summaryrefslogtreecommitdiff
path: root/ssh-keygen.c
blob: a18f66b58b9a71dde498a0a1573f5e4c99ae8677 (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
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
/*

ssh-keygen.c

Author: Tatu Ylonen <ylo@cs.hut.fi>

Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
                   All rights reserved

Created: Mon Mar 27 02:26:40 1995 ylo

Identity and host key generation and maintenance.

*/

#include "includes.h"
RCSID("$Id: ssh-keygen.c,v 1.1.1.1 1999/10/27 03:42:45 damien Exp $");

#include "rsa.h"
#include "ssh.h"
#include "xmalloc.h"

/* Generated private key. */
RSA *private_key;

/* Generated public key. */
RSA *public_key;

/* Number of bits in the RSA key.  This value can be changed on the command
   line. */
int bits = 1024;

/* Flag indicating that we just want to change the passphrase.  This can be
   set on the command line. */
int change_passphrase = 0;

/* Flag indicating that we just want to change the comment.  This can be set
   on the command line. */
int change_comment = 0;

int quiet = 0;

/* This is set to the identity file name if given on the command line. */
char *identity_file = NULL;

/* This is set to the passphrase if given on the command line. */
char *identity_passphrase = NULL;

/* This is set to the new passphrase if given on the command line. */
char *identity_new_passphrase = NULL;

/* This is set to the new comment if given on the command line. */
char *identity_comment = NULL;

/* Perform changing a passphrase.  The argument is the passwd structure
   for the current user. */

void
do_change_passphrase(struct passwd *pw)
{
  char buf[1024], *comment;
  char *old_passphrase, *passphrase1, *passphrase2;
  struct stat st;
  RSA *private_key;

  /* Read key file name. */
  if (identity_file != NULL) {
      strncpy(buf, identity_file, sizeof(buf));
      buf[sizeof(buf) - 1] = '\0';
  } else {
    printf("Enter file in which the key is ($HOME/%s): ", SSH_CLIENT_IDENTITY);
    fflush(stdout);
    if (fgets(buf, sizeof(buf), stdin) == NULL)
      exit(1);
    if (strchr(buf, '\n'))
      *strchr(buf, '\n') = 0;
    if (strcmp(buf, "") == 0)
      snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, SSH_CLIENT_IDENTITY);
  }

  /* Check if the file exists. */
  if (stat(buf, &st) < 0)
    {
      perror(buf);
      exit(1);
    }
  
  /* Try to load the public key from the file the verify that it is
     readable and of the proper format. */
  public_key = RSA_new();
  if (!load_public_key(buf, public_key, NULL))
    {
      printf("%s is not a valid key file.\n", buf);
      exit(1);
    }
  /* Clear the public key since we are just about to load the whole file. */
  RSA_free(public_key);

  /* Try to load the file with empty passphrase. */
  private_key = RSA_new();
  if (!load_private_key(buf, "", private_key, &comment)) {
    /* Read passphrase from the user. */
    if (identity_passphrase)
      old_passphrase = xstrdup(identity_passphrase);
    else
      old_passphrase = read_passphrase("Enter old passphrase: ", 1);
    /* Try to load using the passphrase. */
    if (!load_private_key(buf, old_passphrase, private_key, &comment))
      {
	memset(old_passphrase, 0, strlen(old_passphrase));
	xfree(old_passphrase);
	printf("Bad passphrase.\n");
	exit(1);
      }
    /* Destroy the passphrase. */
    memset(old_passphrase, 0, strlen(old_passphrase));
    xfree(old_passphrase);
  }
  printf("Key has comment '%s'\n", comment);
  
  /* Ask the new passphrase (twice). */
  if (identity_new_passphrase)
    {
      passphrase1 = xstrdup(identity_new_passphrase);
      passphrase2 = NULL;
    }
  else
    {
      passphrase1 = 
	read_passphrase("Enter new passphrase (empty for no passphrase): ", 1);
      passphrase2 = read_passphrase("Enter same passphrase again: ", 1);

      /* Verify that they are the same. */
      if (strcmp(passphrase1, passphrase2) != 0)
	{
	  memset(passphrase1, 0, strlen(passphrase1));
	  memset(passphrase2, 0, strlen(passphrase2));
	  xfree(passphrase1);
	  xfree(passphrase2);
	  printf("Pass phrases do not match.  Try again.\n");
	  exit(1);
	}
      /* Destroy the other copy. */
      memset(passphrase2, 0, strlen(passphrase2));
      xfree(passphrase2);
    }

  /* Save the file using the new passphrase. */
  if (!save_private_key(buf, passphrase1, private_key, comment))
    {
      printf("Saving the key failed: %s: %s.\n",
	     buf, strerror(errno));
      memset(passphrase1, 0, strlen(passphrase1));
      xfree(passphrase1);
      RSA_free(private_key);
      xfree(comment);
      exit(1);
    }
  /* Destroy the passphrase and the copy of the key in memory. */
  memset(passphrase1, 0, strlen(passphrase1));
  xfree(passphrase1);
  RSA_free(private_key); /* Destroys contents */
  xfree(comment);

  printf("Your identification has been saved with the new passphrase.\n");
  exit(0);
}

/* Change the comment of a private key file. */

void
do_change_comment(struct passwd *pw)
{
  char buf[1024], new_comment[1024], *comment;
  RSA *private_key;
  char *passphrase;
  struct stat st;
  FILE *f;
  char *tmpbuf;

  /* Read key file name. */
  if (identity_file)
    {
      strncpy(buf, identity_file, sizeof(buf));
      buf[sizeof(buf) - 1] = '\0';
    }
  else
    {
      printf("Enter file in which the key is ($HOME/%s): ", 
	     SSH_CLIENT_IDENTITY);
      fflush(stdout);
      if (fgets(buf, sizeof(buf), stdin) == NULL)
	exit(1);
      if (strchr(buf, '\n'))
	*strchr(buf, '\n') = 0;
      if (strcmp(buf, "") == 0)
	snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, SSH_CLIENT_IDENTITY);
    }

  /* Check if the file exists. */
  if (stat(buf, &st) < 0)
    {
      perror(buf);
      exit(1);
    }
  
  /* Try to load the public key from the file the verify that it is
     readable and of the proper format. */
  public_key = RSA_new();
  if (!load_public_key(buf, public_key, NULL))
    {
      printf("%s is not a valid key file.\n", buf);
      exit(1);
    }

  private_key = RSA_new();
  /* Try to load the file with empty passphrase. */
  if (load_private_key(buf, "", private_key, &comment))
    passphrase = xstrdup("");
  else
    {
      /* Read passphrase from the user. */
      if (identity_passphrase)
	passphrase = xstrdup(identity_passphrase);
      else
	if (identity_new_passphrase)
	  passphrase = xstrdup(identity_new_passphrase);
	else
	  passphrase = read_passphrase("Enter passphrase: ", 1);
      /* Try to load using the passphrase. */
      if (!load_private_key(buf, passphrase, private_key, &comment))
	{
	  memset(passphrase, 0, strlen(passphrase));
	  xfree(passphrase);
	  printf("Bad passphrase.\n");
	  exit(1);
	}
    }
  printf("Key now has comment '%s'\n", comment);

  if (identity_comment)
    {
      strncpy(new_comment, identity_comment, sizeof(new_comment));
      new_comment[sizeof(new_comment) - 1] = '\0';
    }
  else
    {
      printf("Enter new comment: ");
      fflush(stdout);
      if (!fgets(new_comment, sizeof(new_comment), stdin))
	{
	  memset(passphrase, 0, strlen(passphrase));
	  RSA_free(private_key);
	  exit(1);
	}
      
      /* Remove terminating newline from comment. */
      if (strchr(new_comment, '\n'))
	*strchr(new_comment, '\n') = 0;
    }
      
  /* Save the file using the new passphrase. */
  if (!save_private_key(buf, passphrase, private_key, new_comment))
    {
      printf("Saving the key failed: %s: %s.\n",
	     buf, strerror(errno));
      memset(passphrase, 0, strlen(passphrase));
      xfree(passphrase);
      RSA_free(private_key);
      xfree(comment);
      exit(1);
    }

  /* Destroy the passphrase and the private key in memory. */
  memset(passphrase, 0, strlen(passphrase));
  xfree(passphrase);
  RSA_free(private_key);

  /* Save the public key in text format in a file with the same name but
     .pub appended. */
  strcat(buf, ".pub");
  f = fopen(buf, "w");
  if (!f)
    {
      printf("Could not save your public key in %s\n", buf);
      exit(1);
    }
  fprintf(f, "%d ", BN_num_bits(public_key->n));
  tmpbuf = BN_bn2dec(public_key->e);
  fprintf(f, "%s ", tmpbuf);
  free (tmpbuf);
  tmpbuf = BN_bn2dec(public_key->n);
  fprintf(f, "%s %s\n", tmpbuf, new_comment);
  free (tmpbuf);
  fclose(f);

  xfree(comment);

  printf("The comment in your key file has been changed.\n");
  exit(0);
}

/* Main program for key management. */

int
main(int ac, char **av)
{
  char buf[16384], buf2[1024], *passphrase1, *passphrase2;
  struct passwd *pw;
  char *tmpbuf;
  int opt;
  struct stat st;
  FILE *f;
  char hostname[MAXHOSTNAMELEN];
  extern int optind;
  extern char *optarg;

  /* check if RSA support exists */
  if (rsa_alive() == 0) {
    extern char *__progname;

    fprintf(stderr,
      "%s: no RSA support in libssl and libcrypto.  See ssl(8).\n",
      __progname);
    exit(1);
  }

  /* Get user\'s passwd structure.  We need this for the home directory. */
  pw = getpwuid(getuid());
  if (!pw)
    {
      printf("You don't exist, go away!\n");
      exit(1);
    }

  /* Create ~/.ssh directory if it doesn\'t already exist. */
  snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, SSH_USER_DIR);
  if (stat(buf, &st) < 0)
    if (mkdir(buf, 0755) < 0)
      error("Could not create directory '%s'.", buf);

  /* Parse command line arguments. */
  while ((opt = getopt(ac, av, "qpcb:f:P:N:C:")) != EOF)
    {
      switch (opt)
	{
	case 'b':
	  bits = atoi(optarg);
	  if (bits < 512 || bits > 32768)
	    {
	      printf("Bits has bad value.\n");
	      exit(1);
	    }
	  break;

	case 'p':
	  change_passphrase = 1;
	  break;

	case 'c':
	  change_comment = 1;
	  break;

	case 'f':
	  identity_file = optarg;
	  break;
	  
	case 'P':
	  identity_passphrase = optarg;
	  break;

	case 'N':
	  identity_new_passphrase = optarg;
	  break;

	case 'C':
	  identity_comment = optarg;
	  break;

        case 'q':
	  quiet = 1;
	  break;

	case '?':
	default:
	  printf("ssh-keygen version %s\n", SSH_VERSION);
	  printf("Usage: %s [-b bits] [-p] [-c] [-f file] [-P pass] [-N new-pass] [-C comment]\n", av[0]);
	  exit(1);
	}
    }
  if (optind < ac)
    {
      printf("Too many arguments.\n");
      exit(1);
    }
  if (change_passphrase && change_comment)
    {
      printf("Can only have one of -p and -c.\n");
      exit(1);
    }

  /* If the user requested to change the passphrase, do it now.  This
     function never returns. */
  if (change_passphrase)
    do_change_passphrase(pw);

  /* If the user requested to change the comment, do it now.  This function
     never returns. */
  if (change_comment)
    do_change_comment(pw);

  arc4random_stir();

  if (quiet)
    rsa_set_verbose(0);

  /* Generate the rsa key pair. */
  private_key = RSA_new();
  public_key = RSA_new();
  rsa_generate_key(private_key, public_key, bits);

 ask_file_again:

  /* Ask for a file to save the key in. */
  if (identity_file)
    {
      strncpy(buf, identity_file, sizeof(buf));
      buf[sizeof(buf) - 1] = '\0';
    }
  else
    {
      printf("Enter file in which to save the key ($HOME/%s): ", 
	     SSH_CLIENT_IDENTITY);
      fflush(stdout);
      if (fgets(buf, sizeof(buf), stdin) == NULL)
	exit(1);
      if (strchr(buf, '\n'))
	*strchr(buf, '\n') = 0;
      if (strcmp(buf, "") == 0)
	snprintf(buf, sizeof buf, "%s/%s", pw->pw_dir, SSH_CLIENT_IDENTITY);
    }

  /* If the file aready exists, ask the user to confirm. */
  if (stat(buf, &st) >= 0)
    {
      printf("%s already exists.\n", buf);
      printf("Overwrite (y/n)? ");
      fflush(stdout);
      if (fgets(buf2, sizeof(buf2), stdin) == NULL)
	exit(1);
      if (buf2[0] != 'y' && buf2[0] != 'Y')
	exit(1);
    }
  
  /* Ask for a passphrase (twice). */
  if (identity_passphrase)
    passphrase1 = xstrdup(identity_passphrase);
  else
    if (identity_new_passphrase)
      passphrase1 = xstrdup(identity_new_passphrase);
    else
      {
      passphrase_again:
	passphrase1 = 
	  read_passphrase("Enter passphrase (empty for no passphrase): ", 1);
	passphrase2 = read_passphrase("Enter same passphrase again: ", 1);
	if (strcmp(passphrase1, passphrase2) != 0)
	  {
	    /* The passphrases do not match.  Clear them and retry. */
	    memset(passphrase1, 0, strlen(passphrase1));
	    memset(passphrase2, 0, strlen(passphrase2));
	    xfree(passphrase1);
	    xfree(passphrase2);
	    printf("Passphrases do not match.  Try again.\n");
	    goto passphrase_again;
	  }
	/* Clear the other copy of the passphrase. */
	memset(passphrase2, 0, strlen(passphrase2));
	xfree(passphrase2);
      }

  /* Create default commend field for the passphrase.  The user can later
     edit this field. */
  if (identity_comment)
    {
      strlcpy(buf2, identity_comment, sizeof(buf2));
    }
  else
    {
      if (gethostname(hostname, sizeof(hostname)) < 0)
	{
	  perror("gethostname");
	  exit(1);
	}
      snprintf(buf2, sizeof buf2, "%s@%s", pw->pw_name, hostname);
    }

  /* Save the key with the given passphrase and comment. */
  if (!save_private_key(buf, passphrase1, private_key, buf2))
    {
      printf("Saving the key failed: %s: %s.\n",
	     buf, strerror(errno));
      memset(passphrase1, 0, strlen(passphrase1));
      xfree(passphrase1);
      goto ask_file_again;
    }
  /* Clear the passphrase. */
  memset(passphrase1, 0, strlen(passphrase1));
  xfree(passphrase1);

  /* Clear the private key and the random number generator. */
  RSA_free(private_key);
  arc4random_stir();

  if (!quiet)
    printf("Your identification has been saved in %s.\n", buf);

  /* Display the public key on the screen. */
  if (!quiet) {
    printf("Your public key is:\n");
    printf("%d ", BN_num_bits(public_key->n));
    tmpbuf = BN_bn2dec(public_key->e);
    printf("%s ", tmpbuf);
    free(tmpbuf);
    tmpbuf = BN_bn2dec(public_key->n);
    printf("%s %s\n", tmpbuf, buf2);
    free(tmpbuf);
  }

  /* Save the public key in text format in a file with the same name but
     .pub appended. */
  strcat(buf, ".pub");
  f = fopen(buf, "w");
  if (!f)
    {
      printf("Could not save your public key in %s\n", buf);
      exit(1);
    }
  fprintf(f, "%d ", BN_num_bits(public_key->n));
  tmpbuf = BN_bn2dec(public_key->e);
  fprintf(f, "%s ", tmpbuf);
  free(tmpbuf);
  tmpbuf = BN_bn2dec(public_key->n);
  fprintf(f, "%s %s\n", tmpbuf, buf2);
  free(tmpbuf);
  fclose(f);

  if (!quiet)
    printf("Your public key has been saved in %s\n", buf);
  
  exit(0);
}