jakobsen

[krypto.git] / jakobsen.py

diff --git a/jakobsen.py b/jakobsen.py
index 25f01dc..799559b 100644 (file)
--- a/jakobsen.py
+++ b/jakobsen.py
@@ -1,44 +1,56 @@
-#!/usr/bin/env python
+"""Modul pro praci s Jakobsenovym algoritmem."""

 
 from itertools import combinations
 import pickle
 from ocesavac import ocesat
 
 from itertools import combinations
 import pickle
 from ocesavac import ocesat

-
-MABECEDA = ' ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+from spolecne import MABECEDA

 
 def nova_tabulka(zprava, abc=MABECEDA):
 
 def nova_tabulka(zprava, abc=MABECEDA):

+    """Vraci tabulku cetnosti bigramu ve zprave nad danou abecedou."""

     tabulka = dict()
     for i in abc:
         tabulka[i] = dict()
         for j in abc:
             tabulka[i][j] = 0
     for i in range(len(zprava) - 1):
     tabulka = dict()
     for i in abc:
         tabulka[i] = dict()
         for j in abc:
             tabulka[i][j] = 0
     for i in range(len(zprava) - 1):

-        if zprava[i] in tabulka and zprava[i+1] in tabulka[zprava[i]]:
-            tabulka[zprava[i]][zprava[i+1]] += 1
+        tabulka[zprava[i]][zprava[i+1]] += 1

     celkem = sum(sum(tab2.values()) for tab2 in tabulka.values())
     celkem = sum(sum(tab2.values()) for tab2 in tabulka.values())

-    if celkem != 0:
-        for i in abc:
-            for j in abc:
-                tabulka[i][j] /= float(celkem)
+    for i in abc:
+        for j in abc:
+            tabulka[i][j] /= float(celkem)

     return tabulka
 
 def vzdalenost(tab1, tab2, abc=MABECEDA):
     return tabulka
 
 def vzdalenost(tab1, tab2, abc=MABECEDA):

+    """Vraci soucet strednich kvadratickych odchylek pro dve tabulky cetnosti
+    bigramu nad danou abecedou."""

     rozdil = 0
     for i in abc:
         for j in abc:
             rozdil += abs(tab1[i][j] - tab2[i][j])
     return rozdil
 
     rozdil = 0
     for i in abc:
         for j in abc:
             rozdil += abs(tab1[i][j] - tab2[i][j])
     return rozdil
 

+def vzdalenost2(tab1, tab2):
+    """Vraci soucet strednich kvadratickych odchylek pro dve tabulky cetnosti
+    bigramu nad danou abecedou."""
+    rozdil = 0
+    for i in range(len(tab1)):
+        for j in range(len(tab1)):
+            rozdil += abs(tab1[i][j] - tab2[i][j])
+    return rozdil
+

 def substituce(zprava, slovnik, abc=MABECEDA):
 def substituce(zprava, slovnik, abc=MABECEDA):

+    """Vrati zpravu, ve ktere jsou znaky dane abecedy nahrazenypodle daneho
+    slovniku."""

     pole = []
     pole = []

-    for c in zprava:
-        if c in abc:
-            pole.append(slovnik[c])
+    for char in zprava:
+        if char in abc:
+            pole.append(slovnik[char])

         else:
         else:

-            pole.append(c)
+            pole.append(char)

     return pole
 
 def poradi_dle_frekvence(zprava, abc=MABECEDA):
     return pole
 
 def poradi_dle_frekvence(zprava, abc=MABECEDA):

+    """Vrati znaky dane abecedy v poradi podle frekvence v dane zprave."""

     freq = dict()
     for char in abc:
         freq[char] = 0
     freq = dict()
     for char in abc:
         freq[char] = 0


@@ -50,29 +62,65 @@ def poradi_dle_frekvence(zprava, abc=MABECEDA):
 class reference:
     pass
 
 class reference:
     pass
 

-def jakobsen(zprava, ref):
-    slovnik = dict(zip(poradi_dle_frekvence(zprava), ref.poradi))
-    tabulka = nova_tabulka(substituce(zprava, slovnik))
-    vzdal = vzdalenost(tabulka, ref.tabulka)
+def prohod(sl_a, sl_b, tabulka):
+    """Vrati tabulku s prohozenou dvojici sloupcu a radku."""
+    tabulka[sl_a], tabulka[sl_b] = tabulka[sl_b], tabulka[sl_a]
+    for c in tabulka.keys():
+        tabulka[c][sl_a], tabulka[c][sl_b] = tabulka[c][sl_b], tabulka[c][sl_a]
+    return
+
+def prohod2(sl_a, sl_b, tabulka):
+    """Vrati tabulku s prohozenou dvojici sloupcu a radku."""
+    tabulka[sl_a], tabulka[sl_b] = tabulka[sl_b], tabulka[sl_a]
+    for c in range(len(tabulka)):
+        tabulka[c][sl_a], tabulka[c][sl_b] = tabulka[c][sl_b], tabulka[c][sl_a]
+    return

 
 

+def dicty_na_listy(tabulka, abeceda):
+    listy = []
+    for a in abeceda:
+        listy.append([tabulka[a][b] for b in abeceda])
+    return listy
+
+def jakobsen(zprava, ref):
+    """Pro danou sifrovanou zpravu vrati substitucni slovnik odvozeny s pomoci
+    Jakobsenova algoritmu s danou referencni tabulkou."""
+    slovnik = poradi_dle_frekvence(zprava, ref.abeceda)
+    tab = nova_tabulka(zprava, ref.abeceda)
+    
+    tabulka = dicty_na_listy(tab, slovnik)
+    reftab = dicty_na_listy(ref.tabulka, ref.poradi)    
+ 
+    vzdal = vzdalenost2(tabulka, reftab)
+    

     vzdal_old = vzdal + 1
     while vzdal_old > vzdal:
         vzdal_old = vzdal
     vzdal_old = vzdal + 1
     while vzdal_old > vzdal:
         vzdal_old = vzdal

-        for (x, y) in combinations(ref.abeceda, 2):
-            slovnik[x], slovnik[y] = slovnik[y], slovnik[x]
-            v1 = vzdalenost(nova_tabulka(substituce(zprava, slovnik)),
-                            ref.tabulka)
-            if  v1 < vzdal:
-                vzdal = v1
-            else:
+        for (x, y) in combinations(range(len(ref.abeceda)), 2):
+            prohod2(x, y, tabulka)
+            nova_vzdalenost = vzdalenost2(tabulka, reftab)
+            if nova_vzdalenost < vzdal:
+                vzdal = nova_vzdalenost

                 slovnik[x], slovnik[y] = slovnik[y], slovnik[x]
                 slovnik[x], slovnik[y] = slovnik[y], slovnik[x]

-
-    return '\n'.join([''.join(substituce(zprava, slovnik)),
+            else:
+                prohod2(x, y, tabulka)
+    return dict(zip(slovnik, ref.poradi))
+    
+def desifruj(zprava, mezery=True):
+    """Vrati vysledek pokusu dekodovat zpravu Jakobsenovym algoritmem."""
+    if mezery:
+        soubor = open('ref')
+    else:
+        soubor = open('bref')
+    ref = pickle.load(soubor)
+    soubor.close()
+    slovnik = jakobsen(ocesat(zprava, mezery), ref)
+    return '\n'.join([''.join(substituce(zprava, slovnik, ref.abeceda)),

                       ' '.join(ref.abeceda),
                       ' '.join([slovnik[c] for c in ref.abeceda])])
 
                       ' '.join(ref.abeceda),
                       ' '.join([slovnik[c] for c in ref.abeceda])])
 

-def desifruj(zprava, refs):
-    f = open(refs, 'rb')
-    ref = pickle.load(f)
-    f.close()
-    return jakobsen(zprava, ref)
+def __test():
+    print desifruj('Mxbhfxn cbfbhinpr, wnx fv f gvzuyr cbenqv.'.upper())
+
+def __test2():
+    print desifruj('Sel pes do lesa a potkal dlazebni kostku. Chtelo by to jeste o neco delsi test, to tedy jo.'.upper())