From 0c85abb2d428e11e7175522a1669c0396e6f372b Mon Sep 17 00:00:00 2001
From: rlaphoenix <rlaphoenix@pm.me>
Date: Sun, 31 Jul 2022 13:17:49 +0100
Subject: [PATCH] Cdm: Save Service Certificate in SignedMessage form

We may need the signature for external verification, and most APIs require it to be in a SignedMessage to be accepted, even though the SignedMessage is pretty much empty (not even actually signed lol).
---
 pywidevine/cdm.py     | 6 +++++-
 pywidevine/session.py | 4 ++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/pywidevine/cdm.py b/pywidevine/cdm.py
index fc00502..1b891a1 100644
--- a/pywidevine/cdm.py
+++ b/pywidevine/cdm.py
@@ -150,6 +150,10 @@ class Cdm:
                 signed_drm_certificate.ParseFromString(certificate)
                 if signed_drm_certificate.SerializeToString() != certificate:
                     raise DecodeError()
+                # 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:
             # could be a direct unsigned DrmCertificate, but reject those anyway
             raise DecodeError("Could not parse certificate as a SignedDrmCertificate")
@@ -164,9 +168,9 @@ 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)
-            session.service_certificate = drm_certificate
             return drm_certificate.provider_id
 
     def get_license_challenge(
diff --git a/pywidevine/session.py b/pywidevine/session.py
index c3373cd..cc123df 100644
--- a/pywidevine/session.py
+++ b/pywidevine/session.py
@@ -3,12 +3,12 @@ from typing import Optional
 from Crypto.Random import get_random_bytes
 
 from pywidevine.key import Key
-from pywidevine.license_protocol_pb2 import DrmCertificate
+from pywidevine.license_protocol_pb2 import SignedMessage
 
 
 class Session:
     def __init__(self):
         self.id = get_random_bytes(16)
-        self.service_certificate: Optional[DrmCertificate] = None
+        self.service_certificate: Optional[SignedMessage] = None
         self.context: dict[bytes, tuple[bytes, bytes]] = {}
         self.keys: list[Key] = []