X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=cipher.py;fp=cipher.py;h=83700a538cec2cd55f01b390967565e21e7afbd3;hb=c4e708c39107fc0065684ceed82c6b53a0640a81;hp=f7e3ece485cf1800a1e1d703959b10f05b217cf2;hpb=8eb6246a9b4f99e6b3cd68047e6cef21289417ec;p=cipher-tools.git

diff --git a/cipher.py b/cipher.py
index f7e3ece..83700a5 100644
--- a/cipher.py
+++ b/cipher.py
@@ -632,6 +632,93 @@ def railfence_decipher(message, height, fillvalue=''):
     up_rows.reverse()
     return ''.join(c for r in zip_longest(*(down_rows + up_rows), fillvalue='') for c in r)
 
+def make_cadenus_keycolumn(doubled_letters = 'vw', start='a', reverse=False):
+    """Makes the key column for a Cadenus cipher (the column down between the
+        rows of letters)
+
+    >>> make_cadenus_keycolumn()['a']
+    0
+    >>> make_cadenus_keycolumn()['b']
+    1
+    >>> make_cadenus_keycolumn()['c']
+    2
+    >>> make_cadenus_keycolumn()['v']
+    21
+    >>> make_cadenus_keycolumn()['w']
+    21
+    >>> make_cadenus_keycolumn()['z']
+    24
+    >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['a']
+    1
+    >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['b']
+    0
+    >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['c']
+    24
+    >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['i']
+    18
+    >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['j']
+    18
+    >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['v']
+    6
+    >>> make_cadenus_keycolumn(doubled_letters='ij', start='b', reverse=True)['z']
+    2
+    """
+    index_to_remove = string.ascii_lowercase.find(doubled_letters[0])
+    short_alphabet = string.ascii_lowercase[:index_to_remove] + string.ascii_lowercase[index_to_remove+1:]
+    if reverse:
+        short_alphabet = ''.join(reversed(short_alphabet))
+    start_pos = short_alphabet.find(start)
+    rotated_alphabet = short_alphabet[start_pos:] + short_alphabet[:start_pos]
+    keycolumn = {l: i for i, l in enumerate(rotated_alphabet)}
+    keycolumn[doubled_letters[0]] = keycolumn[doubled_letters[1]]
+    return keycolumn
+
+def cadenus_encipher(message, keyword, keycolumn, fillvalue='a'):
+    """Encipher with the Cadenus cipher
+
+    >>> cadenus_encipher(sanitise('Whoever has made a voyage up the Hudson ' \
+                                  'must remember the Kaatskill mountains. ' \
+                                  'They are a dismembered branch of the great'), \
+                'wink', \
+                make_cadenus_keycolumn(doubled_letters='vw', start='a', reverse=True))
+    'antodeleeeuhrsidrbhmhdrrhnimefmthgeaetakseomehetyaasuvoyegrastmmuuaeenabbtpchehtarorikswosmvaleatned'
+    >>> cadenus_encipher(sanitise('a severe limitation on the usefulness of ' \
+                                  'the cadenus is that every message must be ' \
+                                  'a multiple of twenty-five letters long'), \
+                'easy', \
+                make_cadenus_keycolumn(doubled_letters='vw', start='a', reverse=True))
+    'systretomtattlusoatleeesfiyheasdfnmschbhneuvsnpmtofarenuseieeieltarlmentieetogevesitfaisltngeeuvowul'
+    """
+    rows = chunks(message, len(message) // 25, fillvalue=fillvalue)
+    columns = zip(*rows)
+    rotated_columns = [col[start:] + col[:start] for start, col in zip([keycolumn[l] for l in keyword], columns)]    
+    rotated_rows = zip(*rotated_columns)
+    transpositions = transpositions_of(keyword)
+    transposed = [transpose(r, transpositions) for r in rotated_rows]
+    return ''.join(chain(*transposed))
+
+def cadenus_decipher(message, keyword, keycolumn, fillvalue='a'):
+    """
+    >>> cadenus_decipher('antodeleeeuhrsidrbhmhdrrhnimefmthgeaetakseomehetyaa' \
+                         'suvoyegrastmmuuaeenabbtpchehtarorikswosmvaleatned', \
+                 'wink', \
+                 make_cadenus_keycolumn(reverse=True))
+    'whoeverhasmadeavoyageupthehudsonmustrememberthekaatskillmountainstheyareadismemberedbranchofthegreat'
+    >>> cadenus_decipher('systretomtattlusoatleeesfiyheasdfnmschbhneuvsnpmtof' \
+                        'arenuseieeieltarlmentieetogevesitfaisltngeeuvowul', \
+                 'easy', \
+                 make_cadenus_keycolumn(reverse=True))
+    'aseverelimitationontheusefulnessofthecadenusisthateverymessagemustbeamultipleoftwentyfiveletterslong'
+    """
+    rows = chunks(message, len(message) // 25, fillvalue=fillvalue)
+    transpositions = transpositions_of(keyword)
+    untransposed_rows = [untranspose(r, transpositions) for r in rows]
+    columns = zip(*untransposed_rows)
+    rotated_columns = [col[-start:] + col[:-start] for start, col in zip([keycolumn[l] for l in keyword], columns)]    
+    rotated_rows = zip(*rotated_columns)
+    # return rotated_columns
+    return ''.join(chain(*rotated_rows))
+
 
 def hill_encipher(matrix, message_letters, fillvalue='a'):
     """Hill cipher