diff --git a/src/Module/Inbox.php b/src/Module/Inbox.php
index 86fdae7c90..0bc78b030c 100644
--- a/src/Module/Inbox.php
+++ b/src/Module/Inbox.php
@@ -9,6 +9,7 @@ use Friendica\Database\DBA;
 use Friendica\Model\Contact;
 use Friendica\Util\HTTPSignature;
 use Friendica\Util\Network;
+use Friendica\Core\System;
 
 /**
  * ActivityPub Inbox
@@ -18,30 +19,16 @@ class Inbox extends BaseModule
 	public static function init()
 	{
 		$a = self::getApp();
-		logger('Blubb: init 1');
 
 		$postdata = file_get_contents('php://input');
 
-		$obj = json_decode($postdata);
-
-		if (empty($obj)) {
-			exit();
+		if (empty($postdata)) {
+			System::httpExit(400);
 		}
 
 		$tempfile = tempnam(get_temppath(), 'activitypub');
-		file_put_contents($tempfile, json_encode(['header' => $_SERVER, 'body' => $obj]));
+		file_put_contents($tempfile, json_encode(['header' => $_SERVER, 'body' => $postdata]));
 
-		logger('Blubb: init ' . $tempfile);
-		exit();
-//		goaway($dest);
-	}
-
-	public static function post()
-	{
-		$a = self::getApp();
-
-		logger('Blubb: post');
-		exit();
-//		goaway($dest);
+		System::httpExit(200);
 	}
 }
diff --git a/src/Protocol/ActivityPub.php b/src/Protocol/ActivityPub.php
index f1d885b6c6..8992c525b0 100644
--- a/src/Protocol/ActivityPub.php
+++ b/src/Protocol/ActivityPub.php
@@ -25,6 +25,9 @@ use Friendica\Content\Text\BBCode;
  *
  * https://blog.joinmastodon.org/2018/06/how-to-implement-a-basic-activitypub-server/
  * https://blog.joinmastodon.org/2018/07/how-to-make-friends-and-verify-requests/
+ *
+ * Digest: https://tools.ietf.org/html/rfc5843
+ * https://tools.ietf.org/html/draft-cavage-http-signatures-10#ref-15
  */
 class ActivityPub
 {