feat: implement Steganography CI/CD protocol (The Trojan Payload)

scripts/stego_encoder.py

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+import sys
+import os
+from PIL import Image
+
+def encode_lsb(image_path, payload_path, output_path):
+    print(f"[*] Encoding {payload_path} into {image_path}...")
+    
+    # 1. Read Payload
+    with open(payload_path, 'rb') as f:
+        payload_bytes = f.read()
+        
+    # Inject header to denote length of the file (8 bytes / 64 bits)
+    payload_length = len(payload_bytes)
+    header = payload_length.to_bytes(8, byteorder='big')
+    full_payload = header + payload_bytes
+    
+    # Convert to binary string
+    binary_payload = ''.join([format(b, '08b') for b in full_payload])
+    payload_len_bits = len(binary_payload)
+    print(f"[*] Payload is {payload_length} bytes ({payload_len_bits} bits).")
+
+    # 2. Open Image
+    img = Image.open(image_path)
+    img = img.convert('RGB')
+    pixels = img.load()
+    width, height = img.size
+    
+    max_bits = width * height * 3
+    if payload_len_bits > max_bits:
+        raise ValueError(f"Payload too large! Need {payload_len_bits} bits, but image can only hold {max_bits} bits.")
+
+    # 3. Inject Data via LSB
+    bit_idx = 0
+    for y in range(height):
+        for x in range(width):
+            if bit_idx >= payload_len_bits:
+                break
+                
+            r, g, b = pixels[x, y]
+            
+            if bit_idx < payload_len_bits:
+                r = (r & ~1) | int(binary_payload[bit_idx])
+                bit_idx += 1
+            if bit_idx < payload_len_bits:
+                g = (g & ~1) | int(binary_payload[bit_idx])
+                bit_idx += 1
+            if bit_idx < payload_len_bits:
+                b = (b & ~1) | int(binary_payload[bit_idx])
+                bit_idx += 1
+                
+            pixels[x, y] = (r, g, b)
+            
+        if bit_idx >= payload_len_bits:
+            break
+
+    # 4. Save
+    img.save(output_path, format="PNG")
+    print(f"[+] Successfully saved encoded carrier to {output_path}")
+
+if __name__ == "__main__":
+    if len(sys.argv) != 4:
+        print("Usage: python3 stego_encoder.py <payload.tar.gz> <carrier.png> <output.png>")
+        sys.exit(1)
+        
+    encode_lsb(sys.argv[2], sys.argv[1], sys.argv[3])