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 "lib/crypto/crypto.h"
27 static unsigned char hash[258];
28 static uint32 counter;
30 static BOOL done_reseed = False;
31 static void (*reseed_callback)(int *newseed);
33 /****************************************************************
34 Copy any user given reseed data.
35 *****************************************************************/
37 void set_rand_reseed_callback(void (*fn)(int *))
40 set_need_random_reseed();
43 void set_need_random_reseed(void)
48 static void get_rand_reseed_data(int *reseed_data)
50 if (reseed_callback) {
51 reseed_callback(reseed_data);
57 /****************************************************************
59 *****************************************************************/
61 static void seed_random_stream(unsigned char *seedval, size_t seedlen)
66 for (ind = 0; ind < 256; ind++)
67 hash[ind] = (unsigned char)ind;
69 for( ind = 0; ind < 256; ind++) {
72 j += (hash[ind] + seedval[ind%seedlen]);
83 /****************************************************************
84 Get datasize bytes worth of random data.
85 *****************************************************************/
87 static void get_random_stream(unsigned char *data, size_t datasize)
89 unsigned char index_i = hash[256];
90 unsigned char index_j = hash[257];
93 for( ind = 0; ind < datasize; ind++) {
98 index_j += hash[index_i];
101 hash[index_i] = hash[index_j];
104 t = hash[index_i] + hash[index_j];
112 /****************************************************************
113 Get a 16 byte hash from the contents of a file.
114 Note that the hash is not initialised.
115 *****************************************************************/
117 static void do_filehash(const char *fname, unsigned char *the_hash)
119 unsigned char buf[1011]; /* deliberate weird size */
120 unsigned char tmp_md4[16];
123 fd = open(fname,O_RDONLY,0);
127 while ((n = read(fd, (char *)buf, sizeof(buf))) > 0) {
128 mdfour(tmp_md4, buf, n);
130 the_hash[n] ^= tmp_md4[n];
135 /**************************************************************
136 Try and get a good random number seed. Try a number of
137 different factors. Firstly, try /dev/urandom - use if exists.
139 We use /dev/urandom as a read of /dev/random can block if
140 the entropy pool dries up. This leads clients to timeout
141 or be very slow on connect.
143 If we can't use /dev/urandom then seed the stream random generator
145 **************************************************************/
147 static int do_reseed(BOOL use_fd, int fd)
149 unsigned char seed_inbuf[40];
150 uint32 v1, v2; struct timeval tval; pid_t mypid;
157 fd = open( "/dev/urandom", O_RDONLY,0);
162 /* Add in some secret file contents */
164 do_filehash("/etc/shadow", &seed_inbuf[0]);
165 do_filehash(lp_smb_passwd_file(), &seed_inbuf[16]);
168 * Add the counter, time of day, and pid.
173 v1 = (counter++) + mypid + tval.tv_sec;
174 v2 = (counter++) * mypid + tval.tv_usec;
176 SIVAL(seed_inbuf, 32, v1 ^ IVAL(seed_inbuf, 32));
177 SIVAL(seed_inbuf, 36, v2 ^ IVAL(seed_inbuf, 36));
180 * Add any user-given reseed data.
183 get_rand_reseed_data(&reseed_data);
186 for (i = 0; i < sizeof(seed_inbuf); i++)
187 seed_inbuf[i] ^= ((char *)(&reseed_data))[i % sizeof(reseed_data)];
190 seed_random_stream(seed_inbuf, sizeof(seed_inbuf));
195 /*******************************************************************
196 Interface to the (hopefully) good crypto random number generator.
197 ********************************************************************/
199 void generate_random_buffer( unsigned char *out, int len)
201 static int urand_fd = -1;
202 unsigned char md4_buf[64];
203 unsigned char tmp_buf[16];
207 urand_fd = do_reseed(True, urand_fd);
211 if (urand_fd != -1 && len > 0) {
213 if (read(urand_fd, out, len) == len)
214 return; /* len bytes of random data read from urandom. */
216 /* Read of urand error, drop back to non urand method. */
219 do_reseed(False, -1);
224 * Generate random numbers in chunks of 64 bytes,
225 * then md4 them & copy to the output buffer.
226 * This way the raw state of the stream is never externally
232 int copy_len = len > 16 ? 16 : len;
234 get_random_stream(md4_buf, sizeof(md4_buf));
235 mdfour(tmp_buf, md4_buf, sizeof(md4_buf));
236 memcpy(p, tmp_buf, copy_len);
243 very basic password quality checker
245 BOOL check_password_quality(const char *s)
247 int has_digit=0, has_capital=0, has_lower=0;
251 } else if (isupper(*s)) {
253 } else if (islower(*s)) {
259 return has_digit && has_lower && has_capital;
262 /*******************************************************************
263 Use the random number generator to generate a random string.
264 ********************************************************************/
266 char *generate_random_str_list(TALLOC_CTX *mem_ctx, size_t len, const char *list)
269 size_t list_len = strlen(list);
271 char *retstr = talloc(mem_ctx, len + 1);
272 if (!retstr) return NULL;
274 generate_random_buffer(retstr, len);
275 for (i = 0; i < len; i++) {
276 retstr[i] = list[retstr[i] % list_len];
283 char *generate_random_str(TALLOC_CTX *mem_ctx, size_t len)
286 const char *c_list = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+_-#.,";
289 retstr = generate_random_str_list(mem_ctx, len, c_list);
290 if (!retstr) return NULL;
292 /* we need to make sure the random string passes basic quality tests
293 or it might be rejected by windows as a password */
294 if (len >= 7 && !check_password_quality(retstr)) {