diff --git a/pkg/onionkey/v3.go b/pkg/onionkey/v3.go
index 155c6b1..cbd6c73 100644
--- a/pkg/onionkey/v3.go
+++ b/pkg/onionkey/v3.go
@@ -1,3 +1,5 @@
+// Implements Tor v3 onion key based on ed25519.
+
 package onionkey
 
 import (