summaryrefslogtreecommitdiff
path: root/package/ead/src/tinysrp/t_misc.c
blob: a23986f90f2cdcf6b9802aa8e19c74f7977c6297 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
/*
 * Copyright (c) 1997-1999  The Stanford SRP Authentication Project
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
 *
 * IN NO EVENT SHALL STANFORD BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
 * INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
 * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF
 * THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * In addition, the following conditions apply:
 *
 * 1. Any software that incorporates the SRP authentication technology
 *    must display the following acknowlegment:
 *    "This product uses the 'Secure Remote Password' cryptographic
 *     authentication system developed by Tom Wu (tjw@CS.Stanford.EDU)."
 *
 * 2. Any software that incorporates all or part of the SRP distribution
 *    itself must also display the following acknowledgment:
 *    "This product includes software developed by Tom Wu and Eugene
 *     Jhong for the SRP Distribution (http://srp.stanford.edu/srp/)."
 *
 * 3. Redistributions in source or binary form must retain an intact copy
 *    of this copyright notice and list of conditions.
 */

#include "t_defines.h"

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif /* HAVE_UNISTD_H */

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "t_sha.h"

#ifndef NULL
#define NULL 0
#endif

static unsigned char randpool[SHA_DIGESTSIZE], randout[SHA_DIGESTSIZE];
static unsigned long randcnt = 0;
static unsigned int outpos = 0;
SHA1_CTX randctxt;

/*
 * t_envhash - Generate a 160-bit SHA hash of the environment
 *
 * This routine performs an SHA hash of all the "name=value" pairs
 * in the environment concatenated together and dumps them in the
 * output.  While it is true that anyone on the system can see
 * your environment, someone not on the system will have a very
 * difficult time guessing it, especially since some systems play
 * tricks with variable ordering and sometimes define quirky
 * environment variables like $WINDOWID or $_.
 */
extern char ** environ;

static void
t_envhash(out)
     unsigned char * out;
{
  char ** ptr;
  char ebuf[256];
  SHA1_CTX ctxt;

  SHA1Init(&ctxt);
  for(ptr = environ; *ptr; ++ptr) {
    strncpy(ebuf, *ptr, 255);
    ebuf[255] = '\0';
    SHA1Update(&ctxt, ebuf, strlen(ebuf));
  }
  SHA1Final(out, &ctxt);
}

/*
 * t_fshash - Generate a 160-bit SHA hash from the file system
 *
 * This routine climbs up the directory tree from the current
 * directory, running stat() on each directory until it hits the
 * root directory.  This information is sensitive to the last
 * access/modification times of all the directories above you,
 * so someone who lists one of those directories injects some
 * entropy into the system.  Obviously, this hash is very sensitive
 * to your current directory when the program is run.
 *
 * For good measure, it also performs an fstat on the standard input,
 * usually your tty, throws that into the buffer, creates a file in
 * /tmp (the inode is unpredictable on a busy system), and runs stat()
 * on that before deleting it.
 *
 * The entire buffer is run once through SHA to obtain the final result.
 */
static void
t_fshash(out)
     unsigned char * out;
{
  char dotpath[128];
  struct stat st;
  SHA1_CTX ctxt;
  int i, pinode;
  dev_t pdev;

  SHA1Init(&ctxt);
  if(stat(".", &st) >= 0) {
    SHA1Update(&ctxt, (unsigned char *) &st, sizeof(st));
    pinode = st.st_ino;
    pdev = st.st_dev;
    strcpy(dotpath, "..");
    for(i = 0; i < 40; ++i) {
      if(stat(dotpath, &st) < 0)
	break;
      if(st.st_ino == pinode && st.st_dev == pdev)
	break;
      SHA1Update(&ctxt, (unsigned char *) &st, sizeof(st));
      pinode = st.st_ino;
      pdev = st.st_dev;
      strcat(dotpath, "/..");
    }
  }

  if(fstat(0, &st) >= 0)
    SHA1Update(&ctxt, (unsigned char *) &st, sizeof(st));

  sprintf(dotpath, "/tmp/rnd.%d", getpid());
  if(creat(dotpath, 0600) >= 0 && stat(dotpath, &st) >= 0)
    SHA1Update(&ctxt, (unsigned char *) &st, sizeof(st));
  unlink(dotpath);

  SHA1Final(out, &ctxt);
}

/*
 * Generate a high-entropy seed for the strong random number generator.
 * This uses a wide variety of quickly gathered and somewhat unpredictable
 * system information.  The 'preseed' structure is assembled from:
 *
 *   The system time in seconds
 *   The system time in microseconds
 *   The current process ID
 *   The parent process ID
 *   A hash of the user's environment
 *   A hash gathered from the file system
 *   Input from a random device, if available
 *   Timings of system interrupts
 *
 * The entire structure (60 bytes on most systems) is fed to SHA to produce
 * a 160-bit seed for the strong random number generator.  It is believed
 * that in the worst case (on a quiet system with no random device versus
 * an attacker who has access to the system already), the seed contains at
 * least about 80 bits of entropy.  Versus an attacker who does not have
 * access to the system, the entropy should be slightly over 128 bits.
 */
static char initialized = 0;

static struct {
  unsigned int trand1;
  time_t sec;
  time_t usec;
  short pid;
  short ppid;
  unsigned char envh[SHA_DIGESTSIZE];
  unsigned char fsh[SHA_DIGESTSIZE];
  unsigned char devrand[20];
  unsigned int trand2;
} preseed;

unsigned long raw_truerand();

void
t_initrand()
{
  SHA1_CTX ctxt;
#ifdef USE_FTIME
  struct timeb t;
#else
  struct timeval t;
#endif
  int i, r=0;

  if(initialized)
    return;

  initialized = 1;

  i = open("/dev/urandom", O_RDONLY);
  if(i > 0) {
    r += read(i, preseed.devrand, sizeof(preseed.devrand));
    close(i);
  }

  /* Resort to truerand only if desperate for some Real entropy */
  if(r == 0)
    preseed.trand1 = raw_truerand();

#ifdef USE_FTIME
  ftime(&t);
#else
  gettimeofday(&t, NULL);
#endif

#ifdef USE_FTIME
  preseed.sec = t.time;
  preseed.usec = t.millitm;
#else
  preseed.sec = t.tv_sec;
  preseed.usec = t.tv_usec;
#endif
  preseed.pid = getpid();
  preseed.ppid = getppid();
  t_envhash(preseed.envh);
  t_fshash(preseed.fsh);

  if(r == 0)
    preseed.trand2 = raw_truerand();

  SHA1Init(&ctxt);
  SHA1Update(&ctxt, (unsigned char *) &preseed, sizeof(preseed));
  SHA1Final(randpool, &ctxt);
  outpos = 0;
  memset((unsigned char *) &preseed, 0, sizeof(preseed));
  memset((unsigned char *) &ctxt, 0, sizeof(ctxt));
}

#define NUM_RANDOMS 12

/*
 * The strong random number generator.  This uses a 160-bit seed
 * and uses SHA-1 in a feedback configuration to generate successive
 * outputs.  If S[0] is set to the initial seed, then:
 *
 *         S[i+1] = SHA-1(i || S[i])
 *         A[i] = SHA-1(S[i])
 *
 * where the A[i] are the output blocks starting with i=0.
 * Each cycle generates 20 bytes of new output.
 */
_TYPE( void )
t_random(data, size)
     unsigned char * data;
     unsigned size;
{
  if(!initialized)
    t_initrand();

  if(size <= 0)         /* t_random(NULL, 0) forces seed initialization */
    return;

  while(size > outpos) {
    if(outpos > 0) {
      memcpy(data, randout + (sizeof(randout) - outpos), outpos);
      data += outpos;
      size -= outpos;
    }

    /* Recycle */
    SHA1Init(&randctxt);
    SHA1Update(&randctxt, randpool, sizeof(randpool));
    SHA1Final(randout, &randctxt);
    SHA1Init(&randctxt);
    SHA1Update(&randctxt, (unsigned char *) &randcnt, sizeof(randcnt));
    SHA1Update(&randctxt, randpool, sizeof(randpool));
    SHA1Final(randpool, &randctxt);
    ++randcnt;
    outpos = sizeof(randout);
  }

  if(size > 0) {
    memcpy(data, randout + (sizeof(randout) - outpos), size);
    outpos -= size;
  }
}

/*
 * The interleaved session-key hash.  This separates the even and the odd
 * bytes of the input (ignoring the first byte if the input length is odd),
 * hashes them separately, and re-interleaves the two outputs to form a
 * single 320-bit value.
 */
_TYPE( unsigned char * )
t_sessionkey(key, sk, sklen)
     unsigned char * key;
     unsigned char * sk;
     unsigned sklen;
{
  unsigned i, klen;
  unsigned char * hbuf;
  unsigned char hout[SHA_DIGESTSIZE];
  SHA1_CTX ctxt;

  while(sklen > 0 && *sk == 0) {        /* Skip leading 0's */
    --sklen;
    ++sk;
  }

  klen = sklen / 2;
  if((hbuf = malloc(klen * sizeof(char))) == 0)
    return 0;

  for(i = 0; i < klen; ++i)
    hbuf[i] = sk[sklen - 2 * i - 1];
  SHA1Init(&ctxt);
  SHA1Update(&ctxt, hbuf, klen);
  SHA1Final(hout, &ctxt);
  for(i = 0; i < sizeof(hout); ++i)
    key[2 * i] = hout[i];

  for(i = 0; i < klen; ++i)
    hbuf[i] = sk[sklen - 2 * i - 2];
  SHA1Init(&ctxt);
  SHA1Update(&ctxt, hbuf, klen);
  SHA1Final(hout, &ctxt);
  for(i = 0; i < sizeof(hout); ++i)
    key[2 * i + 1] = hout[i];

  memset(hout, 0, sizeof(hout));
  memset(hbuf, 0, klen);
  free(hbuf);
  return key;
}