Merge pull request #14453 from benpicco/sys/random-hwrng

sys/random: add option to use HWRNG as source of randomness

Makefile.dep

@@ -786,6 +786,10 @@ ifneq (,$(filter random,$(USEMODULE)))
     USEMODULE += hashes
   endif
 
+  ifneq (,$(filter prng_hwrng,$(USEMODULE)))
+    FEATURES_REQUIRED += periph_hwrng
+  endif
+
   ifeq (,$(filter puf_sram,$(USEMODULE)))
     FEATURES_OPTIONAL += periph_hwrng
   endif

sys/include/random.h

@@ -22,6 +22,9 @@
  *  - Simple Park-Miller PRNG
  *  - Musl C PRNG
  *  - Fortuna (CS)PRNG
+ *  - Hardware Random Number Generator (non-seedable)
+ *    HWRNG differ in how they generate random numbers and may not use a PRNG internally.
+ *    Refer to the manual of your MCU for details.
  */
 
 #ifndef RANDOM_H

sys/random/hwrng.c

@@ -0,0 +1,38 @@
+/**
+ * Copyright (C) 2020 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+ /**
+ * @ingroup sys_random
+ * @{
+ * @file
+ *
+ * @brief   Use the HWRNG as source of randomness
+ *
+ * @author  Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ * @}
+ */
+
+#include "kernel_defines.h"
+#include "periph/hwrng.h"
+#include "random.h"
+
+uint32_t random_uint32(void)
+{
+    uint32_t rnd;
+    hwrng_read(&rnd, sizeof(rnd));
+    return rnd;
+}
+
+void random_init(uint32_t val)
+{
+    (void) val;
+
+    if (!IS_ACTIVE(MODULE_PERIPH_INIT_HWRNG)) {
+        hwrng_init();
+    }
+}

tests/rng/test.c

@@ -65,6 +65,8 @@ static void test_init(char *name)
         puts("Tiny Mersenne Twister PRNG.\n");
 #elif MODULE_PRNG_XORSHIFT
         puts("XOR Shift PRNG.\n");
+#elif MODULE_PRNG_HWRNG
+        puts("Hardware RNG.\n");
 #else
         puts("unknown PRNG.\n");
 #endif