Tinyscript steganography tool implementing the Pixel Value Differencing algorithm

README.md

StegoPVD

This Tinyscript-based tool allows to apply steganography based on PVD (Pixel Value Differencing) in order to retrieve hidden data from an image.

$ pip install tinyscript
$ tsm install stegopvd

This tool is especially useful in the use cases hereafter.

Extract hidden data from an image using PVD stegano

$ stegopvd -v extract test.png --zigzag
12:34:56 [DEBUG] Image size: 600x800
12:34:56 [DEBUG] Channels RGB, zigzag True
12:34:56 [INFO] Hidden data:
[...]

Bruteforce PVD stegano parameters to recover hidden data from an image

This will display readable strings recovered using bruteforced parameters.

$ stegopvd bruteforce test.png
12:34:56 [INFO] [...]

stegopvd.py

#!/usr/bin/python3
# -*- coding: UTF-8 -*-
from PIL import Image
from tinyscript import *


__author__    = "Alexandre D'Hondt"
__version__   = "1.1"
__copyright__ = ("A. D'Hondt", 2020)
__license__   = "gpl-3.0"
__examples__  = ["extract test.png -z", "bruteforce test.png -c"]
__doc__ = """
*StegoPVD* allows to apply steganography based on PVD (Pixel Value Differencing) in order to retrieve hidden data from an image.
"""


BANNER_FONT       = "standard"
BANNER_STYLE      = {'fgcolor': "lolcat"}
SCRIPTNAME_FORMAT = "none"


class PVD(object):
    def __init__(self, image, secret=None):
        self.__image = image
        self.__secret = secret
        self.__obj = Image.open(image).convert('RGB')
        logger.debug("Image size: {}x{}".format(*self.__obj.size))
    
    def bruteforce(self, channels=False, nchars=16):
        for ch in (ts.bruteforce(3, "RGB", repeat=False) if channels else \
                   ["RGB"]):
            for zigzag in [True, False]:
                self.extract(ch, zigzag)
                for s in ts.strings(self.data, nchars):
                    logger.info(s)
                    if self.__secret:
                        self.write(content=s)
    
    def extract(self, channels="B", zigzag=True):
        logger.debug("Channels {}, zigzag {}".format(channels, zigzag))
        i = self.__obj
        w, h = i.size
        data = ""
        for y in range(h):
            for x in range(1, w, 2):
                if zigzag and (y % 2 == 1):
                    x = -x % w
                pixel = {k: v for k, v in zip("RGB", i.getpixel((x, y)))}
                prev_pixel = {k: v for k, v in zip("RGB", i.getpixel((x-1, y)))}
                for c in channels:
                    d = int(abs(pixel[c] - prev_pixel[c]))
                    if 0 <= d <= 7:
                        b, lower = 3, 0
                    elif 8 <= d <= 15:
                        b, lower = 3, 8
                    elif 16 <= d <= 31:
                        b, lower = 4, 16
                    elif 32 <= d <= 63:
                        b, lower = 5, 32
                    elif 64 <= d <= 127:
                        b, lower = 6, 64
                    elif 128 <= d <= 255:
                        b, lower = 7, 128
                    data += bin(d - lower)[2:].zfill(b)
        self.data = ts.bin2str(data)

    def hide(self, data):
        bin_data = ts.str2bin(data)
        #TODO: implement hiding data
        bin_len = ts.int2bin(len(bin_data))
        return self

    def write(self, filename=None, content=None):
        filename = self.__secret or filename
        if filename is None:
            filename = os.path.basename(self.__image)
            filename, _ = os.path.splitext(filename)
            filename = "{}-secret.txt".format(filename)
        with open(filename, 'ab') as f:
            f.write(b(content or self.data))
        return self


if __name__ == "__main__":
    parser.add_argument("-w", "--write", help="write data to a file")
    subparsers = parser.add_subparsers(help="commands", dest="command")
    extract = subparsers.add_parser('extract',
                                    help="manually extract hidden data")
    bruteforce = subparsers.add_parser('bruteforce', help="bruteforce "
                                       "parameters for extracting hidden data")
    extract.add_argument("image", type=ts.file_exists, help="image path")
    extract.add_argument("-c", "--channels", default="RGB",
                         help="channels to be considered")
    extract.add_argument("-z", "--zigzag", action="store_true",
                         help="apply Zig-Zag Traversing Scheme (ZZTS)")
    bruteforce.add_argument("image", type=ts.file_exists, help="image path")
    bruteforce.add_argument("-c", "--channels", action="store_true",
                            help="bruteforce the color channels",
                            note="if false, RGB are considered")
    bruteforce.add_argument("-n", "--nchars", type=ts.pos_int, default=16,
                            help="minimal length for readable strings")
    initialize(noargs_action="demo")
    p = PVD(args.image, args.write)
    if args.command == "bruteforce":
        p.bruteforce(args.channels)
    elif args.command == "extract":
        p.extract()
        logger.info("Hidden data:\n" + p.data)
        if args.write:
            p.write()

Hi,
since python3.9 and above it generates an HTMLParser error as the unescape() method has been removed from the html.parser.HTMParser class.
more details here: https://www.datasciencelearner.com/attributeerror-htmlparser-object-has-no-attribute-unescape-solved/

example on my python 3.10

...
File "/usr/local/lib/python3.10/dist-packages/mdv/markdownviewer.py", line 970, in formatter
    t = html_parser.unescape(t)
AttributeError: 'HTMLParser' object has no attribute 'unescape'

some error happend, and this is solution.

cannot import name 'etree' from 'markdown.util'

Python-Markdown/markdown#1284 (comment)

I'm confused. It looks like you're running stegopvd straight from the shell after the following?

$ pip install tinyscript
$ tsm install stegopvd

I don't seem to be able to run it this way.

@thelulzy Thank you for mentioning. This came from a bug in Tinyscript. Please Pip-upgrade to version 1.30.7 and it should work fine ;

$ pip install --upgrade tinyscript
$ tsm install --force stegopvd
$ stegopvd --help