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/filesys.h"
25 #include "lib/crypto/crypto.h"
26 #include "system/locale.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 _PUBLIC_ void set_rand_reseed_callback(void (*fn)(int *))
46 set_need_random_reseed();
50 * Tell the random number generator it needs to reseed.
52 _PUBLIC_ void set_need_random_reseed(void)
57 static void get_rand_reseed_data(int *reseed_data)
59 if (reseed_callback) {
60 reseed_callback(reseed_data);
66 /****************************************************************
68 *****************************************************************/
70 static void seed_random_stream(unsigned char *seedval, size_t seedlen)
75 for (ind = 0; ind < 256; ind++)
76 hash[ind] = (unsigned char)ind;
78 for( ind = 0; ind < 256; ind++) {
81 j += (hash[ind] + seedval[ind%seedlen]);
92 /****************************************************************
93 Get datasize bytes worth of random data.
94 *****************************************************************/
96 static void get_random_stream(unsigned char *data, size_t datasize)
98 unsigned char index_i = hash[256];
99 unsigned char index_j = hash[257];
102 for( ind = 0; ind < datasize; ind++) {
107 index_j += hash[index_i];
110 hash[index_i] = hash[index_j];
113 t = hash[index_i] + hash[index_j];
121 /****************************************************************
122 Get a 16 byte hash from the contents of a file.
124 Note that the hash is initialised, because the extra entropy is not
125 worth the valgrind pain.
126 *****************************************************************/
128 static void do_filehash(const char *fname, unsigned char *the_hash)
130 unsigned char buf[1011]; /* deliberate weird size */
131 unsigned char tmp_md4[16];
134 ZERO_STRUCT(tmp_md4);
136 fd = open(fname,O_RDONLY,0);
140 while ((n = read(fd, (char *)buf, sizeof(buf))) > 0) {
141 mdfour(tmp_md4, buf, n);
143 the_hash[n] ^= tmp_md4[n];
148 /**************************************************************
149 Try and get a good random number seed. Try a number of
150 different factors. Firstly, try /dev/urandom - use if exists.
152 We use /dev/urandom as a read of /dev/random can block if
153 the entropy pool dries up. This leads clients to timeout
154 or be very slow on connect.
156 If we can't use /dev/urandom then seed the stream random generator
158 **************************************************************/
160 static int do_reseed(BOOL use_fd, int fd)
162 unsigned char seed_inbuf[40];
163 uint32_t v1, v2; struct timeval tval; pid_t mypid;
170 fd = open( "/dev/urandom", O_RDONLY,0);
175 /* Add in some secret file contents */
177 do_filehash("/etc/shadow", &seed_inbuf[0]);
180 * Add the counter, time of day, and pid.
185 v1 = (counter++) + mypid + tval.tv_sec;
186 v2 = (counter++) * mypid + tval.tv_usec;
188 SIVAL(seed_inbuf, 32, v1 ^ IVAL(seed_inbuf, 32));
189 SIVAL(seed_inbuf, 36, v2 ^ IVAL(seed_inbuf, 36));
192 * Add any user-given reseed data.
195 get_rand_reseed_data(&reseed_data);
198 for (i = 0; i < sizeof(seed_inbuf); i++)
199 seed_inbuf[i] ^= ((char *)(&reseed_data))[i % sizeof(reseed_data)];
202 seed_random_stream(seed_inbuf, sizeof(seed_inbuf));
208 Interface to the (hopefully) good crypto random number generator.
210 _PUBLIC_ void generate_random_buffer(uint8_t *out, int len)
212 static int urand_fd = -1;
213 unsigned char md4_buf[64];
214 unsigned char tmp_buf[16];
218 urand_fd = do_reseed(True, urand_fd);
222 if (urand_fd != -1 && len > 0) {
224 if (read(urand_fd, out, len) == len)
225 return; /* len bytes of random data read from urandom. */
227 /* Read of urand error, drop back to non urand method. */
230 do_reseed(False, -1);
235 * Generate random numbers in chunks of 64 bytes,
236 * then md4 them & copy to the output buffer.
237 * This way the raw state of the stream is never externally
243 int copy_len = len > 16 ? 16 : len;
245 get_random_stream(md4_buf, sizeof(md4_buf));
246 mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
247 memcpy(p, tmp_buf, copy_len);
254 generate a single random uint32_t
256 _PUBLIC_ uint32_t generate_random(void)
259 generate_random_buffer(v, 4);
265 very basic password quality checker
267 _PUBLIC_ BOOL check_password_quality(const char *s)
269 int has_digit=0, has_capital=0, has_lower=0;
271 if (isdigit((unsigned char)*s)) {
273 } else if (isupper((unsigned char)*s)) {
275 } else if (islower((unsigned char)*s)) {
281 return has_digit && has_lower && has_capital;
285 Use the random number generator to generate a random string.
288 _PUBLIC_ char *generate_random_str_list(TALLOC_CTX *mem_ctx, size_t len, const char *list)
291 size_t list_len = strlen(list);
293 char *retstr = talloc_array(mem_ctx, char, len + 1);
294 if (!retstr) return NULL;
296 generate_random_buffer((uint8_t *)retstr, len);
297 for (i = 0; i < len; i++) {
298 retstr[i] = list[retstr[i] % list_len];
306 * Generate a random text string consisting of the specified length.
307 * The returned string will be allocated.
309 * Characters used are: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,
312 _PUBLIC_ char *generate_random_str(TALLOC_CTX *mem_ctx, size_t len)
315 const char *c_list = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,";
318 retstr = generate_random_str_list(mem_ctx, len, c_list);
319 if (!retstr) return NULL;
321 /* we need to make sure the random string passes basic quality tests
322 or it might be rejected by windows as a password */
323 if (len >= 7 && !check_password_quality(retstr)) {