sike_ifma/sidh_ref/random/random.c

/********************************************************************************************
* Hardware-based random number generation function using /dev/urandom
*********************************************************************************************/ 

#include "random.h"
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
static int lock = -1;


static __inline void delay(unsigned int count)
{
	while (count--) {}
}


int randombytes(unsigned char* random_array, unsigned long long nbytes)
{ // Generation of "nbytes" of random values
    int r, n = (int)nbytes, count = 0;
    
    if (lock == -1) {
	    do {
		    lock = open("/dev/urandom", O_RDONLY);
		    if (lock == -1) {
			    delay(0xFFFFF);
		    }
	    } while (lock == -1);
    }

	while (n > 0) {
		do {
			r = read(lock, random_array+count, n);
			if (r == -1) {
				delay(0xFFFF);
			}
		} while (r == -1);
		count += r;
		n -= r;
	}

	return 0;
}