import string
import collections
-import norms
import logging
+from itertools import zip_longest, cycle, chain
+from language_models import *
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)
-keywords = []
-with open('words.txt', 'r') as f:
- keywords = [line.rstrip() for line in f]
-
-
-modular_division_table = [[0]*26 for x in range(26)]
+modular_division_table = [[0]*26 for _ in range(26)]
for a in range(26):
for b in range(26):
c = (a * b) % 26
modular_division_table[b][c] = a
-modular_division_table_one_based = [[0]*27 for x in range(27)]
-for a in range(27):
- for b in range(27):
- c = ((a * b)-1) % 26 + 1
- modular_division_table_one_based[b][c] = a
+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 sanitise(text):
- """Remove all non-alphabetic characters and convert the text to lowercase
+def combine_every_nth(split_text):
+ """Reforms a text split into every_nth strings
- >>> sanitise('The Quick')
- 'thequick'
- >>> sanitise('The Quick BROWN fox jumped! over... the (9lazy) DOG')
- 'thequickbrownfoxjumpedoverthelazydog'
+ >>> 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 chunks(text, n, fillvalue=None):
+ """Split a text into chunks of n characters
+
+ >>> chunks('abcdefghi', 3)
+ ['abc', 'def', 'ghi']
+ >>> chunks('abcdefghi', 4)
+ ['abcd', 'efgh', 'i']
+ >>> chunks('abcdefghi', 4, fillvalue='!')
+ ['abcd', 'efgh', 'i!!!']
"""
- sanitised = [c.lower() for c in text if c in string.ascii_letters]
- return ''.join(sanitised)
+ if fillvalue:
+ padding = fillvalue[0] * (n - len(text) % n)
+ else:
+ padding = ''
+ return [(text+padding)[i:i+n] for i in range(0, len(text), n)]
-def ngrams(text, n):
- """Returns all n-grams of a text
+def transpose(items, transposition):
+ """Moves items around according to the given transposition
- >>> ngrams(sanitise('the quick brown fox'), 2)
- [('t', 'h'), ('h', 'e'), ('e', 'q'), ('q', 'u'), ('u', 'i'), ('i', 'c'), ('c', 'k'), ('k', 'b'), ('b', 'r'), ('r', 'o'), ('o', 'w'), ('w', 'n'), ('n', 'f'), ('f', 'o'), ('o', 'x')]
- >>> ngrams(sanitise('the quick brown fox'), 4)
- [('t', 'h', 'e', 'q'), ('h', 'e', 'q', 'u'), ('e', 'q', 'u', 'i'), ('q', 'u', 'i', 'c'), ('u', 'i', 'c', 'k'), ('i', 'c', 'k', 'b'), ('c', 'k', 'b', 'r'), ('k', 'b', 'r', 'o'), ('b', 'r', 'o', 'w'), ('r', 'o', 'w', 'n'), ('o', 'w', 'n', 'f'), ('w', 'n', 'f', 'o'), ('n', 'f', 'o', 'x')]
+ >>> 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]
"""
- return [tuple(text[i:i+n]) for i in range(len(text)-n+1)]
+ transposed = [''] * len(transposition)
+ for p, t in enumerate(transposition):
+ transposed[p] = items[t]
+ return transposed
-def letter_frequencies(text):
- """Count the number of occurrences of each character in text
+def untranspose(items, transposition):
+ """Undoes a transpose
- >>> sorted(letter_frequencies('abcdefabc').items())
- [('a', 2), ('b', 2), ('c', 2), ('d', 1), ('e', 1), ('f', 1)]
- >>> sorted(letter_frequencies('the quick brown fox jumped over the lazy dog').items())
- [(' ', 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(letter_frequencies('The Quick BROWN fox jumped! over... the (9lazy) DOG').items())
- [(' ', 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(letter_frequencies(sanitise('The Quick BROWN fox jumped! over... the (9lazy) DOG')).items())
- [('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)]
+ >>> 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]
"""
- counts = collections.defaultdict(int)
- for c in text:
- counts[c] += 1
- return counts
+ transposed = [''] * len(transposition)
+ for p, t in enumerate(transposition):
+ transposed[t] = items[p]
+ return transposed
def deduplicate(text):
return list(collections.OrderedDict.fromkeys(text))
-
def caesar_encipher_letter(letter, shift):
"""Encipher a letter, given a shift amount
alphabet_start = ord('A')
else:
alphabet_start = ord('a')
- return chr(((ord(letter) - alphabet_start + shift) % 26) + alphabet_start)
+ return chr(((ord(letter) - alphabet_start + shift) % 26) +
+ alphabet_start)
else:
return letter
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])
+ >>> ''.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])
+ >>> ''.join([affine_encipher_letter(l, 3, 5, False) \
+ for l in string.ascii_uppercase])
'FILORUXADGJMPSVYBEHKNQTWZC'
"""
if letter in string.ascii_letters:
alphabet_start = ord('a')
letter_number = ord(letter) - alphabet_start
if one_based: letter_number += 1
- raw_cipher_number = (letter_number * multiplier + adder)
- cipher_number = 0
- if one_based:
- cipher_number = (raw_cipher_number - 1) % 26
- else:
- cipher_number = raw_cipher_number % 26
- return chr(cipher_number + alphabet_start)
+ 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'])
+ >>> ''.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'])
+ >>> ''.join([affine_decipher_letter(l, 3, 5, False) \
+ for l in 'FILORUXADGJMPSVYBEHKNQTWZC'])
'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
"""
if letter in string.ascii_letters:
alphabet_start = ord('a')
cipher_number = ord(letter) - alphabet_start
if one_based: cipher_number += 1
- plaintext_number = 0
- if one_based:
- plaintext_number = (modular_division_table_one_based[multiplier][(cipher_number - adder + 26) % 26] - 1) % 26
- else:
- #plaintext_number = (modular_division_table[multiplier][cipher_number] - adder) % 26
- plaintext_number = modular_division_table[multiplier][(cipher_number - adder + 26) % 26]
- return chr(plaintext_number + alphabet_start)
+ 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)
+ >>> 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]
+ 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)
+ >>> 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]
+ enciphered = [affine_decipher_letter(l, multiplier, adder, one_based)
+ for l in message]
return ''.join(enciphered)
-def keyword_cipher_alphabet_of(keyword, wrap_alphabet=False):
- """Find the cipher alphabet given a keyword
-
- >>> keyword_cipher_alphabet_of('harry')
- 'harybcdefgijklmnopqstuvwxz'
- >>> keyword_cipher_alphabet_of('harry', True)
- 'haryzbcdefgijklmnopqstuvwx'
- >>> keyword_cipher_alphabet_of('harry', False)
- 'harybcdefgijklmnopqstuvwxz'
+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'
"""
- cipher_alphabet = ''
- if wrap_alphabet:
- last_keyword_letter = deduplicate(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))
+ if wrap_alphabet == 0:
+ cipher_alphabet = ''.join(deduplicate(sanitise(keyword) +
+ string.ascii_lowercase))
else:
- cipher_alphabet = ''.join(deduplicate(sanitise(keyword) + string.ascii_lowercase))
+ 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=False):
- """Enciphers a message with a keyword substitution cipher
-
- >>> keyword_encipher('test message', 'harry')
- 'sbqs kbqqhdb'
- >>> keyword_encipher('test message', 'harry', True)
- 'qzpq jzpphcz'
- >>> keyword_encipher('test message', 'harry', False)
- 'sbqs kbqqhdb'
+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=False):
- """Deciphers a message with a keyword substitution cipher
-
- >>> keyword_decipher('sbqs kbqqhdb', 'harry')
+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('qzpq jzpphcz', 'harry', True)
+ >>> keyword_decipher('lskl dskkbus', 'bayes', 1)
'test message'
- >>> keyword_decipher('sbqs kbqqhdb', 'harry', False)
+ >>> 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 caesar_break(message, metric=norms.euclidean_distance, target_frequencies=normalised_english_counts, message_frequency_scaling=norms.normalise):
- """Breaks a Caesar cipher using frequency analysis
-
- >>> caesar_break('ibxcsyorsaqcheyklxivoexlevmrimwxsfiqevvmihrsasrxliwyrhecjsppsamrkwleppfmergefifvmhixscsymjcsyqeoixlm') # doctest: +ELLIPSIS
- (4, 0.31863952890183...)
- >>> caesar_break('wxwmaxdgheetgwuxztgptedbgznitgwwhpguxyhkxbmhvvtlbhgteeraxlmhiixweblmxgxwmhmaxybkbgztgwztsxwbgmxgmert') # doctest: +ELLIPSIS
- (19, 0.42152901235832...)
- >>> caesar_break('yltbbqnqnzvguvaxurorgenafsbezqvagbnornfgsbevpnaabjurersvaquvzyvxrnznazlybequrvfohgriraabjtbaruraprur') # doctest: +ELLIPSIS
- (13, 0.316029208075451...)
+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 '
"""
- sanitised_message = sanitise(message)
- best_shift = 0
- best_fit = float("inf")
- for shift in range(26):
- plaintext = caesar_decipher(sanitised_message, shift)
- frequencies = message_frequency_scaling(letter_frequencies(plaintext))
- fit = metric(target_frequencies, frequencies)
- 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_frequencies=normalised_english_counts, message_frequency_scaling=norms.normalise):
- """Breaks an affine cipher using frequency analysis
+ 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.
- >>> 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...)
+ >>> 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.
+
+ If passed a tuple, assume it's already a transposition and just return it.
+
+ >>> transpositions_of('clever')
+ (0, 2, 1, 4, 3)
+ >>> transpositions_of('fred')
+ (3, 2, 0, 1)
+ >>> transpositions_of((3, 2, 0, 1))
+ (3, 2, 0, 1)
+ """
+ if isinstance(keyword, tuple):
+ return keyword
+ else:
+ key = deduplicate(keyword)
+ transpositions = tuple(key.index(l) for l in sorted(key))
+ return transpositions
+
+def pad(message_len, group_len, fillvalue):
+ padding_length = group_len - message_len % group_len
+ if padding_length == group_len: padding_length = 0
+ padding = ''
+ for i in range(padding_length):
+ if callable(fillvalue):
+ padding += fillvalue()
+ else:
+ padding += fillvalue
+ return padding
+
+def column_transposition_encipher(message, keyword, fillvalue=' ',
+ fillcolumnwise=False,
+ emptycolumnwise=False):
+ """Enciphers using the column transposition cipher.
+ Message is padded to allow all rows to be the same length.
+
+ >>> column_transposition_encipher('hellothere', 'abcdef', fillcolumnwise=True)
+ 'hlohr eltee '
+ >>> column_transposition_encipher('hellothere', 'abcdef', fillcolumnwise=True, emptycolumnwise=True)
+ 'hellothere '
+ >>> column_transposition_encipher('hellothere', 'abcdef')
+ 'hellothere '
+ >>> column_transposition_encipher('hellothere', 'abcde')
+ 'hellothere'
+ >>> column_transposition_encipher('hellothere', 'abcde', fillcolumnwise=True, emptycolumnwise=True)
+ 'hellothere'
+ >>> column_transposition_encipher('hellothere', 'abcde', fillcolumnwise=True, emptycolumnwise=False)
+ 'hlohreltee'
+ >>> column_transposition_encipher('hellothere', 'abcde', fillcolumnwise=False, emptycolumnwise=True)
+ 'htehlelroe'
+ >>> column_transposition_encipher('hellothere', 'abcde', fillcolumnwise=False, emptycolumnwise=False)
+ 'hellothere'
+ >>> column_transposition_encipher('hellothere', 'clever', fillcolumnwise=True, emptycolumnwise=True)
+ 'heotllrehe'
+ >>> column_transposition_encipher('hellothere', 'clever', fillcolumnwise=True, emptycolumnwise=False)
+ 'holrhetlee'
+ >>> column_transposition_encipher('hellothere', 'clever', fillcolumnwise=False, emptycolumnwise=True)
+ 'htleehoelr'
+ >>> column_transposition_encipher('hellothere', 'clever', fillcolumnwise=False, emptycolumnwise=False)
+ 'hleolteher'
+ >>> column_transposition_encipher('hellothere', 'cleverly')
+ 'hleolthre e '
+ >>> column_transposition_encipher('hellothere', 'cleverly', fillvalue='!')
+ 'hleolthre!e!'
+ >>> column_transposition_encipher('hellothere', 'cleverly', fillvalue=lambda: '*')
+ 'hleolthre*e*'
+ """
+ transpositions = transpositions_of(keyword)
+ message += pad(len(message), len(transpositions), fillvalue)
+ if fillcolumnwise:
+ rows = every_nth(message, len(message) // len(transpositions))
+ else:
+ rows = chunks(message, len(transpositions))
+ transposed = [transpose(r, transpositions) for r in rows]
+ if emptycolumnwise:
+ return combine_every_nth(transposed)
+ else:
+ return ''.join(chain(*transposed))
+
+def column_transposition_decipher(message, keyword, fillvalue=' ',
+ fillcolumnwise=False,
+ emptycolumnwise=False):
+ """Deciphers using the column transposition cipher.
+ Message is padded to allow all rows to be the same length.
+
+ >>> column_transposition_decipher('hellothere', 'abcde', fillcolumnwise=True, emptycolumnwise=True)
+ 'hellothere'
+ >>> column_transposition_decipher('hlohreltee', 'abcde', fillcolumnwise=True, emptycolumnwise=False)
+ 'hellothere'
+ >>> column_transposition_decipher('htehlelroe', 'abcde', fillcolumnwise=False, emptycolumnwise=True)
+ 'hellothere'
+ >>> column_transposition_decipher('hellothere', 'abcde', fillcolumnwise=False, emptycolumnwise=False)
+ 'hellothere'
+ >>> column_transposition_decipher('heotllrehe', 'clever', fillcolumnwise=True, emptycolumnwise=True)
+ 'hellothere'
+ >>> column_transposition_decipher('holrhetlee', 'clever', fillcolumnwise=True, emptycolumnwise=False)
+ 'hellothere'
+ >>> column_transposition_decipher('htleehoelr', 'clever', fillcolumnwise=False, emptycolumnwise=True)
+ 'hellothere'
+ >>> column_transposition_decipher('hleolteher', 'clever', fillcolumnwise=False, emptycolumnwise=False)
+ 'hellothere'
"""
- 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)
- frequencies = message_frequency_scaling(letter_frequencies(plaintext))
- fit = metric(target_frequencies, frequencies)
- 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_frequencies=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', True))
- (('elephant', True), 0.41643991598441...) # doctest: +ELLIPSIS
+ # >>> column_transposition_decipher('hleolteher', 'clever')
+ # 'hellothere'
+ # >>> column_transposition_decipher('hleolthre!e!', 'cleverly', fillvalue='?')
+ # 'hellothere!!'
+ # >>> column_transposition_decipher('htleehoelr', 'clever', columnwise=True)
+ # 'hellothere'
+ # """
+ transpositions = transpositions_of(keyword)
+ message += pad(len(message), len(transpositions), '*')
+ if emptycolumnwise:
+ rows = every_nth(message, len(message) // len(transpositions))
+ else:
+ rows = chunks(message, len(transpositions))
+ untransposed = [untranspose(r, transpositions) for r in rows]
+ if fillcolumnwise:
+ return combine_every_nth(untransposed)
+ else:
+ return ''.join(chain(*untransposed))
+
+
+def vigenere_encipher(message, keyword):
+ """Vigenere encipher
+
+ >>> vigenere_encipher('hello', 'abc')
+ 'hfnlp'
"""
- best_keyword = ''
- best_wrap_alphabet = True
- best_fit = float("inf")
- for wrap_alphabet in [True, False]:
- for keyword in wordlist:
- plaintext = keyword_decipher(message, keyword, wrap_alphabet)
- frequencies = message_frequency_scaling(letter_frequencies(plaintext))
- fit = metric(target_frequencies, frequencies)
- logger.debug('Keyword break attempt using key {0} ({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} ({1}) gives fit of {2} and decrypt starting: {3}'.format(best_keyword, best_wrap_alphabet, best_fit, sanitise(keyword_decipher(message, best_keyword))[:50]))
- return (best_keyword, best_wrap_alphabet), best_fit
+ shifts = [ord(l) - ord('a') for l in sanitise(keyword)]
+ pairs = zip(message, cycle(shifts))
+ return ''.join([caesar_encipher_letter(l, k) for l, k in pairs])
+
+def vigenere_decipher(message, keyword):
+ """Vigenere decipher
+
+ >>> vigenere_decipher('hfnlp', 'abc')
+ 'hello'
+ """
+ shifts = [ord(l) - ord('a') for l in sanitise(keyword)]
+ pairs = zip(message, cycle(shifts))
+ return ''.join([caesar_decipher_letter(l, k) for l, k in pairs])
+
+beaufort_encipher=vigenere_decipher
+beaufort_decipher=vigenere_encipher
if __name__ == "__main__":
projects / cipher-tools.git / blobdiff