1 /* 2 * Copyright (c) 1998, 1999 Kungliga Tekniska Högskolan 3 * (Royal Institute of Technology, Stockholm, Sweden). 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * 3. Neither the name of the Institute nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include "kadmin_locl.h" 35 36 /* This file defines some a function that generates a random password, 37 that can be used when creating a large amount of principals (such 38 as for a batch of students). Since this is a political matter, you 39 should think about how secure generated passwords has to be. 40 41 Both methods defined here will give you at least 55 bits of 42 entropy. 43 */ 44 45 /* If you want OTP-style passwords, define OTP_STYLE */ 46 47 #ifdef OTP_STYLE 48 #include <otp.h> 49 #else 50 static void generate_password(char **pw, int num_classes, ...); 51 #endif 52 53 void 54 random_password(char *pw, size_t len) 55 { 56 #ifdef OTP_STYLE 57 { 58 OtpKey newkey; 59 60 krb5_generate_random_block(&newkey, sizeof(newkey)); 61 otp_print_stddict (newkey, pw, len); 62 strlwr(pw); 63 } 64 #else 65 char *pass; 66 generate_password(&pass, 3, 67 "abcdefghijklmnopqrstuvwxyz", 7, 68 "ABCDEFGHIJKLMNOPQRSTUVWXYZ", 2, 69 "@$%&*()-+=:,/<>1234567890", 1); 70 strlcpy(pw, pass, len); 71 memset(pass, 0, strlen(pass)); 72 free(pass); 73 #endif 74 } 75 76 /* some helper functions */ 77 78 #ifndef OTP_STYLE 79 /* return a random value in range 0-127 */ 80 static int 81 RND(unsigned char *key, int keylen, int *left) 82 { 83 if(*left == 0){ 84 krb5_generate_random_block(key, keylen); 85 *left = keylen; 86 } 87 (*left)--; 88 return ((unsigned char*)key)[*left]; 89 } 90 91 /* This a helper function that generates a random password with a 92 number of characters from a set of character classes. 93 94 If there are n classes, and the size of each class is Pi, and the 95 number of characters from each class is Ni, the number of possible 96 passwords are (given that the character classes are disjoint): 97 98 n n 99 ----- / ---- \ 100 | | Ni | \ | 101 | | Pi | \ Ni| ! 102 | | ---- * | / | 103 | | Ni! | /___ | 104 i=1 \ i=1 / 105 106 Since it uses the RND function above, neither the size of each 107 class, nor the total length of the generated password should be 108 larger than 127 (without fixing RND). 109 110 */ 111 static void 112 generate_password(char **pw, int num_classes, ...) 113 { 114 struct { 115 const char *str; 116 int len; 117 int freq; 118 } *classes; 119 va_list ap; 120 int len, i; 121 unsigned char rbuf[8]; /* random buffer */ 122 int rleft = 0; 123 124 *pw = NULL; 125 126 classes = malloc(num_classes * sizeof(*classes)); 127 if(classes == NULL) 128 return; 129 va_start(ap, num_classes); 130 len = 0; 131 for(i = 0; i < num_classes; i++){ 132 classes[i].str = va_arg(ap, const char*); 133 classes[i].len = strlen(classes[i].str); 134 classes[i].freq = va_arg(ap, int); 135 len += classes[i].freq; 136 } 137 va_end(ap); 138 *pw = malloc(len + 1); 139 if(*pw == NULL) { 140 free(classes); 141 return; 142 } 143 for(i = 0; i < len; i++) { 144 int j; 145 int x = RND(rbuf, sizeof(rbuf), &rleft) % (len - i); 146 int t = 0; 147 for(j = 0; j < num_classes; j++) { 148 if(x < t + classes[j].freq) { 149 (*pw)[i] = classes[j].str[RND(rbuf, sizeof(rbuf), &rleft) 150 % classes[j].len]; 151 classes[j].freq--; 152 break; 153 } 154 t += classes[j].freq; 155 } 156 } 157 (*pw)[len] = '\0'; 158 memset(rbuf, 0, sizeof(rbuf)); 159 free(classes); 160 } 161 #endif 162