diff --git a/services/companion/Android.bp b/services/companion/Android.bp
index 4ae9365d3b9fc..e3926b48d61d9 100644
--- a/services/companion/Android.bp
+++ b/services/companion/Android.bp
@@ -9,7 +9,10 @@ package {
 
 filegroup {
     name: "services.companion-sources",
-    srcs: ["java/**/*.java"],
+    srcs: [
+        "java/**/*.java",
+        "java/**/*.proto",
+    ],
     path: "java",
     visibility: ["//frameworks/base/services"],
 }
@@ -17,6 +20,9 @@ filegroup {
 java_library_static {
     name: "services.companion",
     defaults: ["platform_service_defaults"],
+    proto: {
+        type: "stream",
+    },
     srcs: [":services.companion-sources"],
     libs: ["services.core"],
 }
diff --git a/services/companion/java/com/android/server/companion/proto/companion_apps_permissions.proto b/services/companion/java/com/android/server/companion/proto/companion_apps_permissions.proto
new file mode 100644
index 0000000000000..b786bcc5e0df9
--- /dev/null
+++ b/services/companion/java/com/android/server/companion/proto/companion_apps_permissions.proto
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+syntax = "proto3";
+
+option java_multiple_files = true;
+
+/* Represents granted permissions of a list of apps */
+message CompanionAppsPermissions {
+  // granted permissions of apps
+  repeated AppPermissions appPermissions = 1;
+
+  /* Represents the granted permissions of an app */
+  message AppPermissions {
+    // package name of the app
+    string packageName = 1;
+
+    // signing certificates used to sign the APK contents of this app
+    bytes certificates = 2;
+
+    // granted permissions
+    repeated string permission = 3;
+  }
+}
diff --git a/services/companion/java/com/android/server/companion/proto/companion_message.proto b/services/companion/java/com/android/server/companion/proto/companion_message.proto
new file mode 100644
index 0000000000000..2309be3afd940
--- /dev/null
+++ b/services/companion/java/com/android/server/companion/proto/companion_message.proto
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+syntax = "proto3";
+
+option java_multiple_files = true;
+
+/* Represents a message between companion devices */
+message CompanionMessage {
+  // id of the message
+  int32 messageId = 1;
+
+  // type of the message
+  CompanionMessageType type = 2;
+
+  // data contained in the message
+  bytes data = 3;
+
+  // types of CompanionMessage
+  enum CompanionMessageType {
+    // default value for proto3
+    UNKNOWN = 0;
+
+    // handshake message to establish secure channel
+    SECURE_CHANNEL_HANDSHAKE = 1;
+
+    // permission sync
+    PERMISSION_SYNC = 2;
+  }
+}