-"""A set of ciphers with implementations for both enciphering and deciphering
-them. See cipherbreak for automatic breaking of these ciphers
-"""
-
import string
import collections
+import math
from enum import Enum
-from itertools import zip_longest, cycle, chain
-from language_models import unaccent, sanitise
+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)]
def every_nth(text, n, fillvalue=''):
- """Returns n strings, each of which consists of every nth character,
+ """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',
+ ['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!']
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))
>>> combine_every_nth(every_nth(string.ascii_lowercase, 26))
'abcdefghijklmnopqrstuvwxyz'
"""
- return ''.join([''.join(l)
- for l in zip_longest(*split_text, fillvalue='')])
+ 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
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))
"""
transposed = [''] * len(transposition)
for p, t in enumerate(transposition):
- transposed[p] = items[t]
+ transposed[p] = items[t]
return transposed
def untranspose(items, transposition):
"""
transposed = [''] * len(transposition)
for p, t in enumerate(transposition):
- transposed[t] = items[p]
+ transposed[t] = items[p]
return transposed
def deduplicate(text):
- """If a string contains duplicate letters, remove all but the first. Retain
- the order of the letters.
-
- >>> deduplicate('cat')
- ['c', 'a', 't']
- >>> deduplicate('happy')
- ['h', 'a', 'p', 'y']
- >>> deduplicate('cattca')
- ['c', 'a', 't']
- """
return list(collections.OrderedDict.fromkeys(text))
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):
+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'
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'
alphabet_start = ord('a')
cipher_number = ord(letter) - alphabet_start
if one_based: cipher_number += 1
- plaintext_number = (
+ plaintext_number = (
modular_division_table[multiplier]
- [(cipher_number - adder) % 26] )
+ [(cipher_number - adder) % 26])
if one_based: plaintext_number -= 1
- return chr(plaintext_number % 26 + alphabet_start)
+ 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)
+ 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)
+ enciphered = [affine_decipher_letter(l, multiplier, adder, one_based)
for l in message]
return ''.join(enciphered)
-class Keyword_wrap_alphabet(Enum):
- """Ways of wrapping the alphabet for keyword-based substitution ciphers."""
+class KeywordWrapAlphabet(Enum):
from_a = 1
from_last = 2
from_largest = 3
-def keyword_cipher_alphabet_of(keyword,
- wrap_alphabet=Keyword_wrap_alphabet.from_a):
+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', Keyword_wrap_alphabet.from_a)
+ >>> keyword_cipher_alphabet_of('bayes', KeywordWrapAlphabet.from_a)
'bayescdfghijklmnopqrtuvwxz'
- >>> keyword_cipher_alphabet_of('bayes', Keyword_wrap_alphabet.from_last)
+ >>> keyword_cipher_alphabet_of('bayes', KeywordWrapAlphabet.from_last)
'bayestuvwxzcdfghijklmnopqr'
- >>> keyword_cipher_alphabet_of('bayes', Keyword_wrap_alphabet.from_largest)
+ >>> keyword_cipher_alphabet_of('bayes', KeywordWrapAlphabet.from_largest)
'bayeszcdfghijklmnopqrtuvwx'
"""
- if wrap_alphabet == Keyword_wrap_alphabet.from_a:
- cipher_alphabet = ''.join(deduplicate(sanitise(keyword) +
+ if wrap_alphabet == KeywordWrapAlphabet.from_a:
+ cipher_alphabet = ''.join(deduplicate(sanitise(keyword) +
string.ascii_lowercase))
else:
- if wrap_alphabet == Keyword_wrap_alphabet.from_last:
+ 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:] +
+ deduplicate(sanitise(keyword) +
+ string.ascii_lowercase[last_keyword_position:] +
string.ascii_lowercase))
return cipher_alphabet
-def keyword_encipher(message, keyword,
- wrap_alphabet=Keyword_wrap_alphabet.from_a):
+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.
>>> keyword_encipher('test message', 'bayes')
'rsqr ksqqbds'
- >>> keyword_encipher('test message', 'bayes', Keyword_wrap_alphabet.from_a)
+ >>> keyword_encipher('test message', 'bayes', KeywordWrapAlphabet.from_a)
'rsqr ksqqbds'
- >>> keyword_encipher('test message', 'bayes', Keyword_wrap_alphabet.from_last)
+ >>> keyword_encipher('test message', 'bayes', KeywordWrapAlphabet.from_last)
'lskl dskkbus'
- >>> keyword_encipher('test message', 'bayes', Keyword_wrap_alphabet.from_largest)
+ >>> 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=Keyword_wrap_alphabet.from_a):
+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', Keyword_wrap_alphabet.from_a)
+ >>> keyword_decipher('rsqr ksqqbds', 'bayes', KeywordWrapAlphabet.from_a)
'test message'
- >>> keyword_decipher('lskl dskkbus', 'bayes', Keyword_wrap_alphabet.from_last)
+ >>> keyword_decipher('lskl dskkbus', 'bayes', KeywordWrapAlphabet.from_last)
'test message'
- >>> keyword_decipher('qspq jsppbcs', 'bayes', Keyword_wrap_alphabet.from_largest)
+ >>> keyword_decipher('qspq jsppbcs', 'bayes', KeywordWrapAlphabet.from_largest)
'test message'
"""
cipher_alphabet = keyword_cipher_alphabet_of(keyword, wrap_alphabet)
return transpositions
def pad(message_len, group_len, fillvalue):
- """Returns the padding required to extend a message of message_len to an
- even multiple of group_len, by adding repreated copies of fillvalue.
- fillvalue can either be a character or a function that returns a character.
-
- >>> pad(10, 4, '!')
- '!!'
- >>> pad(8, 4, '!')
- ''
- >>> pad(16, 4, '!')
- ''
- >>> pad(10, 4, lambda: '*')
- '**'
- """
padding_length = group_len - message_len % group_len
if padding_length == group_len: padding_length = 0
padding = ''
- for _ in range(padding_length):
+ for i in range(padding_length):
if callable(fillvalue):
padding += fillvalue()
else:
padding += fillvalue
return padding
-def column_transposition_encipher(message, keyword, fillvalue=' ',
+def column_transposition_encipher(message, keyword, fillvalue=' ',
fillcolumnwise=False,
emptycolumnwise=False):
"""Enciphers using the column transposition cipher.
else:
return ''.join(chain(*transposed))
-def column_transposition_decipher(message, keyword, fillvalue=' ',
+def column_transposition_decipher(message, keyword, fillvalue=' ',
fillcolumnwise=False,
emptycolumnwise=False):
"""Deciphers using the column transposition cipher.
'hellothere'
"""
transpositions = transpositions_of(keyword)
- message += pad(len(message), len(transpositions), '*')
+ message += pad(len(message), len(transpositions), fillvalue)
if emptycolumnwise:
rows = every_nth(message, len(message) // len(transpositions))
else:
>>> 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,
+ return column_transposition_encipher(message, transpositions,
fillvalue=fillvalue, fillcolumnwise=True, emptycolumnwise=False)
def scytale_decipher(message, rows):
>>> 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,
+ 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 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'])
+
+def amsco_transposition_positions(message, keyword,
+ fillpattern=(1, 2),
+ 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 = []
+ while current_position < message_length:
+ row = []
+ 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]
+ return [transpose(r, transpositions) for r in grid]
+
+def amsco_transposition_encipher(message, keyword, fillpattern=(1,2)):
+ """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', 'cipher', fillpattern=(1, 2))
+ 'hecsoisttererteipexhomen'
+ >>> amsco_transposition_encipher('hereissometexttoencipher', 'cipher', fillpattern=(2, 1))
+ 'heetcisooestrrepeixthemn'
+ >>> amsco_transposition_encipher('hereissometexttoencipher', 'cipher', fillpattern=(1, 3, 2))
+ 'hxomeiphscerettoisenteer'
+ """
+ grid = amsco_transposition_positions(message, keyword, fillpattern=fillpattern)
+ 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)):
+ """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('hecsoisttererteipexhomen', 'cipher', fillpattern=(1, 2))
+ 'hereissometexttoencipher'
+ >>> amsco_transposition_decipher('heetcisooestrrepeixthemn', 'cipher', fillpattern=(2, 1))
+ 'hereissometexttoencipher'
+ >>> amsco_transposition_decipher('hxomeiphscerettoisenteer', 'cipher', fillpattern=(1, 3, 2))
+ 'hereissometexttoencipher'
+ """
+
+ grid = amsco_transposition_positions(message, keyword, fillpattern=fillpattern)
+ 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
+ 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'):
>>> pe.position
0
"""
- self.wheel1 = [('a', 'z'), ('b', 'e'), ('c', 'x'), ('d', 'k'),
- ('f', 'h'), ('g', 'j'), ('i', 'm'), ('l', 'r'), ('n', 'o'),
+ 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'),
+ 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)
"""
if letter in string.ascii_lowercase:
return chr(
- (self.wheel_map[(ord(letter) - ord('a') - self.position) % 26] +
- self.position) % 26 +
+ (self.wheel_map[(ord(letter) - ord('a') - self.position) % 26] +
+ self.position) % 26 +
ord('a'))
else:
return ''