Update Changelog for v1.5.1

Currently, even though self.version would be 0, it would dump as a version=1 box with key_IDs set to data (where possible).

This is because pymp4 sets the version to 1 if key_IDs is set with data, as that would make it a v1 PSSH box. So effectively .dump() and .dumps() forces a v1 box as output even if you loaded or created a v0 box.

Fixes #16

CHANGELOG.md

@@ -5,6 +5,35 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.5.1] - 2022-10-23
+
+### Added
+
+- Added import path shortcuts in the `__init__.py` package constructor to all the user classes. Now you can do e.g.,
+  `from pywidevine import PSSH` instead of `from pywidevine.pssh import PSSH`. You can still do it both ways.
+- Improved error handling and sanitization checks when parsing some Service Certificates in `set_service_certificate()`.
+
+### Changed
+
+- Maximum concurrent Cdm sessions are now set to 16 as it seems tto be a more common limit on more up-to-date CDMs,
+  including Android's OEMCrypto Library. This also helps encourage people to close their sessions when they are no
+  longer required.
+- Service Certificates are now stored in the session as a `SignedDrmCertificate`. This is to keep the signature with
+  the stored Certificate for use by the user if necessary. It also reduces code repetition relating to the usage of the
+  signature.
+
+### Fixed
+
+- Improved reliability of computing License Signatures. Some license messages when parsed would be slightly different
+  when re-serialized with `SerializeToString()`, therefore the computed signature would have always mismatched.
+- Added support for Key IDs that are integer values. Effectively all values are now considered to be a UUID as 16 bytes
+  (in hex or bytes) or an integer value with support for up to 16 bytes. All integer values are converted to a UUID and
+  are loaded big-endian.
+- Fixed acquisition of the Certificate's provider_id within `set_service_certificate()` in some edge cases, but also
+  when you try to remove the certificate by setting it to `None`.
+- PSSH now dumps in the same version the PSSH was loaded or created in. Previously it would always dump as a v1 PSSH
+  box due to a cascading check in pymp4. It now also honors the currently set version in the case it gets overridden.
+
 ## [1.5.0] - 2022-09-24
 
 With just one change this brings along a reduced dependency tree, smoother experience across different platforms, and
@@ -296,6 +325,7 @@ This release is primarily a maintenance release for `serve` functionality but so
 
 Initial Release.
 
+[1.5.1]: https://github.com/rlaphoenix/pywidevine/releases/tag/v1.5.1
 [1.5.0]: https://github.com/rlaphoenix/pywidevine/releases/tag/v1.5.0
 [1.4.4]: https://github.com/rlaphoenix/pywidevine/releases/tag/v1.4.4
 [1.4.3]: https://github.com/rlaphoenix/pywidevine/releases/tag/v1.4.3

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "pywidevine"
-version = "1.5.0"
+version = "1.5.1"
 description = "Widevine CDM (Content Decryption Module) implementation in Python."
 authors = ["rlaphoenix <rlaphoenix@pm.me>"]
 license = "GPL-3.0-only"

pywidevine/__init__.py

@@ -1 +1,9 @@
-__version__ = "1.5.0"
+from .cdm import *
+from .device import *
+from .key import *
+from .pssh import *
+from .remotecdm import *
+from .session import *
+
+
+__version__ = "1.5.1"

pywidevine/cdm.py

@@ -62,7 +62,7 @@ class Cdm:
     root_cert = DrmCertificate()
     root_cert.ParseFromString(root_signed_cert.drm_certificate)
 
-    MAX_NUM_OF_SESSIONS = 50  # most common limit
+    MAX_NUM_OF_SESSIONS = 16
 
     def __init__(
         self,
@@ -185,10 +185,14 @@ class Cdm:
             raise InvalidSession(f"Session identifier {session_id!r} is invalid.")
 
         if certificate is None:
-            drm_certificate = DrmCertificate()
-            drm_certificate.ParseFromString(session.service_certificate.drm_certificate)
+            if session.service_certificate:
+                drm_certificate = DrmCertificate()
+                drm_certificate.ParseFromString(session.service_certificate.drm_certificate)
+                provider_id = drm_certificate.provider_id
+            else:
+                provider_id = None
             session.service_certificate = None
-            return drm_certificate.provider_id
+            return provider_id
 
         if isinstance(certificate, str):
             try:
@@ -200,6 +204,7 @@ class Cdm:
 
         signed_message = SignedMessage()
         signed_drm_certificate = SignedDrmCertificate()
+        drm_certificate = DrmCertificate()
 
         try:
             signed_message.ParseFromString(certificate)
@@ -209,10 +214,6 @@ class Cdm:
                 signed_drm_certificate.ParseFromString(certificate)
                 if signed_drm_certificate.SerializeToString() != certificate:
                     raise DecodeError("partial parse")
-                # Craft a SignedMessage as it's stored as a SignedMessage
-                signed_message.Clear()
-                signed_message.msg = signed_drm_certificate.SerializeToString()
-                # we don't need to sign this message, this is normal
         except DecodeError as e:
             # could be a direct unsigned DrmCertificate, but reject those anyway
             raise DecodeError(f"Could not parse certificate as a SignedDrmCertificate, {e}")
@@ -226,13 +227,20 @@ class Cdm:
                 )
         except (ValueError, TypeError):
             raise SignatureMismatch("Signature Mismatch on SignedDrmCertificate, rejecting certificate")
-        else:
-            session.service_certificate = signed_message
-            drm_certificate = DrmCertificate()
-            drm_certificate.ParseFromString(signed_drm_certificate.drm_certificate)
-            return drm_certificate.provider_id
 
-    def get_service_certificate(self, session_id: bytes) -> Optional[SignedMessage]:
+        try:
+            drm_certificate.ParseFromString(signed_drm_certificate.drm_certificate)
+            if drm_certificate.SerializeToString() != signed_drm_certificate.drm_certificate:
+                raise DecodeError("partial parse")
+        except DecodeError as e:
+            raise DecodeError(f"Could not parse signed certificate's message as a DrmCertificate, {e}")
+
+        # must be stored as a SignedDrmCertificate as the signature needs to be kept for RemoteCdm
+        # if we store as DrmCertificate (no signature) then RemoteCdm cannot verify the Certificate
+        session.service_certificate = signed_drm_certificate
+        return drm_certificate.provider_id
+
+    def get_service_certificate(self, session_id: bytes) -> Optional[SignedDrmCertificate]:
         """
         Get the currently set Service Privacy Certificate of the Session.
 
@@ -405,9 +413,12 @@ class Cdm:
             key=self.__decrypter.decrypt(license_message.session_key)
         )
 
+        # explicitly use the original `license_message.msg` instead of a re-serializing from `licence`
+        # as some differences may end up in the output due to differences in the proto
+
         computed_signature = HMAC. \
             new(mac_key_server, digestmod=SHA256). \
-            update(licence.SerializeToString()). \
+            update(license_message.msg). \
             digest()
 
         if license_message.signature != computed_signature:
@@ -541,7 +552,7 @@ class Cdm:
     @staticmethod
     def encrypt_client_id(
         client_id: ClientIdentification,
-        service_certificate: Union[SignedMessage, SignedDrmCertificate, DrmCertificate],
+        service_certificate: Union[SignedDrmCertificate, DrmCertificate],
         key: bytes = None,
         iv: bytes = None
     ) -> EncryptedClientIdentification:
@@ -549,10 +560,6 @@ class Cdm:
         privacy_key = key or get_random_bytes(16)
         privacy_iv = iv or get_random_bytes(16)
 
-        if isinstance(service_certificate, SignedMessage):
-            signed_drm_certificate = SignedDrmCertificate()
-            signed_drm_certificate.ParseFromString(service_certificate.msg)
-            service_certificate = signed_drm_certificate
         if isinstance(service_certificate, SignedDrmCertificate):
             drm_certificate = DrmCertificate()
             drm_certificate.ParseFromString(service_certificate.drm_certificate)

pywidevine/pssh.py

@@ -19,8 +19,8 @@ class PSSH:
     """PSSH-related utilities. Somewhat Widevine-biased."""
 
     class SystemId:
-        Widevine = UUID(bytes=b"\xed\xef\x8b\xa9\x79\xd6\x4a\xce\xa3\xc8\x27\xdc\xd5\x1d\x21\xed")
-        PlayReady = UUID(bytes=b"\x9a\x04\xf0\x79\x98\x40\x42\x86\xab\x92\xe6\x5b\xe0\x88\x5f\x95")
+        Widevine = UUID(hex="edef8ba979d64acea3c827dcd51d21ed")
+        PlayReady = UUID(hex="9a04f07998404286ab92e65be0885f95")
 
     def __init__(self, data: Union[Container, str, bytes], strict: bool = False):
         """
@@ -199,7 +199,11 @@ class PSSH:
             cenc_header.ParseFromString(self.init_data)
             return [
                 # the key_ids value may or may not be hex underlying
-                UUID(bytes=key_id) if len(key_id) == 16 else UUID(hex=key_id.decode())
+                (
+                    UUID(bytes=key_id) if len(key_id) == 16 else  # normal
+                    UUID(hex=key_id.decode()) if len(key_id) == 32 else  # stored as hex
+                    UUID(int=int.from_bytes(key_id, "big"))  # assuming as number
+                )
                 for key_id in cenc_header.key_ids
             ]
 
@@ -231,7 +235,7 @@ class PSSH:
             version=self.version,
             flags=self.flags,
             system_ID=self.system_id,
-            key_IDs=self.key_ids,
+            key_IDs=self.key_ids if self.version == 1 and self.key_ids else None,
             init_data=self.init_data
         ))
 

pywidevine/remotecdm.py

@@ -143,7 +143,7 @@ class RemoteCdm(Cdm):
 
         return r["provider_id"]
 
-    def get_service_certificate(self, session_id: bytes) -> Optional[SignedMessage]:
+    def get_service_certificate(self, session_id: bytes) -> Optional[SignedDrmCertificate]:
         r = self.__session.post(
             url=f"{self.host}/{self.device_name}/get_service_certificate",
             json={
@@ -159,21 +159,12 @@ class RemoteCdm(Cdm):
             return None
 
         service_certificate = base64.b64decode(service_certificate)
-        signed_message = SignedMessage()
         signed_drm_certificate = SignedDrmCertificate()
 
         try:
-            signed_message.ParseFromString(service_certificate)
-            if signed_message.SerializeToString() == service_certificate:
-                signed_drm_certificate.ParseFromString(signed_message.msg)
-            else:
-                signed_drm_certificate.ParseFromString(service_certificate)
-                if signed_drm_certificate.SerializeToString() != service_certificate:
-                    raise DecodeError("partial parse")
-                # Craft a SignedMessage as it's stored as a SignedMessage
-                signed_message.Clear()
-                signed_message.msg = signed_drm_certificate.SerializeToString()
-                # we don't need to sign this message, this is normal
+            signed_drm_certificate.ParseFromString(service_certificate)
+            if signed_drm_certificate.SerializeToString() != service_certificate:
+                raise DecodeError("partial parse")
         except DecodeError as e:
             # could be a direct unsigned DrmCertificate, but reject those anyway
             raise DecodeError(f"Could not parse certificate as a SignedDrmCertificate, {e}")
@@ -187,8 +178,8 @@ class RemoteCdm(Cdm):
                 )
         except (ValueError, TypeError):
             raise SignatureMismatch("Signature Mismatch on SignedDrmCertificate, rejecting certificate")
-        else:
-            return signed_message
+
+        return signed_drm_certificate
 
     def get_license_challenge(
         self,

pywidevine/session.py

@@ -3,13 +3,13 @@ from typing import Optional
 from Crypto.Random import get_random_bytes
 
 from pywidevine.key import Key
-from pywidevine.license_protocol_pb2 import SignedMessage
+from pywidevine.license_protocol_pb2 import SignedDrmCertificate
 
 
 class Session:
     def __init__(self, number: int):
         self.number = number
         self.id = get_random_bytes(16)
-        self.service_certificate: Optional[SignedMessage] = None
+        self.service_certificate: Optional[SignedDrmCertificate] = None
         self.context: dict[bytes, tuple[bytes, bytes]] = {}
         self.keys: list[Key] = []