hedroed / png-parser Goto Github PK

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Analyse PNG file format for CTF, python API and CLI

License: MIT License

Python 100.00%

python steg steganography ctf ctf-tools cli pythonapi png parser parser-library

png-parser's People

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benetsi crackercat simonjang nickwoodhams alexguo1998 b0oml synchx00 kolomenek swissairone asealp

png-parser's Issues

Not working in Python 3.10

PS C:\Windows\System32> png-parser
Traceback (most recent call last):
  File "C:\Users\Anton\AppData\Roaming\Python\Python310\Scripts\png-parser-script.py", line 33, in <module>
    sys.exit(load_entry_point('png-parser==2.0.0', 'console_scripts', 'png-parser')())
  File "C:\Users\Anton\AppData\Roaming\Python\Python310\Scripts\png-parser-script.py", line 25, in importlib_load_entry_point
    return next(matches).load()
  File "C:\Program Files\Python310\lib\importlib\metadata\__init__.py", line 162, in load
    module = import_module(match.group('module'))
  File "C:\Program Files\Python310\lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 992, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "C:\Users\Anton\AppData\Roaming\Python\Python310\site-packages\pngparser\__init__.py", line 1, in <module>
    from .png import PngParser, PNG_MAGIC_NUMBER
  File "C:\Users\Anton\AppData\Roaming\Python\Python310\site-packages\pngparser\png.py", line 9, in <module>
    from .chunks import create_chunk, ChunkRaw
  File "C:\Users\Anton\AppData\Roaming\Python\Python310\site-packages\pngparser\chunks\__init__.py", line 6, in <module>
    from .ihdr import ChunkIHDR
  File "C:\Users\Anton\AppData\Roaming\Python\Python310\site-packages\pngparser\chunks\ihdr.py", line 3, in <module>
    from ..utils import pixel_type_to_length
  File "C:\Users\Anton\AppData\Roaming\Python\Python310\site-packages\pngparser\utils.py", line 30, in <module>
    class BitArray(collections.Iterator):
AttributeError: module 'collections' has no attribute 'Iterator'

Parsing binary data

Can i use this parser for parsing binary data and find PNG inside it?

Fail with pal2/pal4/rgb48 images

I tried png-parser with pal2/pal4/rgb48 images:

pngparser -v -s test.png

... and they all fail. There are mainly 3 problems.

For all images, scanline_width is incorrect, so each scanline read is either too short or too long.

png-parser/pngparser/imagedata.py

Lines 232 to 234 in 4d75f17

 # line_width = pixel_count_in_line * bytes_count_by_pixel + the_filter_byte 

 line_width = self.header.width * self.header.pixel_len 

 logging.debug('%d bytes per scanline', line_width)

Guess it should be like:

# line_width_bit = pixel_count_per_line * components_per_pixel * bit_per_component
line_width_bit = self.header.width * self.header.pixel_len * self.header.bit_depth
# line_width = round_up(line_width_bit / 8) + the_filter_byte
line_width = (line_width_bit + 7) // 8 + 1

i.e. include bit_per_component(actually self.header.bit_depth) in calculation.

(I suggest renaming pixel_len to component_count, but it's also a little weird: paletted images can have more than 1 component, so maybe a better name?)

For pal2/pal4 images, it failed to convert index to pixel.

png-parser/pngparser/imagedata.py

Lines 332 to 333 in 4d75f17

 if self.palette: 

 pixels = [self.palette[i] for i in row]

The correct way is:

if self.palette:
    bit_depth = self.header.bit_depth  # bit count per sample
    pixels = [self.palette[i] for i in BitArray(row, bit_depth)]

For rgb48 images, it failed to scale pixel value to 0~255 range when displaying.

png-parser/pngparser/imagedata.py

Lines 337 to 341 in 4d75f17

 for val in BitArray(row, bit_depth): 

 if bit_depth != 8: 

 # shrink value between 0 and 255 

 val = val * (2**bit_depth - 1) 

 px.append(val)

With rgb48, bit_depth is 16, i.e. val in range(0, 65536).
So val should be divided by 256, or be shifted 8 bits to the right:

if bit_depth > 8:
    # shrink value between 0 and 255
    val = val >> (bit_depth - 8)

I can craft a PR for these issues, but I'm not sure about the wording problem. Anyone has an idea?

hedroed / png-parser Goto Github PK

png-parser's People

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png-parser's Issues

Not working in Python 3.10

Parsing binary data

Fail with pal2/pal4/rgb48 images

Add --raw with --data to pipe into other command

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	# line_width = pixel_count_in_line * bytes_count_by_pixel + the_filter_byte
	line_width = self.header.width * self.header.pixel_len
	logging.debug('%d bytes per scanline', line_width)

	for val in BitArray(row, bit_depth):
	if bit_depth != 8:
	# shrink value between 0 and 255
	val = val * (2**bit_depth - 1)
	px.append(val)