-import string
-import collections
-import norms
-import logging
-import math
-from itertools import zip_longest, repeat
-from segment import segment
-from multiprocessing import Pool
+# import string
+# import collections
+# import math
+# from enum import Enum
+# from itertools import zip_longest, cycle, chain, count
+# import numpy as np
+# from numpy import matrix
+# from numpy import linalg
+# from language_models import *
+# import pprint
+
+
+
+from utilities import *
+from segment import *
+from text_prettify import *
+from plot_frequency_histogram import *
+
+from caesar import *
+from affine import *
+from keyword import *
+from polybius import *
+from column_transposition import *
+from railfence import *
+from cadenus import *
+from hill import *
+from amsco import *
+from bifid import *
+from autokey import *
+from pocket_enigma 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
-
-logger = logging.getLogger(__name__)
-logger.addHandler(logging.FileHandler('cipher.log'))
-logger.setLevel(logging.WARNING)
-#logger.setLevel(logging.INFO)
-#logger.setLevel(logging.DEBUG)
-
-english_counts = collections.defaultdict(int)
-with open('count_1l.txt', 'r') as f:
- for line in f:
- (letter, count) = line.split("\t")
- english_counts[letter] = int(count)
-normalised_english_counts = norms.normalise(english_counts)
-
-english_bigram_counts = collections.defaultdict(int)
-with open('count_2l.txt', 'r') as f:
- for line in f:
- (bigram, count) = line.split("\t")
- english_bigram_counts[bigram] = int(count)
-normalised_english_bigram_counts = norms.normalise(english_bigram_counts)
-
-english_trigram_counts = collections.defaultdict(int)
-with open('count_3l.txt', 'r') as f:
- for line in f:
- (trigram, count) = line.split("\t")
- english_trigram_counts[trigram] = int(count)
-normalised_english_trigram_counts = norms.normalise(english_trigram_counts)
-
-
-with open('words.txt', 'r') as f:
- keywords = [line.rstrip() for line in f]
-
-modular_division_table = [[0]*26 for x in range(26)]
-for a in range(26):
- for b in range(26):
- c = (a * b) % 26
- modular_division_table[b][c] = a
-
-
-def sanitise(text):
- """Remove all non-alphabetic characters and convert the text to lowercase
-
- >>> sanitise('The Quick')
- 'thequick'
- >>> sanitise('The Quick BROWN fox jumped! over... the (9lazy) DOG')
- 'thequickbrownfoxjumpedoverthelazydog'
- """
- sanitised = [c.lower() for c in text if c in string.ascii_letters]
- return ''.join(sanitised)
-
-def ngrams(text, n):
- """Returns all n-grams of a text
-
- >>> ngrams(sanitise('the quick brown fox'), 2) # doctest: +NORMALIZE_WHITESPACE
- ['th', 'he', 'eq', 'qu', 'ui', 'ic', 'ck', 'kb', 'br', 'ro', 'ow', 'wn',
- 'nf', 'fo', 'ox']
- >>> ngrams(sanitise('the quick brown fox'), 4) # doctest: +NORMALIZE_WHITESPACE
- ['theq', 'hequ', 'equi', 'quic', 'uick', 'ickb', 'ckbr', 'kbro', 'brow',
- 'rown', 'ownf', 'wnfo', 'nfox']
- """
- return [text[i:i+n] for i in range(len(text)-n+1)]
-
-def every_nth(text, n, fillvalue=''):
- """Returns n strings, each of which consists of every nth character,
- starting with the 0th, 1st, 2nd, ... (n-1)th character
-
- >>> every_nth(string.ascii_lowercase, 5)
- ['afkpuz', 'bglqv', 'chmrw', 'dinsx', 'ejoty']
- >>> every_nth(string.ascii_lowercase, 1)
- ['abcdefghijklmnopqrstuvwxyz']
- >>> every_nth(string.ascii_lowercase, 26) # doctest: +NORMALIZE_WHITESPACE
- ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
- 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']
- >>> every_nth(string.ascii_lowercase, 5, fillvalue='!')
- ['afkpuz', 'bglqv!', 'chmrw!', 'dinsx!', 'ejoty!']
- """
- split_text = [text[i:i+n] for i in range(0, len(text), n)]
- return [''.join(l) for l in zip_longest(*split_text, fillvalue=fillvalue)]
-
-def combine_every_nth(split_text):
- """Reforms a text split into every_nth strings
-
- >>> combine_every_nth(every_nth(string.ascii_lowercase, 5))
- 'abcdefghijklmnopqrstuvwxyz'
- >>> combine_every_nth(every_nth(string.ascii_lowercase, 1))
- 'abcdefghijklmnopqrstuvwxyz'
- >>> combine_every_nth(every_nth(string.ascii_lowercase, 26))
- 'abcdefghijklmnopqrstuvwxyz'
- """
- return ''.join([''.join(l)
- for l in zip_longest(*split_text, fillvalue='')])
-
-def transpose(items, transposition):
- """Moves items around according to the given transposition
-
- >>> transpose(['a', 'b', 'c', 'd'], [0,1,2,3])
- ['a', 'b', 'c', 'd']
- >>> transpose(['a', 'b', 'c', 'd'], [3,1,2,0])
- ['d', 'b', 'c', 'a']
- >>> transpose([10,11,12,13,14,15], [3,2,4,1,5,0])
- [13, 12, 14, 11, 15, 10]
- """
- transposed = list(repeat('', len(transposition)))
- for p, t in enumerate(transposition):
- transposed[p] = items[t]
- return transposed
-
-def untranspose(items, transposition):
- """Undoes a transpose
-
- >>> untranspose(['a', 'b', 'c', 'd'], [0,1,2,3])
- ['a', 'b', 'c', 'd']
- >>> untranspose(['d', 'b', 'c', 'a'], [3,1,2,0])
- ['a', 'b', 'c', 'd']
- >>> untranspose([13, 12, 14, 11, 15, 10], [3,2,4,1,5,0])
- [10, 11, 12, 13, 14, 15]
- """
- transposed = list(repeat('', len(transposition)))
- for p, t in enumerate(transposition):
- transposed[t] = items[p]
- return transposed
-
-
-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)]
- """
- counts = collections.defaultdict(int)
- for c in text:
- counts[c] += 1
- return counts
-letter_frequencies = frequencies
-
-def deduplicate(text):
- return list(collections.OrderedDict.fromkeys(text))
-
-
-
-def caesar_encipher_letter(letter, shift):
- """Encipher a letter, given a shift amount
-
- >>> caesar_encipher_letter('a', 1)
- 'b'
- >>> caesar_encipher_letter('a', 2)
- 'c'
- >>> caesar_encipher_letter('b', 2)
- 'd'
- >>> caesar_encipher_letter('x', 2)
- 'z'
- >>> caesar_encipher_letter('y', 2)
- 'a'
- >>> caesar_encipher_letter('z', 2)
- 'b'
- >>> caesar_encipher_letter('z', -1)
- 'y'
- >>> caesar_encipher_letter('a', -1)
- 'z'
- """
- if letter in string.ascii_letters:
- if letter in string.ascii_uppercase:
- alphabet_start = ord('A')
- else:
- alphabet_start = ord('a')
- return chr(((ord(letter) - alphabet_start + shift) % 26) +
- alphabet_start)
- else:
- return letter
-
-def caesar_decipher_letter(letter, shift):
- """Decipher a letter, given a shift amount
-
- >>> caesar_decipher_letter('b', 1)
- 'a'
- >>> caesar_decipher_letter('b', 2)
- 'z'
- """
- return caesar_encipher_letter(letter, -shift)
-
-def caesar_encipher(message, shift):
- """Encipher a message with the Caesar cipher of given shift
-
- >>> caesar_encipher('abc', 1)
- 'bcd'
- >>> caesar_encipher('abc', 2)
- 'cde'
- >>> caesar_encipher('abcxyz', 2)
- 'cdezab'
- >>> caesar_encipher('ab cx yz', 2)
- 'cd ez ab'
- """
- enciphered = [caesar_encipher_letter(l, shift) for l in message]
- return ''.join(enciphered)
-
-def caesar_decipher(message, shift):
- """Encipher a message with the Caesar cipher of given shift
-
- >>> caesar_decipher('bcd', 1)
- 'abc'
- >>> caesar_decipher('cde', 2)
- 'abc'
- >>> caesar_decipher('cd ez ab', 2)
- 'ab cx yz'
- """
- return caesar_encipher(message, -shift)
-
-def affine_encipher_letter(letter, multiplier=1, adder=0, one_based=True):
- """Encipher a letter, given a multiplier and adder
-
- >>> ''.join([affine_encipher_letter(l, 3, 5, True) \
- for l in string.ascii_uppercase])
- 'HKNQTWZCFILORUXADGJMPSVYBE'
- >>> ''.join([affine_encipher_letter(l, 3, 5, False) \
- for l in string.ascii_uppercase])
- 'FILORUXADGJMPSVYBEHKNQTWZC'
- """
- if letter in string.ascii_letters:
- if letter in string.ascii_uppercase:
- alphabet_start = ord('A')
- else:
- alphabet_start = ord('a')
- letter_number = ord(letter) - alphabet_start
- if one_based: letter_number += 1
- cipher_number = (letter_number * multiplier + adder) % 26
- if one_based: cipher_number -= 1
- return chr(cipher_number % 26 + alphabet_start)
- else:
- return letter
-
-def affine_decipher_letter(letter, multiplier=1, adder=0, one_based=True):
- """Encipher a letter, given a multiplier and adder
-
- >>> ''.join([affine_decipher_letter(l, 3, 5, True) \
- for l in 'HKNQTWZCFILORUXADGJMPSVYBE'])
- 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
- >>> ''.join([affine_decipher_letter(l, 3, 5, False) \
- for l in 'FILORUXADGJMPSVYBEHKNQTWZC'])
- 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
- """
- if letter in string.ascii_letters:
- if letter in string.ascii_uppercase:
- alphabet_start = ord('A')
- else:
- alphabet_start = ord('a')
- cipher_number = ord(letter) - alphabet_start
- if one_based: cipher_number += 1
- plaintext_number = ( modular_division_table[multiplier]
- [(cipher_number - adder) % 26] )
- if one_based: plaintext_number -= 1
- return chr(plaintext_number % 26 + alphabet_start)
- else:
- return letter
-
-def affine_encipher(message, multiplier=1, adder=0, one_based=True):
- """Encipher a message
-
- >>> affine_encipher('hours passed during which jerico tried every ' \
- 'trick he could think of', 15, 22, True)
- 'lmyfu bkuusd dyfaxw claol psfaom jfasd snsfg jfaoe ls omytd jlaxe mh'
- """
- enciphered = [affine_encipher_letter(l, multiplier, adder, one_based)
- for l in message]
- return ''.join(enciphered)
-
-def affine_decipher(message, multiplier=1, adder=0, one_based=True):
- """Decipher a message
-
- >>> affine_decipher('lmyfu bkuusd dyfaxw claol psfaom jfasd snsfg ' \
- 'jfaoe ls omytd jlaxe mh', 15, 22, True)
- 'hours passed during which jerico tried every trick he could think of'
- """
- enciphered = [affine_decipher_letter(l, multiplier, adder, one_based)
- for l in message]
- return ''.join(enciphered)
-
-
-def keyword_cipher_alphabet_of(keyword, wrap_alphabet=0):
- """Find the cipher alphabet given a keyword.
- wrap_alphabet controls how the rest of the alphabet is added
- after the keyword.
- 0 : from 'a'
- 1 : from the last letter in the sanitised keyword
- 2 : from the largest letter in the sanitised keyword
-
- >>> keyword_cipher_alphabet_of('bayes')
- 'bayescdfghijklmnopqrtuvwxz'
- >>> keyword_cipher_alphabet_of('bayes', 0)
- 'bayescdfghijklmnopqrtuvwxz'
- >>> keyword_cipher_alphabet_of('bayes', 1)
- 'bayestuvwxzcdfghijklmnopqr'
- >>> keyword_cipher_alphabet_of('bayes', 2)
- 'bayeszcdfghijklmnopqrtuvwx'
- """
- if wrap_alphabet == 0:
- cipher_alphabet = ''.join(deduplicate(sanitise(keyword) +
- string.ascii_lowercase))
- else:
- if wrap_alphabet == 1:
- last_keyword_letter = deduplicate(sanitise(keyword))[-1]
- else:
- last_keyword_letter = sorted(sanitise(keyword))[-1]
- last_keyword_position = string.ascii_lowercase.find(
- last_keyword_letter) + 1
- cipher_alphabet = ''.join(
- deduplicate(sanitise(keyword) +
- string.ascii_lowercase[last_keyword_position:] +
- string.ascii_lowercase))
- return cipher_alphabet
-
-
-def keyword_encipher(message, keyword, wrap_alphabet=0):
- """Enciphers a message with a keyword substitution cipher.
- wrap_alphabet controls how the rest of the alphabet is added
- after the keyword.
- 0 : from 'a'
- 1 : from the last letter in the sanitised keyword
- 2 : from the largest letter in the sanitised keyword
-
- >>> keyword_encipher('test message', 'bayes')
- 'rsqr ksqqbds'
- >>> keyword_encipher('test message', 'bayes', 0)
- 'rsqr ksqqbds'
- >>> keyword_encipher('test message', 'bayes', 1)
- 'lskl dskkbus'
- >>> keyword_encipher('test message', 'bayes', 2)
- 'qspq jsppbcs'
- """
- cipher_alphabet = keyword_cipher_alphabet_of(keyword, wrap_alphabet)
- cipher_translation = ''.maketrans(string.ascii_lowercase, cipher_alphabet)
- return message.lower().translate(cipher_translation)
-
-def keyword_decipher(message, keyword, wrap_alphabet=0):
- """Deciphers a message with a keyword substitution cipher.
- wrap_alphabet controls how the rest of the alphabet is added
- after the keyword.
- 0 : from 'a'
- 1 : from the last letter in the sanitised keyword
- 2 : from the largest letter in the sanitised keyword
-
- >>> keyword_decipher('rsqr ksqqbds', 'bayes')
- 'test message'
- >>> keyword_decipher('rsqr ksqqbds', 'bayes', 0)
- 'test message'
- >>> keyword_decipher('lskl dskkbus', 'bayes', 1)
- 'test message'
- >>> keyword_decipher('qspq jsppbcs', 'bayes', 2)
- 'test message'
- """
- cipher_alphabet = keyword_cipher_alphabet_of(keyword, wrap_alphabet)
- cipher_translation = ''.maketrans(cipher_alphabet, string.ascii_lowercase)
- return message.lower().translate(cipher_translation)
-
-def scytale_encipher(message, rows):
- """Enciphers using the scytale transposition cipher.
- Message is padded with spaces to allow all rows to be the same length.
-
- >>> scytale_encipher('thequickbrownfox', 3)
- 'tcnhkfeboqrxuo iw '
- >>> scytale_encipher('thequickbrownfox', 4)
- 'tubnhirfecooqkwx'
- >>> scytale_encipher('thequickbrownfox', 5)
- 'tubn hirf ecoo qkwx '
- >>> scytale_encipher('thequickbrownfox', 6)
- 'tqcrnxhukof eibwo '
- >>> scytale_encipher('thequickbrownfox', 7)
- 'tqcrnx hukof eibwo '
- """
- if len(message) % rows != 0:
- message += ' '*(rows - len(message) % rows)
- row_length = round(len(message) / rows)
- slices = [message[i:i+row_length]
- for i in range(0, len(message), row_length)]
- return ''.join([''.join(r) for r in zip_longest(*slices, fillvalue='')])
-
-def scytale_decipher(message, rows):
- """Deciphers using the scytale transposition cipher.
- Assumes the message is padded so that all rows are the same length.
-
- >>> scytale_decipher('tcnhkfeboqrxuo iw ', 3)
- 'thequickbrownfox '
- >>> scytale_decipher('tubnhirfecooqkwx', 4)
- 'thequickbrownfox'
- >>> scytale_decipher('tubn hirf ecoo qkwx ', 5)
- 'thequickbrownfox '
- >>> scytale_decipher('tqcrnxhukof eibwo ', 6)
- 'thequickbrownfox '
- >>> scytale_decipher('tqcrnx hukof eibwo ', 7)
- 'thequickbrownfox '
- """
- cols = round(len(message) / rows)
- columns = [message[i:i+rows] for i in range(0, cols * rows, rows)]
- return ''.join([''.join(c) for c in zip_longest(*columns, fillvalue='')])
-
-
-def transpositions_of(keyword):
- """Finds the transpostions given by a keyword. For instance, the keyword
- 'clever' rearranges to 'celrv', so the first column (0) stays first, the
- second column (1) moves to third, the third column (2) moves to second,
- and so on.
-
- >>> transpositions_of('clever')
- [0, 2, 1, 4, 3]
- """
- key = deduplicate(keyword)
- transpositions = [key.index(l) for l in sorted(key)]
- return transpositions
-
-def column_transposition_encipher(message, keyword, fillvalue=' '):
- """Enciphers using the column transposition cipher.
- Message is padded to allow all rows to be the same length.
-
- >>> column_transposition_encipher('hellothere', 'clever')
- 'hleolteher'
- >>> column_transposition_encipher('hellothere', 'cleverly', fillvalue='!')
- 'hleolthre!e!'
- """
- return column_transposition_worker(message, keyword, encipher=True,
- fillvalue=fillvalue)
-
-def column_transposition_decipher(message, keyword, fillvalue=' '):
- """Deciphers using the column transposition cipher.
- Message is padded to allow all rows to be the same length.
-
- >>> column_transposition_decipher('hleolteher', 'clever')
- 'hellothere'
- >>> column_transposition_decipher('hleolthre!e!', 'cleverly', fillvalue='?')
- 'hellothere!!'
- """
- return column_transposition_worker(message, keyword, encipher=False,
- fillvalue=fillvalue)
-
-def column_transposition_worker(message, keyword,
- encipher=True, fillvalue=' '):
- """Does the actual work of the column transposition cipher.
- Message is padded with spaces to allow all rows to be the same length.
-
- >>> column_transposition_worker('hellothere', 'clever')
- 'hleolteher'
- >>> column_transposition_worker('hellothere', 'clever', encipher=True)
- 'hleolteher'
- >>> column_transposition_worker('hleolteher', 'clever', encipher=False)
- 'hellothere'
- """
- transpositions = transpositions_of(keyword)
- columns = every_nth(message, len(transpositions), fillvalue=fillvalue)
- if encipher:
- transposed_columns = transpose(columns, transpositions)
- else:
- transposed_columns = untranspose(columns, transpositions)
- return combine_every_nth(transposed_columns)
-
-
-
-def caesar_break(message,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise):
- """Breaks a Caesar cipher using frequency analysis
-
- >>> caesar_break('ibxcsyorsaqcheyklxivoexlevmrimwxsfiqevvmihrsasrxliwyrh' \
- 'ecjsppsamrkwleppfmergefifvmhixscsymjcsyqeoixlm') # doctest: +ELLIPSIS
- (4, 0.31863952890183...)
- >>> caesar_break('wxwmaxdgheetgwuxztgptedbgznitgwwhpguxyhkxbmhvvtlbhgtee' \
- 'raxlmhiixweblmxgxwmhmaxybkbgztgwztsxwbgmxgmert') # doctest: +ELLIPSIS
- (19, 0.42152901235832...)
- >>> caesar_break('yltbbqnqnzvguvaxurorgenafsbezqvagbnornfgsbevpnaabjurer' \
- 'svaquvzyvxrnznazlybequrvfohgriraabjtbaruraprur') # doctest: +ELLIPSIS
- (13, 0.316029208075451...)
- """
- sanitised_message = sanitise(message)
- best_shift = 0
- best_fit = float("inf")
- for shift in range(26):
- plaintext = caesar_decipher(sanitised_message, shift)
- counts = message_frequency_scaling(letter_frequencies(plaintext))
- fit = metric(target_counts, counts)
- 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,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_counts,
- message_frequency_scaling=norms.normalise):
- """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), 0.23570361818655...)
- """
- 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 range(1, 26, 2):
- for adder in range(26):
- plaintext = affine_decipher(sanitised_message,
- multiplier, adder, one_based)
- counts = message_frequency_scaling(letter_frequencies(plaintext))
- fit = metric(target_counts, counts)
- 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,
- 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
-
- >>> keyword_break(keyword_encipher('this is a test message for the ' \
- 'keyword decipherment', 'elephant', 1), \
- wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
- (('elephant', 1), 0.41643991598441...)
- """
- best_keyword = ''
- best_wrap_alphabet = True
- 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(letter_frequencies(plaintext))
- fit = metric(target_counts, counts)
- 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,
- 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
- frequency analysis
-
- >>> keyword_break_mp(keyword_encipher('this is a test message for the ' \
- 'keyword decipherment', 'elephant', 1), \
- wordlist=['cat', 'elephant', 'kangaroo']) # doctest: +ELLIPSIS
- (('elephant', 1), 0.41643991598441...)
- """
- 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
- # (limitation of Pool.starmap)
- breaks = pool.starmap(keyword_break_one, helper_args, chunksize)
- return min(breaks, key=lambda k: k[1])
-
-def keyword_break_one(message, keyword, wrap_alphabet, metric, target_counts,
- message_frequency_scaling):
- plaintext = keyword_decipher(message, keyword, wrap_alphabet)
- counts = message_frequency_scaling(letter_frequencies(plaintext))
- fit = metric(target_counts, counts)
- 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, 0.83453041115025...)
- """
- best_key = 0
- 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), 2)))
- 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(message,
- wordlist=keywords,
- metric=norms.euclidean_distance,
- target_counts=normalised_english_bigram_counts,
- message_frequency_scaling=norms.normalise):
- """Breaks a column transposition cipher using a dictionary and
- n-gram frequency analysis
-
- >>> column_transposition_break(column_transposition_encipher(sanitise( \
- "Turing's homosexuality resulted in a criminal prosecution in 1952, \
- when homosexual acts were still illegal in the United Kingdom. "), \
- 'encipher'), \
- wordlist=['encipher', 'keyword', 'fourteen']) # doctest: +ELLIPSIS
- ('encipher', 0.898128626285...)
- >>> column_transposition_break(column_transposition_encipher(sanitise( \
- "Turing's homosexuality resulted in a criminal prosecution in 1952, " \
- "when homosexual acts were still illegal in the United Kingdom."), \
- 'encipher'), \
- wordlist=['encipher', 'keyword', 'fourteen'], \
- target_counts=normalised_english_trigram_counts) # doctest: +ELLIPSIS
- ('encipher', 1.1958792913127...)
- """
- best_keyword = ''
- best_fit = float("inf")
- ngram_length = len(next(iter(target_counts.keys())))
- for keyword in wordlist:
- if len(message) % len(deduplicate(keyword)) == 0:
- plaintext = column_transposition_decipher(message, keyword)
- 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(
- keyword, fit,
- sanitise(plaintext)[:50]))
- if fit < best_fit:
- best_fit = fit
- best_keyword = keyword
- logger.info('Column transposition break best fit with key {0} gives fit '
- 'of {1} and decrypt starting: {2}'.format(best_keyword,
- best_fit, sanitise(
- column_transposition_decipher(message,
- best_keyword))[:50]))
- return best_keyword, best_fit
-
-
-def column_transposition_break_mp(message,
- wordlist=keywords,
- 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( \
- "Turing's homosexuality resulted in a criminal prosecution in 1952, \
- when homosexual acts were still illegal in the United Kingdom. "), \
- 'encipher'), \
- wordlist=['encipher', 'keyword', 'fourteen']) # doctest: +ELLIPSIS
- ('encipher', 0.898128626285...)
- >>> column_transposition_break_mp(column_transposition_encipher(sanitise( \
- "Turing's homosexuality resulted in a criminal prosecution in 1952, " \
- "when homosexual acts were still illegal in the United Kingdom."), \
- 'encipher'), \
- wordlist=['encipher', 'keyword', 'fourteen'], \
- target_counts=normalised_english_trigram_counts) # doctest: +ELLIPSIS
- ('encipher', 1.1958792913127...)
- """
- ngram_length = len(next(iter(target_counts.keys())))
- with Pool() as pool:
- helper_args = [(message, word, metric, target_counts, ngram_length,
- message_frequency_scaling)
- for word in wordlist]
- # 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])
-
-def column_transposition_break_worker(message, keyword, metric, target_counts,
- ngram_length, message_frequency_scaling):
- plaintext = column_transposition_decipher(message, keyword)
- 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(
- keyword, fit,
- sanitise(plaintext)[:50]))
- return keyword, fit
-
-
-
-if __name__ == "__main__":
- import doctest
- doctest.testmod()
projects / cipher-tools.git / blobdiff