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 2 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, write to the Free Software
20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 #include "system/iconv.h"
25 #include "system/filesys.h"
26 #include "lib/crypto/crypto.h"
30 * @brief Random number generation
33 static unsigned char hash[258];
34 static uint32_t counter;
36 static BOOL done_reseed = False;
37 static void (*reseed_callback)(int *newseed);
40 Copy any user given reseed data.
43 void set_rand_reseed_callback(void (*fn)(int *))
46 set_need_random_reseed();
49 void set_need_random_reseed(void)
54 static void get_rand_reseed_data(int *reseed_data)
56 if (reseed_callback) {
57 reseed_callback(reseed_data);
63 /****************************************************************
65 *****************************************************************/
67 static void seed_random_stream(unsigned char *seedval, size_t seedlen)
72 for (ind = 0; ind < 256; ind++)
73 hash[ind] = (unsigned char)ind;
75 for( ind = 0; ind < 256; ind++) {
78 j += (hash[ind] + seedval[ind%seedlen]);
89 /****************************************************************
90 Get datasize bytes worth of random data.
91 *****************************************************************/
93 static void get_random_stream(unsigned char *data, size_t datasize)
95 unsigned char index_i = hash[256];
96 unsigned char index_j = hash[257];
99 for( ind = 0; ind < datasize; ind++) {
104 index_j += hash[index_i];
107 hash[index_i] = hash[index_j];
110 t = hash[index_i] + hash[index_j];
118 /****************************************************************
119 Get a 16 byte hash from the contents of a file.
121 Note that the hash is initialised, because the extra entropy is not
122 worth the valgrind pain.
123 *****************************************************************/
125 static void do_filehash(const char *fname, unsigned char *the_hash)
127 unsigned char buf[1011]; /* deliberate weird size */
128 unsigned char tmp_md4[16];
131 ZERO_STRUCT(tmp_md4);
133 fd = open(fname,O_RDONLY,0);
137 while ((n = read(fd, (char *)buf, sizeof(buf))) > 0) {
138 mdfour(tmp_md4, buf, n);
140 the_hash[n] ^= tmp_md4[n];
145 /**************************************************************
146 Try and get a good random number seed. Try a number of
147 different factors. Firstly, try /dev/urandom - use if exists.
149 We use /dev/urandom as a read of /dev/random can block if
150 the entropy pool dries up. This leads clients to timeout
151 or be very slow on connect.
153 If we can't use /dev/urandom then seed the stream random generator
155 **************************************************************/
157 static int do_reseed(BOOL use_fd, int fd)
159 unsigned char seed_inbuf[40];
160 uint32_t v1, v2; struct timeval tval; pid_t mypid;
167 fd = open( "/dev/urandom", O_RDONLY,0);
172 /* Add in some secret file contents */
174 do_filehash("/etc/shadow", &seed_inbuf[0]);
177 * Add the counter, time of day, and pid.
182 v1 = (counter++) + mypid + tval.tv_sec;
183 v2 = (counter++) * mypid + tval.tv_usec;
185 SIVAL(seed_inbuf, 32, v1 ^ IVAL(seed_inbuf, 32));
186 SIVAL(seed_inbuf, 36, v2 ^ IVAL(seed_inbuf, 36));
189 * Add any user-given reseed data.
192 get_rand_reseed_data(&reseed_data);
195 for (i = 0; i < sizeof(seed_inbuf); i++)
196 seed_inbuf[i] ^= ((char *)(&reseed_data))[i % sizeof(reseed_data)];
199 seed_random_stream(seed_inbuf, sizeof(seed_inbuf));
205 Interface to the (hopefully) good crypto random number generator.
207 void generate_random_buffer(uint8_t *out, int len)
209 static int urand_fd = -1;
210 unsigned char md4_buf[64];
211 unsigned char tmp_buf[16];
215 urand_fd = do_reseed(True, urand_fd);
219 if (urand_fd != -1 && len > 0) {
221 if (read(urand_fd, out, len) == len)
222 return; /* len bytes of random data read from urandom. */
224 /* Read of urand error, drop back to non urand method. */
227 do_reseed(False, -1);
232 * Generate random numbers in chunks of 64 bytes,
233 * then md4 them & copy to the output buffer.
234 * This way the raw state of the stream is never externally
240 int copy_len = len > 16 ? 16 : len;
242 get_random_stream(md4_buf, sizeof(md4_buf));
243 mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
244 memcpy(p, tmp_buf, copy_len);
251 generate a single random uint32_t
253 uint32_t generate_random(void)
256 generate_random_buffer(v, 4);
262 very basic password quality checker
264 BOOL check_password_quality(const char *s)
266 int has_digit=0, has_capital=0, has_lower=0;
268 if (isdigit((unsigned char)*s)) {
270 } else if (isupper((unsigned char)*s)) {
272 } else if (islower((unsigned char)*s)) {
278 return has_digit && has_lower && has_capital;
282 Use the random number generator to generate a random string.
285 char *generate_random_str_list(TALLOC_CTX *mem_ctx, size_t len, const char *list)
288 size_t list_len = strlen(list);
290 char *retstr = talloc_array(mem_ctx, char, len + 1);
291 if (!retstr) return NULL;
293 generate_random_buffer((uint8_t *)retstr, len);
294 for (i = 0; i < len; i++) {
295 retstr[i] = list[retstr[i] % list_len];
302 char *generate_random_str(TALLOC_CTX *mem_ctx, size_t len)
305 const char *c_list = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,";
308 retstr = generate_random_str_list(mem_ctx, len, c_list);
309 if (!retstr) return NULL;
311 /* we need to make sure the random string passes basic quality tests
312 or it might be rejected by windows as a password */
313 if (len >= 7 && !check_password_quality(retstr)) {