added XORSHIFT128+ random number generator

Makefile.in

@@ -7,7 +7,7 @@ GIT_COMMITS=@GIT_COMMITS@
 
 CC?=gcc
 DEBUG?=-g3
-OPTIMIZATION?=-O3 #-march=native
+OPTIMIZATION?=-O3 -march=native
 WARN?=-Wall
 
 #Ultrasparc64 users experiencing SIGBUS should try the following gcc options
@@ -51,7 +51,7 @@ N2N_LIB=libn2n.a
 N2N_OBJS=n2n.o wire.o minilzo.o twofish.o speck.o \
 	 edge_utils.o sn_utils.o \
          transform_null.o transform_tf.o transform_aes.o transform_cc20.o transform_speck.o \
-         tuntap_freebsd.o tuntap_netbsd.o tuntap_linux.o \
+         tuntap_freebsd.o tuntap_netbsd.o tuntap_linux.o random_numbers.o \
 	 tuntap_osx.o
 LIBS_EDGE+=$(LIBS_EDGE_OPT)
 LIBS_SN=

edge.c

@@ -17,6 +17,7 @@
  */
 
 #include "n2n.h"
+#include "random_numbers.h"
 #ifdef WIN32
 #include <sys/stat.h>
 #else
@@ -871,7 +872,7 @@ int main(int argc, char* argv[]) {
   traceEvent(TRACE_NORMAL, "Using %s cipher.", transop_str(conf.transop_id));
 
   /* Random seed */
-  srand(time(NULL));
+  n2n_srand (n2n_seed());
 
   if(0 == strcmp("dhcp", ec.ip_mode)) {
     traceEvent(TRACE_NORMAL, "Dynamic IP address assignment enabled.");

edge_utils.c

@@ -18,6 +18,7 @@
 
 #include "n2n.h"
 #include "lzoconf.h"
+#include "random_numbers.h"
 
 #ifdef HAVE_LIBZSTD
 #include <zstd.h>
@@ -759,7 +760,7 @@ static void send_register_super(n2n_edge_t * eee,
   memcpy(cmn.community, eee->conf.community_name, N2N_COMMUNITY_SIZE);
 
   for(idx=0; idx < N2N_COOKIE_SIZE; ++idx)
-    eee->last_cookie[idx] = rand() % 0xff;
+    eee->last_cookie[idx] = n2n_rand() % 0xff;
 
   memcpy(reg.cookie, eee->last_cookie, N2N_COOKIE_SIZE);
   reg.auth.scheme=0; /* No auth yet */

example_edge_embed_quick_edge_init.c

@@ -17,6 +17,7 @@
  */
 
 #include "n2n.h"
+#include "random_numbers.h"
 
 /*
   This tool demonstrates how to easily embed
@@ -36,7 +37,7 @@ int main(int argc, char* argv[]) {
   setTraceLevel(10);
 
   /* Random seed */
-  srand(time(NULL));
+  n2n_srand (n2n_seed());
 
   /* 
      NOTE

random_numbers.c

@@ -0,0 +1,116 @@
+/* The following code offers an alterate pseudo random number generator
+   namely XORSHIFT128+ to use instead of C's rand(). Its performance is
+   on par with C's rand().
+ */
+
+
+#include "random_numbers.h"
+
+
+/* The state must be seeded in a way that it is not all zero, choose some
+   arbitrary defaults (in this case: taken from splitmix64) */
+static struct rn_generator_state_t rn_current_state = {
+    .a    = 0x9E3779B97F4A7C15,
+    .b    = 0xBF58476D1CE4E5B9 };
+
+
+/* used for mixing the initializing seed */
+static uint64_t splitmix64 (struct splitmix64_state_t *state) {
+
+    uint64_t result = state->s;
+
+    state->s = result + 0x9E3779B97F4A7C15;
+
+    result = (result ^ (result >> 30)) * 0xBF58476D1CE4E5B9;
+    result = (result ^ (result >> 27)) * 0x94D049BB133111EB;
+
+    return result ^ (result >> 31);
+}
+
+
+int n2n_srand (uint64_t seed) {
+
+    struct splitmix64_state_t smstate = {seed};
+
+    rn_current_state.a = 0;
+    rn_current_state.b = 0;
+
+    rn_current_state.a = splitmix64 (&smstate);
+    rn_current_state.b = splitmix64 (&smstate);
+
+    /* the following lines could be deleted as soon as it is formally prooved that
+       there is no seed leading to (a == b == 0). Until then, just to be safe: */
+    if ( (rn_current_state.a == 0) && (rn_current_state.b == 0) ) {
+	rn_current_state.a = 0x9E3779B97F4A7C15;
+	rn_current_state.b = 0xBF58476D1CE4E5B9;
+    }
+
+    /* stabilize in unlikely case of weak state with only a few bits set */
+    for (uint8_t i = 0; i < 32; i++)
+	n2n_rand();
+
+    return 0;
+}
+
+
+/* The following code of xorshift128p was taken from
+   https://en.wikipedia.org/wiki/Xorshift as of July, 2019
+   and thus is considered public domain. */
+uint64_t n2n_rand () {
+
+    uint64_t t       = rn_current_state.a;
+    uint64_t const s = rn_current_state.b;
+
+    rn_current_state.a = s;
+    t ^= t << 23;
+    t ^= t >> 17;
+    t ^= s ^ (s >> 26);
+    rn_current_state.b = t;
+
+    return t + s;
+}
+
+
+/* The following code tries to gather some entropy from several sources
+   for use as seed. Note, that this code does not set the random generator
+   state yet, a call to   n2n_srand ( n2n_seed() )   would do. */
+uint64_t n2n_seed (void) {
+
+  uint64_t seed = 0;
+  uint64_t ret  = 0;
+
+#ifdef SYS_getrandom
+    syscall (SYS_getrandom, &seed, sizeof(seed), GRND_NONBLOCK);
+    ret += seed;
+#endif
+
+// __RDRND__ is set only if architecturual feature is set, e.g. compile with -march=native
+#ifdef __RDRND__
+    _rdrand64_step ((unsigned long long*)&seed);
+    ret += seed;
+#endif
+
+// __RDSEED__ ist set only if architecturual feature is set, e.g. compile with -march=native
+#ifdef __RDSEED__
+    _rdseed64_step((unsigned long long*)&seed);
+    ret += seed;
+#endif
+
+/* The WIN32 code is still untested and thus commented
+#ifdef WIN32
+    HCRYPTPROV crypto_provider;
+    CryptAcquireContext (&crypto_provider, NULL, (LPCWSTR)L"Microsoft Base Cryptographic Provider v1.0",
+                         PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
+    CryptGenRandom (crypto_provider, 8, &seed);
+    CryptReleaseContext (crypto_provider, 0);
+    ret += seed;
+#endif */
+
+    seed = time(NULL); /* UTC in seconds */
+    ret += seed;
+
+    seed = clock() * 8996146197;  /* clock() = ticks since program start */
+    ret += seed;
+
+    return ret;
+}

random_numbers.h

@@ -0,0 +1,34 @@
+#include <stdint.h>
+#include <time.h>
+
+
+#if defined (__linux__)
+  #include <sys/syscall.h>
+  #include <unistd.h>
+  #define GRND_NONBLOCK       1
+#endif
+
+#if defined (__RDRND__) || defined (__RDSEED__)
+  #include <immintrin.h>
+#endif
+
+/* The WIN32 code is still untested and thus commented
+#if defined (WIN32)
+  #include <Wincrypt.h>
+#endif */
+
+
+struct rn_generator_state_t {
+    uint64_t a, b;
+};
+
+struct splitmix64_state_t {
+    uint64_t s;
+};
+
+
+int n2n_srand (uint64_t seed);
+
+uint64_t n2n_rand ();
+
+uint64_t n2n_seed ();

transform_aes.c

@@ -18,6 +18,7 @@
 
 #include "n2n.h"
 #include "n2n_transforms.h"
+#include "random_numbers.h"
 
 #ifdef N2N_HAVE_AES
 
@@ -169,17 +170,17 @@ static int transop_encode_aes(n2n_trans_op_t * arg,
       /* Encode the aes format version. */
       encode_uint8(outbuf, &idx, N2N_AES_TRANSFORM_VERSION);
 
-      /* Generate and encode the IV seed using as many calls to rand() as neccessary.
+      /* Generate and encode the IV seed using as many calls to n2n_rand() as neccessary.
        * Note: ( N2N_AES_IV_SEED_SIZE % sizeof(rand_value) ) not neccessarily equals 0. */
-      uint32_t rand_value;
+      uint64_t rand_value;
       int8_t i;
       for (i = TRANSOP_AES_IV_SEED_SIZE; i >= sizeof(rand_value); i -= sizeof(rand_value)) {
-        rand_value = rand(); // CONCERN: rand() is not consideren cryptographicly secure, REPLACE later
+        rand_value = n2n_rand();
         memcpy(iv_seed + TRANSOP_AES_IV_SEED_SIZE - i, &rand_value, sizeof(rand_value));
       }
       /* Are there bytes left to fill? */
       if (i != 0) {
-        rand_value = rand(); // CONCERN: rand() is not consideren cryptographicly secure, REPLACE later
+        rand_value = n2n_rand();
         memcpy(iv_seed, &rand_value, i);
       }
       encode_buf(outbuf, &idx, iv_seed, TRANSOP_AES_IV_SEED_SIZE);

transform_cc20.c

@@ -18,6 +18,7 @@
 
 #include "n2n.h"
 #include "n2n_transforms.h"
+#include "random_numbers.h"
 
 #ifdef HAVE_OPENSSL_1_1
 
@@ -79,9 +80,9 @@ static char *openssl_err_as_string (void) {
 
 static void set_cc20_iv(transop_cc20_t *priv, n2n_cc20_ivec_t ivec) {
   // keep in mind the following condition: N2N_CC20_IVEC_SIZE % sizeof(rand_value) == 0 !
-  uint32_t rand_value;
+  uint64_t rand_value;
   for (uint8_t i = 0; i < N2N_CC20_IVEC_SIZE; i += sizeof(rand_value)) {
-    rand_value = rand(); // CONCERN: rand() is not consideren cryptographicly secure, REPLACE later
+    rand_value = n2n_rand();
     memcpy(ivec + i, &rand_value, sizeof(rand_value));
   }
 }

transform_speck.c

@@ -19,6 +19,7 @@
 #include "n2n.h"
 #include "n2n_transforms.h"
 #include "speck.h"
+#include "random_numbers.h"
 
 #define N2N_SPECK_TRANSFORM_VERSION       1  /* version of the transform encoding */
 #define N2N_SPECK_IVEC_SIZE               16
@@ -53,11 +54,11 @@ static int transop_deinit_speck(n2n_trans_op_t *arg) {
 
 static void set_speck_iv(transop_speck_t *priv, n2n_speck_ivec_t ivec) {
   // keep in mind the following condition: N2N_SPECK_IVEC_SIZE % sizeof(rand_value) == 0 !
-  uint32_t rand_value;
+  uint64_t rand_value;
   uint8_t i;
 
   for (i = 0; i < N2N_SPECK_IVEC_SIZE; i += sizeof(rand_value)) {
-    rand_value = rand(); // CONCERN: rand() is not considered cryptographicly secure, REPLACE later
+    rand_value = n2n_rand();
     memcpy(ivec + i, &rand_value, sizeof(rand_value));
   }
 }

transform_tf.c

@@ -19,6 +19,7 @@
 #include "n2n.h"
 #include "n2n_transforms.h"
 #include "twofish.h"
+#include "random_numbers.h"
 #ifndef _MSC_VER
 /* Not included in Visual Studio 2008 */
 #include <strings.h> /* index() */
@@ -89,7 +90,7 @@ static int transop_encode_twofish( n2n_trans_op_t * arg,
 	   * written in first followed by the packet payload. The whole
 	   * contents of assembly are encrypted. */
 	  pnonce = (uint32_t *)assembly;
-	  *pnonce = rand();
+	  *pnonce = n2n_rand();
 	  memcpy( assembly + TRANSOP_TF_NONCE_SIZE, inbuf, in_len );
 
 	  /* Encrypt the assembly contents and write the ciphertext after the SA. */

tuntap_linux.c

@@ -25,6 +25,7 @@
 #include <linux/if_tun.h>
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
+#include "random_numbers.h"
 
 /* ********************************** */
 
@@ -152,7 +153,7 @@ int tuntap_open(tuntap_dev *device,
     int i;
 
     for(i = 0; i < 6; i++)
-      device->mac_addr[i] = rand();
+      device->mac_addr[i] = n2n_rand();
 
     device->mac_addr[0] &= ~0x01; /* Clear multicast bit */
     device->mac_addr[0] |= 0x02;  /* Set locally-assigned bit */

twofish.c

@@ -41,6 +41,7 @@
 #include <ctype.h>
 #include <sys/types.h>
 #include "twofish.h"
+#include "random_numbers.h"
 
 /* Fixed 8x8 permutation S-boxes */
 static const uint8_t TwoFish_P[2][256] =
@@ -403,7 +404,7 @@ uint32_t TwoFishEncrypt(uint8_t *in,
 	*out=TwoFishAlloc(ilen,binhex,FALSE,tfdata);  /* ...we'll (re-)allocate buffer space. */
       if(*out!=NULL)
 	{	tfdata->output=*out;							/* set output buffer. */
-	  tfdata->header.salt=rand()*65536+rand();		/* toss in some salt. */
+	  tfdata->header.salt=n2n_rand()*65536+n2n_rand();		/* toss in some salt. */
 	  tfdata->header.length[0]= (uint8_t)(ilen);
 	  tfdata->header.length[1]= (uint8_t)(ilen>>8);
 	  tfdata->header.length[2]= (uint8_t)(ilen>>16);
@@ -980,7 +981,7 @@ int main(int argc, char* argv[])
 
     for ( i=0; i<TEST_DATA_SIZE; ++i )
     {
-        in[i] = rand() & 0xff;
+        in[i] = n2n_rand() & 0xff;
     }
 
     outp=outbuf;