class PixelScraper:
"""
Scrapes the pixel data back out of the file.
"""
def __init__(self, path: str):
self._pixelManipulator = PixelManipulator(path)
def get_header(self, length: int=128) -> (int, bytearray):
pixgen = self._pixelManipulator.get_pixel_generator()
cleartext = bytearray()
for index, pixel in enumerate(pixgen):
if index == length:
break
charvalue = 0
for i in reversed(range(4)):
charvalue <<= 2
charvalue += pixel[i] & 3
cleartext.append(charvalue)
size = unpack("<I", cleartext[0:4])[0]
filename = cleartext[4:].strip(b'\0')
return size, filename
def get_data(self):
size, filename = self.get_header()
pixgen = self._pixelManipulator.get_pixel_generator()
# skip the header
for i in range(128):
next(pixgen)
cleartext = bytearray()
for index, pixel in enumerate(pixgen):
if index == size:
break
charvalue = 0
for i in reversed(range(4)):
charvalue <<= 2
charvalue += pixel[i] & 3
cleartext.append(charvalue)
return cleartext
def inject_file(imagepath: str, secretpath: str, outputpath: str):
secretfilename = basename(secretpath).encode()
with open(secretpath, "rb") as f:
secretdata = f.read()
header = bytearray(b"\0" * 128)
header[0:4] = pack("<I", len(secretdata))
header[4:4 + len(secretfilename)] = secretfilename
header = header[:128] # cap anything that's too long
pixelmanipulator = PixelManipulator(imagepath)
maxfilesize = (pixelmanipulator.get_maximum_size() - 128)
if maxfilesize < len(secretdata):
print(
"The target container is too small for the secret. Maximum file size is",
maxfilesize, "bytes")
sys.exit(1)
bitfactory = BitFactory(secretdata)
pixelmanipulator.apply_bits(header, bitfactory)
pixelmanipulator.save(outputpath)
def inject_file(imagepath: str, secretpath: str, outputpath: str):
secretfilename = basename(secretpath).encode()
with open(secretpath, "rb") as f:
secretdata = f.read()
header = bytearray(b"\0" * 128)
header[0:4] = pack("<I", len(secretdata))
header[4:4 + len(secretfilename)] = secretfilename
header = header[:128] # cap anything that's too long
pixelmanipulator = PixelManipulator(imagepath)
maxfilesize = (pixelmanipulator.get_maximum_size() - 128)
if maxfilesize < len(secretdata):
print("The target container is too small for the secret. Maximum file size is", maxfilesize, "bytes")
sys.exit(1)
bitfactory = BitFactory(secretdata)
pixelmanipulator.apply_bits(header, bitfactory)
pixelmanipulator.save(outputpath)
def __init__(self, path: str):
self._pixelManipulator = PixelManipulator(path)
def get_maximum_size(imagepath: str) -> int:
return PixelManipulator(imagepath).get_maximum_size()