X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=cipher.py;h=6ef01c325d81a7055760d924c400f86b8b718340;hb=19a359ab34be225b4ab7df3974368a2833d45648;hp=865a1b9808e8c7f9f439243f822bd6738835901f;hpb=afc6b4e900c2215e205ea97d191dd5b78619d250;p=cipher-tools.git diff --git a/cipher.py b/cipher.py index 865a1b9..6ef01c3 100644 --- a/cipher.py +++ b/cipher.py @@ -1,7 +1,8 @@ import string import collections import logging -from itertools import zip_longest, cycle +from itertools import zip_longest, cycle, chain +from counts import * logger = logging.getLogger(__name__) @@ -11,6 +12,19 @@ logger.setLevel(logging.WARNING) #logger.setLevel(logging.DEBUG) +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) + +choices, weights = zip(*weighted_choices) +cumdist = list(itertools.accumulate(weights)) +x = random.random() * cumdist[-1] +choices[bisect.bisect(cumdist, x)] + + modular_division_table = [[0]*26 for x in range(26)] for a in range(26): for b in range(26): @@ -80,6 +94,22 @@ def combine_every_nth(split_text): 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 @@ -110,13 +140,10 @@ def untranspose(items, transposition): transposed[t] = items[p] return transposed - - def deduplicate(text): return list(collections.OrderedDict.fromkeys(text)) - def caesar_encipher_letter(letter, shift): """Encipher a letter, given a shift amount @@ -224,8 +251,9 @@ 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: @@ -394,7 +422,20 @@ def transpositions_of(keyword): transpositions = tuple(key.index(l) for l in sorted(key)) return transpositions -def column_transposition_encipher(message, keyword, fillvalue=' '): +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. @@ -402,11 +443,24 @@ def column_transposition_encipher(message, keyword, fillvalue=' '): 'hleolteher' >>> column_transposition_encipher('hellothere', 'cleverly', fillvalue='!') 'hleolthre!e!' + >>> column_transposition_encipher('hellothere', 'clever', columnwise=True) + 'htleehoelr' """ - return column_transposition_worker(message, keyword, encipher=True, - fillvalue=fillvalue) + transpositions = transpositions_of(keyword) + message += pad(len(message), len(transpositions), fillvalue) + if fillcolumnwise: + rows = every_nth(message, len(transpositions)) + else: + rows = chunks(mesage, len(transpositions)) + columns = every_nth(message, len(transpositions), fillvalue=fillvalue) + 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=' '): +def column_transposition_decipher(message, keyword, fillvalue=' ', + columnwise=False): """Deciphers using the column transposition cipher. Message is padded to allow all rows to be the same length. @@ -414,29 +468,17 @@ def column_transposition_decipher(message, keyword, fillvalue=' '): 'hellothere' >>> column_transposition_decipher('hleolthre!e!', 'cleverly', fillvalue='?') 'hellothere!!' - """ - return column_transposition_worker(message, keyword, encipher=False, - fillvalue=fillvalue) - -def column_transposition_worker(message, keyword, - encipher=True, fillvalue=' '): - """Does the actual work of the column transposition cipher. - Message is padded with spaces to allow all rows to be the same length. - - >>> column_transposition_worker('hellothere', 'clever') - 'hleolteher' - >>> column_transposition_worker('hellothere', 'clever', encipher=True) - 'hleolteher' - >>> column_transposition_worker('hleolteher', 'clever', encipher=False) + >>> column_transposition_decipher('htleehoelr', 'clever', columnwise=True) 'hellothere' """ transpositions = transpositions_of(keyword) - columns = every_nth(message, len(transpositions), fillvalue=fillvalue) - if encipher: - transposed_columns = transpose(columns, transpositions) + if columnwise: + columns = chunks(message, int(len(message) / len(transpositions))) else: - transposed_columns = untranspose(columns, transpositions) - return combine_every_nth(transposed_columns) + columns = every_nth(message, len(transpositions), fillvalue=fillvalue) + untransposed_columns = untranspose(columns, transpositions) + return combine_every_nth(untransposed_columns) + def vigenere_encipher(message, keyword): """Vigenere encipher @@ -458,6 +500,8 @@ def vigenere_decipher(message, 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 if __name__ == "__main__":