X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=cipher.py;h=2eb89f72306e30e4db99e539e36733aa792d13c4;hb=21c390a77d42729afa23844ef2f1295106bed3de;hp=b883abea3cbc32bf81bb37a342efeaf576ffbf02;hpb=ac47ee478ba8e785037c9f25367c111f630eea54;p=cipher-tools.git diff --git a/cipher.py b/cipher.py index b883abe..2eb89f7 100644 --- a/cipher.py +++ b/cipher.py @@ -1,138 +1,547 @@ import string import collections -import norms +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 -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) -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' +from utilities import * +from segment import * + +from caesar import * +from affine import * +from keyword import * +from polybius import * +from column_transposition import * +from railfence import * + + +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 """ - sanitised = [c.lower() for c in text if c in string.ascii_letters] - return ''.join(sanitised) + 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 = cat(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 ngrams(text, n): - return [tuple(text[i:i+n]) for i in range(len(text)-n+1)] +def cadenus_encipher(message, keyword, keycolumn, fillvalue='a'): + """Encipher with the Cadenus cipher -def letter_frequencies(text): - """Count the number of occurrences of each character in text - - >>> 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)] + >>> 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 cat(chain(*transposed)) + +def cadenus_decipher(message, keyword, keycolumn, fillvalue='a'): """ - counts = collections.defaultdict(int) - for c in text: - counts[c] += 1 - return counts - -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' + >>> cadenus_decipher('antodeleeeuhrsidrbhmhdrrhnimefmthgeaetakseomehetyaa' \ + 'suvoyegrastmmuuaeenabbtpchehtarorikswosmvaleatned', \ + 'wink', \ + make_cadenus_keycolumn(reverse=True)) + 'whoeverhasmadeavoyageupthehudsonmustrememberthekaatskillmountainstheyareadismemberedbranchofthegreat' + >>> cadenus_decipher('systretomtattlusoatleeesfiyheasdfnmschbhneuvsnpmtof' \ + 'arenuseieeieltarlmentieetogevesitfaisltngeeuvowul', \ + 'easy', \ + make_cadenus_keycolumn(reverse=True)) + 'aseverelimitationontheusefulnessofthecadenusisthateverymessagemustbeamultipleoftwentyfiveletterslong' """ - 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) + 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 cat(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: - return letter + padding = '' + message = [pos(c) 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 cat([unpos(round(l)) + for l in sum(enciphered_chunks, [])]) -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' +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' """ - return caesar_encipher_letter(letter, -shift) + 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) -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' + +# 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)]] """ - enciphered = [caesar_encipher_letter(l, shift) for l in message] - return ''.join(enciphered) + transpositions = transpositions_of(keyword) + fill_iterator = cycle(fillpattern) + indices = count() + message_length = len(message) -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' + 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' """ - return caesar_encipher(message, -shift) -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 + 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 cat(plaintext_list) + + +def bifid_grid(keyword, wrap_alphabet, letter_mapping): + """Create the grids for a Bifid cipher + """ + cipher_alphabet = keyword_cipher_alphabet_of(keyword, wrap_alphabet) + if letter_mapping is None: + letter_mapping = {'j': 'i'} + translation = ''.maketrans(letter_mapping) + cipher_alphabet = cat(collections.OrderedDict.fromkeys(cipher_alphabet.translate(translation))) + f_grid = {k: ((i // 5) + 1, (i % 5) + 1) + for i, k in enumerate(cipher_alphabet)} + r_grid = {((i // 5) + 1, (i % 5) + 1): k + for i, k in enumerate(cipher_alphabet)} + return translation, f_grid, r_grid + +def bifid_encipher(message, keyword, wrap_alphabet=KeywordWrapAlphabet.from_a, + letter_mapping=None, period=None, fillvalue=None): + """Bifid cipher + + >>> bifid_encipher("indiajelly", 'iguana') + 'ibidonhprm' + >>> bifid_encipher("indiacurry", 'iguana', period=4) + 'ibnhgaqltm' + >>> bifid_encipher("indiacurry", 'iguana', period=4, fillvalue='x') + 'ibnhgaqltzml' + """ + translation, f_grid, r_grid = bifid_grid(keyword, wrap_alphabet, letter_mapping) + + t_message = message.translate(translation) + pairs0 = [f_grid[l] for l in sanitise(t_message)] + if period: + chunked_pairs = [pairs0[i:i+period] for i in range(0, len(pairs0), period)] + if len(chunked_pairs[-1]) < period and fillvalue: + chunked_pairs[-1] += [f_grid[fillvalue]] * (period - len(chunked_pairs[-1])) + else: + chunked_pairs = [pairs0] + pairs1 = [] + for c in chunked_pairs: + items = sum(list(list(i) for i in zip(*c)), []) + p = [(items[i], items[i+1]) for i in range(0, len(items), 2)] + pairs1 += p - >>> caesar_break('ibxcsyorsaqcheyklxivoexlevmrimwxsfiqevvmihrsasrxliwyrhecjsppsamrkwleppfmergefifvmhixscsymjcsyqeoixlm') - (4, 0.3186395289018361) - >>> caesar_break('jhzhuhfrqilqhgwrdevwudfwuhdvrqlqjwkhqkdylqjvxemhfwhgwrfulwlflvpwkhhasodqdwlrqrisrzhuwkdwmxulglfdovfl') - (3, 0.32902042861730835) - >>> caesar_break('wxwmaxdgheetgwuxztgptedbgznitgwwhpguxyhkxbmhvvtlbhgteeraxlmhiixweblmxgxwmhmaxybkbgztgwztsxwbgmxgmert') - (19, 0.4215290123583277) - >>> caesar_break('yltbbqnqnzvguvaxurorgenafsbezqvagbnornfgsbevpnaabjurersvaquvzyvxrnznazlybequrvfohgriraabjtbaruraprur') - (13, 0.31602920807545154) + return cat(r_grid[p] for p in pairs1) + + +def bifid_decipher(message, keyword, wrap_alphabet=KeywordWrapAlphabet.from_a, + letter_mapping=None, period=None, fillvalue=None): + """Decipher with bifid cipher + + >>> bifid_decipher('ibidonhprm', 'iguana') + 'indiaielly' + >>> bifid_decipher("ibnhgaqltm", 'iguana', period=4) + 'indiacurry' + >>> bifid_decipher("ibnhgaqltzml", 'iguana', period=4) + 'indiacurryxx' + """ + translation, f_grid, r_grid = bifid_grid(keyword, wrap_alphabet, letter_mapping) + + t_message = message.translate(translation) + pairs0 = [f_grid[l] for l in sanitise(t_message)] + if period: + chunked_pairs = [pairs0[i:i+period] for i in range(0, len(pairs0), period)] + if len(chunked_pairs[-1]) < period and fillvalue: + chunked_pairs[-1] += [f_grid[fillvalue]] * (period - len(chunked_pairs[-1])) + else: + chunked_pairs = [pairs0] + + pairs1 = [] + for c in chunked_pairs: + items = [j for i in c for j in i] + gap = len(c) + p = [(items[i], items[i+gap]) for i in range(gap)] + pairs1 += p + + return cat(r_grid[p] for p in pairs1) + + +def autokey_encipher(message, keyword): + """Encipher with the autokey cipher + + >>> autokey_encipher('meetatthefountain', 'kilt') + 'wmpmmxxaeyhbryoca' """ - 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) - if fit < best_fit: - best_fit = fit - best_shift = shift - return best_shift, best_fit + shifts = [pos(l) for l in keyword + message] + pairs = zip(message, shifts) + return cat([caesar_encipher_letter(l, k) for l, k in pairs]) + +def autokey_decipher(ciphertext, keyword): + """Decipher with the autokey cipher + + >>> autokey_decipher('wmpmmxxaeyhbryoca', 'kilt') + 'meetatthefountain' + """ + plaintext = [] + keys = list(keyword) + for c in ciphertext: + plaintext_letter = caesar_decipher_letter(c, pos(keys[0])) + plaintext += [plaintext_letter] + keys = keys[1:] + [plaintext_letter] + return cat(plaintext) + + +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 = pos(position) + 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[pos(p[0])] = pos(p[1]) + self.wheel_map[pos(p[1])] = pos(p[0]) + 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 + >>> cat([pe.lookup(l) for l in string.ascii_lowercase]) + 'udhbfejcpgmokrliwntsayqzvx' + >>> pe.lookup('A') + '' + """ + if letter in string.ascii_lowercase: + return unpos( + (self.wheel_map[(pos(letter) - self.position) % 26] + + self.position)) + 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 = pos(position) + return self.position if __name__ == "__main__": import doctest - doctest.testmod() + doctest.testmod(extraglobs={'pe': PocketEnigma(1, 'a')})