sys/random: add SHA1PRNG

Makefile.dep

@@ -631,6 +631,10 @@ ifneq (,$(filter random,$(USEMODULE)))
     USEMODULE += tinymt32
   endif
 
+  ifneq (,$(filter prng_sha1prng,$(USEMODULE)))
+    USEMODULE += hashes
+  endif
+
   USEMODULE += luid
 endif
 

sys/random/sha1prng.c

+/*
+ * Copyright (C) 2018 HAW Hamburg
+ *
+ * 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 referring to Docjar
+ * (http://www.docjar.net/html/api/gnu/java/security/provider/SHA1PRNG.java.html)
+ */
+
+ /**
+ * @ingroup sys_random
+ * @{
+ * @file
+ *
+ * @brief   SHA1PRNG random number generator implementation
+ *
+ * @author Peter Kietzmann <peter.kietzmann@haw-hamburg.de>
+ * @}
+ */
+
+#include <stdint.h>
+#include <string.h>
+
+#include "hashes/sha1.h"
+
+#define SEED_SIZE           (20)
+
+static sha1_context ctx;
+static uint32_t datapos = SEED_SIZE;
+static int8_t digestdata[SEED_SIZE];
+static int8_t prng_state[SEED_SIZE];
+
+void _updatestate(int8_t *state)
+{
+    signed last = 1;
+    char zf = 0;
+
+    for (int i = 0; i < 20; i++) {
+        signed v;
+        char t;
+        /* add two bytes */
+        v = (int)state[i] + (int)digestdata[i] + last;
+
+        /* result is lower 8 bits */
+        t = (char)(v & 0xff);
+
+        /* check for state collision */
+        zf = zf | (state[i] != t);
+
+        /* store result, */
+        state[i] = t;
+
+        /* high 8 bits are carry, store for next iteration */
+        last = (v >> 8);
+    }
+
+    /* make sure at least one bit changes! */
+    if (!zf) {
+       state[0]++;
+    }
+
+    /* update SHA1 state */
+    sha1_update(&ctx, (void *)state, sizeof(state));
+}
+
+void _random_bytes(uint8_t *bytes, size_t size) /* TODO: use with global API */
+{
+    uint32_t loc = 0;
+    while (loc < size)
+    {
+        int copy;
+        /* find min between remaining out bytes and so far unused seed bytes */
+        if ( (size-loc) < (SEED_SIZE - datapos) )
+        {
+            copy = size-loc;
+        }
+        else
+        {
+            /* in first iteration this will be 0 */
+            copy = SEED_SIZE - datapos;
+        }
+        if (copy > 0)
+        {
+            /* directly copy data to out buffer */
+            memcpy(bytes + loc, digestdata + datapos, copy);
+            datapos += copy;
+            loc += copy;
+        }
+        /* no out data ready, (re)fill internal buffer */
+        else
+        {
+            /* reset SHA1 internal state */
+            sha1_init(&ctx);
+
+            /* update SHA1 internal state with PRNG state */
+            sha1_update(&ctx, (void *)prng_state, sizeof(prng_state));
+
+            /* get the digest */
+            sha1_final(&ctx, digestdata);
+
+            /* update PRNG state for next round */
+            _updatestate(prng_state);
+
+            /* reset counter for buffer position */
+            datapos = 0;
+        }
+    }
+}
+
+void random_init(uint32_t seed)
+{
+    sha1_init(&ctx);
+    sha1_update(&ctx, (void *)&seed, sizeof(uint32_t));
+    sha1_final(&ctx, digestdata);
+
+    /* copy seeded SHA1 state to PRNG state */
+    memcpy(prng_state, &ctx.state, 20);
+}
+void random_init_by_array(uint32_t init_key[], int key_length)
+{
+    sha1_init(&ctx);
+    sha1_update(&ctx, (void *)init_key, key_length);
+    sha1_final(&ctx, digestdata);
+
+    /* copy seeded SHA1 state to PRNG state */
+    memcpy(prng_state, &ctx.state, 20);
+}
+
+uint32_t random_uint32(void)
+{
+    uint32_t ret;
+    int8_t bytes[sizeof(uint32_t)];
+    _random_bytes((uint8_t *)bytes, sizeof(uint32_t));
+
+    ret = ((bytes[0] & 0xff) << 24)
+        | ((bytes[1] & 0xff) << 16)
+        | ((bytes[2] & 0xff) <<  8)
+        |  (bytes[3] & 0xff);
+
+    return ret;
+}

tests/rng/test.c

@@ -59,6 +59,8 @@ static void test_init(char *name)
         puts("Park & Miller Minimal Standard PRNG.\n");
 #elif MODULE_PRNG_MUSL_LCG
         puts("Musl C PRNG.\n");
+#elif MODULE_PRNG_SHA1PRNG
+        puts("SHA1 PRNG.\n");
 #elif MODULE_PRNG_TINYMT32
         puts("Tiny Mersenne Twister PRNG.\n");
 #elif MODULE_PRNG_XORSHIFT