glibc/manual/examples/genpass.c

60 lines
1.6 KiB
C

/* Encrypting Passwords
Copyright (C) 1991-2023 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, see <https://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <unistd.h>
#include <crypt.h>
int
main(void)
{
unsigned char ubytes[16];
char salt[20];
const char *const saltchars =
"./0123456789ABCDEFGHIJKLMNOPQRST"
"UVWXYZabcdefghijklmnopqrstuvwxyz";
char *hash;
int i;
/* Retrieve 16 unpredictable bytes from the operating system. */
if (getentropy (ubytes, sizeof ubytes))
{
perror ("getentropy");
return 1;
}
/* Use them to fill in the salt string. */
salt[0] = '$';
salt[1] = '5'; /* SHA-256 */
salt[2] = '$';
for (i = 0; i < 16; i++)
salt[3+i] = saltchars[ubytes[i] & 0x3f];
salt[3+i] = '\0';
/* Read in the user's passphrase and hash it. */
hash = crypt (getpass ("Enter new passphrase: "), salt);
if (!hash || hash[0] == '*')
{
perror ("crypt");
return 1;
}
/* Print the results. */
puts (hash);
return 0;
}