Adding license headers.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>

src/rng/random.h

@@ -1,3 +1,24 @@
+/* 
+ * This file is part of the Pico HSM distribution (https://github.com/polhenarejos/pico-hsm).
+ * Copyright (c) 2022 Pol Henarejos.
+ * 
+ * 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, version 3.
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+
+
+#ifndef _RANDOM_H_
+#define _RANDOM_H_
+
 void random_init (void);
 void random_fini (void);
 
@@ -10,3 +31,5 @@ void random_get_salt (uint8_t *p);
 
 /* iterator returning a byta at a time */
 int random_gen (void *arg, unsigned char *output, size_t output_len);
+
+#endif