From c9b3365286a520d28e52054306b73f2a7379aae4 Mon Sep 17 00:00:00 2001
From: stelar7 <dudedbz@gmail.com>
Date: Thu, 31 Jul 2025 13:28:31 +0200
Subject: [PATCH] LibWeb/EME: Implement is_supported_key_system

---
 .../EncryptedMediaExtensions/Algorithms.cpp   | 20 +++++++++++++++++++
 .../EncryptedMediaExtensions/Algorithms.h     |  2 ++
 2 files changed, 22 insertions(+)

diff --git a/Libraries/LibWeb/EncryptedMediaExtensions/Algorithms.cpp b/Libraries/LibWeb/EncryptedMediaExtensions/Algorithms.cpp
index ac720f1d765..8329b950d30 100644
--- a/Libraries/LibWeb/EncryptedMediaExtensions/Algorithms.cpp
+++ b/Libraries/LibWeb/EncryptedMediaExtensions/Algorithms.cpp
@@ -399,4 +399,24 @@ Optional<ConsentConfiguration> get_supported_configuration(KeySystem const& impl
     return supported_configuration;
 }
 
+// https://w3c.github.io/encrypted-media/#dfn-common-key-systems
+bool is_supported_key_system(Utf16String const& key_system)
+{
+    constexpr Array<Utf16View, 1> supported_key_systems = {
+        // https://w3c.github.io/encrypted-media/#clear-key
+        "org.w3.clearkey"sv,
+    };
+
+    return supported_key_systems.contains_slow(key_system);
+}
+
+NonnullOwnPtr<KeySystem> key_system_from_string(Utf16String const& key_system)
+{
+    if (key_system == "org.w3.clearkey"_utf16) {
+        return adopt_own(*new ClearKeySystem());
+    }
+
+    VERIFY_NOT_REACHED();
+}
+
 }
diff --git a/Libraries/LibWeb/EncryptedMediaExtensions/Algorithms.h b/Libraries/LibWeb/EncryptedMediaExtensions/Algorithms.h
index 00fa3c123c0..05b3bcc17d1 100644
--- a/Libraries/LibWeb/EncryptedMediaExtensions/Algorithms.h
+++ b/Libraries/LibWeb/EncryptedMediaExtensions/Algorithms.h
@@ -17,6 +17,8 @@ namespace Web::EncryptedMediaExtensions {
 
 bool supports_container(Utf16String const& container);
 bool is_persistent_session_type(Utf16String const& session_type);
+bool is_supported_key_system(Utf16String const& key_system);
+NonnullOwnPtr<KeySystem> key_system_from_string(Utf16String const& key_system);
 ConsentStatus get_consent_status(Bindings::MediaKeySystemConfiguration const&, MediaKeyRestrictions&, URL::Origin const&);
 Optional<Vector<Bindings::MediaKeySystemMediaCapability>> get_supported_capabilities_for_audio_video_type(KeySystem const&, CapabilitiesType, Vector<Bindings::MediaKeySystemMediaCapability>, Bindings::MediaKeySystemConfiguration, MediaKeyRestrictions);
 Optional<ConsentConfiguration> get_supported_configuration_and_consent(KeySystem const&, Bindings::MediaKeySystemConfiguration const&, MediaKeyRestrictions&, URL::Origin const&);