mirror of
https://github.com/cedricbonhomme/Stegano.git
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112 lines
3.8 KiB
Python
112 lines
3.8 KiB
Python
#!/usr/bin/env python
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# Stegano - Stéganô is a basic Python Steganography module.
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# Copyright (C) 2010-2024 Cédric Bonhomme - https://www.cedricbonhomme.org
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#
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# For more information : https://github.com/cedricbonhomme/Stegano
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>
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__author__ = "Cedric Bonhomme"
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__version__ = "$Revision: 0.2 $"
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__date__ = "$Date: 2010/10/01 $"
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__revision__ = "$Date: 2017/02/06 $"
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__license__ = "GPLv3"
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import wave
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from typing import IO, Union
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from stegano import tools
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def hide(
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input_file: Union[str, IO[bytes]],
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message: str,
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output_file: Union[str, IO[bytes]],
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encoding: str = "UTF-8",
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):
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"""
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Hide a message (string) in a .wav audio file.
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Use the lsb of each PCM encoded sample to hide the message string characters as ASCII values.
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The first eight bits are used for message_length of the string.
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"""
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message_length = len(message)
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assert message_length != 0, "message message_length is zero"
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assert message_length < 255, "message is too long"
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output = wave.open(output_file, "wb")
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with wave.open(input_file, "rb") as input:
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# get .wav params
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nchannels, sampwidth, framerate, nframes, comptype, _ = input.getparams()
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assert comptype == "NONE", "only uncompressed files are supported"
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nsamples = nframes * nchannels
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message_bits = f"{message_length:08b}" + "".join(
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tools.a2bits_list(message, encoding)
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)
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assert len(message_bits) <= nsamples, "message is too long"
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# copy over .wav params to output
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output.setnchannels(nchannels)
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output.setsampwidth(sampwidth)
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output.setframerate(framerate)
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# encode message in frames
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frames = bytearray(input.readframes(nsamples))
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for i in range(nsamples):
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if i < len(message_bits):
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if message_bits[i] == "0":
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frames[i] = frames[i] & ~1
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else:
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frames[i] = frames[i] | 1
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# write out
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output.writeframes(frames)
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def reveal(input_file: Union[str, IO[bytes]], encoding: str = "UTF-8"):
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"""
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Find a message in an image.
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Check the lsb of each PCM encoded sample for hidden message characters (ASCII values).
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The first eight bits are used for message_length of the string.
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"""
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message = ""
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encoding_len = tools.ENCODINGS[encoding]
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with wave.open(input_file, "rb") as input:
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nchannels, _, _, nframes, comptype, _ = input.getparams()
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assert comptype == "NONE", "only uncompressed files are supported"
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nsamples = nframes * nchannels
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frames = bytearray(input.readframes(nsamples))
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# Read first 8 bits for message length
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length_bits = ""
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for i in range(8):
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length_bits += str(frames[i] & 1)
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message_length = int(length_bits, 2)
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# Read message bits
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message_bits = ""
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for i in range(8, 8 + message_length * encoding_len):
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message_bits += str(frames[i] & 1)
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# Convert bits to string
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chars = [
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chr(int(message_bits[i : i + encoding_len], 2))
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for i in range(0, len(message_bits), encoding_len)
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]
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message = "".join(chars)
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return message
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