X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=cipher.py;h=a511e2492667dfa4abad4ada7f15d67a4aa30d75;hb=07c3f8b652e218c94ad2a0dd1fb4657be4c6fe17;hp=e39abce8adf96fa495b631370057ba1470bc6525;hpb=fd4d8412589611d63f59a23424e919350fa827ed;p=cipher-training.git diff --git a/cipher.py b/cipher.py index e39abce..a511e24 100644 --- a/cipher.py +++ b/cipher.py @@ -1,9 +1,11 @@ +"""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 * +from language_models import unaccent, sanitise modular_division_table = [[0]*26 for _ in range(26)] @@ -13,83 +15,17 @@ for a in range(26): modular_division_table[b][c] = a -def every_nth(text, n, fillvalue=''): - """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', - 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'] - >>> every_nth(string.ascii_lowercase, 5, fillvalue='!') - ['afkpuz', 'bglqv!', 'chmrw!', 'dinsx!', 'ejoty!'] - """ - split_text = [text[i:i+n] for i in range(0, len(text), n)] - return [''.join(l) for l in zip_longest(*split_text, fillvalue=fillvalue)] - -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)) - 'abcdefghijklmnopqrstuvwxyz' - >>> combine_every_nth(every_nth(string.ascii_lowercase, 26)) - 'abcdefghijklmnopqrstuvwxyz' - """ - 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 - - >>> transpose(['a', 'b', 'c', 'd'], (0,1,2,3)) - ['a', 'b', 'c', 'd'] - >>> transpose(['a', 'b', 'c', 'd'], (3,1,2,0)) - ['d', 'b', 'c', 'a'] - >>> transpose([10,11,12,13,14,15], (3,2,4,1,5,0)) - [13, 12, 14, 11, 15, 10] - """ - transposed = [''] * len(transposition) - for p, t in enumerate(transposition): - transposed[p] = items[t] - return transposed - -def untranspose(items, transposition): - """Undoes a transpose - - >>> untranspose(['a', 'b', 'c', 'd'], [0,1,2,3]) - ['a', 'b', 'c', 'd'] - >>> untranspose(['d', 'b', 'c', 'a'], [3,1,2,0]) - ['a', 'b', 'c', 'd'] - >>> untranspose([13, 12, 14, 11, 15, 10], [3,2,4,1,5,0]) - [10, 11, 12, 13, 14, 15] - """ - transposed = [''] * len(transposition) - for p, t in enumerate(transposition): - 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)) @@ -123,14 +59,14 @@ def caesar_encipher_letter(accented_letter, shift): 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) @@ -140,7 +76,7 @@ def caesar_decipher_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) @@ -157,7 +93,7 @@ def caesar_encipher(message, shift): def caesar_decipher(message, shift): """Decipher a message with the Caesar cipher of given shift - + >>> caesar_decipher('bcd', 1) 'abc' >>> caesar_decipher('cde', 2) @@ -169,9 +105,9 @@ def caesar_decipher(message, shift): """ 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' @@ -195,7 +131,7 @@ def affine_encipher_letter(accented_letter, multiplier=1, adder=0, one_based=Tru 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' @@ -210,75 +146,79 @@ 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 = ( + 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): +class KeywordWrapAlphabet(Enum): + """Ways of wrapping the alphabet for keyword-based substitution ciphers.""" 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. @@ -288,219 +228,39 @@ def keyword_encipher(message, keyword, wrap_alphabet=Keyword_wrap_alphabet.from_ >>> 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) cipher_translation = ''.maketrans(cipher_alphabet, string.ascii_lowercase) return message.lower().translate(cipher_translation) - -def vigenere_encipher(message, keyword): - """Vigenere encipher - - >>> vigenere_encipher('hello', 'abc') - 'hfnlp' - """ - shifts = [ord(l) - ord('a') for l in sanitise(keyword)] - pairs = zip(message, cycle(shifts)) - return ''.join([caesar_encipher_letter(l, k) for l, k in pairs]) - -def vigenere_decipher(message, keyword): - """Vigenere decipher - - >>> vigenere_decipher('hfnlp', 'abc') - 'hello' - """ - shifts = [ord(l) - ord('a') for l in sanitise(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 - - -def transpositions_of(keyword): - """Finds the transpostions given by a keyword. For instance, the keyword - 'clever' rearranges to 'celrv', so the first column (0) stays first, the - second column (1) moves to third, the third column (2) moves to second, - and so on. - - If passed a tuple, assume it's already a transposition and just return it. - - >>> transpositions_of('clever') - (0, 2, 1, 4, 3) - >>> transpositions_of('fred') - (3, 2, 0, 1) - >>> transpositions_of((3, 2, 0, 1)) - (3, 2, 0, 1) - """ - if isinstance(keyword, tuple): - return keyword - else: - key = deduplicate(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=' ', - 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', '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', 'cleverly', fillvalue=lambda: '*') - 'hleolthre*e*' - """ - transpositions = transpositions_of(keyword) - 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 ''.join(chain(*transposed)) - -def column_transposition_decipher(message, keyword, fillvalue=' ', - 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('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('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' - """ - transpositions = transpositions_of(keyword) - 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: - return ''.join(chain(*untransposed)) - -def scytale_encipher(message, rows, fillvalue=' '): - """Enciphers using the scytale transposition cipher. - Message is padded with spaces to allow all rows to be the same length. - - >>> scytale_encipher('thequickbrownfox', 3) - 'tcnhkfeboqrxuo iw ' - >>> scytale_encipher('thequickbrownfox', 4) - 'tubnhirfecooqkwx' - >>> scytale_encipher('thequickbrownfox', 5) - 'tubnhirfecooqkwx' - >>> scytale_encipher('thequickbrownfox', 6) - 'tqcrnxhukof eibwo ' - >>> scytale_encipher('thequickbrownfox', 7) - 'tqcrnxhukof eibwo ' - """ - transpositions = [i for i in range(math.ceil(len(message) / rows))] - return column_transposition_encipher(message, transpositions, - fillcolumnwise=False, emptycolumnwise=True) - -def scytale_decipher(message, rows): - """Deciphers using the scytale transposition cipher. - Assumes the message is padded so that all rows are the same length. - - >>> scytale_decipher('tcnhkfeboqrxuo iw ', 3) - 'thequickbrownfox ' - >>> scytale_decipher('tubnhirfecooqkwx', 4) - 'thequickbrownfox' - >>> scytale_decipher('tubnhirfecooqkwx', 5) - 'thequickbrownfox' - >>> scytale_decipher('tqcrnxhukof eibwo ', 6) - 'thequickbrownfox ' - >>> scytale_decipher('tqcrnxhukof eibwo ', 7) - 'thequickbrownfox ' - """ - transpositions = [i for i in range(math.ceil(len(message) / rows))] - return column_transposition_decipher(message, transpositions, - fillcolumnwise=False, emptycolumnwise=True) - - if __name__ == "__main__": import doctest doctest.testmod()