Ox: Don't encrypt empty messages.

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 ### Changed
 - Ox: Improved error messages for failed key requests.
+- Ox: Don't encrypt empty messages.
 
 ## [v0.5.1] 2022-05-22
 ### Changed

ox.go

@@ -662,6 +662,9 @@ func oxGetPublicKeyRing(client *xmpp.Client, iqc chan xmpp.IQ,
 
 func oxEncrypt(client *xmpp.Client, iqc chan xmpp.IQ, oxPrivKey *crypto.Key,
 	recipient string, keyRing *crypto.KeyRing, message string) (string, error) {
+	if message == "" {
+		return "", nil
+	}
 	privKeyRing, err := crypto.NewKeyRing(oxPrivKey)
 	if err != nil {
 		return "error", err