157 lines
4.6 KiB
C
157 lines
4.6 KiB
C
/*
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* Copyright (c) 1998, 1999 Kungliga Tekniska Högskolan
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* (Royal Institute of Technology, Stockholm, Sweden).
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "kadmin_locl.h"
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RCSID("$Id: random_password.c,v 1.3 1999/12/02 17:04:58 joda Exp $");
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/* This file defines some a function that generates a random password,
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that can be used when creating a large amount of principals (such
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as for a batch of students). Since this is a political matter, you
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should think about how secure generated passwords has to be.
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Both methods defined here will give you at least 55 bits of
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entropy.
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*/
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/* If you want OTP-style passwords, define OTP_STYLE */
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#ifdef OTP_STYLE
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#include <otp.h>
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#else
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static void generate_password(char **pw, int num_classes, ...);
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#endif
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void
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random_password(char *pw, size_t len)
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{
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#ifdef OTP_STYLE
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{
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des_cblock newkey;
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des_new_random_key(&newkey);
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otp_print_stddict (newkey, pw, len);
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strlwr(pw);
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}
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#else
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char *pass;
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generate_password(&pass, 3,
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"abcdefghijklmnopqrstuvwxyz", 7,
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"ABCDEFGHIJKLMNOPQRSTUVWXYZ", 2,
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"@$%&*()-+=:,/<>1234567890", 1);
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strlcpy(pw, pass, len);
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memset(pass, 0, strlen(pass));
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free(pass);
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#endif
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}
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/* some helper functions */
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#ifndef OTP_STYLE
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/* return a random value in range 0-127 */
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static int
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RND(des_cblock *key, int *left)
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{
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if(*left == 0){
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des_new_random_key(key);
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*left = 8;
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}
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(*left)--;
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return ((unsigned char*)key)[*left];
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}
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/* This a helper function that generates a random password with a
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number of characters from a set of character classes.
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If there are n classes, and the size of each class is Pi, and the
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number of characters from each class is Ni, the number of possible
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passwords are (given that the character classes are disjoint):
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n n
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----- / ---- \
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| | Ni | \ |
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| | Pi | \ Ni| !
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| | ---- * | / |
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| | Ni! | /___ |
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i=1 \ i=1 /
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Since it uses the RND function above, neither the size of each
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class, nor the total length of the generated password should be
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larger than 127 (without fixing RND).
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*/
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static void
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generate_password(char **pw, int num_classes, ...)
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{
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struct {
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const char *str;
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int len;
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int freq;
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} *classes;
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va_list ap;
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int len, i;
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des_cblock rbuf; /* random buffer */
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int rleft = 0;
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classes = malloc(num_classes * sizeof(*classes));
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va_start(ap, num_classes);
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len = 0;
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for(i = 0; i < num_classes; i++){
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classes[i].str = va_arg(ap, const char*);
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classes[i].len = strlen(classes[i].str);
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classes[i].freq = va_arg(ap, int);
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len += classes[i].freq;
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}
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va_end(ap);
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*pw = malloc(len + 1);
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if(*pw == NULL)
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return;
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for(i = 0; i < len; i++) {
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int j;
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int x = RND(&rbuf, &rleft) % (len - i);
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int t = 0;
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for(j = 0; j < num_classes; j++) {
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if(x < t + classes[j].freq) {
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(*pw)[i] = classes[j].str[RND(&rbuf, &rleft) % classes[j].len];
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classes[j].freq--;
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break;
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}
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t += classes[j].freq;
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}
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}
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(*pw)[len] = '\0';
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memset(rbuf, 0, sizeof(rbuf));
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free(classes);
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}
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#endif
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