Question

This is my code:

#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <crypt.h>
#include <string.h>
#include <stdlib.h>

int main(void){

int i;
unsigned long seed[2];

/* Generate a (not very) random seed */
seed[0] = time(NULL);
seed[1] = getpid() ^ (seed[0] >> 14 & 0x30000);

printf("Seed 0: %lu ; Seed 1: %lu", seed[0], seed[1]);
return 0;
}

I want to generate some very random seed that will be used into an hash function but i don’t know how to do it!

Answer 1

You can read the random bits you need from /dev/random.

When read, the /dev/random device will only return random bytes within the estimated number of bits of noise in the entropy pool. /dev/random should be suitable for uses that need very high quality randomness such as one-time pad or key generation. When the entropy pool is empty, reads from /dev/random will block until additional environmental noise is gathered.(http://www.kernel.org/doc/man-pages/online/pages/man4/random.4.html)

int randomSrc = open("/dev/random", O_RDONLY);
unsigned long seed[2];
read(randomSrc , seed, 2 * sizeof(long) );
close(randomSrc);