diff --git a/includes/init.php b/includes/init.php
index c866234..6e1cd81 100644
--- a/includes/init.php
+++ b/includes/init.php
@@ -17,6 +17,12 @@ add_action( 'rest_api_init', function() {
 add_action( 'user_register', function( $user_id ) {
     $slug = get_the_author_meta( 'user_nicename', $user_id );
     \pterotype\actors\create_actor( $slug, 'user' );
+    $actor_id = \pterotype\actors\get_actor_id( $slug );
+    $keys_created = \pterotype\pgp\get_public_key( $slug );
+    if ( ! $keys_created ) {
+        $keys = \pterotype\pgp\gen_key( $slug );
+        \pterotype\pgp\persist_key( $actor_id, $keys['publickey'], $keys['privatekey'] );
+    }
 } );
 
 add_action( 'pterotype_init', function() {
diff --git a/includes/server/deliver.php b/includes/server/deliver.php
index 467b171..5cb3345 100644
--- a/includes/server/deliver.php
+++ b/includes/server/deliver.php
@@ -130,7 +130,7 @@ function post_activity_to_inboxes( $actor_id, $activity, $recipients ) {
             $request->set_method('POST');
             $request->set_body( $activity );
             $request->add_header( 'Content-Type', 'application/ld+json' );
-            $request->add_header( 'Signature', signature_header( $inbox, $actor_id ) );
+            $request->add_header( 'Signature', signature_header( $inbox, $actor_id, $date_str ) );
             $request->add_header( 'Date', $date_str );
             $server = rest_get_server();
             $response = $server->dispatch( $request );