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Little modifications in the structure. Added comments.

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cedricbonhomme 2010-10-02 09:48:27 +02:00
parent 410c3a3d05
commit 35299d8d05
2 changed files with 36 additions and 35 deletions
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14
LSB.py
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@ -9,7 +9,7 @@ import tools
from PIL import Image from PIL import Image
def encode_image(img, message): def hide(img, message):
""" """
Hide a message (string) in an image with the Hide a message (string) in an image with the
LSB (Less Significant Bit) technic. LSB (Less Significant Bit) technic.
@ -59,7 +59,7 @@ def encode_image(img, message):
return encoded return encoded
def decode_image(img): def reveal(img):
""" """
Find a message in an encoded image (with the Find a message in an encoded image (with the
LSB technic). LSB technic).
@ -86,16 +86,14 @@ if __name__ == '__main__':
# Point of entry in execution mode # Point of entry in execution mode
original_image_file = "./pictures/Lenna.png" original_image_file = "./pictures/Lenna.png"
encoded_image_file = "Lenna_enc.png" encoded_image_file = "Lenna_enc.png"
secret_message = "Avec la technique LSB (Least Significant Bit) l'oeil humain (un normal ;-)) ne voit plus la difference!"
img = Image.open(original_image_file) img1 = Image.open(original_image_file)
img_encoded = hide(img1, secret_message)
secret_msg = "Avec la technique LSB (Least Significant Bit) l'oeil humain (un normal ;-)) ne voit plus la difference!"
img_encoded = encode_image(img, secret_msg)
if img_encoded: if img_encoded:
# Save it # Save it
img_encoded.save(encoded_image_file) img_encoded.save(encoded_image_file)
# Test it # Test it
img2 = Image.open(encoded_image_file) img2 = Image.open(encoded_image_file)
print(decode_image(img2)) print reveal(img2)

57
basic.py
View file

@ -1,14 +1,18 @@
# -*- coding: utf-8 -*- # -*- coding: utf-8 -*-
__author__ = "Cedric Bonhomme"
__version__ = "$Revision: 0.1 $"
__date__ = "$Date: 2010/10/01 $"
from PIL import Image from PIL import Image
def encode_image(img, msg): def hide(img, message):
""" """
use the red portion of an image (r, g, b) tuple to use the red portion of an image (r, g, b) tuple to
hide the msg string characters as ASCII values hide the message string characters as ASCII values
the red value of the first pixel is used for length of string the red value of the first pixel is used for length of string
""" """
length = len(msg) length = len(message)
# limit length of message to 255 # limit length of message to 255
if length > 255: if length > 255:
return False return False
@ -19,11 +23,11 @@ def encode_image(img, msg):
for row in range(height): for row in range(height):
for col in range(width): for col in range(width):
(r, g, b) = img.getpixel((col, row)) (r, g, b) = img.getpixel((col, row))
# first value is length of msg # first value is length of message
if row == 0 and col == 0 and index < length: if row == 0 and col == 0 and index < length:
asc = length asc = length
elif index <= length: elif index <= length:
c = msg[index -1] c = message[index -1]
asc = ord(c) asc = ord(c)
else: else:
asc = r asc = r
@ -31,15 +35,14 @@ def encode_image(img, msg):
index += 1 index += 1
return encoded return encoded
def reveal(img):
def decode_image(img):
""" """
check the red portion of an image (r, g, b) tuple for check the red portion of an image (r, g, b) tuple for
hidden message characters (ASCII values) hidden message characters (ASCII values)
the red value of the first pixel is used for length of string the red value of the first pixel is used for length of string
""" """
width, height = img.size width, height = img.size
msg = "" message = ""
index = 0 index = 0
for row in range(height): for row in range(height):
for col in range(width): for col in range(width):
@ -48,25 +51,25 @@ def decode_image(img):
if row == 0 and col == 0: if row == 0 and col == 0:
length = r length = r
elif index <= length: elif index <= length:
msg += chr(r) message += chr(r)
index += 1 index += 1
return msg return message
if __name__ == '__main__':
# Point of entry in execution mode
original_image_file = "./pictures/Lenna.png"
encoded_image_file = "./pictures/Lenna_enc.png"
# at this point don't exceed 255 characters
secret_message = "Parce que je le vaut bien!"
img1 = Image.open(original_image_file)
img_encoded = hide(img1, secret_message)
original_image_file = "./pictures/Lenna.png" if img_encoded:
encoded_image_file = "./pictures/Lenna_enc.png" # Save it
img = Image.open(original_image_file) img_encoded.save(encoded_image_file)
# Test it
img2 = Image.open(encoded_image_file)
# at this point don't exceed 255 characters print reveal(img2)
secret_msg = "Parce que je le vaut bien!" else:
img_encoded = encode_image(img, secret_msg) print("text too long! (don't exeed 255 characters)")
if img_encoded:
# save it ...
img_encoded.save(encoded_image_file)
# test it ...
img2 = Image.open(encoded_image_file)
print(decode_image(img2))
else:
print("text too long! (don't exeed 255 characters)")