diff --git a/header_encryption.c b/header_encryption.c
index 7d3184c..0da17ef 100644
--- a/header_encryption.c
+++ b/header_encryption.c
@@ -1,3 +1,21 @@
+/**
+ * (C) 2007-20 - ntop.org and contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not see see <http://www.gnu.org/licenses/>
+ *
+ */
+
 #include "header_encryption.h"
 
 #include <string.h>
diff --git a/header_encryption.h b/header_encryption.h
index 4fafd0c..504b106 100644
--- a/header_encryption.h
+++ b/header_encryption.h
@@ -1,3 +1,21 @@
+/**
+ * (C) 2007-20 - ntop.org and contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not see see <http://www.gnu.org/licenses/>
+ *
+ */
+
 #include <stdint.h>