84 lines
2.5 KiB
Python
84 lines
2.5 KiB
Python
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import sys
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from PIL import Image
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def decode_lsb(image_path, output_path):
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print(f"[*] Extracting payload from {image_path}...")
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img = Image.open(image_path)
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img = img.convert('RGB')
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pixels = img.load()
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width, height = img.size
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# 1. Read the first 64 bits (8 bytes) to get the payload length
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header_bits = ""
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bit_idx = 0
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header_length = 64
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for y in range(height):
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for x in range(width):
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r, g, b = pixels[x, y]
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if bit_idx < header_length:
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header_bits += str(r & 1)
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bit_idx += 1
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if bit_idx < header_length:
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header_bits += str(g & 1)
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bit_idx += 1
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if bit_idx < header_length:
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header_bits += str(b & 1)
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bit_idx += 1
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if bit_idx >= header_length:
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break
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if bit_idx >= header_length:
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break
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payload_length_bytes = int(header_bits, 2)
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payload_length_bits = payload_length_bytes * 8
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print(f"[*] Detected embedded payload of size: {payload_length_bytes} bytes.")
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# 2. Read the actual payload
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payload_bits = ""
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bit_idx = 0
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total_bits_to_read = header_length + payload_length_bits
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for y in range(height):
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for x in range(width):
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r, g, b = pixels[x, y]
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if bit_idx >= header_length and bit_idx < total_bits_to_read:
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payload_bits += str(r & 1)
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bit_idx += 1
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if bit_idx >= header_length and bit_idx < total_bits_to_read:
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payload_bits += str(g & 1)
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bit_idx += 1
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if bit_idx >= header_length and bit_idx < total_bits_to_read:
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payload_bits += str(b & 1)
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bit_idx += 1
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if bit_idx >= total_bits_to_read:
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break
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if bit_idx >= total_bits_to_read:
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break
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# Convert bits to bytes
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payload_bytes = bytearray()
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for i in range(0, len(payload_bits), 8):
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byte = payload_bits[i:i+8]
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payload_bytes.append(int(byte, 2))
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# 3. Save Payload
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with open(output_path, 'wb') as f:
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f.write(payload_bytes)
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print(f"[+] Successfully extracted payload to {output_path}")
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if __name__ == "__main__":
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if len(sys.argv) != 3:
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print("Usage: python3 stego_decoder.py <encoded_carrier.png> <output_payload.tar.gz>")
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sys.exit(1)
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decode_lsb(sys.argv[1], sys.argv[2])
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