add logic to detect occurences of signatureCipher in stream_data formats (#631)

* add logic to detect occurrences of signatureCipher in stream_data formats
* add unit test to check signatureCipher key is correctly handled

pytube/extract.py

@@ -315,7 +315,11 @@ def apply_descrambler(stream_data: Dict, key: str) -> None:
             ]
         except KeyError:
             cipher_url = [
-                parse_qs(formats[i]["cipher"])
+                parse_qs(
+                    formats[i][
+                        "cipher" if "cipher" in data.keys() else "signatureCipher"
+                    ]
+                )
                 for i, data in enumerate(formats)
             ]
             stream_data[key] = [

tests/conftest.py

@@ -75,3 +75,16 @@ def playlist_long_html():
     )
     with gzip.open(file_path, "rb") as f:
         return f.read().decode("utf-8")
+
+
+@pytest.fixture
+def stream_dict():
+    """Youtube instance initialized with video id WXxV9g7lsFE."""
+    file_path = os.path.join(
+        os.path.dirname(os.path.realpath(__file__)),
+        "mocks",
+        "yt-video-WXxV9g7lsFE.json.gz",
+    )
+    with gzip.open(file_path, "rb") as f:
+        content = f.read().decode("utf-8")
+        return json.loads(content)

tests/test_extract.py

@@ -87,3 +87,8 @@ def test_mime_type_codec_with_no_match_should_error():
 def test_get_ytplayer_config_with_no_match_should_error():
     with pytest.raises(RegexMatchError):
         extract.get_ytplayer_config("")
+
+
+def test_signature_cipher_does_not_error(stream_dict):
+    extract.apply_descrambler(stream_dict, "url_encoded_fmt_stream_map")
+    assert "s" in stream_dict["url_encoded_fmt_stream_map"][0].keys()