added a shift parameter for the lsbset module.

CHANGELOG.rst

@@ -1,6 +1,11 @@
 Release History
 ===============
 
+0.9.0 (2018-12-18)
+------------------
+
+* added the possibility to shift the encoded bits when using the lsbset module.
+
 0.8.6 (2018-11-05)
 ------------------
 

bin/stegano-lsb-set

@@ -55,6 +55,8 @@ parser_hide.add_argument("-g", "--generator", dest="generator_function",
                 choices=[generator[0] for generator in \
                             inspect.getmembers(generators, inspect.isfunction)],
                 required=True, help="Generator")
+parser_hide.add_argument("-s", "--shift", dest="shift",
+                default=0, help="Shift for the generator")
 
 group_secret = parser_hide.add_mutually_exclusive_group(required=True)
 # Non binary secret message to hide
@@ -81,6 +83,8 @@ parser_reveal.add_argument("-g", "--generator", dest="generator_function",
                 choices=[generator[0] for generator in \
                             inspect.getmembers(generators, inspect.isfunction)],
                 required=True, help="Generator")
+parser_reveal.add_argument("-s", "--shift", dest="shift",
+                default=0, help="Shift for the generator")
 parser_reveal.add_argument("-o", dest="secret_binary",
                 help="Output for the binary secret (Text or any binary file).")
 
@@ -111,7 +115,8 @@ if arguments.command == 'hide':
     elif arguments.secret_file != "":
         secret = tools.binary2base64(arguments.secret_file)
 
-    img_encoded = lsbset.hide(arguments.input_image_file, secret, generator)
+    img_encoded = lsbset.hide(arguments.input_image_file, secret, generator,
+                              int(arguments.shift))
     try:
         img_encoded.save(arguments.output_image_file)
     except Exception as e:
@@ -120,7 +125,8 @@ if arguments.command == 'hide':
 
 elif arguments.command == 'reveal':
     try:
-        secret = lsbset.reveal(arguments.input_image_file, generator)
+        secret = lsbset.reveal(arguments.input_image_file, generator,
+                               int(arguments.shift))
     except IndexError:
         print("Impossible to detect message.")
         exit(0)

setup.py

@@ -33,7 +33,7 @@ with codecs.open(os.path.join(here, 'CHANGELOG.rst'), encoding='utf-8') as f:
 
 setup(
     name='Stegano',
-    version='0.8.6',
+    version='0.9.0',
     author='Cédric Bonhomme',
     author_email='cedric@cedricbonhomme.org',
     packages=packages,

stegano/lsbset/lsbset.py

@@ -2,7 +2,7 @@
 #-*- coding: utf-8 -*-
 
 # Stéganô - Stéganô is a basic Python Steganography module.
-# Copyright (C) 2010-2017  Cédric Bonhomme - https://www.cedricbonhomme.org
+# Copyright (C) 2010-2018  Cédric Bonhomme - https://www.cedricbonhomme.org
 #
 # For more information : https://github.com/cedricbonhomme/Stegano
 #
@@ -20,9 +20,9 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>
 
 __author__ = "Cedric Bonhomme"
-__version__ = "$Revision: 0.5 $"
+__version__ = "$Revision: 0.6 $"
 __date__ = "$Date: 2016/03/13 $"
-__revision__ = "$Date: 2017/05/04 $"
+__revision__ = "$Date: 2018/12/18 $"
 __license__ = "GPLv3"
 
 import sys
@@ -36,6 +36,7 @@ from . import generators
 def hide(input_image: Union[str, IO[bytes]],
         message: str,
         generator: Iterator[int],
+        shift: int = 0,
         encoding: str = 'UTF-8',
         auto_convert_rgb: bool = False):
     """Hide a message (string) in an image with the
@@ -68,6 +69,9 @@ def hide(input_image: Union[str, IO[bytes]],
     if len_message_bits > npixels * 3:
         raise Exception("The message you want to hide is too long: {}". \
                                                         format(message_length))
+    while shift != 0:
+        next(generator)
+        shift -= 1
 
     while index + 3 <= len_message_bits :
         generated_number = next(generator)
@@ -97,6 +101,7 @@ def hide(input_image: Union[str, IO[bytes]],
 
 def reveal(input_image: Union[str, IO[bytes]],
             generator: Iterator[int],
+            shift: int = 0,
             encoding: str = 'UTF-8'):
     """Find a message in an image (with the LSB technique).
     """
@@ -107,6 +112,10 @@ def reveal(input_image: Union[str, IO[bytes]],
     bitab = []
     limit = None
 
+    while shift != 0:
+        next(generator)
+        shift -= 1
+
     while True:
         generated_number = next(generator)
         # color = [r, g, b]

tests/test_lsb.py

@@ -54,20 +54,20 @@ class TestLSB(unittest.TestCase):
     def test_hide_and_reveal_UTF32LE(self):
         messages_to_hide = 'I love 🍕 and 🍫!'
         secret = lsb.hide("./tests/sample-files/Lenna.png",
-                            messages_to_hide, 'UTF-32LE')
+                            messages_to_hide, encoding='UTF-32LE')
         secret.save("./image.png")
 
-        clear_message = lsb.reveal("./image.png", 'UTF-32LE')
+        clear_message = lsb.reveal("./image.png", encoding='UTF-32LE')
         self.assertEqual(messages_to_hide, clear_message)
 
     def test_with_transparent_png(self):
         messages_to_hide = ['🍕', 'a', 'foo', 'Hello World!', ':Python:']
         for message in messages_to_hide:
             secret = lsb.hide("./tests/sample-files/transparent.png",
-                                message, 'UTF-32LE')
+                                message, encoding='UTF-32LE')
             secret.save("./image.png")
 
-            clear_message = lsb.reveal("./image.png", 'UTF-32LE')
+            clear_message = lsb.reveal("./image.png", encoding='UTF-32LE')
 
             self.assertEqual(message, clear_message)
 
@@ -75,19 +75,19 @@ class TestLSB(unittest.TestCase):
     def test_manual_convert_rgb(self, input):
         message_to_hide = 'I love 🍕 and 🍫!'
         secret = lsb.hide("./tests/sample-files/Lenna-grayscale.png",
-                            message_to_hide, 'UTF-32LE')
+                            message_to_hide, encoding='UTF-32LE')
 
     @patch('builtins.input', return_value='n')
     def test_refuse_convert_rgb(self, input):
         message_to_hide = 'I love 🍕 and 🍫!'
         with self.assertRaises(Exception):
             secret = lsb.hide("./tests/sample-files/Lenna-grayscale.png",
-                                    message_to_hide, 'UTF-32LE')
+                                    message_to_hide, encoding='UTF-32LE')
 
     def test_auto_convert_rgb(self):
         message_to_hide = 'I love 🍕 and 🍫!'
         secret = lsb.hide("./tests/sample-files/Lenna-grayscale.png",
-                            message_to_hide, 'UTF-32LE', True)
+                            message_to_hide, encoding='UTF-32LE', auto_convert_rgb=True)
 
     def test_with_text_file(self):
         text_file_to_hide = './tests/sample-files/lorem_ipsum.txt'

tests/test_lsbset.py

@@ -54,16 +54,28 @@ class TestLSBSet(unittest.TestCase):
 
             self.assertEqual(message, clear_message)
             
+    def test_hide_and_reveal_with_shift(self):
+        messages_to_hide = ["a", "foo", "Hello World!", ":Python:"]
+        for message in messages_to_hide:
+            secret = lsbset.hide("./tests/sample-files/Lenna.png", message,
+                                    generators.eratosthenes(), 4)
+            secret.save("./image.png")
+
+            clear_message = lsbset.reveal("./image.png",
+                                    generators.eratosthenes(), 4)
+
+            self.assertEqual(message, clear_message)
+
     def test_hide_and_reveal_UTF32LE(self):
         messages_to_hide = 'I love 🍕 and 🍫!'
         secret = lsbset.hide("./tests/sample-files/Lenna.png",
                             messages_to_hide,
                             generators.eratosthenes(),
-                            'UTF-32LE')
+                            encoding='UTF-32LE')
         secret.save("./image.png")
 
         clear_message = lsbset.reveal("./image.png", generators.eratosthenes(),
-                                        'UTF-32LE')
+                                        encoding='UTF-32LE')
         self.assertEqual(messages_to_hide, clear_message)
 
     def test_with_transparent_png(self):