caesar_decipher(sanitised_message, best_shift)[:50]))
return best_shift, best_fit
-def affine_break(message,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise):
+def affine_break(message, fitness=Pletters):
"""Breaks an affine cipher using frequency analysis
>>> affine_break('lmyfu bkuusd dyfaxw claol psfaom jfasd snsfg jfaoe ls ' \
best_multiplier = 0
best_adder = 0
best_one_based = True
- best_fit = float("inf")
+ best_fit = float("-inf")
for one_based in [True, False]:
for multiplier in range(1, 26, 2):
for adder in range(26):
plaintext = affine_decipher(sanitised_message,
multiplier, adder, one_based)
- counts = message_frequency_scaling(frequencies(plaintext))
- fit = metric(target_counts, counts)
+ 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:
+ if fit > best_fit:
best_fit = fit
best_multiplier = multiplier
best_adder = adder
best_adder, best_one_based)[:50]))
return (best_multiplier, best_adder, best_one_based), best_fit
-def keyword_break(message,
- wordlist=keywords,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise):
+def keyword_break(message, wordlist=keywords, fitness=Pletters):
"""Breaks a keyword substitution cipher using a dictionary and
frequency analysis
"""
best_keyword = ''
best_wrap_alphabet = True
- best_fit = float("inf")
+ best_fit = float("-inf")
for wrap_alphabet in range(3):
for keyword in wordlist:
plaintext = keyword_decipher(message, keyword, wrap_alphabet)
- counts = message_frequency_scaling(frequencies(plaintext))
- fit = metric(target_counts, counts)
+ 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:
+ if fit > best_fit:
best_fit = fit
best_keyword = keyword
best_wrap_alphabet = wrap_alphabet
best_wrap_alphabet))[:50]))
return (best_keyword, best_wrap_alphabet), best_fit
-def keyword_break_mp(message,
- wordlist=keywords,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise,
- chunksize=500):
+def keyword_break_mp(message, wordlist=keywords, fitness=Pletters, chunksize=500):
"""Breaks a keyword substitution cipher using a dictionary and
frequency analysis
(('elephant', 1), 0.106645344886...)
"""
with Pool() as pool:
- helper_args = [(message, word, wrap, metric, target_counts,
- message_frequency_scaling)
+ helper_args = [(message, word, wrap, fitness)
for word in wordlist for wrap in range(3)]
# 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)
- return min(breaks, key=lambda k: k[1])
+ return max(breaks, key=lambda k: k[1])
-def keyword_break_worker(message, keyword, wrap_alphabet, metric, target_counts,
- message_frequency_scaling):
+def keyword_break_worker(message, keyword, wrap_alphabet, fitness):
plaintext = keyword_decipher(message, keyword, wrap_alphabet)
- counts = message_frequency_scaling(frequencies(plaintext))
- fit = metric(target_counts, counts)
+ 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 scytale_break(message,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_bigram_counts,
- message_frequency_scaling=norms.normalise):
+def scytale_break(message, fitness=Pbigrams):
"""Breaks a Scytale cipher
>>> scytale_break('tfeulchtrtteehwahsdehneoifeayfsondmwpltmaoalhikotoere' \
(6, 0.092599933059...)
"""
best_key = 0
- best_fit = float("inf")
- ngram_length = len(next(iter(target_counts.keys())))
+ best_fit = float("-inf")
for key in range(1, 20):
if len(message) % key == 0:
plaintext = scytale_decipher(message, key)
- counts = message_frequency_scaling(frequencies(
- ngrams(sanitise(plaintext), ngram_length)))
- fit = metric(target_counts, counts)
+ fit = fitness(sanitise(plaintext))
logger.debug('Scytale break attempt using key {0} gives fit of '
'{1} and decrypt starting: {2}'.format(key,
fit, sanitise(plaintext)[:50]))
- if fit < best_fit:
+ if fit > best_fit:
best_fit = fit
best_key = key
logger.info('Scytale break best fit with key {0} gives fit of {1} and '
return best_key, best_fit
-def column_transposition_break_mp(message,
- translist=transpositions,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_bigram_counts,
- message_frequency_scaling=norms.normalise,
- chunksize=500):
+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
"""
# target_counts=normalised_english_trigram_counts) # doctest: +ELLIPSIS
# (((2, 0, 5, 3, 1, 4, 6), False), 0.0592259560...)
# """
- ngram_length = len(next(iter(target_counts.keys())))
with Pool() as pool:
- helper_args = [(message, trans, columnwise, metric, target_counts, ngram_length,
- message_frequency_scaling)
- for trans in translist.keys() for columnwise in [True, False]]
+ helper_args = [(message, trans, columnwise, fitness)
+ for trans in translist.keys()
+ for columnwise 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 min(breaks, key=lambda k: k[1])
+ 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, columnwise, metric, target_counts,
- ngram_length, message_frequency_scaling):
+def column_transposition_break_worker(message, transposition, columnwise,
+ fitness):
plaintext = column_transposition_decipher(message, transposition, columnwise=columnwise)
- counts = message_frequency_scaling(frequencies(
- ngrams(sanitise(plaintext), ngram_length)))
- fit = metric(target_counts, counts)
+ fit = fitness(sanitise(plaintext))
logger.debug('Column transposition break attempt using key {0} '
'gives fit of {1} and decrypt starting: {2}'.format(
transposition, fit,
return (transposition, columnwise), fit
-def transposition_break_exhaustive(message):
+def transposition_break_exhaustive(message, fitness=Pbigrams):
best_transposition = ''
- best_pw = -float('inf')
+ best_pw = float('-inf')
for keylength in range(1, 21):
if len(message) % keylength == 0:
for transposition in permutations(range(keylength)):
for columnwise in [True, False]:
plaintext = column_transposition_decipher(message,
transposition, columnwise=columnwise)
- # pw = Pwords(segment(plaintext))
- pw = sum([log10(bigram_likelihood(b,
- normalised_english_bigram_counts,
- normalised_english_counts))
- for b in ngrams(plaintext, 2)])
+ fit=fitness(plaintext)
logger.debug('Column transposition break attempt using key {0} {1} '
'gives fit of {2} and decrypt starting: {3}'.format(
transposition, columnwise, pw,
sanitise(plaintext)[:50]))
- if pw > best_pw:
+ if fit > best_fit:
best_transposition = transposition
best_columnwise = columnwise
- best_pw = pw
+ best_fit = fit
return (best_transposition, best_columnwise), best_pw
-def vigenere_keyword_break(message,
- wordlist=keywords,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise):
+def vigenere_keyword_break(message, wordlist=keywords, fitness=Pletters):
"""Breaks a vigenere cipher using a dictionary and
frequency analysis
('cat', 0.15965224935...)
"""
best_keyword = ''
- best_fit = float("inf")
+ best_fit = float("-inf")
for keyword in wordlist:
plaintext = vigenere_decipher(message, keyword)
- counts = message_frequency_scaling(frequencies(plaintext))
- fit = metric(target_counts, counts)
+ fit = fitness(plaintext)
logger.debug('Vigenere break attempt using key {0} '
'gives fit of {1} and decrypt starting: {2}'.format(
keyword, fit,
sanitise(plaintext)[:50]))
- if fit < best_fit:
+ if fit > best_fit:
best_fit = fit
best_keyword = keyword
logger.info('Vigenere break best fit with key {0} gives fit '
vigenere_decipher(message, best_keyword))[:50]))
return best_keyword, best_fit
-def vigenere_keyword_break_mp(message,
- wordlist=keywords,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise,
+def vigenere_keyword_break_mp(message, wordlist=keywords, fitness=Pletters,
chunksize=500):
"""Breaks a vigenere cipher using a dictionary and
frequency analysis
('cat', 0.159652249358...)
"""
with Pool() as pool:
- helper_args = [(message, word, metric, target_counts,
- message_frequency_scaling)
+ 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 min(breaks, key=lambda k: k[1])
-def vigenere_keyword_break_worker(message, keyword, metric, target_counts,
- message_frequency_scaling):
+def vigenere_keyword_break_worker(message, keyword, fitness):
plaintext = vigenere_decipher(message, keyword)
- counts = message_frequency_scaling(frequencies(plaintext))
- fit = metric(target_counts, counts)
+ 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]))
-def vigenere_frequency_break(message,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise):
+def vigenere_frequency_break(message, 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."), 'florence')) # doctest: +ELLIPSIS
+ "attic. I jump every time I hear a footstep on the stairs, " \
+ "certain that the theft has been discovered and that I will " \
+ "and that I will be caught. The SS officer visits less often now " \
+ "that he is sure"), 'florence')) # doctest: +ELLIPSIS
('florence', 0.077657073...)
"""
- best_fit = float("inf")
+ best_fit = float("-inf")
best_key = ''
sanitised_message = sanitise(message)
for trial_length in range(1, 20):
splits = every_nth(sanitised_message, trial_length)
key = ''.join([chr(caesar_break(s)[0] + ord('a')) for s in splits])
plaintext = vigenere_decipher(sanitised_message, key)
- counts = message_frequency_scaling(frequencies(plaintext))
- fit = metric(target_counts, counts)
+ fit = fitness(plaintext)
logger.debug('Vigenere key length of {0} ({1}) gives fit of {2}'.
format(trial_length, key, fit))
- if fit < best_fit:
+ if fit > best_fit:
best_fit = fit
best_key = key
logger.info('Vigenere break best fit with key {0} gives fit '
vigenere_decipher(message, best_key))[:50]))
return best_key, best_fit
-def beaufort_frequency_break(message,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise):
+def beaufort_frequency_break(message, 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."), 'florence')) # doctest: +ELLIPSIS
+ "attic. I jump every time I hear a footstep on the stairs, " \
+ "certain that the theft has been discovered and that I will " \
+ "and that I will be caught. The SS officer visits less often now " \
+ "that he is sure"), 'florence')) # doctest: +ELLIPSIS
('florence', 0.077657073...)
"""
- best_fit = float("inf")
+ best_fit = float("-inf")
best_key = ''
sanitised_message = sanitise(message)
for trial_length in range(1, 20):
splits = every_nth(sanitised_message, trial_length)
key = ''.join([chr(caesar_break(s)[0] + ord('a')) for s in splits])
plaintext = beaufort_decipher(sanitised_message, key)
- counts = message_frequency_scaling(frequencies(plaintext))
- fit = metric(target_counts, counts)
+ fit = fitness(plaintext)
logger.debug('Beaufort key length of {0} ({1}) gives fit of {2}'.
format(trial_length, key, fit))
- if fit < best_fit:
+ if fit > best_fit:
best_fit = fit
best_key = key
logger.info('Beaufort break best fit with key {0} gives fit '
projects / cipher-tools.git / commitdiff