/* Sample application to demonstrate the use of the PRNGD daemon */
/* for reading random numbers.                                   */

/*****************************************************************
Compiling and running the example application.
******************************************************************
[jones1@master mpihello]$ cc test_rand.c -lssl
[jones1@master mpihello]$ ./a.out
Random number is 92
Random number is 213
Random number is 189
Random number is 222
Random number is 141
Random number is 105
Random number is 244
Random number is 175
Random number is 52
Random number is 166
******************************************************************/

#include <string.h>
#include <openssl/rand.h>

int main(int argc, char *argv[])
{
   int i, j, status;
   int prngd_bytes, random_num;
   unsigned char random_bytes[4];
   static char egd_path[]="/var/run/egd-pool";

   /* First action is to seed the PRNG via the PRNGD daemon. */
   prngd_bytes = RAND_egd(egd_path);
   if (prngd_bytes == -1) {
      printf("Problem seeding the PRNG!\n");
   }

   /* Ok, let's read something from the randomness pool. */
   for (i=0; i < 10; i++) {
      /* Zero out the integer so there's nothing left behind. */
      memset((void *) &random_num, 0x0, 4);

      /* Now go and get some number of bytes of randomness from the pool. */
      /* The second parameter is the number of bytes to read.  For an     */
      /* integer, the obvious values are 1, 2, and 4 depending on the     */
      /* desired range of the random number.                              */
      status = RAND_bytes((char *) &random_num, 1);
      if (status != 1) {
         printf("Problem: Not enough randomness available.\n");
      }

      /* Print the random number as an unsigned integer. */
      printf("Random number is %u\n", random_num);
   }

   /* Innocuous return value. */
   return(0);
}