Caesar ciphers

[cipher-training.git] / cipherbreak.py

diff --git a/cipherbreak.py b/cipherbreak.py
deleted file mode 100644 (file)
index ddcb423..0000000
--- a/cipherbreak.py
+++ /dev/null
@@ -1,103 +0,0 @@
-"""A set of functions to break the ciphers give in ciphers.py.
-"""
-
-import string
-import collections
-import norms
-import logging
-import math
-
-import matplotlib.pyplot as plt
-
-logger = logging.getLogger(__name__)
-logger.addHandler(logging.FileHandler('cipher.log'))
-logger.setLevel(logging.WARNING)
-#logger.setLevel(logging.INFO)
-#logger.setLevel(logging.DEBUG)
-
-from cipher import *
-from language_models import *
-
-# To time a run:
-#
-# import timeit
-# c5a = open('2012/5a.ciphertext', 'r').read()
-# timeit.timeit('keyword_break(c5a)', setup='gc.enable() ; from __main__ import c5a ; from cipher import keyword_break', number=1)
-# timeit.repeat('keyword_break_mp(c5a, chunksize=500)', setup='gc.enable() ; from __main__ import c5a ; from cipher import keyword_break_mp', repeat=5, number=1)
-
-
-def frequencies(text):
-    """Count the number of occurrences of each character in text
-
-    >>> sorted(frequencies('abcdefabc').items())
-    [('a', 2), ('b', 2), ('c', 2), ('d', 1), ('e', 1), ('f', 1)]
-    >>> sorted(frequencies('the quick brown fox jumped over the lazy ' \
-         'dog').items()) # doctest: +NORMALIZE_WHITESPACE
-    [(' ', 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(frequencies('The Quick BROWN fox jumped! over... the ' \
-         '(9lazy) DOG').items()) # doctest: +NORMALIZE_WHITESPACE
-    [(' ', 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(frequencies(sanitise('The Quick BROWN fox jumped! over... '\
-         'the (9lazy) DOG')).items()) # doctest: +NORMALIZE_WHITESPACE
-    [('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)]
-    >>> frequencies('abcdefabcdef')['x']
-    0
-    """
-    return collections.Counter(c for c in text)
-
-
-def caesar_break(message, fitness=Pletters):
-    """Breaks a Caesar cipher using frequency analysis
-
-    >>> caesar_break('ibxcsyorsaqcheyklxivoexlevmrimwxsfiqevvmihrsasrxliwyrh' \
-          'ecjsppsamrkwleppfmergefifvmhixscsymjcsyqeoixlm') # doctest: +ELLIPSIS
-    (4, -130.849989015...)
-    >>> caesar_break('wxwmaxdgheetgwuxztgptedbgznitgwwhpguxyhkxbmhvvtlbhgtee' \
-          'raxlmhiixweblmxgxwmhmaxybkbgztgwztsxwbgmxgmert') # doctest: +ELLIPSIS
-    (19, -128.82410410...)
-    >>> caesar_break('yltbbqnqnzvguvaxurorgenafsbezqvagbnornfgsbevpnaabjurer' \
-          'svaquvzyvxrnznazlybequrvfohgriraabjtbaruraprur') # doctest: +ELLIPSIS
-    (13, -126.25403935...)
-    """
-    sanitised_message = sanitise(message)
-    best_shift = 0
-    best_fit = float('-inf')
-    for shift in range(26):
-        plaintext = caesar_decipher(sanitised_message, shift)
-        fit = fitness(plaintext)
-        logger.debug('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 plot_frequency_histogram(freqs, sort_key=None):
-    x = range(len(freqs.keys()))
-    y = [freqs[l] for l in sorted(freqs.keys(), key=sort_key)]
-    f = plt.figure()
-    ax = f.add_axes([0.1, 0.1, 0.9, 0.9])
-    ax.bar(x, y, align='center')
-    ax.set_xticks(x)
-    ax.set_xticklabels(sorted(freqs.keys(), key=sort_key))
-    f.show()
-
-
-if __name__ == "__main__":
-    import doctest
-    doctest.testmod()