Change path in example
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libstegano.py
288
libstegano.py
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"""
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A library for the steganography program
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Copyright (C) 2022 Valentin Moguérou
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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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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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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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"""
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from typing import BinaryIO
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from PIL import Image
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# ================= BINARY OPERATIONS =================
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def write_lsb_in_bin(byte, bit):
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"Write the specified bit in the LSB of the specified byte"
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return byte & 254 | bit if bit==1 else byte & 254
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def read_lsb_in_bin(byte):
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return byte & 1
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def combine_bits_to_byte(bits):
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"""
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Turns a sequence of bits into an integer.
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Example: turns [0, 1, 1, 0, 1, 1, 0, 1] into 0b01101101 or 109
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"""
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return sum(bits[-1-i]<<i for i in range(len(bits)))
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def split_byte_into_bits(integer):
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"""
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Turns an integer into an array of bits
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Example: turns 109 or 0b01101101 into [0, 1, 1, 0, 1, 1, 0, 1]
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"""
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return [integer>>(7-i)&1 for i in range(8)]
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def hex_print(byte_list, margin=0, line_width=16):
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"Prints a byte list in hexadecimal"
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for line in range(0, len(byte_list), line_width):
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print(' '*margin + ' '.join(f'{byte:02X}' for byte in byte_list[line:line+line_width]))
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# ================= STRING OPERATIONS =================
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def encode_string(string: str) -> bytearray:
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"Turns the given string into a byte array"
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return bytearray(ord(ch) for ch in string+'\0')
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def decode_string(bytelist: bytearray) -> str:
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"Turns the given byte array into a string"
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return ''.join(chr(b) for b in bytelist)
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# ================= WRITE OPERATIONS =================
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def write_band(band: bytearray, byte_list: bytearray, starting_pos=0) -> bool:
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"Writes a byte sequence in the given band"
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for index in range(starting_pos, len(band), 8):
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band[index:index+8] = (write_lsb_in_bin(band[index+i], bit) for i, bit in enumerate(split_byte_into_bits(byte_list[index//8])))
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if byte_list[index//8] == 0:
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return True, index+8 # finished writing
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return False, index+8 # didn't finish writing, return last index
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def write_image(img: Image.Image, byte_list, verbose=False):
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data = [bytearray(band.tobytes()) for band in img.split()]
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ok, position = write_band(data[0], byte_list)
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if not ok:
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ok, position = write_band(data[1], byte_list, position)
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if not ok:
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ok, position = write_band(data[2], byte_list, position)
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if not ok:
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raise ValueError("The byte sequence is too long.")
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if verbose:
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print(f"{position} bits, {position//8} bytes successfully written.")
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return Image.merge(img.mode, [Image.frombytes('L', img.size, bytes(band)) for band in data])
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def write_file(from_file: BinaryIO, to_file: BinaryIO, byte_list, verbose=False):
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write_image(Image.open(from_file), byte_list, verbose=verbose).save(to_file)
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# ================= READ OPERATIONS =================
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def read_band(band: bytes, byte_list: bytearray) -> bool:
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"Turns a sequence of pixels into a byte list"
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for i in range(0, len(band), 8):
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bits = [read_lsb_in_bin(b) for b in band[i:i+8]]
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if all(b==0 for b in bits):
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return True # finished reading
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byte_list.append(combine_bits_to_byte(bits))
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return False # didn't finish reading
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def read_image(img: Image.Image, verbose=False):
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"Read the whole image"
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data = [band.tobytes() for band in img.split()]
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byte_list = bytearray()
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if read_band(data[0], byte_list):
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if verbose:
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print("Successfully finished reading.")
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elif read_band(data[1], byte_list):
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if verbose:
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print("Successfully finished reading.")
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print("Read the whole red band.")
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elif read_band(data[1], byte_list):
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if verbose:
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print("Successfully finished reading.")
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print("Read the whole green band.")
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else:
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if verbose:
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print("Read the whole blue band.")
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raise ValueError("Invalid image, did not find end control sequence.")
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return byte_list
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def read_file(from_file: BinaryIO, verbose=False):
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return read_image(Image.open(from_file), verbose=verbose)
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# ================= EXAMPLE PROGRAM =================
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def main():
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s = "This is a string"
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oldimg = Image.open('guitar.jpg')
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oldimg.load()
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print(encode_string(s))
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newimg = write_image(oldimg, encode_string(s))
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newimg.save('dissimulated.png', 'PNG')
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print('Written...')
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print(f"String: --> {read_image(Image.open('guitar.jpg'))} (guitar.jpg)")
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print(f"String: --> {decode_string(read_image(Image.open('dissimulated.png')))} (dissimulated.png)")
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if __name__ == '__main__':
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"""
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A library for the steganography program
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Copyright (C) 2022 Valentin Moguérou
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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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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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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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"""
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from typing import BinaryIO
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from PIL import Image
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# ================= BINARY OPERATIONS =================
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def write_lsb_in_bin(byte, bit):
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"Write the specified bit in the LSB of the specified byte"
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return byte & 254 | bit if bit==1 else byte & 254
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def read_lsb_in_bin(byte):
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return byte & 1
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def combine_bits_to_byte(bits):
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"""
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Turns a sequence of bits into an integer.
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Example: turns [0, 1, 1, 0, 1, 1, 0, 1] into 0b01101101 or 109
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"""
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return sum(bits[-1-i]<<i for i in range(len(bits)))
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def split_byte_into_bits(integer):
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"""
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Turns an integer into an array of bits
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Example: turns 109 or 0b01101101 into [0, 1, 1, 0, 1, 1, 0, 1]
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"""
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return [integer>>(7-i)&1 for i in range(8)]
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def hex_print(byte_list, margin=0, line_width=16):
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"Prints a byte list in hexadecimal"
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for line in range(0, len(byte_list), line_width):
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print(' '*margin + ' '.join(f'{byte:02X}' for byte in byte_list[line:line+line_width]))
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# ================= STRING OPERATIONS =================
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def encode_string(string: str) -> bytearray:
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"Turns the given string into a byte array"
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return bytearray(ord(ch) for ch in string+'\0')
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def decode_string(bytelist: bytearray) -> str:
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"Turns the given byte array into a string"
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return ''.join(chr(b) for b in bytelist)
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# ================= WRITE OPERATIONS =================
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def write_band(band: bytearray, byte_list: bytearray, starting_pos=0) -> bool:
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"Writes a byte sequence in the given band"
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for index in range(starting_pos, len(band), 8):
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band[index:index+8] = (write_lsb_in_bin(band[index+i], bit) for i, bit in enumerate(split_byte_into_bits(byte_list[index//8])))
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if byte_list[index//8] == 0:
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return True, index+8 # finished writing
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return False, index+8 # didn't finish writing, return last index
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def write_image(img: Image.Image, byte_list, verbose=False):
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data = [bytearray(band.tobytes()) for band in img.split()]
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ok, position = write_band(data[0], byte_list)
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if not ok:
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ok, position = write_band(data[1], byte_list, position)
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if not ok:
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ok, position = write_band(data[2], byte_list, position)
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if not ok:
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raise ValueError("The byte sequence is too long.")
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if verbose:
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print(f"{position} bits, {position//8} bytes successfully written.")
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return Image.merge(img.mode, [Image.frombytes('L', img.size, bytes(band)) for band in data])
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def write_file(from_file: BinaryIO, to_file: BinaryIO, byte_list, verbose=False):
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write_image(Image.open(from_file), byte_list, verbose=verbose).save(to_file)
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# ================= READ OPERATIONS =================
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def read_band(band: bytes, byte_list: bytearray) -> bool:
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"Turns a sequence of pixels into a byte list"
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for i in range(0, len(band), 8):
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bits = [read_lsb_in_bin(b) for b in band[i:i+8]]
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if all(b==0 for b in bits):
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return True # finished reading
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byte_list.append(combine_bits_to_byte(bits))
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return False # didn't finish reading
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def read_image(img: Image.Image, verbose=False):
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"Read the whole image"
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data = [band.tobytes() for band in img.split()]
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byte_list = bytearray()
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if read_band(data[0], byte_list):
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if verbose:
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print("Successfully finished reading.")
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elif read_band(data[1], byte_list):
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if verbose:
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print("Successfully finished reading.")
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print("Read the whole red band.")
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elif read_band(data[1], byte_list):
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if verbose:
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print("Successfully finished reading.")
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print("Read the whole green band.")
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else:
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if verbose:
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print("Read the whole blue band.")
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raise ValueError("Invalid image, did not find end control sequence.")
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return byte_list
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def read_file(from_file: BinaryIO, verbose=False):
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return read_image(Image.open(from_file), verbose=verbose)
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# ================= EXAMPLE PROGRAM =================
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def main():
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s = "This is a string"
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oldimg = Image.open('default_image.jpg')
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oldimg.load()
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print(encode_string(s))
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newimg = write_image(oldimg, encode_string(s))
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newimg.save('dissimulated.png', 'PNG')
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print('Written...')
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print(f"String: --> {read_image(Image.open('guitar.jpg'))} (guitar.jpg)")
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print(f"String: --> {decode_string(read_image(Image.open('dissimulated.png')))} (dissimulated.png)")
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if __name__ == '__main__':
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main()
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