2 Unix SMB/CIFS implementation.
4 Functions to create reasonable random numbers for crypto use.
6 Copyright (C) Jeremy Allison 2001
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>.
23 #include "system/filesys.h"
24 #include "lib/crypto/crypto.h"
25 #include "system/locale.h"
29 * @brief Random number generation
32 static unsigned char hash[258];
33 static uint32_t counter;
35 static BOOL done_reseed = False;
36 static void (*reseed_callback)(int *newseed);
39 Copy any user given reseed data.
42 _PUBLIC_ void set_rand_reseed_callback(void (*fn)(int *))
45 set_need_random_reseed();
49 * Tell the random number generator it needs to reseed.
51 _PUBLIC_ void set_need_random_reseed(void)
56 static void get_rand_reseed_data(int *reseed_data)
58 if (reseed_callback) {
59 reseed_callback(reseed_data);
65 /****************************************************************
67 *****************************************************************/
69 static void seed_random_stream(unsigned char *seedval, size_t seedlen)
74 for (ind = 0; ind < 256; ind++)
75 hash[ind] = (unsigned char)ind;
77 for( ind = 0; ind < 256; ind++) {
80 j += (hash[ind] + seedval[ind%seedlen]);
91 /****************************************************************
92 Get datasize bytes worth of random data.
93 *****************************************************************/
95 static void get_random_stream(unsigned char *data, size_t datasize)
97 unsigned char index_i = hash[256];
98 unsigned char index_j = hash[257];
101 for( ind = 0; ind < datasize; ind++) {
106 index_j += hash[index_i];
109 hash[index_i] = hash[index_j];
112 t = hash[index_i] + hash[index_j];
120 /****************************************************************
121 Get a 16 byte hash from the contents of a file.
123 Note that the hash is initialised, because the extra entropy is not
124 worth the valgrind pain.
125 *****************************************************************/
127 static void do_filehash(const char *fname, unsigned char *the_hash)
129 unsigned char buf[1011]; /* deliberate weird size */
130 unsigned char tmp_md4[16];
133 ZERO_STRUCT(tmp_md4);
135 fd = open(fname,O_RDONLY,0);
139 while ((n = read(fd, (char *)buf, sizeof(buf))) > 0) {
140 mdfour(tmp_md4, buf, n);
142 the_hash[n] ^= tmp_md4[n];
147 /**************************************************************
148 Try and get a good random number seed. Try a number of
149 different factors. Firstly, try /dev/urandom - use if exists.
151 We use /dev/urandom as a read of /dev/random can block if
152 the entropy pool dries up. This leads clients to timeout
153 or be very slow on connect.
155 If we can't use /dev/urandom then seed the stream random generator
157 **************************************************************/
159 static int do_reseed(BOOL use_fd, int fd)
161 unsigned char seed_inbuf[40];
162 uint32_t v1, v2; struct timeval tval; pid_t mypid;
169 fd = open( "/dev/urandom", O_RDONLY,0);
174 /* Add in some secret file contents */
176 do_filehash("/etc/shadow", &seed_inbuf[0]);
179 * Add the counter, time of day, and pid.
184 v1 = (counter++) + mypid + tval.tv_sec;
185 v2 = (counter++) * mypid + tval.tv_usec;
187 SIVAL(seed_inbuf, 32, v1 ^ IVAL(seed_inbuf, 32));
188 SIVAL(seed_inbuf, 36, v2 ^ IVAL(seed_inbuf, 36));
191 * Add any user-given reseed data.
194 get_rand_reseed_data(&reseed_data);
197 for (i = 0; i < sizeof(seed_inbuf); i++)
198 seed_inbuf[i] ^= ((char *)(&reseed_data))[i % sizeof(reseed_data)];
201 seed_random_stream(seed_inbuf, sizeof(seed_inbuf));
207 Interface to the (hopefully) good crypto random number generator.
209 _PUBLIC_ void generate_random_buffer(uint8_t *out, int len)
211 static int urand_fd = -1;
212 unsigned char md4_buf[64];
213 unsigned char tmp_buf[16];
217 urand_fd = do_reseed(True, urand_fd);
221 if (urand_fd != -1 && len > 0) {
223 if (read(urand_fd, out, len) == len)
224 return; /* len bytes of random data read from urandom. */
226 /* Read of urand error, drop back to non urand method. */
229 do_reseed(False, -1);
234 * Generate random numbers in chunks of 64 bytes,
235 * then md4 them & copy to the output buffer.
236 * This way the raw state of the stream is never externally
242 int copy_len = len > 16 ? 16 : len;
244 get_random_stream(md4_buf, sizeof(md4_buf));
245 mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
246 memcpy(p, tmp_buf, copy_len);
253 generate a single random uint32_t
255 _PUBLIC_ uint32_t generate_random(void)
258 generate_random_buffer(v, 4);
264 very basic password quality checker
266 _PUBLIC_ BOOL check_password_quality(const char *s)
268 int has_digit=0, has_capital=0, has_lower=0;
270 if (isdigit((unsigned char)*s)) {
272 } else if (isupper((unsigned char)*s)) {
274 } else if (islower((unsigned char)*s)) {
280 return has_digit && has_lower && has_capital;
284 Use the random number generator to generate a random string.
287 _PUBLIC_ char *generate_random_str_list(TALLOC_CTX *mem_ctx, size_t len, const char *list)
290 size_t list_len = strlen(list);
292 char *retstr = talloc_array(mem_ctx, char, len + 1);
293 if (!retstr) return NULL;
295 generate_random_buffer((uint8_t *)retstr, len);
296 for (i = 0; i < len; i++) {
297 retstr[i] = list[retstr[i] % list_len];
305 * Generate a random text string consisting of the specified length.
306 * The returned string will be allocated.
308 * Characters used are: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,
311 _PUBLIC_ char *generate_random_str(TALLOC_CTX *mem_ctx, size_t len)
314 const char *c_list = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,";
317 retstr = generate_random_str_list(mem_ctx, len, c_list);
318 if (!retstr) return NULL;
320 /* we need to make sure the random string passes basic quality tests
321 or it might be rejected by windows as a password */
322 if (len >= 7 && !check_password_quality(retstr)) {