sys: random: add entropy collector

Makefile.pseudomodules

@@ -2,6 +2,7 @@ PSEUDOMODULES += conn
 PSEUDOMODULES += conn_ip
 PSEUDOMODULES += conn_tcp
 PSEUDOMODULES += conn_udp
+PSEUDOMODULES += entropy
 PSEUDOMODULES += gnrc_netif_default
 PSEUDOMODULES += gnrc_ipv6_default
 PSEUDOMODULES += gnrc_ipv6_router
@@ -23,3 +24,6 @@ PSEUDOMODULES += netif
 # include variants of the AT86RF2xx drivers as pseudo modules
 PSEUDOMODULES += at86rf23%
 PSEUDOMODULES += at86rf21%
+
+# add all pseudo random number generator variants as pseudomodules
+PSEUDOMODULES += prng_%

dist/tools/test_random/Makefile

@@ -0,0 +1,37 @@
+RIOTBASE := ../../..
+INCLUDES := $(RIOTBASE)/sys/include
+
+CFLAGS += $(patsubst %,-I%,$(INCLUDES))
+CFLAGS += -Wall -O3
+
+PRNGS ?= mersenne minstd musl_lcg
+
+comma:= ,
+empty:=
+space:= $(empty) $(empty)
+PRNGS_CSV:= $(subst $(space),$(comma),$(PRNGS))
+
+all: $(PRNGS:%=test_%) $(PRNGS:%=test_%_entropy)
+
+clean:
+	rm -f test_*_entropy
+	rm -f test_{$(PRNGS_CSV)}
+
+test_%: test_random.c $(RIOTBASE)/sys/random/%.c
+	$(CC) $(CFLAGS) $^ -o $@$(SUFFIX)
+
+test_%_entropy: test_random.c $(RIOTBASE)/sys/random/%.c $(RIOTBASE)/sys/random/entropy.c
+	$(CC) $(CFLAGS) -DMODULE_ENTROPY -DURANDOM $^ -o $@$(SUFFIX)
+
+MODIFIED_ENT:=""#"Chi-percent,"
+
+run_tests: all
+	echo "prng,Entropy_injection_freq,unused,File-bytes,Entropy,Chi-square,$(MODIFIED_ENT)Mean,Monte-Carlo-Pi,Serial-Correlation" > ent_results.txt
+	for prng in $(PRNGS) ; do \
+		./test_$${prng} > test_$${prng}_out ; \
+		echo $${prng},-1,$$(ent -t test_$${prng}_out | tail -n 1) >> ent_results.txt; \
+		for freq in 1024 4096 16384 65536 262144 1048576 4194304 16777216; do \
+			./test_$${prng}_entropy $${freq}> test_$${prng}_entropy_freq_$${freq}_out ; \
+			echo $${prng},$${freq},$$(ent -t test_$${prng}_entropy_freq_$${freq}_out | tail -n 1) >> ent_results.txt; \
+			done ; \
+		done

dist/tools/test_random/test_random.c

@@ -0,0 +1,46 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#ifdef MODULE_ENTROPY
+#include "entropy.h"
+#define ENTROPY_FREQ_DEFAULT 1024
+#endif
+
+uint32_t genrand_uint32(void);
+void genrand_init(uint32_t s);
+
+#define N_WORDS (2<<24)
+
+int main(int argc, char *argv[]) {
+    uint32_t random;
+    uint32_t n = N_WORDS;
+
+#ifdef MODULE_ENTROPY
+    uint32_t entropy_freq;
+
+    if (argc>1) {
+        entropy_freq = atoi(argv[1]);
+    } else {
+        entropy_freq = ENTROPY_FREQ_DEFAULT;
+    }
+
+    fprintf(stderr, "Injecting a random byte every %u times.\n", entropy_freq);
+#endif
+
+    while(n--) {
+
+#ifdef MODULE_ENTROPY
+        if (! (n % entropy_freq)) {
+            fprintf(stderr, "Collecting entropy... %u\n", n);
+            entropy_collect();
+        }
+#endif
+
+        random = genrand_uint32();
+        write(STDOUT_FILENO, &random, 4);
+    }
+
+    return 0;
+}

sys/include/div.h

@@ -77,6 +77,28 @@ static inline uint32_t div_u32_by_15625div512(uint32_t val)
     return ((uint64_t)(val) * 0x431bde83ul) >> (12 + 32 - 9);
 }
 
+/**
+ * @brief Integer divide val by 44488
+ *
+ * @param[in]   val     dividend
+ * @return      (val / 44488)
+ */
+static inline uint32_t div_u32_by_44488(uint32_t val)
+{
+    return ((uint64_t)val * 0xBC8F1391UL) >> (15 + 32);
+}
+
+/**
+ * @brief Modulo 44488
+ *
+ * @param[in]   val     dividend
+ * @return      (val % 44488)
+ */
+static inline uint32_t div_u32_mod_44488(uint32_t val)
+{
+    return val - (div_u32_by_44488(val)*44488); 
+}
+
 #ifdef __cplusplus
 }
 #endif

sys/include/entropy.h

@@ -0,0 +1,9 @@
+#ifndef ENTROPY_H
+#define ENTROPY_H
+
+#include <stdint.h>
+
+extern uint32_t entropy;
+void entropy_collect(void);
+
+#endif /* ENTROPY_H */

sys/random/Makefile

@@ -1 +1,14 @@
+ifeq (,$(filter prng_%,$(USEMODULE)))
+    USEMODULE += prng_mersenne
+endif
+ifneq (,$(filter prng_mersenne,$(USEMODULE)))
+    SRC += mersenne.c
+endif
+ifneq (,$(filter prng_minstd,$(USEMODULE)))
+    SRC += minstd.c
+endif
+ifneq (,$(filter prng_musl_lcg,$(USEMODULE)))
+    SRC += musl_lcg.c
+endif
+
 include $(RIOTBASE)/Makefile.base

sys/random/entropy.c

@@ -0,0 +1,36 @@
+#include <stdint.h>
+
+#ifdef MODULE_XTIMER
+#include "xtimer.h"
+static uint32_t _last_event;
+#endif
+
+#if defined(URANDOM)
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#endif
+
+uint32_t entropy;
+static unsigned _n = 0;
+
+#ifndef ENTROPY_OP
+#define ENTROPY_OP(x) (x & 0xFF)
+#endif
+
+void entropy_collect(void)
+{
+#ifdef MODULE_XTIMER
+    uint32_t now = _lltimer_now();
+    uint32_t diff = now - _last_event;
+    _last_event = now;
+#elif defined(URANDOM)
+    int fd = open("/dev/urandom", O_RDONLY);
+    char randbyte;
+    read(fd, &randbyte, 1);
+    uint32_t diff = (uint8_t) randbyte;
+    close(fd);
+#endif
+
+    entropy ^= ((ENTROPY_OP(diff)) << ((_n++ & 0x3) * 8));
+}

sys/random/mersenne.c

@@ -55,6 +55,10 @@
 static uint32_t mt[N]; /** the array for the state vector  */
 static uint16_t mti = MTI_UNINITIALIZED;
 
+#ifdef MODULE_ENTROPY
+#include "entropy.h"
+#endif
+
 void genrand_init(uint32_t s)
 {
     mt[0] = s;
@@ -129,7 +133,12 @@ uint32_t genrand_uint32(void)
     y ^= (y << 7) & 0x9d2c5680UL;
     y ^= (y << 15) & 0xefc60000UL;
     y ^= y >> 18;
+
+#ifdef MODULE_ENTROPY
+    return y + entropy;
+#else
     return y;
+#endif
 }
 
 #if PRNG_FLOAT

sys/random/minstd.c

@@ -0,0 +1,84 @@
+/**
+ * Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * 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.
+ *
+ * Code taken from C FAQ (http://c-faq.com/lib/rand.html).
+ */
+
+ /**
+ * @ingroup sys_random
+ * @{
+ * @file
+ *
+ * @brief Simple Park & Miller "minimal standard" PRNG
+ *
+ * This file contains a simple Park-Miller pseudo random number generator.
+ *
+ * While not very random when considering crypto requirements, this is probably
+ * random enough anywhere where pseudo-randomness is sufficient, e.g., when
+ * provided with a sensible seed source, for MAC algorithms.
+ *
+ * The implementation is taken from the C FAQ, but modified to use magic number
+ * division and adapted to RIOT's coding conventions..
+ *
+ * @author Kaspar Schleiser <kaspar@schleiser.de>
+ * @}
+ */
+
+#include <stdint.h>
+
+#include "div.h"
+
+#ifdef MODULE_ENTROPY
+#include "entropy.h"
+#endif
+
+#define a 48271
+#define m 2147483647
+#define q (m / a) /* 44488 */
+#define r (m % a) /* 3399 */
+
+static uint32_t _seed = 1;
+
+int rand_minstd(void)
+{
+    uint32_t hi = div_u32_by_44488(_seed);
+    uint32_t lo = div_u32_mod_44488(_seed);
+    uint32_t test = (a * lo) - (r * hi);
+
+    if(test > 0) {
+        _seed = test;
+    }
+    else {
+        _seed = test + m;
+    }
+
+    return _seed;
+}
+
+uint32_t genrand_uint32(void)
+{
+    /* minstd as implemented returns only values from 1 to 2147483647,
+     * so run it two times to get 32bits */
+    uint16_t A = (rand_minstd() >> 15);
+    uint16_t B = (rand_minstd() >> 15);
+
+    uint32_t res = (((uint32_t)A) << 16) | B;
+
+#ifdef MODULE_ENTROPY
+    return res ^ entropy;
+#else
+    return res;
+#endif
+}
+
+void genrand_init(uint32_t val)
+{
+    if (!val) {
+        val = 1;
+    }
+    _seed = val;
+}

sys/random/musl_lcg.c

@@ -0,0 +1,53 @@
+/**
+ * Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * 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.
+ *
+ * Code taken from Musl C library. Original copyright notice:
+ *
+ * Copyright © 2005-2014 Rich Felker, et al.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <stdint.h>
+
+#ifdef MODULE_ENTROPY
+#include "entropy.h"
+#endif
+
+static uint64_t _seed;
+
+void genrand_init(uint32_t s)
+{
+    _seed = s-1;
+}
+
+uint32_t genrand_uint32(void)
+{
+    _seed = 6364136223846793005ULL*_seed + 1;
+#ifdef MODULE_ENTROPY
+    return (_seed>>31) ^ entropy;
+#else
+    return _seed>>31;
+#endif
+}

sys/shell/commands/Makefile

@@ -21,7 +21,7 @@ ifneq (,$(filter lpc2387,$(USEMODULE)))
   SRC += sc_heap.c
 endif
 ifneq (,$(filter random,$(USEMODULE)))
-  SRC += sc_mersenne.c
+  SRC += sc_random.c
 endif
 ifeq ($(CPU),x86)
   SRC += sc_x86_lspci.c

sys/shell/commands/sc_mersenne.c → sys/shell/commands/sc_random.c

@@ -12,7 +12,7 @@
  * @{
  *
  * @file
- * @brief       Shell commands for mersenne twister
+ * @brief       Shell commands for random generators
  *
  * @author      Christian Mehlis <mehlis@inf.fu-berlin.de>
  * @author      Kaspar Schleiser <kaspar@schleiser.de>
@@ -30,7 +30,7 @@
 
 #include "random.h"
 
-int _mersenne_init(int argc, char **argv)
+int _random_init(int argc, char **argv)
 {
     int initval;
 
@@ -53,7 +53,7 @@ int _mersenne_init(int argc, char **argv)
     return 0;
 }
 
-int _mersenne_get(int argc, char **argv)
+int _random_get(int argc, char **argv)
 {
     (void) argc;
     (void) argv;