X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=cipher.py;h=248155edb8a54956df51348a64fc26c9532db339;hb=3d8f7067b9c3a48ef140d7cff834d18ee91f58b3;hp=58d381290e9fbe33f533b558f1644a7552e052d8;hpb=3e9738b298b69adc2bc9f545a3cb21f3e4926575;p=cipher-tools.git diff --git a/cipher.py b/cipher.py index 58d3812..248155e 100644 --- a/cipher.py +++ b/cipher.py @@ -1,214 +1,31 @@ -import string -import collections -import norms -import logging +# import string +# import collections +# 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 + + + +from utilities import * +from segment import * +from text_prettify import * +from plot_frequency_histogram import * + +from caesar import * +from affine import * +from keyword import * +from polybius import * +from column_transposition import * +from railfence import * +from cadenus import * +from hill import * +from amsco import * +from bifid import * +from autokey import * +from pocket_enigma import * -logger = logging.getLogger(__name__) -logger.addHandler(logging.FileHandler('cipher.log')) -# logging.basicConfig(filename='cipher.log',level=logging.WARNING) -logger.setLevel(logging.INFO) - -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) - - -modular_division_table = [[0]*26 for x in range(26)] -for a in range(26): - for b in range(26): - c = (a * b) % 26 - modular_division_table[b][c] = a - - -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) - -def ngrams(text, n): - return [tuple(text[i:i+n]) for i in range(len(text)-n+1)] - -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)] - """ - 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' - """ - 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) - 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) - 'z' - """ - return caesar_encipher_letter(letter, -shift) - -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' - """ - enciphered = [caesar_encipher_letter(l, shift) for l in message] - return ''.join(enciphered) - -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' - """ - return caesar_encipher(message, -shift) - -def affine_encipher_letter(letter, multiplier, adder, multiply_then_add=True): - 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 - cipher_number = 0 - if multiply_then_add: - cipher_number = (letter_number * multiplier + adder) % 26 - else: - cipher_number = ((letter_number + adder) * multiplier) % 26 - return chr(cipher_number + alphabet_start) - else: - return letter - -def affine_decipher_letter(letter, multiplier, adder, multiply_then_add=True): - 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 - plaintext_number = 0 - if multiply_then_add: - plaintext_number = modular_division_table[multiplier][(cipher_number - adder + 26) % 26] - else: - plaintext_number = (modular_division_table[multiplier][cipher_number] - adder) % 26 - return chr(plaintext_number + alphabet_start) - else: - return letter - -def affine_encipher(message, multiplier, adder, multiply_then_add=True): - enciphered = [affine_encipher_letter(l, multiplier, adder, multiply_then_add) for l in message] - return ''.join(enciphered) - -def affine_decipher(message, multiplier, adder, multiply_then_add=True): - enciphered = [affine_decipher_letter(l, multiplier, adder, multiply_then_add) for l in message] - return ''.join(enciphered) - - -def caesar_break(message, metric=norms.euclidean_distance, target_frequencies=normalised_english_counts, message_frequency_scaling=norms.normalise): - """Breaks a Caesar cipher using frequency analysis - - >>> caesar_break('ibxcsyorsaqcheyklxivoexlevmrimwxsfiqevvmihrsasrxliwyrhecjsppsamrkwleppfmergefifvmhixscsymjcsyqeoixlm') - (4, 0.3186395289018361) - >>> caesar_break('wxwmaxdgheetgwuxztgptedbgznitgwwhpguxyhkxbmhvvtlbhgteeraxlmhiixweblmxgxwmhmaxybkbgztgwztsxwbgmxgmert') - (19, 0.4215290123583277) - >>> caesar_break('yltbbqnqnzvguvaxurorgenafsbezqvagbnornfgsbevpnaabjurersvaquvzyvxrnznazlybequrvfohgriraabjtbaruraprur') - (13, 0.31602920807545154) - """ - sanitised_message = sanitise(message) - best_shift = 0 - best_fit = float("inf") - for shift in range(26): - plaintext = caesar_decipher(sanitised_message, shift) - frequencies = message_frequency_scaling(letter_frequencies(plaintext)) - fit = metric(target_frequencies, frequencies) - logger.info('Caesar break attempt using key {0} gives fit of {1} and decrypt starting: {2}'.format(shift, fit, plaintext[:50])) - if fit < best_fit: - best_fit = fit - best_shift = shift - logger.info('Caesar break best fit: key {0} gives fit of {1} and decrypt starting: {2}'.format(best_shift, best_fit, caesar_decipher(sanitised_message, best_shift)[:50])) - return best_shift, best_fit - -def affine_break(message, metric=norms.euclidean_distance, target_frequencies=normalised_english_counts, message_frequency_scaling=norms.normalise): - """Breaks an affine cipher using frequency analysis - """ - sanitised_message = sanitise(message) - best_multiplier = 0 - best_adder = 0 - best_multiply_then_add = True - best_fit = float("inf") - for multiply_then_add in [True, False]: - for multiplier in range(1, 26, 2): - for adder in range(26): - plaintext = affine_decipher(sanitised_message, multiplier, adder, multiply_then_add) - frequencies = message_frequency_scaling(letter_frequencies(plaintext)) - fit = metric(target_frequencies, frequencies) - logger.info('Affine break attempt using key {0}x+{1} ({2}) gives fit of {3} and decrypt starting: {4}'.format(multiplier, adder, multiply_then_add, fit, plaintext[:50])) - if fit < best_fit: - best_fit = fit - best_multiplier = multiplier - best_adder = adder - best_multiply_then_add = multiply_then_add - logger.info('Affine break best fit with key {0}x+{1} ({2}) gives fit of {3} and decrypt starting: {4}'.format(best_multiplier, best_adder, best_multiply_then_add, best_fit, affine_decipher(sanitised_message, best_multiplier, best_adder, best_multiply_then_add)[:50])) - return (best_multiplier, best_adder, best_multiply_then_add), best_fit - - -if __name__ == "__main__": - import doctest - doctest.testmod()