Adding back subtitle decrypt modules (#18)

* Adding back subtitle decrypt modules

* Adding cryptography library

* isort and black format

* poetry update

* Add timeout to requests

pyproject.toml

@@ -12,9 +12,9 @@ requests = "^2.28.2"
 pydantic = "^1.10.5"
 validators = "^0.20.0"
 yt-dlp = "^2023.2.17"
-pycryptodome = "^3.19.0"
 pysrt = "^1.1.2"
 python-dotenv = "^1.0.0"
+cryptography = "^41.0.7"
 
 [tool.poetry.dev-dependencies]
 datamodel-code-generator = { extras = ["http"], version = "^0.17.1" }

src/kisskh_downloader/downloader.py

@@ -47,7 +47,7 @@ def download_subtitles(
         for subtitle in subtitles:
             logger.info(f"Downloading {subtitle.label} sub...")
             extension = os.path.splitext(urlparse(subtitle.src).path)[-1]
-            response = requests.get(subtitle.src)
+            response = requests.get(subtitle.src, timeout=60)
             output_path = Path(f"{filepath}.{subtitle.land}{extension}")
             output_path.write_bytes(response.content)
             if decrypter is not None:

src/kisskh_downloader/helper/aes_cipher.py

@@ -0,0 +1,31 @@
+from base64 import b64decode, b64encode
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import padding
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+
+
+class AESCipher:
+    def __init__(self, key, initialization_vector):
+        self.key = key.encode("utf8")
+        self.initialization_vector = initialization_vector.encode("utf8")
+
+    def __get_cipher(self):
+        return Cipher(algorithms.AES(self.key), modes.CBC(self.initialization_vector), backend=default_backend())
+
+    def decrypt(self, encrypted_text):
+        cipher = self.__get_cipher()
+        decryptor = cipher.decryptor()
+        decrypted_text = decryptor.update(b64decode(encrypted_text)) + decryptor.finalize()
+        unpadder = padding.PKCS7(128).unpadder()
+        decrypted_text = unpadder.update(decrypted_text) + unpadder.finalize()
+        decrypted_text = decrypted_text.rstrip(b"\0").decode("utf8")
+        return decrypted_text
+
+    def encrypt(self, text):
+        cipher = self.__get_cipher()
+        padder = padding.PKCS7(128).padder()
+        padded_data = padder.update(text.encode("utf8")) + padder.finalize()
+        encryptor = cipher.encryptor()
+        encrypted = encryptor.update(padded_data) + encryptor.finalize()
+        return b64encode(encrypted).decode("utf8")

src/kisskh_downloader/helper/decrypt_subtitle.py

@@ -0,0 +1,17 @@
+import pysrt
+
+from kisskh_downloader.helper.aes_cipher import AESCipher
+
+
+class SubtitleDecrypter:
+    def __init__(self, key, initialization_vector):
+        self.cipher = AESCipher(key, initialization_vector)
+
+    def decrypt_subtitles(self, file_path):
+        subs = pysrt.open(file_path)
+
+        for sub in subs:
+            decrypted_text = self.cipher.decrypt(sub.text)
+            sub.text = decrypted_text
+
+        return subs

tests/helper/test_aes_cipher.py

@@ -0,0 +1,11 @@
+from kisskh_downloader.helper.aes_cipher import AESCipher
+
+
+def test_decrypt():
+    text = "Hello There"
+    key = "7846286482638268"
+    initialization_vector = "4628745283719461"
+
+    aes_cipher = AESCipher(key=key, initialization_vector=initialization_vector)
+    encrypted_text = aes_cipher.encrypt(text)
+    assert aes_cipher.decrypt(encrypted_text) == text