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https://github.com/cedricbonhomme/Stegano.git
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Create Hider and Revealer class
This commit is contained in:
Flavien
parent
58dbb94c5e
commit
0d98e1834c
3 changed files with 128 additions and 142 deletions
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@ -31,7 +31,7 @@ from stegano import tools
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def hide(
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input_image: Union[str, IO[bytes]],
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image: Union[str, IO[bytes]],
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message: str,
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encoding: str = "UTF-8",
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shift: int = 0,
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@ -40,91 +40,35 @@ def hide(
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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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hider = tools.Hider(image, message, encoding, auto_convert_rgb)
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width, height = hider.encoded_image.size
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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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for row in range(height):
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for col in range(width):
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if shift != 0:
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shift -= 1
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continue
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if index + 3 <= len_message_bits:
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# Get the colour component.
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pixel = img.getpixel((col, row))
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r = pixel[0]
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g = pixel[1]
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b = pixel[2]
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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((col, row), (r, g, b, pixel[3]))
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if hider.encode_another_pixel():
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hider.encode_pixel((col, row))
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else:
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encoded.putpixel((col, row), (r, g, b))
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index += 3
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else:
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img.close()
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return encoded
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return hider.encoded_image
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def reveal(input_image: Union[str, IO[bytes]], encoding: str = "UTF-8", shift: int = 0):
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def reveal(
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encoded_image: Union[str, IO[bytes]],
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encoding: str = "UTF-8",
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shift: int = 0,
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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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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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revealer = tools.Revealer(encoded_image, encoding)
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width, height = revealer.encoded_image.size
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for row in range(height):
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for col in range(width):
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if shift != 0:
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shift -= 1
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continue
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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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try:
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limit = int("".join(bitab[:-1]))
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except Exception:
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pass
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if len(bitab) - len(str(limit)) - 1 == limit:
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img.close()
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return "".join(bitab)[len(str(limit)) + 1 :]
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if revealer.decode_pixel((col, row)):
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return revealer.secret_message
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@ -31,7 +31,7 @@ from stegano import tools
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def hide(
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input_image: Union[str, IO[bytes]],
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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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@ -41,75 +41,33 @@ def hide(
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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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hider = tools.Hider(image, message, encoding, auto_convert_rgb)
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width = hider.encoded_image.width
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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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while hider.encode_another_pixel():
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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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hider.encode_pixel((col, row))
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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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return hider.encoded_image
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def reveal(
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input_image: Union[str, IO[bytes]],
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encoded_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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revealer = tools.Revealer(encoded_image, encoding)
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width = revealer.encoded_image.width
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while shift != 0:
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next(generator)
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@ -121,22 +79,5 @@ def reveal(
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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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if revealer.decode_pixel((col, row)):
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return revealer.secret_message
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101
stegano/tools.py
101
stegano/tools.py
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@ -115,3 +115,104 @@ def open_image(fname_or_instance: Union[str, IO[bytes]]):
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return fname_or_instance
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return Image.open(fname_or_instance)
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class Hider:
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def __init__(
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self,
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input_image: Union[str, IO[bytes]],
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message: str,
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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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self._index = 0
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message_length = len(message)
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assert message_length != 0, "message length is zero"
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image = open_image(input_image)
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if image.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(image.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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image = image.convert("RGB")
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self.encoded_image = image.copy()
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image.close()
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message = str(message_length) + ":" + str(message)
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self._message_bits = "".join(a2bits_list(message, encoding))
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self._message_bits += "0" * ((3 - (len(self._message_bits) % 3)) % 3)
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width, height = self.encoded_image.size
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npixels = width * height
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self._len_message_bits = len(self._message_bits)
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if self._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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def encode_another_pixel(self):
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return True if self._index + 3 <= self._len_message_bits else False
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def encode_pixel(self, coordinate: tuple):
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# Get the colour component.
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r, g, b, *a = self.encoded_image.getpixel(coordinate)
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# Change the Least Significant Bit of each colour component.
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r = setlsb(r, self._message_bits[self._index])
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g = setlsb(g, self._message_bits[self._index + 1])
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b = setlsb(b, self._message_bits[self._index + 2])
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# Save the new pixel
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if self.encoded_image.mode == "RGBA":
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self.encoded_image.putpixel(coordinate, (r, g, b, *a))
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else:
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self.encoded_image.putpixel(coordinate, (r, g, b))
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self._index += 3
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class Revealer:
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def __init__(self, encoded_image: Union[str, IO[bytes]], encoding: str = "UTF-8"):
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self.encoded_image = open_image(encoded_image)
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self._encoding_length = ENCODINGS[encoding]
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self._buff, self._count = 0, 0
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self._bitab = []
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self._limit = None
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self.secret_message = ""
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def decode_pixel(self, coordinate: tuple):
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# pixel = [r, g, b] or [r,g,b,a]
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pixel = self.encoded_image.getpixel(coordinate)
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if self.encoded_image.mode == "RGBA":
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pixel = pixel[:3] # ignore the alpha
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for color in pixel:
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self._buff += (color & 1) << (self._encoding_length - 1 - self._count)
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self._count += 1
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if self._count == self._encoding_length:
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self._bitab.append(chr(self._buff))
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self._buff, self._count = 0, 0
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if self._bitab[-1] == ":" and self._limit is None:
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if "".join(self._bitab[:-1]).isdigit():
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self._limit = int("".join(self._bitab[:-1]))
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else:
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raise IndexError("Impossible to detect message.")
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if len(self._bitab) - len(str(self._limit)) - 1 == self._limit:
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self.secret_message = "".join(self._bitab)[len(str(self._limit)) + 1 :]
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self.encoded_image.close()
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return True
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else:
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return False
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