[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Noob dumb question (extending emacs)
From: |
Emanuel Berg |
Subject: |
Re: Noob dumb question (extending emacs) |
Date: |
Sat, 23 Oct 2021 21:52:15 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) |
>> It is *not* okay to offer a library for password generation
>> using a weak generator to other people without explaining
>> its entropy characteristics so that they could assess
>> their risk.
>
> But what is the method stipulated then, we'll just do
> a `random-passwd' with that ...
>From pwgen on Debian 11:
/*
* randnum.c -- generate (good) randum numbers.
*
* Copyright (C) 2001,2002 by Theodore Ts'o
*
* This file may be distributed under the terms of the GNU Public
* License.
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include "pwgen.h"
#ifdef HAVE_DRAND48
extern double drand48(void);
#endif
static int get_random_fd(void);
/* Borrowed/adapted from e2fsprogs's UUID generation code */
static int get_random_fd()
{
struct timeval tv;
static int fd = -2;
if (fd == -2) {
gettimeofday(&tv, 0);
fd = open("/dev/urandom", O_RDONLY);
if (fd == -1)
fd = open("/dev/random", O_RDONLY | O_NONBLOCK);
}
return fd;
}
/*
* Generate a random number n, where 0 <= n < max_num, using
* /dev/urandom if possible.
*/
int pw_random_number(max_num)
int max_num;
{
unsigned int rand_num;
int i, fd = get_random_fd();
int lose_counter = 0, nbytes = sizeof(rand_num);
char *cp = (char *) &rand_num;
if (fd >= 0) {
while (nbytes > 0) {
i = read(fd, cp, nbytes);
if ((i < 0) &&
((errno == EINTR) || (errno == EAGAIN)))
continue;
if (i <= 0) {
if (lose_counter++ == 8)
break;
continue;
}
nbytes -= i;
cp += i;
lose_counter = 0;
}
}
if (nbytes == 0)
return (rand_num % max_num);
/* We weren't able to use /dev/random, fail hard */
fprintf(stderr, "No entropy available!\n");
exit(1);
}
--
underground experts united
https://dataswamp.org/~incal
- Re: Noob dumb question (extending emacs), (continued)
- Re: Noob dumb question (extending emacs), Michael Heerdegen, 2021/10/25
- Re: Noob dumb question (extending emacs), Emanuel Berg, 2021/10/25
- Re: Noob dumb question (extending emacs), Jean Louis, 2021/10/25
- Re: Noob dumb question (extending emacs), Emanuel Berg, 2021/10/25
- Re: Noob dumb question (extending emacs), Jean Louis, 2021/10/25
- Re: Noob dumb question (extending emacs), Jean Louis, 2021/10/25
- Re: Noob dumb question (extending emacs), Michael Heerdegen, 2021/10/25
- About randomity, entropy, random passwords - was Re: Noob dumb question (extending emacs), Jean Louis, 2021/10/25
- Message not available
- Message not available
- Re: Noob dumb question (extending emacs), Jean Louis, 2021/10/27
- Re: Noob dumb question (extending emacs), Emanuel Berg, 2021/10/23
- Re: Noob dumb question (extending emacs),
Emanuel Berg <=
- Re: Noob dumb question (extending emacs), Jean Louis, 2021/10/24
- Re: Noob dumb question (extending emacs), Michael Heerdegen, 2021/10/24
- Re: Noob dumb question (extending emacs), Jean Louis, 2021/10/24
- Re: Noob dumb question (extending emacs), Emanuel Berg, 2021/10/24
- Re: Noob dumb question (extending emacs), Jean Louis, 2021/10/24
- Re: Noob dumb question (extending emacs), Emanuel Berg, 2021/10/24
- Re: Noob dumb question (extending emacs), Jean Louis, 2021/10/25
- Re: Noob dumb question (extending emacs), Emanuel Berg, 2021/10/27
- Re: Noob dumb question (extending emacs), Emanuel Berg, 2021/10/23
- Re: Noob dumb question (extending emacs), Michael Heerdegen, 2021/10/24