From 2af929a83d32bb4afa734268c2809711bbdccd0f Mon Sep 17 00:00:00 2001
From: rlaphoenix <rlaphoenix@pm.me>
Date: Sun, 21 Aug 2022 22:39:26 +0100
Subject: [PATCH] Cdm: Use reversed OEMCrypto request id formula for Android
 devices

It's effectively 8 random bytes with a counter thats right-padded (to 8 bytes). This counter is the Session number.
---
 pywidevine/cdm.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pywidevine/cdm.py b/pywidevine/cdm.py
index eab5231..b1a6493 100644
--- a/pywidevine/cdm.py
+++ b/pywidevine/cdm.py
@@ -279,7 +279,10 @@ class Cdm:
         except ValueError:
             raise InvalidLicenseType(f"License Type {type_!r} is invalid")
 
-        request_id = get_random_bytes(16)
+        if self.device_type == Device.Types.ANDROID:
+            request_id = get_random_bytes(8) + session.number.to_bytes(8, "little")
+        else:
+            request_id = get_random_bytes(16)
 
         license_request = LicenseRequest()
         license_request.type = LicenseRequest.RequestType.Value("NEW")