mirror of
https://github.com/cedricbonhomme/Stegano.git
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142 lines
4.4 KiB
Python
142 lines
4.4 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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# Stegano - Stegano is a pure Python steganography module.
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# Copyright (C) 2010-2022 Cédric Bonhomme - https://www.cedricbonhomme.org
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#
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# For more information : https://git.sr.ht/~cedric/stegano
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>
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__author__ = "Cedric Bonhomme"
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__version__ = "$Revision: 0.7 $"
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__date__ = "$Date: 2016/03/13 $"
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__revision__ = "$Date: 2019/05/31 $"
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__license__ = "GPLv3"
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from typing import IO, Iterator, Union
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from stegano import tools
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def hide(
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input_image: Union[str, IO[bytes]],
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message: str,
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generator: Iterator[int],
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shift: int = 0,
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encoding: str = "UTF-8",
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auto_convert_rgb: bool = False,
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):
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"""Hide a message (string) in an image with the
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LSB (Least Significant Bit) technique.
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"""
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message_length = len(message)
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assert message_length != 0, "message length is zero"
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img = tools.open_image(input_image)
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if img.mode not in ["RGB", "RGBA"]:
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if not auto_convert_rgb:
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print("The mode of the image is not RGB. Mode is {}".format(img.mode))
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answer = input("Convert the image to RGB ? [Y / n]\n") or "Y"
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if answer.lower() == "n":
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raise Exception("Not a RGB image.")
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img = img.convert("RGB")
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encoded = img.copy()
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width, height = img.size
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index = 0
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message = str(message_length) + ":" + str(message)
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message_bits = "".join(tools.a2bits_list(message, encoding))
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message_bits += "0" * ((3 - (len(message_bits) % 3)) % 3)
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npixels = width * height
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len_message_bits = len(message_bits)
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if len_message_bits > npixels * 3:
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raise Exception(
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"The message you want to hide is too long: {}".format(message_length)
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)
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while shift != 0:
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next(generator)
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shift -= 1
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while index + 3 <= len_message_bits:
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generated_number = next(generator)
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col = generated_number % width
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row = int(generated_number / width)
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coordinate = (col, row)
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r, g, b, *a = encoded.getpixel(coordinate)
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# Change the Least Significant Bit of each colour component.
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r = tools.setlsb(r, message_bits[index])
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g = tools.setlsb(g, message_bits[index + 1])
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b = tools.setlsb(b, message_bits[index + 2])
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# Save the new pixel
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if img.mode == "RGBA":
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encoded.putpixel(coordinate, (r, g, b, *a))
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else:
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encoded.putpixel(coordinate, (r, g, b))
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index += 3
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return encoded
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def reveal(
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input_image: Union[str, IO[bytes]],
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generator: Iterator[int],
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shift: int = 0,
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encoding: str = "UTF-8",
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):
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"""Find a message in an image (with the LSB technique)."""
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img = tools.open_image(input_image)
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img_list = list(img.getdata())
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width, height = img.size
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buff, count = 0, 0
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bitab = []
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limit = None
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while shift != 0:
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next(generator)
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shift -= 1
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while True:
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generated_number = next(generator)
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col = generated_number % width
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row = int(generated_number / width)
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# pixel = [r, g, b] or [r,g,b,a]
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pixel = img.getpixel((col, row))
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if img.mode == "RGBA":
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pixel = pixel[:3] # ignore the alpha
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for color in pixel:
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buff += (color & 1) << (tools.ENCODINGS[encoding] - 1 - count)
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count += 1
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if count == tools.ENCODINGS[encoding]:
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bitab.append(chr(buff))
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buff, count = 0, 0
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if bitab[-1] == ":" and limit is None:
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if "".join(bitab[:-1]).isdigit():
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limit = int("".join(bitab[:-1]))
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else:
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raise IndexError("Impossible to detect message.")
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if len(bitab) - len(str(limit)) - 1 == limit:
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return "".join(bitab)[len(str(limit)) + 1 :]
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