-"""A set of ciphers with implementations for both enciphering and deciphering
-them. See cipherbreak for automatic breaking of these ciphers
-"""
-
import string
import collections
-from language_models import unaccent, sanitise
+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 *
+
+
+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
+
+
+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 = chunks(text, n, fillvalue)
+ 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 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!!!']
+ """
+ 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 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 = [''] * 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 = [''] * 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(accented_letter, shift):
alphabet_start = ord('A')
else:
alphabet_start = ord('a')
- return chr(((ord(letter) - alphabet_start + shift) % 26) +
+ 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)
def caesar_encipher(message, shift):
"""Encipher a message with the Caesar cipher of given shift
-
+
>>> caesar_encipher('abc', 1)
'bcd'
>>> caesar_encipher('abc', 2)
def caesar_decipher(message, shift):
"""Decipher a message with the Caesar cipher of given shift
-
+
>>> caesar_decipher('bcd', 1)
'abc'
>>> caesar_decipher('cde', 2)
"""
return caesar_encipher(message, -shift)
+def affine_encipher_letter(accented_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'
+ """
+ letter = unaccent(accented_letter)
+ 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)
+
+
+class KeywordWrapAlphabet(Enum):
+ from_a = 1
+ from_last = 2
+ from_largest = 3
+
+
+def keyword_cipher_alphabet_of(keyword, wrap_alphabet=KeywordWrapAlphabet.from_a):
+ """Find the cipher alphabet given a keyword.
+ wrap_alphabet controls how the rest of the alphabet is added
+ after the keyword.
+
+ >>> keyword_cipher_alphabet_of('bayes')
+ 'bayescdfghijklmnopqrtuvwxz'
+ >>> keyword_cipher_alphabet_of('bayes', KeywordWrapAlphabet.from_a)
+ 'bayescdfghijklmnopqrtuvwxz'
+ >>> keyword_cipher_alphabet_of('bayes', KeywordWrapAlphabet.from_last)
+ 'bayestuvwxzcdfghijklmnopqr'
+ >>> keyword_cipher_alphabet_of('bayes', KeywordWrapAlphabet.from_largest)
+ 'bayeszcdfghijklmnopqrtuvwx'
+ """
+ if wrap_alphabet == KeywordWrapAlphabet.from_a:
+ cipher_alphabet = ''.join(deduplicate(sanitise(keyword) +
+ string.ascii_lowercase))
+ else:
+ if wrap_alphabet == KeywordWrapAlphabet.from_last:
+ 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=KeywordWrapAlphabet.from_a):
+ """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', KeywordWrapAlphabet.from_a)
+ 'rsqr ksqqbds'
+ >>> keyword_encipher('test message', 'bayes', KeywordWrapAlphabet.from_last)
+ 'lskl dskkbus'
+ >>> keyword_encipher('test message', 'bayes', KeywordWrapAlphabet.from_largest)
+ 'qspq jsppbcs'
+ """
+ cipher_alphabet = keyword_cipher_alphabet_of(keyword, wrap_alphabet)
+ cipher_translation = ''.maketrans(string.ascii_lowercase, cipher_alphabet)
+ return unaccent(message).lower().translate(cipher_translation)
+
+def keyword_decipher(message, keyword, wrap_alphabet=KeywordWrapAlphabet.from_a):
+ """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', KeywordWrapAlphabet.from_a)
+ 'test message'
+ >>> keyword_decipher('lskl dskkbus', 'bayes', KeywordWrapAlphabet.from_last)
+ 'test message'
+ >>> keyword_decipher('qspq jsppbcs', 'bayes', KeywordWrapAlphabet.from_largest)
+ '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 vigenere_encipher(message, keyword):
+ """Vigenere encipher
+
+ >>> vigenere_encipher('hello', 'abc')
+ 'hfnlp'
+ """
+ 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
+
+
+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'
+ """
+ transpositions = transpositions_of(keyword)
+ message += pad(len(message), len(transpositions), fillvalue)
+ 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 scytale_encipher(message, rows, fillvalue=' '):
+ """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 '
+ """
+ # transpositions = [i for i in range(math.ceil(len(message) / rows))]
+ # return column_transposition_encipher(message, transpositions,
+ # fillvalue=fillvalue, fillcolumnwise=False, emptycolumnwise=True)
+ transpositions = [i for i in range(rows)]
+ return column_transposition_encipher(message, transpositions,
+ fillvalue=fillvalue, fillcolumnwise=True, emptycolumnwise=False)
+
+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 '
+ """
+ # transpositions = [i for i in range(math.ceil(len(message) / rows))]
+ # return column_transposition_decipher(message, transpositions,
+ # fillcolumnwise=False, emptycolumnwise=True)
+ transpositions = [i for i in range(rows)]
+ return column_transposition_decipher(message, transpositions,
+ fillcolumnwise=True, emptycolumnwise=False)
+
+
+def railfence_encipher(message, height, fillvalue=''):
+ """Railfence cipher.
+ Works by splitting the text into sections, then reading across them to
+ generate the rows in the cipher. The rows are then combined to form the
+ ciphertext.
+
+ Example: the plaintext "hellotherefriends", with a height of four, written
+ out in the railfence as
+ h h i
+ etere*
+ lorfns
+ l e d
+ (with the * showing the one character to finish the last section).
+ Each 'section' is two columns, but unfolded. In the example, the first
+ section is 'hellot'.
+
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 2, fillvalue='!')
+ 'hlohraateerishsslnpeefetotsigaleccpeselteevsmhatetiiaogicotxfretnrifneihr!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 3, fillvalue='!')
+ 'horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihr!!lhateihsnefttiaece!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 5, fillvalue='!')
+ 'hresleogcseeemhetaocofrnrner!!lhateihsnefttiaece!!ltvsatiigitxetifih!!oarspeslp!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 10, fillvalue='!')
+ 'hepisehagitnr!!lernesge!!lmtocerh!!otiletap!!tseaorii!!hassfolc!!evtitffe!!rahsetec!!eixn!'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 3)
+ 'horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihrlhateihsnefttiaece'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 5)
+ 'hresleogcseeemhetaocofrnrnerlhateihsnefttiaeceltvsatiigitxetifihoarspeslp'
+ >>> railfence_encipher('hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers', 7)
+ 'haspolsevsetgifrifrlatihnettaeelemtiocxernhorersleesgcptehaiaottneihesfic'
+ """
+ sections = chunks(message, (height - 1) * 2, fillvalue=fillvalue)
+ n_sections = len(sections)
+ # Add the top row
+ rows = [''.join([s[0] for s in sections])]
+ # process the middle rows of the grid
+ for r in range(1, height-1):
+ rows += [''.join([s[r:r+1] + s[height*2-r-2:height*2-r-1] for s in sections])]
+ # process the bottom row
+ rows += [''.join([s[height - 1:height] for s in sections])]
+ # rows += [' '.join([s[height - 1] for s in sections])]
+ return ''.join(rows)
+
+def railfence_decipher(message, height, fillvalue=''):
+ """Railfence decipher.
+ Works by reconstructing the grid used to generate the ciphertext, then
+ unfolding the sections so the text can be concatenated together.
+
+ Example: given the ciphertext 'hhieterelorfnsled' and a height of 4, first
+ work out that the second row has a character missing, find the rows of the
+ grid, then split the section into its two columns.
+
+ 'hhieterelorfnsled' is split into
+ h h i
+ etere
+ lorfns
+ l e d
+ (spaces added for clarity), which is stored in 'rows'. This is then split
+ into 'down_rows' and 'up_rows':
+
+ down_rows:
+ hhi
+ eee
+ lrn
+ led
+
+ up_rows:
+ tr
+ ofs
+
+ These are then zipped together (after the up_rows are reversed) to recover
+ the plaintext.
+
+ Most of the procedure is about finding the correct lengths for each row then
+ splitting the ciphertext into those rows.
+
+ >>> railfence_decipher('hlohraateerishsslnpeefetotsigaleccpeselteevsmhatetiiaogicotxfretnrifneihr!', 2).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihr!!lhateihsnefttiaece!', 3).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('hresleogcseeemhetaocofrnrner!!lhateihsnefttiaece!!ltvsatiigitxetifih!!oarspeslp!', 5).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('hepisehagitnr!!lernesge!!lmtocerh!!otiletap!!tseaorii!!hassfolc!!evtitffe!!rahsetec!!eixn!', 10).strip('!')
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('horaersslpeeosglcpselteevsmhatetiiaogicotxfretnrifneihrlhateihsnefttiaece', 3)
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('hresleogcseeemhetaocofrnrnerlhateihsnefttiaeceltvsatiigitxetifihoarspeslp', 5)
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ >>> railfence_decipher('haspolsevsetgifrifrlatihnettaeelemtiocxernhorersleesgcptehaiaottneihesfic', 7)
+ 'hellothereavastmeheartiesthisisalongpieceoftextfortestingrailfenceciphers'
+ """
+ # find the number and size of the sections, including how many characters
+ # are missing for a full grid
+ n_sections = math.ceil(len(message) / ((height - 1) * 2))
+ padding_to_add = n_sections * (height - 1) * 2 - len(message)
+ # row_lengths are for the both up rows and down rows
+ row_lengths = [n_sections] * (height - 1) * 2
+ for i in range((height - 1) * 2 - 1, (height - 1) * 2 - (padding_to_add + 1), -1):
+ row_lengths[i] -= 1
+ # folded_rows are the combined row lengths in the middle of the railfence
+ folded_row_lengths = [row_lengths[0]]
+ for i in range(1, height-1):
+ folded_row_lengths += [row_lengths[i] + row_lengths[-i]]
+ folded_row_lengths += [row_lengths[height - 1]]
+ # find the rows that form the railfence grid
+ rows = []
+ row_start = 0
+ for i in folded_row_lengths:
+ rows += [message[row_start:row_start + i]]
+ row_start += i
+ # split the rows into the 'down_rows' (those that form the first column of
+ # a section) and the 'up_rows' (those that ofrm the second column of a
+ # section).
+ down_rows = [rows[0]]
+ up_rows = []
+ for i in range(1, height-1):
+ down_rows += [''.join([c for n, c in enumerate(rows[i]) if n % 2 == 0])]
+ up_rows += [''.join([c for n, c in enumerate(rows[i]) if n % 2 == 1])]
+ down_rows += [rows[-1]]
+ up_rows.reverse()
+ return ''.join(c for r in zip_longest(*(down_rows + up_rows), fillvalue='') for c in r)
+
+def make_cadenus_keycolumn(doubled_letters = 'vw', start='a', reverse=False):
+ """Makes the key column for a Cadenus cipher (the column down between the
+ rows of letters)
+
+ >>> make_cadenus_keycolumn()['a']
+ 0
+ >>> make_cadenus_keycolumn()['b']
+ 1
+ >>> make_cadenus_keycolumn()['c']
+ 2
+ >>> make_cadenus_keycolumn()['v']
+ 21
+ >>> make_cadenus_keycolumn()['w']
+ 21
+ >>> make_cadenus_keycolumn()['z']
+ 24
+ >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['a']
+ 1
+ >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['b']
+ 0
+ >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['c']
+ 24
+ >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['i']
+ 18
+ >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['j']
+ 18
+ >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['v']
+ 6
+ >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['z']
+ 2
+ """
+ index_to_remove = string.ascii_lowercase.find(doubled_letters[0])
+ short_alphabet = string.ascii_lowercase[:index_to_remove] + string.ascii_lowercase[index_to_remove+1:]
+ if reverse:
+ short_alphabet = ''.join(reversed(short_alphabet))
+ start_pos = short_alphabet.find(start)
+ rotated_alphabet = short_alphabet[start_pos:] + short_alphabet[:start_pos]
+ keycolumn = {l: i for i, l in enumerate(rotated_alphabet)}
+ keycolumn[doubled_letters[0]] = keycolumn[doubled_letters[1]]
+ return keycolumn
+
+def cadenus_encipher(message, keyword, keycolumn, fillvalue='a'):
+ """Encipher with the Cadenus cipher
+
+ >>> cadenus_encipher(sanitise('Whoever has made a voyage up the Hudson ' \
+ 'must remember the Kaatskill mountains. ' \
+ 'They are a dismembered branch of the great'), \
+ 'wink', \
+ make_cadenus_keycolumn(doubled_letters='vw', start='a', reverse=True))
+ 'antodeleeeuhrsidrbhmhdrrhnimefmthgeaetakseomehetyaasuvoyegrastmmuuaeenabbtpchehtarorikswosmvaleatned'
+ >>> cadenus_encipher(sanitise('a severe limitation on the usefulness of ' \
+ 'the cadenus is that every message must be ' \
+ 'a multiple of twenty-five letters long'), \
+ 'easy', \
+ make_cadenus_keycolumn(doubled_letters='vw', start='a', reverse=True))
+ 'systretomtattlusoatleeesfiyheasdfnmschbhneuvsnpmtofarenuseieeieltarlmentieetogevesitfaisltngeeuvowul'
+ """
+ rows = chunks(message, len(message) // 25, fillvalue=fillvalue)
+ columns = zip(*rows)
+ rotated_columns = [col[start:] + col[:start] for start, col in zip([keycolumn[l] for l in keyword], columns)]
+ rotated_rows = zip(*rotated_columns)
+ transpositions = transpositions_of(keyword)
+ transposed = [transpose(r, transpositions) for r in rotated_rows]
+ return ''.join(chain(*transposed))
+
+def cadenus_decipher(message, keyword, keycolumn, fillvalue='a'):
+ """
+ >>> cadenus_decipher('antodeleeeuhrsidrbhmhdrrhnimefmthgeaetakseomehetyaa' \
+ 'suvoyegrastmmuuaeenabbtpchehtarorikswosmvaleatned', \
+ 'wink', \
+ make_cadenus_keycolumn(reverse=True))
+ 'whoeverhasmadeavoyageupthehudsonmustrememberthekaatskillmountainstheyareadismemberedbranchofthegreat'
+ >>> cadenus_decipher('systretomtattlusoatleeesfiyheasdfnmschbhneuvsnpmtof' \
+ 'arenuseieeieltarlmentieetogevesitfaisltngeeuvowul', \
+ 'easy', \
+ make_cadenus_keycolumn(reverse=True))
+ 'aseverelimitationontheusefulnessofthecadenusisthateverymessagemustbeamultipleoftwentyfiveletterslong'
+ """
+ rows = chunks(message, len(message) // 25, fillvalue=fillvalue)
+ transpositions = transpositions_of(keyword)
+ untransposed_rows = [untranspose(r, transpositions) for r in rows]
+ columns = zip(*untransposed_rows)
+ rotated_columns = [col[-start:] + col[:-start] for start, col in zip([keycolumn[l] for l in keyword], columns)]
+ rotated_rows = zip(*rotated_columns)
+ # return rotated_columns
+ return ''.join(chain(*rotated_rows))
+
+
+def hill_encipher(matrix, message_letters, fillvalue='a'):
+ """Hill cipher
+
+ >>> hill_encipher(np.matrix([[7,8], [11,11]]), 'hellothere')
+ 'drjiqzdrvx'
+ >>> hill_encipher(np.matrix([[6, 24, 1], [13, 16, 10], [20, 17, 15]]), \
+ 'hello there')
+ 'tfjflpznvyac'
+ """
+ n = len(matrix)
+ sanitised_message = sanitise(message_letters)
+ if len(sanitised_message) % n != 0:
+ padding = fillvalue[0] * (n - len(sanitised_message) % n)
+ else:
+ padding = ''
+ message = [ord(c) - ord('a') for c in sanitised_message + padding]
+ message_chunks = [message[i:i+n] for i in range(0, len(message), n)]
+ # message_chunks = chunks(message, len(matrix), fillvalue=None)
+ enciphered_chunks = [((matrix * np.matrix(c).T).T).tolist()[0]
+ for c in message_chunks]
+ return ''.join([chr(int(round(l)) % 26 + ord('a'))
+ for l in sum(enciphered_chunks, [])])
+
+def hill_decipher(matrix, message, fillvalue='a'):
+ """Hill cipher
+
+ >>> hill_decipher(np.matrix([[7,8], [11,11]]), 'drjiqzdrvx')
+ 'hellothere'
+ >>> hill_decipher(np.matrix([[6, 24, 1], [13, 16, 10], [20, 17, 15]]), \
+ 'tfjflpznvyac')
+ 'hellothereaa'
+ """
+ adjoint = linalg.det(matrix)*linalg.inv(matrix)
+ inverse_determinant = modular_division_table[int(round(linalg.det(matrix))) % 26][1]
+ inverse_matrix = (inverse_determinant * adjoint) % 26
+ return hill_encipher(inverse_matrix, message, fillvalue)
+
+
+# Where each piece of text ends up in the AMSCO transpositon cipher.
+# 'index' shows where the slice appears in the plaintext, with the slice
+# from 'start' to 'end'
+AmscoSlice = collections.namedtuple('AmscoSlice', ['index', 'start', 'end'])
+
+class AmscoFillStyle(Enum):
+ continuous = 1
+ same_each_row = 2
+ reverse_each_row = 3
+
+def amsco_transposition_positions(message, keyword,
+ fillpattern=(1, 2),
+ fillstyle=AmscoFillStyle.continuous,
+ fillcolumnwise=False,
+ emptycolumnwise=True):
+ """Creates the grid for the AMSCO transposition cipher. Each element in the
+ grid shows the index of that slice and the start and end positions of the
+ plaintext that go to make it up.
+
+ >>> amsco_transposition_positions(string.ascii_lowercase, 'freddy', \
+ fillpattern=(1, 2)) # doctest: +NORMALIZE_WHITESPACE
+ [[AmscoSlice(index=3, start=4, end=6),
+ AmscoSlice(index=2, start=3, end=4),
+ AmscoSlice(index=0, start=0, end=1),
+ AmscoSlice(index=1, start=1, end=3),
+ AmscoSlice(index=4, start=6, end=7)],
+ [AmscoSlice(index=8, start=12, end=13),
+ AmscoSlice(index=7, start=10, end=12),
+ AmscoSlice(index=5, start=7, end=9),
+ AmscoSlice(index=6, start=9, end=10),
+ AmscoSlice(index=9, start=13, end=15)],
+ [AmscoSlice(index=13, start=19, end=21),
+ AmscoSlice(index=12, start=18, end=19),
+ AmscoSlice(index=10, start=15, end=16),
+ AmscoSlice(index=11, start=16, end=18),
+ AmscoSlice(index=14, start=21, end=22)],
+ [AmscoSlice(index=18, start=27, end=28),
+ AmscoSlice(index=17, start=25, end=27),
+ AmscoSlice(index=15, start=22, end=24),
+ AmscoSlice(index=16, start=24, end=25),
+ AmscoSlice(index=19, start=28, end=30)]]
+ """
+ transpositions = transpositions_of(keyword)
+ fill_iterator = cycle(fillpattern)
+ indices = count()
+ message_length = len(message)
+
+ current_position = 0
+ grid = []
+ current_fillpattern = fillpattern
+ while current_position < message_length:
+ row = []
+ if fillstyle == AmscoFillStyle.same_each_row:
+ fill_iterator = cycle(fillpattern)
+ if fillstyle == AmscoFillStyle.reverse_each_row:
+ fill_iterator = cycle(current_fillpattern)
+ for _ in range(len(transpositions)):
+ index = next(indices)
+ gap = next(fill_iterator)
+ row += [AmscoSlice(index, current_position, current_position + gap)]
+ current_position += gap
+ grid += [row]
+ if fillstyle == AmscoFillStyle.reverse_each_row:
+ current_fillpattern = list(reversed(current_fillpattern))
+ return [transpose(r, transpositions) for r in grid]
+
+def amsco_transposition_encipher(message, keyword,
+ fillpattern=(1,2), fillstyle=AmscoFillStyle.reverse_each_row):
+ """AMSCO transposition encipher.
+
+ >>> amsco_transposition_encipher('hellothere', 'abc', fillpattern=(1, 2))
+ 'hoteelhler'
+ >>> amsco_transposition_encipher('hellothere', 'abc', fillpattern=(2, 1))
+ 'hetelhelor'
+ >>> amsco_transposition_encipher('hellothere', 'acb', fillpattern=(1, 2))
+ 'hotelerelh'
+ >>> amsco_transposition_encipher('hellothere', 'acb', fillpattern=(2, 1))
+ 'hetelorlhe'
+ >>> amsco_transposition_encipher('hereissometexttoencipher', 'encode')
+ 'etecstthhomoerereenisxip'
+ >>> amsco_transposition_encipher('hereissometexttoencipher', 'cipher', fillpattern=(1, 2))
+ 'hetcsoeisterereipexthomn'
+ >>> amsco_transposition_encipher('hereissometexttoencipher', 'cipher', fillpattern=(1, 2), fillstyle=AmscoFillStyle.continuous)
+ 'hecsoisttererteipexhomen'
+ >>> amsco_transposition_encipher('hereissometexttoencipher', 'cipher', fillpattern=(2, 1))
+ 'heecisoosttrrtepeixhemen'
+ >>> amsco_transposition_encipher('hereissometexttoencipher', 'cipher', fillpattern=(1, 3, 2))
+ 'hxtomephescieretoeisnter'
+ >>> amsco_transposition_encipher('hereissometexttoencipher', 'cipher', fillpattern=(1, 3, 2), fillstyle=AmscoFillStyle.continuous)
+ 'hxomeiphscerettoisenteer'
+ """
+ grid = amsco_transposition_positions(message, keyword,
+ fillpattern=fillpattern, fillstyle=fillstyle)
+ ct_as_grid = [[message[s.start:s.end] for s in r] for r in grid]
+ return combine_every_nth(ct_as_grid)
+
+
+def amsco_transposition_decipher(message, keyword,
+ fillpattern=(1,2), fillstyle=AmscoFillStyle.reverse_each_row):
+ """AMSCO transposition decipher
+
+ >>> amsco_transposition_decipher('hoteelhler', 'abc', fillpattern=(1, 2))
+ 'hellothere'
+ >>> amsco_transposition_decipher('hetelhelor', 'abc', fillpattern=(2, 1))
+ 'hellothere'
+ >>> amsco_transposition_decipher('hotelerelh', 'acb', fillpattern=(1, 2))
+ 'hellothere'
+ >>> amsco_transposition_decipher('hetelorlhe', 'acb', fillpattern=(2, 1))
+ 'hellothere'
+ >>> amsco_transposition_decipher('etecstthhomoerereenisxip', 'encode')
+ 'hereissometexttoencipher'
+ >>> amsco_transposition_decipher('hetcsoeisterereipexthomn', 'cipher', fillpattern=(1, 2))
+ 'hereissometexttoencipher'
+ >>> amsco_transposition_decipher('hecsoisttererteipexhomen', 'cipher', fillpattern=(1, 2), fillstyle=AmscoFillStyle.continuous)
+ 'hereissometexttoencipher'
+ >>> amsco_transposition_decipher('heecisoosttrrtepeixhemen', 'cipher', fillpattern=(2, 1))
+ 'hereissometexttoencipher'
+ >>> amsco_transposition_decipher('hxtomephescieretoeisnter', 'cipher', fillpattern=(1, 3, 2))
+ 'hereissometexttoencipher'
+ >>> amsco_transposition_decipher('hxomeiphscerettoisenteer', 'cipher', fillpattern=(1, 3, 2), fillstyle=AmscoFillStyle.continuous)
+ 'hereissometexttoencipher'
+ """
+
+ grid = amsco_transposition_positions(message, keyword,
+ fillpattern=fillpattern, fillstyle=fillstyle)
+ transposed_sections = [s for c in [l for l in zip(*grid)] for s in c]
+ plaintext_list = [''] * len(transposed_sections)
+ current_pos = 0
+ for slice in transposed_sections:
+ plaintext_list[slice.index] = message[current_pos:current_pos-slice.start+slice.end][:len(message[slice.start:slice.end])]
+ current_pos += len(message[slice.start:slice.end])
+ return ''.join(plaintext_list)
+
+
+class PocketEnigma(object):
+ """A pocket enigma machine
+ The wheel is internally represented as a 26-element list self.wheel_map,
+ where wheel_map[i] == j shows that the position i places on from the arrow
+ maps to the position j places on.
+ """
+ def __init__(self, wheel=1, position='a'):
+ """initialise the pocket enigma, including which wheel to use and the
+ starting position of the wheel.
+
+ The wheel is either 1 or 2 (the predefined wheels) or a list of letter
+ pairs.
+
+ The position is the letter pointed to by the arrow on the wheel.
+
+ >>> pe.wheel_map
+ [25, 4, 23, 10, 1, 7, 9, 5, 12, 6, 3, 17, 8, 14, 13, 21, 19, 11, 20, 16, 18, 15, 24, 2, 22, 0]
+ >>> pe.position
+ 0
+ """
+ self.wheel1 = [('a', 'z'), ('b', 'e'), ('c', 'x'), ('d', 'k'),
+ ('f', 'h'), ('g', 'j'), ('i', 'm'), ('l', 'r'), ('n', 'o'),
+ ('p', 'v'), ('q', 't'), ('s', 'u'), ('w', 'y')]
+ self.wheel2 = [('a', 'c'), ('b', 'd'), ('e', 'w'), ('f', 'i'),
+ ('g', 'p'), ('h', 'm'), ('j', 'k'), ('l', 'n'), ('o', 'q'),
+ ('r', 'z'), ('s', 'u'), ('t', 'v'), ('x', 'y')]
+ if wheel == 1:
+ self.make_wheel_map(self.wheel1)
+ elif wheel == 2:
+ self.make_wheel_map(self.wheel2)
+ else:
+ self.validate_wheel_spec(wheel)
+ self.make_wheel_map(wheel)
+ if position in string.ascii_lowercase:
+ self.position = ord(position) - ord('a')
+ else:
+ self.position = position
+
+ def make_wheel_map(self, wheel_spec):
+ """Expands a wheel specification from a list of letter-letter pairs
+ into a full wheel_map.
+
+ >>> pe.make_wheel_map(pe.wheel2)
+ [2, 3, 0, 1, 22, 8, 15, 12, 5, 10, 9, 13, 7, 11, 16, 6, 14, 25, 20, 21, 18, 19, 4, 24, 23, 17]
+ """
+ self.validate_wheel_spec(wheel_spec)
+ self.wheel_map = [0] * 26
+ for p in wheel_spec:
+ self.wheel_map[ord(p[0]) - ord('a')] = ord(p[1]) - ord('a')
+ self.wheel_map[ord(p[1]) - ord('a')] = ord(p[0]) - ord('a')
+ return self.wheel_map
+
+ def validate_wheel_spec(self, wheel_spec):
+ """Validates that a wheel specificaiton will turn into a valid wheel
+ map.
+
+ >>> pe.validate_wheel_spec([])
+ Traceback (most recent call last):
+ ...
+ ValueError: Wheel specification has 0 pairs, requires 13
+ >>> pe.validate_wheel_spec([('a', 'b', 'c')]*13)
+ Traceback (most recent call last):
+ ...
+ ValueError: Not all mappings in wheel specificationhave two elements
+ >>> pe.validate_wheel_spec([('a', 'b')]*13)
+ Traceback (most recent call last):
+ ...
+ ValueError: Wheel specification does not contain 26 letters
+ """
+ if len(wheel_spec) != 13:
+ raise ValueError("Wheel specification has {} pairs, requires 13".
+ format(len(wheel_spec)))
+ for p in wheel_spec:
+ if len(p) != 2:
+ raise ValueError("Not all mappings in wheel specification"
+ "have two elements")
+ if len(set([p[0] for p in wheel_spec] +
+ [p[1] for p in wheel_spec])) != 26:
+ raise ValueError("Wheel specification does not contain 26 letters")
+
+ def encipher_letter(self, letter):
+ """Enciphers a single letter, by advancing the wheel before looking up
+ the letter on the wheel.
+
+ >>> pe.set_position('f')
+ 5
+ >>> pe.encipher_letter('k')
+ 'h'
+ """
+ self.advance()
+ return self.lookup(letter)
+ decipher_letter = encipher_letter
+
+ def lookup(self, letter):
+ """Look up what a letter enciphers to, without turning the wheel.
+
+ >>> pe.set_position('f')
+ 5
+ >>> ''.join([pe.lookup(l) for l in string.ascii_lowercase])
+ 'udhbfejcpgmokrliwntsayqzvx'
+ >>> pe.lookup('A')
+ ''
+ """
+ if letter in string.ascii_lowercase:
+ return chr(
+ (self.wheel_map[(ord(letter) - ord('a') - self.position) % 26] +
+ self.position) % 26 +
+ ord('a'))
+ else:
+ return ''
+
+ def advance(self):
+ """Advances the wheel one position.
+
+ >>> pe.set_position('f')
+ 5
+ >>> pe.advance()
+ 6
+ """
+ self.position = (self.position + 1) % 26
+ return self.position
+
+ def encipher(self, message, starting_position=None):
+ """Enciphers a whole message.
+
+ >>> pe.set_position('f')
+ 5
+ >>> pe.encipher('helloworld')
+ 'kjsglcjoqc'
+ >>> pe.set_position('f')
+ 5
+ >>> pe.encipher('kjsglcjoqc')
+ 'helloworld'
+ >>> pe.encipher('helloworld', starting_position = 'x')
+ 'egrekthnnf'
+ """
+ if starting_position:
+ self.set_position(starting_position)
+ transformed = ''
+ for l in message:
+ transformed += self.encipher_letter(l)
+ return transformed
+ decipher = encipher
+
+ def set_position(self, position):
+ """Sets the position of the wheel, by specifying the letter the arrow
+ points to.
+
+ >>> pe.set_position('a')
+ 0
+ >>> pe.set_position('m')
+ 12
+ >>> pe.set_position('z')
+ 25
+ """
+ self.position = ord(position) - ord('a')
+ return self.position
+
if __name__ == "__main__":
import doctest
- doctest.testmod()
+ doctest.testmod(extraglobs={'pe': PocketEnigma(1, 'a')})
projects / cipher-training.git / commitdiff