X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=cipherbreak.py;h=b1af48c2e40d1ba60b948e75c758ab162f242233;hb=14ac787d794684b5aceacb307d687597e464e7b4;hp=6f4d2aed7d037e509df96970891a7b9e1808c088;hpb=159c157fee78d4370a0e603de450bd8e2def305b;p=cipher-tools.git

diff --git a/cipherbreak.py b/cipherbreak.py
index 6f4d2ae..b1af48c 100644
--- a/cipherbreak.py
+++ b/cipherbreak.py
@@ -416,6 +416,19 @@ def scytale_break_mp(message, max_key_length=20,
 scytale_break = scytale_break_mp
 
 
+def railfence_break(message, max_key_length=20,
+                     fitness=Pletters, chunksize=500):
+    """Breaks a hill cipher using a matrix of given rank and letter frequencies
+
+    
+    """
+    
+    sanitised_message = sanitise(message)
+    results = starmap(worker, [(sanitised_message, i, fitness)
+                               for i in range(2, max_key_length+1)])
+    return max(results, key=lambda k: k[1])
+
+
 def railfence_break(message, max_key_length=20,
                      fitness=Pbigrams, chunksize=500):
     """Breaks a railfence cipher using a range of lengths and
@@ -445,24 +458,43 @@ def railfence_break(message, max_key_length=20,
         plaintext = railfence_decipher(message, height)
         fit = fitness(plaintext)
         return height, fit
+
     sanitised_message = sanitise(message)
     results = starmap(worker, [(sanitised_message, i, fitness)
                                for i in range(2, max_key_length+1)])
     return max(results, key=lambda k: k[1])
 
 
+def hill_break(message, matrix_size=2, fitness=Pletters, 
+    number_of_solutions=1, chunksize=500):
+
+    all_matrices = [np.matrix(list(m)) 
+        for m in itertools.product([list(r) 
+            for r in itertools.product(range(26), repeat=matrix_size)], 
+        repeat=matrix_size)]
+    valid_matrices = [m for m, d in 
+        zip(all_matrices, (int(round(linalg.det(m))) for m in all_matrices))
+                  if d != 0
+                  if d % 2 != 0
+                  if d % 13 != 0 ]
     with Pool() as pool:
-        helper_args = [(message, trans, False, True, fitness)
-            for trans in
-                [[col for col in range(math.ceil(len(message)/rows))]
-                    for rows in range(1,max_key_length+1)]]
+        helper_args = [(message, matrix, fitness)
+                       for matrix in valid_matrices]
         # Gotcha: the helper function here needs to be defined at the top level
         #   (limitation of Pool.starmap)
-        breaks = pool.starmap(column_transposition_break_worker,
-                              helper_args, chunksize)
-        best = max(breaks, key=lambda k: k[1])
-        return math.trunc(len(message) / len(best[0][0])), best[1]
-scytale_break = scytale_break_mp
+        breaks = pool.starmap(hill_break_worker, helper_args, chunksize)
+        if number_of_solutions == 1:
+            return max(breaks, key=lambda k: k[1])
+        else:
+            return sorted(breaks, key=lambda k: k[1], reverse=True)[:number_of_solutions]
+
+def hill_break_worker(message, matrix, fitness):
+    plaintext = hill_decipher(matrix, message)
+    fit = fitness(plaintext)
+    logger.debug('Hill cipher break attempt using key {0} gives fit of '
+                 '{1} and decrypt starting: {2}'.format(matrix, 
+                     fit, sanitise(plaintext)[:50]))
+    return matrix, fit
 
 
 def pocket_enigma_break_by_crib(message, wheel_spec, crib, crib_position):