125 lines
4.2 KiB
Python
125 lines
4.2 KiB
Python
import numpy as np
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class txt_steg:
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def __init__(self, text_file: str = None, bit_to_hide: list[int] = None) -> None:
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"""
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Initialize the class
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:param text_file: PathName of the text file to encode or decode (Required)
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:type text_file: str
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:param bit_to_hide: Bit to hide the data in (1 - LSB to 8 - MSB), Default is LSB (index = 7)
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:type bit_to_hide: list[int]
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"""
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if text_file:
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self.text_file = text_file
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else:
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raise FileNotFoundError("Please specify a text file")
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self.bit_to_hide = [8 - bit_pos for bit_pos in bit_to_hide] if bit_to_hide else [7]
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self.delimiter = "abc-123==" # Delimiter to indicate the end of the secret data
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def encode(self, secret_data: str = "Hello World") -> str:
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"""
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Encode the secret data into the text file
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:param secret_data: String
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:type secret_data: str
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"""
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# Read text file
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with open(self.text_file, "r") as f:
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data = f.read()
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secret_data += self.delimiter # Add delimiter
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# Max Bits to encode (1 Character = 8 bits)
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n_bits = len(data) * len(
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self.bit_to_hide) # Bits that can be used (Each character x Number of bits that can be used)
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# Check if secret data can be encoded into text file
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if len(secret_data) * 8 > n_bits:
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raise ValueError(
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f"[-] Error: Binary Secret data length {len(secret_data) * 8} is greater than data length {n_bits}")
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data_index = 0
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# Convert secret data to binary
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binary_secret_data = self.to_bin(secret_data)
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encoded_data = ""
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# Encode data into text
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for char in data:
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bin_char = self.to_bin(char)
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bin_char = "0" * (8 - len(bin_char)) + bin_char
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if data_index >= len(binary_secret_data):
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encoded_data += self.from_bin(''.join(bin_char))
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else:
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for bit_pos in self.bit_to_hide:
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if data_index < len(binary_secret_data):
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bin_char = list(bin_char)
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bin_char[bit_pos] = binary_secret_data[data_index]
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data_index += 1
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encoded_data += self.from_bin(''.join(bin_char))
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return encoded_data
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def decode(self) -> str:
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"""
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Decode the encoded data from the text file
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Secret text is stored in the bit_to_hide positions
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:return: Decoded Data: String
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"""
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# Read text file and covert to binary
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with open(self.text_file, "r") as f:
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data = f.read()
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binary_data = ""
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for char in data:
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bin_char = self.to_bin(char)
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bin_char = "0" * (8 - len(bin_char)) + bin_char
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for bit_pos in self.bit_to_hide:
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binary_data += bin_char[bit_pos]
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all_chars = [binary_data[i:i + 8] for i in range(0, len(binary_data), 8)]
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decoded_data = ""
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for char in all_chars:
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decoded_data += chr(int(char, 2))
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if decoded_data[-len(self.delimiter):] == self.delimiter:
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break
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return decoded_data[:-len(self.delimiter)]
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def to_bin(self, data: str) -> str | list[str]:
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"""
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Convert text file data to binary format as string
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:param data: String
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:type data: str
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:return: Binary Data: String | List[String]
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"""
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if isinstance(data, str):
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return ''.join([format(ord(i), "08b") for i in data])
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elif isinstance(data, bytes) or isinstance(data, np.ndarray):
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return [format(i, "08b") for i in data]
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elif isinstance(data, int) or isinstance(data, np.unit8):
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return format(data, "08b")
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else:
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raise TypeError("Type not supported")
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def from_bin(self, data: str) -> str:
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"""
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Convert binary `data` back to the original format
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:param data: String
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:type data: str
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:return: Original Data: String
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"""
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return ''.join([chr(int(data[i:i + 8], 2)) for i in range(0, len(data), 8)])
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def main():
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raise NotImplementedError("This module is not meant to run by itself")
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if __name__ == "__main__":
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main()
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