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Create Hider and Revealer class

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This commit is contained in:
Flavien 2022-11-08 23:28:39 +01:00
parent 58dbb94c5e
commit 0d98e1834c
3 changed files with 128 additions and 142 deletions
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88
stegano/lsb/lsb.py
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@ -31,7 +31,7 @@ from stegano import tools
def hide(
input_image: Union[str, IO[bytes]],
image: Union[str, IO[bytes]],
message: str,
encoding: str = "UTF-8",
shift: int = 0,
@ -40,91 +40,35 @@ def hide(
"""Hide a message (string) in an image with the
LSB (Least Significant Bit) technique.
"""
message_length = len(message)
assert message_length != 0, "message length is zero"
hider = tools.Hider(image, message, encoding, auto_convert_rgb)
width, height = hider.encoded_image.size
img = tools.open_image(input_image)
if img.mode not in ["RGB", "RGBA"]:
if not auto_convert_rgb:
print("The mode of the image is not RGB. Mode is {}".format(img.mode))
answer = input("Convert the image to RGB ? [Y / n]\n") or "Y"
if answer.lower() == "n":
raise Exception("Not a RGB image.")
img = img.convert("RGB")
encoded = img.copy()
width, height = img.size
index = 0
message = str(message_length) + ":" + str(message)
message_bits = "".join(tools.a2bits_list(message, encoding))
message_bits += "0" * ((3 - (len(message_bits) % 3)) % 3)
npixels = width * height
len_message_bits = len(message_bits)
if len_message_bits > npixels * 3:
raise Exception(
"The message you want to hide is too long: {}".format(message_length)
)
for row in range(height):
for col in range(width):
if shift != 0:
shift -= 1
continue
if index + 3 <= len_message_bits:
# Get the colour component.
pixel = img.getpixel((col, row))
r = pixel[0]
g = pixel[1]
b = pixel[2]
# Change the Least Significant Bit of each colour component.
r = tools.setlsb(r, message_bits[index])
g = tools.setlsb(g, message_bits[index + 1])
b = tools.setlsb(b, message_bits[index + 2])
# Save the new pixel
if img.mode == "RGBA":
encoded.putpixel((col, row), (r, g, b, pixel[3]))
else:
encoded.putpixel((col, row), (r, g, b))
index += 3
if hider.encode_another_pixel():
hider.encode_pixel((col, row))
else:
img.close()
return encoded
return hider.encoded_image
def reveal(input_image: Union[str, IO[bytes]], encoding: str = "UTF-8", shift: int = 0):
def reveal(
encoded_image: Union[str, IO[bytes]],
encoding: str = "UTF-8",
shift: int = 0,
):
"""Find a message in an image (with the LSB technique)."""
img = tools.open_image(input_image)
width, height = img.size
buff, count = 0, 0
bitab = []
limit = None
revealer = tools.Revealer(encoded_image, encoding)
width, height = revealer.encoded_image.size
for row in range(height):
for col in range(width):
if shift != 0:
shift -= 1
continue
# pixel = [r, g, b] or [r,g,b,a]
pixel = img.getpixel((col, row))
if img.mode == "RGBA":
pixel = pixel[:3] # ignore the alpha
for color in pixel:
buff += (color & 1) << (tools.ENCODINGS[encoding] - 1 - count)
count += 1
if count == tools.ENCODINGS[encoding]:
bitab.append(chr(buff))
buff, count = 0, 0
if bitab[-1] == ":" and limit is None:
try:
limit = int("".join(bitab[:-1]))
except Exception:
pass
if len(bitab) - len(str(limit)) - 1 == limit:
img.close()
return "".join(bitab)[len(str(limit)) + 1 :]
if revealer.decode_pixel((col, row)):
return revealer.secret_message