max_iterations, fitness):
- def swap(letters, i, j):
- if i > j:
- i, j = j, i
- if i == j:
- return letters
- else:
- return (letters[:i] + letters[j] + letters[i+1:j] + letters[i] +
- letters[j+1:])
- best_alphabet = alphabet
- best_fitness = float('-inf')
- for i in range(max_iterations):
- alphabet = swap(alphabet, random.randrange(26), random.randrange(26))
- cipher_translation = ''.maketrans(string.ascii_lowercase, alphabet)
- plaintext = message.translate(cipher_translation)
- if fitness(plaintext) > best_fitness:
- best_fitness = fitness(plaintext)
- best_alphabet = alphabet
- print(i, best_alphabet, best_fitness, plaintext)
- return best_alphabet, best_fitness
-
-
-def vigenere_keyword_break_mp(message, wordlist=keywords, fitness=Pletters,
- chunksize=500):
- """Breaks a vigenere cipher using a dictionary and frequency analysis.
-
- >>> 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...)
- """
- with Pool() as pool:
- helper_args = [(message, word, fitness)
- for word in wordlist]
- # Gotcha: the helper function here needs to be defined at the top level
- # (limitation of Pool.starmap)
- breaks = pool.starmap(vigenere_keyword_break_worker, helper_args,
- chunksize)
- return max(breaks, key=lambda k: k[1])
-vigenere_keyword_break = vigenere_keyword_break_mp
-
-def vigenere_keyword_break_worker(message, keyword, fitness):
- plaintext = vigenere_decipher(message, keyword)
- fit = fitness(plaintext)
- logger.debug('Vigenere keyword break attempt using key {0} gives fit of '
- '{1} and decrypt starting: {2}'.format(keyword,
- fit, sanitise(plaintext)[:50]))
- return keyword, fit
-
-
-def vigenere_frequency_break(message, max_key_length=20, fitness=Pletters):
- """Breaks a Vigenere cipher with frequency analysis
-
- >>> vigenere_frequency_break(vigenere_encipher(sanitise("It is time to " \
- "run. She is ready and so am I. I stole Daniel's pocketbook this " \
- "afternoon when he left his jacket hanging on the easel in the " \
- "attic. I jump every time I hear a footstep on the stairs, " \
- "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...)
- """
- def worker(message, key_length, fitness):
- splits = every_nth(sanitised_message, key_length)
- key = ''.join([chr(caesar_break(s)[0] + ord('a')) for s in splits])
- plaintext = vigenere_decipher(message, key)
- fit = fitness(plaintext)
- return key, fit
- sanitised_message = sanitise(message)
- results = starmap(worker, [(sanitised_message, i, fitness)
- for i in range(1, max_key_length+1)])
- return max(results, key=lambda k: k[1])
-
-
-def beaufort_frequency_break(message, max_key_length=20, fitness=Pletters):
- """Breaks a Beaufort cipher with frequency analysis
-
- >>> beaufort_frequency_break(beaufort_encipher(sanitise("It is time to " \
- "run. She is ready and so am I. I stole Daniel's pocketbook this " \
- "afternoon when he left his jacket hanging on the easel in the " \
- "attic. I jump every time I hear a footstep on the stairs, " \
- "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...)
- """
- def worker(message, key_length, fitness):
- splits = every_nth(sanitised_message, key_length)
- key = ''.join([chr(-caesar_break(s)[0] % 26 + ord('a'))
- for s in splits])
- plaintext = beaufort_decipher(message, key)
- fit = fitness(plaintext)
- return key, fit
- sanitised_message = sanitise(message)
- results = starmap(worker, [(sanitised_message, i, fitness)
- for i in range(1, max_key_length+1)])
- return max(results, key=lambda k: k[1])
-
-
-def column_transposition_break_mp(message, translist=transpositions,
- fitness=Pbigrams, chunksize=500):
- """Breaks a column transposition cipher using a dictionary and
- n-gram frequency analysis
-
- >>> column_transposition_break_mp(column_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']}) # doctest: +ELLIPSIS
- (((2, 0, 5, 3, 1, 4, 6), False, False), -709.4646722...)
- >>> column_transposition_break_mp(column_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']}, \
- fitness=Ptrigrams) # doctest: +ELLIPSIS
- (((2, 0, 5, 3, 1, 4, 6), False, False), -997.0129085...)
- """
- with Pool() as pool:
- helper_args = [(message, trans, fillcolumnwise, emptycolumnwise,
- fitness)
- for trans in translist.keys()
- for fillcolumnwise in [True, False]
- for emptycolumnwise in [True, False]]
- # 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)
- return max(breaks, key=lambda k: k[1])
-column_transposition_break = column_transposition_break_mp
-
-def column_transposition_break_worker(message, transposition,
- fillcolumnwise, emptycolumnwise, fitness):
- plaintext = column_transposition_decipher(message, transposition,
- fillcolumnwise=fillcolumnwise, emptycolumnwise=emptycolumnwise)
- fit = fitness(sanitise(plaintext))
- logger.debug('Column transposition break attempt using key {0} '
- 'gives fit of {1} and decrypt starting: {2}'.format(
- transposition, fit,
- sanitise(plaintext)[:50]))
- return (transposition, fillcolumnwise, emptycolumnwise), fit
-
-
-def scytale_break_mp(message, max_key_length=20,
- fitness=Pbigrams, chunksize=500):
- """Breaks a scytale cipher using a range of lengths and
- n-gram frequency analysis
-
- >>> scytale_break_mp(scytale_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."), \
- 5)) # doctest: +ELLIPSIS
- (5, -709.4646722...)
- >>> scytale_break_mp(scytale_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."), \
- 5), \
- fitness=Ptrigrams) # doctest: +ELLIPSIS
- (5, -997.0129085...)
- """
- 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)]]
- # 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
-
-
-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
- n-gram frequency analysis
-
- >>> railfence_break(railfence_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."), \
- 7)) # doctest: +ELLIPSIS
- (7, -709.46467226...)
- >>> railfence_break(railfence_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."), \
- 7), \
- fitness=Ptrigrams) # doctest: +ELLIPSIS
- (7, -997.0129085...)
- """
- def worker(message, height, fitness):
- 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, 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(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):
- """Break a pocket enigma using a crib (some plaintext that's expected to
- be in a certain position). Returns a list of possible starting wheel
- positions that could produce the crib.
-
- >>> pocket_enigma_break_by_crib('kzpjlzmoga', 1, 'h', 0)
- ['a', 'f', 'q']
- >>> pocket_enigma_break_by_crib('kzpjlzmoga', 1, 'he', 0)
- ['a']
- >>> pocket_enigma_break_by_crib('kzpjlzmoga', 1, 'll', 2)
- ['a']
- >>> pocket_enigma_break_by_crib('kzpjlzmoga', 1, 'l', 2)
- ['a']
- >>> pocket_enigma_break_by_crib('kzpjlzmoga', 1, 'l', 3)
- ['a', 'j', 'n']
- >>> pocket_enigma_break_by_crib('aaaaa', 1, 'l', 3)
- []
- """
- pe = PocketEnigma(wheel=wheel_spec)
- possible_positions = []
- for p in string.ascii_lowercase:
- pe.set_position(p)
- plaintext = pe.decipher(message)
- if plaintext[crib_position:crib_position+len(crib)] == crib:
- possible_positions += [p]
- return possible_positions
-
-
-def plot_frequency_histogram(freqs, sort_key=None):
- x = range(len(freqs.keys()))
- y = [freqs[l] for l in sorted(freqs.keys(), key=sort_key)]
- f = plt.figure()
- ax = f.add_axes([0.1, 0.1, 0.9, 0.9])
- ax.bar(x, y, align='center')
- ax.set_xticks(x)
- ax.set_xticklabels(sorted(freqs.keys(), key=sort_key))
- f.show()
-
-
-if __name__ == "__main__":
- import doctest
- doctest.testmod()
projects / cipher-training.git / blobdiff