add license reference to totp.c

diff --git a/totp.c b/totp.c
index 3663d87064f94d351d7b6adc6dd30a90204b3c72..0475c893fdc0754dae2800f045a80f28b67e9330 100644 (file)
--- a/totp.c
+++ b/totp.c
@@ -1,5 +1,11 @@
 
-// totp.c
+/* totp.c
+ *
+ * Copyright (c) 2017, mar77i <mar77i at protonmail dot ch>
+ *
+ * This software may be modified and distributed under the terms
+ * of the ISC license.  See the LICENSE file for details.
+ */
 
 #include <ctype.h>
 #include <inttypes.h>