izcoser / stegpy

Simple steganography program based on the LSB method.

stegpy

A program for encoding information in image and audio files through steganography. Any type of data can be encoded, from raw strings to files, as shown below:

On the left, a house with a steganographically hidden image. On the right, the extracted hidden image of a cat. It is revealed by removing all but the least significant bit of each color component in the host image.

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Supported host formats

• PNG
• BMP
• GIF
• WebP
• WAV

Images in a different format are automatically converted to PNG. Different audio formats are not supported at all.

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Dependencies

• numpy
• cryptography
• Pillow (PIL fork)

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Installation

 pip3 install stegpy

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Usage:

Hide a message or file:

 stegpy "Hello World!" image.png

Extract it:

 stegpy _image.png

Data is encoded without any protection by default, but it can be encrypted with the -p flag:

Encrypt:

 stegpy "Hello World!" image.png -p
Enter password (will not be echoed):
Verify password (will not be echoed):
 stegpy _image.png -p
Enter password (will not be echoed):
Hello World!

More options:

 stegpy -h

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To do

• Add docstrings
• Allow encoding across multiple files
• Support JPEG & FLAC as hosts

stegpy's Issues

'utf-8' codec can't decode byte 0x9d in position 0: invalid start byte

I'm trying to use the library as part of a backend project so i got the code files not the command line tool, the encoding goes just fine. but whenever I try to decode I get this error..
this is the line that causes the problem, in the read_message function

text = bytes(msg[start:end]).decode('utf-8')

bonjour quelle format video stegpy prend t'il en charge

Index 0 is out of bounds

Traceback (most recent call last):
File "/usr/local/bin/stegpy", line 8, in
sys.exit(main())
File "/usr/local/lib/python3.8/dist-packages/stegpy/steg.py", line 52, in main
host.read_message(password)
File "/usr/local/lib/python3.8/dist-packages/stegpy/lsb.py", line 45, in read_message
msg = decode_message(self.data)
File "/usr/local/lib/python3.8/dist-packages/stegpy/lsb.py", line 167, in decode_message
bits = 2 ** ((host_data[0] & 48) >> 4) # bits = 2 ^ (5th and 6th bits)
IndexError: index 0 is out of bounds for axis 0 with size 0

file size increases by huge amount

I used stegpy to embed a message in a .gif file and the resulting file size was about 8 times larger than the original file size.

After embedding my message I got this:

Host dimension: 209,952,000 bytes
Message size: 22 bytes
Maximum size: 52,488,000 bytes

And when looking at the new file's size it was 52M.