+"""A set of functions to break the ciphers give in ciphers.py.
+"""
+
import string
import collections
import norms
import logging
-from itertools import zip_longest, cycle, permutations
+import random
+import math
+from itertools import starmap
from segment import segment
from multiprocessing import Pool
-from math import log10
import matplotlib.pyplot as plt
+# logging.basicConfig(filename="cipher.log", level=logging.INFO)
+# logger = logging.getLogger(__name__)
+
+logger = logging.getLogger('cipherbreak')
+logger.setLevel(logging.WARNING)
+# logger.setLevel(logging.INFO)
+# logger.setLevel(logging.DEBUG)
+
+# create the logging file handler
+fh = logging.FileHandler("cipher.log")
+formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
+fh.setFormatter(formatter)
+
+# add handler to logger object
+logger.addHandler(fh)
+
+
from cipher import *
from language_models import *
# 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)
+
+def index_of_coincidence(text):
+ stext = sanitise(text)
+ counts = collections.Counter(stext)
+ denom = len(stext) * (len(text) - 1) / 26
+ return (
+ sum(max(counts[l] * counts[l] - 1, 0) for l in string.ascii_lowercase)
+ /
+ denom
+ )
+
+
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),
+ [(' ', 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),
+ [(' ', 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... ' \
+ >>> 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),
+ [('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
"""
- #counts = collections.defaultdict(int)
- #for c in text:
- # counts[c] += 1
- #return counts
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, -130.849890899...)
+ (4, -130.849989015...)
>>> caesar_break('wxwmaxdgheetgwuxztgptedbgznitgwwhpguxyhkxbmhvvtlbhgtee' \
'raxlmhiixweblmxgxwmhmaxybkbgztgwztsxwbgmxgmert') # doctest: +ELLIPSIS
- (19, -128.82516920...)
+ (19, -128.82410410...)
>>> caesar_break('yltbbqnqnzvguvaxurorgenafsbezqvagbnornfgsbevpnaabjurer' \
'svaquvzyvxrnznazlybequrvfohgriraabjtbaruraprur') # doctest: +ELLIPSIS
- (13, -126.25233502...)
+ (13, -126.25403935...)
"""
sanitised_message = sanitise(message)
best_shift = 0
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]))
+ 'and decrypt starting: {2}'.format(shift, fit,
+ plaintext[:50]))
if fit > best_fit:
best_fit = fit
best_shift = shift
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 ' \
'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), 0.0598745365924...)
+ ((15, 22, True), -340.601181913...)
"""
sanitised_message = sanitise(message)
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 multiplier in [x for x in range(1, 26, 2) if x != 13]:
for adder in range(26):
- plaintext = affine_decipher(sanitised_message,
+ 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,
+ 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_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]))
+ 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,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise):
- """Breaks a keyword substitution cipher using a dictionary and
- frequency analysis
+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', 1), \
+ 'keyword decipherment', 'elephant', KeywordWrapAlphabet.from_last), \
wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
- (('elephant', 1), 0.1066453448861...)
+ (('elephant', <KeywordWrapAlphabet.from_last: 2>), -52.834575011...)
"""
best_keyword = ''
best_wrap_alphabet = True
- best_fit = float("inf")
- for wrap_alphabet in range(3):
+ best_fit = float("-inf")
+ for wrap_alphabet in KeywordWrapAlphabet:
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,
+ 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
logger.info('Keyword break best fit with key {0} (wrap={1}) gives fit of '
- '{2} and decrypt starting: {3}'.format(best_keyword,
+ '{2} and decrypt starting: {3}'.format(best_keyword,
best_wrap_alphabet, best_fit, sanitise(
- keyword_decipher(message, best_keyword,
+ keyword_decipher(message, best_keyword,
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):
- """Breaks a keyword substitution cipher using a dictionary and
+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', 1), \
+ 'keyword decipherment', 'elephant', KeywordWrapAlphabet.from_last), \
wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
- (('elephant', 1), 0.106645344886...)
+ (('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, metric, target_counts,
- message_frequency_scaling)
- for word in wordlist for wrap in range(3)]
- # Gotcha: the helper function here needs to be defined at the top level
+ 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)
- return min(breaks, key=lambda k: k[1])
+ 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, 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):
- """Breaks a Scytale cipher
-
- >>> scytale_break('tfeulchtrtteehwahsdehneoifeayfsondmwpltmaoalhikotoere' \
- 'dcweatehiplwxsnhooacgorrcrcraotohsgullasenylrendaianeplscdriioto' \
- 'aek') # doctest: +ELLIPSIS
- (6, 0.092599933059...)
- """
- best_key = 0
- best_fit = float("inf")
- ngram_length = len(next(iter(target_counts.keys())))
- 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)
- 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:
- best_fit = fit
- best_key = key
- logger.info('Scytale break best fit with key {0} gives fit of {1} and '
- 'decrypt starting: {2}'.format(best_key, best_fit,
- sanitise(scytale_decipher(message, best_key))[:50]))
- 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):
- """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), 0.0628106372...)
- # >>> 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']}, \
- # 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())))
+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 = cat(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 = cat(this_alphabet)
+ worker_args.append((ciphertext, this_alphabet, max_iterations, fitness))
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]]
- # 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])
-column_transposition_break = column_transposition_break_mp
-
-def column_transposition_break_worker(message, transposition, columnwise, metric, target_counts,
- ngram_length, message_frequency_scaling):
- plaintext = column_transposition_decipher(message, transposition, columnwise=columnwise)
- counts = message_frequency_scaling(frequencies(
- ngrams(sanitise(plaintext), ngram_length)))
- fit = metric(target_counts, counts)
- 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, columnwise), fit
-
-
-def transposition_break_exhaustive(message):
- best_transposition = ''
- 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)])
- 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:
- best_transposition = transposition
- best_columnwise = columnwise
- best_pw = pw
- 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):
- """Breaks a vigenere cipher using a dictionary and
- frequency analysis
-
- >>> vigenere_keyword_break(vigenere_encipher(sanitise('this is a test ' \
- 'message for the vigenere decipherment'), 'cat'), \
- wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
- ('cat', 0.15965224935...)
- """
- best_keyword = ''
- best_fit = float("inf")
- for keyword in wordlist:
- plaintext = vigenere_decipher(message, keyword)
- counts = message_frequency_scaling(frequencies(plaintext))
- fit = metric(target_counts, counts)
- 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:
- best_fit = fit
- best_keyword = keyword
- logger.info('Vigenere break best fit with key {0} gives fit '
- 'of {1} and decrypt starting: {2}'.format(best_keyword,
- best_fit, sanitise(
- 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,
- chunksize=500):
- """Breaks a vigenere cipher using a dictionary and
- frequency analysis
+ 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', 0.159652249358...)
+ ('cat', -52.9472712...)
"""
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
+ # 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])
+ 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, 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,
+ '{1} and decrypt starting: {2}'.format(keyword,
fit, sanitise(plaintext)[:50]))
return keyword, fit
-
-def vigenere_frequency_break(message,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise):
+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."), 'florence')) # doctest: +ELLIPSIS
- ('florence', 0.077657073...)
+ "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', -307.5473096...)
"""
- best_fit = float("inf")
- best_key = ''
+ def worker(message, key_length, fitness):
+ splits = every_nth(sanitised_message, key_length)
+ key = cat([unpos(caesar_break(s)[0]) for s in splits])
+ plaintext = vigenere_decipher(message, key)
+ fit = fitness(plaintext)
+ return key, fit
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)
- logger.debug('Vigenere key length of {0} ({1}) gives fit of {2}'.
- format(trial_length, key, fit))
- if fit < best_fit:
+ 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_sub_break(message, fitness=Pletters):
+ """Breaks one chunk of a Beaufort cipher with frequency analysis
+
+ >>> beaufort_sub_break('samwpplggnnmmyaazgympjapopnwiywwomwspgpjmefwmawx' \
+ 'jafjhxwwwdigxshnlywiamhyshtasxptwueahhytjwsn') # doctest: +ELLIPSIS
+ (0, -117.4492...)
+ >>> beaufort_sub_break('eyprzjjzznxymrygryjqmqhznjrjjapenejznawngnnezgza' \
+ 'dgndknaogpdjneadadazlhkhxkryevrronrmdjnndjlo') # doctest: +ELLIPSIS
+ (17, -114.9598...)
+ """
+ best_shift = 0
+ best_fit = float('-inf')
+ for key in range(26):
+ plaintext = [unpos(key - pos(l)) for l in message]
+ fit = fitness(plaintext)
+ logger.debug('Beaufort sub break attempt using key {0} gives fit of {1} '
+ 'and decrypt starting: {2}'.format(key, fit,
+ plaintext[:50]))
+ if fit > best_fit:
best_fit = fit
best_key = key
- logger.info('Vigenere break best fit with key {0} gives fit '
- 'of {1} and decrypt starting: {2}'.format(best_key,
- best_fit, sanitise(
- vigenere_decipher(message, best_key))[:50]))
+ logger.info('Beaufort sub break best fit: key {0} gives fit of {1} and '
+ 'decrypt starting: {2}'.format(best_key, best_fit,
+ cat([unpos(best_key - pos(l)) for l in message[: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, 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."), 'florence')) # doctest: +ELLIPSIS
- ('florence', 0.077657073...)
+ "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...)
"""
- best_fit = float("inf")
- best_key = ''
+ def worker(message, key_length, fitness):
+ splits = every_nth(message, key_length)
+ key = cat([unpos(beaufort_sub_break(s)[0]) for s in splits])
+ plaintext = beaufort_decipher(message, key)
+ fit = fitness(plaintext)
+ return key, fit
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)
- logger.debug('Beaufort key length of {0} ({1}) gives fit of {2}'.
- format(trial_length, key, fit))
- if fit < best_fit:
- best_fit = fit
- best_key = key
- logger.info('Beaufort break best fit with key {0} gives fit '
- 'of {1} and decrypt starting: {2}'.format(best_key,
- best_fit, sanitise(
- beaufort_decipher(message, best_key))[:50]))
- return best_key, best_fit
+ 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_variant_frequency_break(message, max_key_length=20, fitness=Pletters):
+ """Breaks a Beaufort cipher with frequency analysis
+
+ >>> beaufort_variant_frequency_break(beaufort_variant_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 = cat([unpos(-caesar_break(s)[0]) for s in splits])
+ plaintext = beaufort_variant_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 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 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
+ 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
+ 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), <AmscoFillStyle.continuous: 1>), -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), <AmscoFillStyle.continuous: 1>), -997.0129085...)
+ """
+ with Pool() as pool:
+ helper_args = [(message, trans, pattern, fillstyle, fitness)
+ for trans in translist
+ 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 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
+
+ >>> 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', <KeywordWrapAlphabet.from_last: 2>, 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', <KeywordWrapAlphabet.from_last: 2>, 0), -52.834575011...),
+ (('elephant', <KeywordWrapAlphabet.from_largest: 3>, 0), -52.834575011...)]
+ """
+ with Pool() as pool:
+ helper_args = [(message, word, wrap, period, fitness)
+ for word in wordlist
+ 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)
+ 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 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, period), 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)]
+ x = range(len(freqs))
+ y = [freqs[l] for l in sorted(freqs, 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))
+ ax.set_xticklabels(sorted(freqs, key=sort_key))
f.show()
if __name__ == "__main__":
import doctest
doctest.testmod()
-
projects / cipher-tools.git / blobdiff