Merge pull request #28 from AdrienCos/master

Improved steganalysis.parity

stegano/steganalysis/parity.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-#-*- coding: utf-8 -*-
+# -*- coding: utf-8 -*-
 
 # Stegano - Stegano is a basic Python Steganography module.
 # Copyright (C) 2010-2019  Cédric Bonhomme - https://www.cedricbonhomme.org
@@ -20,22 +20,23 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>
 
 __author__ = "Cedric Bonhomme"
-__version__ = "$Revision: 0.1 $"
+__version__ = "$Revision: 0.9.4 $"
 __date__ = "$Date: 2010/10/01 $"
+__revision__ = "$Date: 2019/06/06 $"
 __license__ = "GPLv3"
 
 from PIL import Image
 
-def steganalyse(img):
+
+def steganalyse(img: Image.Image) -> Image.Image:
     """
     Steganlysis of the LSB technique.
     """
-    encoded = img.copy()
+    encoded = Image.new(img.mode, (img.size))
     width, height = img.size
-    bits = ""
     for row in range(height):
         for col in range(width):
-            r, g, b = img.getpixel((col, row))
+            r, g, b = img.getpixel((col, row))[0:3]
             if r % 2 == 0:
                 r = 0
             else:
@@ -48,5 +49,5 @@ def steganalyse(img):
                 b = 0
             else:
                 b = 255
-            encoded.putpixel((col, row), (r, g , b))
+            encoded.putpixel((col, row), (r, g, b))
     return encoded

tests/expected-results/statistics

@@ -0,0 +1 @@
+([58, 56, 54, 57, 60, 59, 62, 61, 63, 65, 64, 66, 67, 254, 68, 69, 255, 70, 253, 71, 72, 74, 252, 73, 251, 250, 75, 249, 76, 77], [(224, 4327), (221, 4138), (223, 4057), (222, 3987), (225, 3713), (220, 3554), (209, 3516), (207, 3476), (208, 3424), (219, 3360)])

tests/test_steganalysis.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# Stéganô - Stéganô is a basic Python Steganography module.
+# Copyright (C) 2010-2017  Cédric Bonhomme - https://www.cedricbonhomme.org
+#
+# For more information : https://github.com/cedricbonhomme/Stegano
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>
+
+__author__ = "Cedric Bonhomme"
+__version__ = "$Revision: 0.9.4 $"
+__date__ = "$Date: 2019/06/06 $"
+__revision__ = "$Date: 2019/06/06 $"
+__license__ = "GPLv3"
+
+import io
+import os
+import base64
+import unittest
+from unittest.mock import patch
+
+from stegano import lsb
+from stegano.steganalysis import parity, statistics
+from PIL import Image, ImageChops
+
+
+class TestSteganalysis(unittest.TestCase):
+
+    def test_parity(self):
+        """Test stegano.steganalysis.parity
+        """
+        text_file_to_hide = './tests/sample-files/lorem_ipsum.txt'
+        with open(text_file_to_hide) as f:
+            message = f.read()
+        secret = lsb.hide("./tests/sample-files/Lenna.png", message)
+        analysis = parity.steganalyse(secret)
+        target = Image.open("./tests/expected-results/parity.png")
+        diff = ImageChops.difference(target, analysis).getbbox()
+        self.assertTrue(diff is None)
+
+    def test_parity_rgba(self):
+        """ Test that stegano.steganalysis.parity works with RGBA images
+        """
+        img = Image.open('./tests/sample-files/transparent.png')
+        analysis = parity.steganalyse(img)
+        target = Image.open("./tests/expected-results/parity_rgba.png")
+        diff = ImageChops.difference(target, analysis).getbbox()
+        self.assertTrue(diff is None)
+
+    def test_statistics(self):
+        """ Test stegano.steganalysis.statistics
+        """
+        image = Image.open("./tests/sample-files/Lenna.png")
+        stats = str(statistics.steganalyse(image)) + '\n'
+        file = open("./tests/expected-results/statistics")
+        target = file.read()
+        file.close()
+        self.assertEqual(stats, target)
+
+
+if __name__ == '__main__':
+    unittest.main()