X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=cipher.py;h=d2619029de591af1d07e5f85160e187629332751;hb=c03fdcbe5891f43ce328f33121105a71c01eef86;hp=7feaedf90fd289b9fda1da60f0dea9565e1108d1;hpb=d86a492d92a9dfa8f27db824ac67acd641b24714;p=cipher-tools.git diff --git a/cipher.py b/cipher.py index 7feaedf..d261902 100644 --- a/cipher.py +++ b/cipher.py @@ -1,8 +1,8 @@ import string import collections import logging -from itertools import zip_longest, cycle - +from itertools import zip_longest, cycle, chain +from language_models import * logger = logging.getLogger(__name__) logger.addHandler(logging.FileHandler('cipher.log')) @@ -11,32 +11,12 @@ logger.setLevel(logging.WARNING) #logger.setLevel(logging.DEBUG) -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 -def letters(text): - """Remove all non-alphabetic characters from a text - >>> letters('The Quick') - 'TheQuick' - >>> letters('The Quick BROWN fox jumped! over... the (9lazy) DOG') - 'TheQuickBROWNfoxjumpedoverthelazyDOG' - """ - return ''.join([c for c in text if c in string.ascii_letters]) - -def sanitise(text): - """Remove all non-alphabetic characters and convert the text to lowercase - - >>> sanitise('The Quick') - 'thequick' - >>> sanitise('The Quick BROWN fox jumped! over... the (9lazy) DOG') - 'thequickbrownfoxjumpedoverthelazydog' - """ - # sanitised = [c.lower() for c in text if c in string.ascii_letters] - # return ''.join(sanitised) - return letters(text).lower() def ngrams(text, n): """Returns all n-grams of a text @@ -237,8 +217,9 @@ def affine_decipher_letter(letter, multiplier=1, adder=0, one_based=True): 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] ) + plaintext_number = ( + modular_division_table[multiplier] + [(cipher_number - adder) % 26] ) if one_based: plaintext_number -= 1 return chr(plaintext_number % 26 + alphabet_start) else: @@ -407,45 +388,107 @@ def transpositions_of(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=' ', - columnwise=False): + 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', 'clever') + >>> 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', 'clever', columnwise=True) - 'htleehoelr' + >>> column_transposition_encipher('hellothere', 'cleverly', fillvalue=lambda: '*') + 'hleolthre*e*' """ transpositions = transpositions_of(keyword) - columns = every_nth(message, len(transpositions), fillvalue=fillvalue) - transposed_columns = transpose(columns, transpositions) - if columnwise: - return ''.join(transposed_columns) + 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 combine_every_nth(transposed_columns) + return ''.join(chain(*transposed)) def column_transposition_decipher(message, keyword, fillvalue=' ', - columnwise=False): + 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('hleolteher', 'clever') + >>> 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('hleolthre!e!', 'cleverly', fillvalue='?') - 'hellothere!!' - >>> column_transposition_decipher('htleehoelr', 'clever', columnwise=True) + >>> 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' """ + # >>> 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) - if columnwise: - columns = chunks(message, int(len(message) / len(transpositions))) + 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: - columns = every_nth(message, len(transpositions), fillvalue=fillvalue) - untransposed_columns = untranspose(columns, transpositions) - return combine_every_nth(untransposed_columns) + return ''.join(chain(*untransposed)) def vigenere_encipher(message, keyword):