/*
 * TEA Total Copyright (c) Alex Holden <alex@linuxhacker.org> 2000, 2001.
 *
 * This code is public domain; you can do whatever you want with it, though I
 * would prefer you to contribute any bug fixes back to me if possible.
 * This software comes with NO WARRANTY WHATSOEVER, not even the implied
 * warranties of merchantability and fitness for a particular purpose.
 *
 * randdev.c: Generates a random key using /dev/random or equivalent.
 */

#include <fcntl.h>
#include <unistd.h>

#include "teatotal.h"
#include "tea-kgen.h"

#define TEA_KGEN_MSG "If tea-kgen pauses, mash keyboard or move " \
			"mouse to generate more randomness.\n"

/*
 * Generate the key data by simply reading 16 bytes from the system's
 * /dev/random or equivalent.
 */
void generate_key(teastate *state)
{
	int i, fd;

	/* Open the random number generator device */
	if(!(fd = open(RANDOM_DEVICE, O_RDONLY)))
		die("Couldn't open random device\n");

	/* Print a warning message about generating randomness if necessary */
	safe_write(STDERR_FILENO, TEA_KGEN_MSG, sizeof(TEA_KGEN_MSG));

	/* Read 16 bytes (128 bits) of data from it */
	if((i = safe_read(fd, state->k, 16)) == -1)
		die("Couldn't read from random device\n");
	if(i != 16) die("Failed to read enough data from random device\n");

	/* Close the random device */
	close(fd);
}