agent/genkey.c

   1 /* genkey.c - Generate a keypair
   2  *      Copyright (C) 2002, 2003, 2004, 2007 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuPG.
   5  *
   6  * GnuPG is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuPG is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <config.h>
  21 #include <errno.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <ctype.h>
  26 #include <assert.h>
  27
  28 #include "agent.h"
  29 #include "i18n.h"
  30 #include "exechelp.h"
  31 #include "sysutils.h"
  32
  33 static int
  34 store_key (gcry_sexp_t private, const char *passphrase, int force)
  35 {
  36   int rc;
  37   unsigned char *buf;
  38   size_t len;
  39   unsigned char grip[20];
  40
  41   if ( !gcry_pk_get_keygrip (private, grip) )
  42     {
  43       log_error ("can't calculate keygrip\n");
  44       return gpg_error (GPG_ERR_GENERAL);
  45     }
  46
  47   len = gcry_sexp_sprint (private, GCRYSEXP_FMT_CANON, NULL, 0);
  48   assert (len);
  49   buf = gcry_malloc_secure (len);
  50   if (!buf)
  51       return out_of_core ();
  52   len = gcry_sexp_sprint (private, GCRYSEXP_FMT_CANON, buf, len);
  53   assert (len);
  54
  55   if (passphrase)
  56     {
  57       unsigned char *p;
  58
  59       rc = agent_protect (buf, passphrase, &p, &len);
  60       if (rc)
  61         {
  62           xfree (buf);
  63           return rc;
  64         }
  65       xfree (buf);
  66       buf = p;
  67     }
  68
  69   rc = agent_write_private_key (grip, buf, len, force);
  70   xfree (buf);
  71   return rc;
  72 }
  73
  74
  75 /* Count the number of non-alpha characters in S.  Control characters
  76    and non-ascii characters are not considered.  */
  77 static size_t
  78 nonalpha_count (const char *s)
  79 {
  80   size_t n;
  81
  82   for (n=0; *s; s++)
  83     if (isascii (*s) && ( isdigit (*s) || ispunct (*s) ))
  84       n++;
  85
  86   return n;
  87 }
  88
  89
  90 /* Check PW against a list of pattern.  Return 0 if PW does not match
  91    these pattern.  */
  92 static int
  93 check_passphrase_pattern (ctrl_t ctrl, const char *pw)
  94 {
  95   gpg_error_t err = 0;
  96   const char *pgmname = gnupg_module_name (GNUPG_MODULE_NAME_CHECK_PATTERN);
  97   FILE *infp;
  98   const char *argv[10];
  99   pid_t pid;
 100   int result, i;
 101
 102   (void)ctrl;
 103
 104   infp = gnupg_tmpfile ();
 105   if (!infp)
 106     {
 107       err = gpg_error_from_syserror ();
 108       log_error (_("error creating temporary file: %s\n"), strerror (errno));
 109       return 1; /* Error - assume password should not be used.  */
 110     }
 111
 112   if (fwrite (pw, strlen (pw), 1, infp) != 1)
 113     {
 114       err = gpg_error_from_syserror ();
 115       log_error (_("error writing to temporary file: %s\n"),
 116                  strerror (errno));
 117       fclose (infp);
 118       return 1; /* Error - assume password should not be used.  */
 119     }
 120   rewind (infp);
 121
 122   i = 0;
 123   argv[i++] = "--null";
 124   argv[i++] = "--",
 125   argv[i++] = opt.check_passphrase_pattern,
 126   argv[i] = NULL;
 127   assert (i < sizeof argv);
 128
 129   if (gnupg_spawn_process_fd (pgmname, argv, fileno (infp), -1, -1, &pid))
 130     result = 1; /* Execute error - assume password should no be used.  */
 131   else if (gnupg_wait_process (pgmname, pid, NULL))
 132     result = 1; /* Helper returned an error - probably a match.  */
 133   else
 134     result = 0; /* Success; i.e. no match.  */
 135
 136   /* Overwrite our temporary file. */
 137   rewind (infp);
 138   for (i=((strlen (pw)+99)/100)*100; i > 0; i--)
 139     putc ('\xff', infp);
 140   fflush (infp);
 141   fclose (infp);
 142   return result;
 143 }
 144
 145
 146 static int
 147 take_this_one_anyway2 (ctrl_t ctrl, const char *desc, const char *anyway_btn)
 148 {
 149   gpg_error_t err;
 150
 151   if (opt.enforce_passphrase_constraints)
 152     {
 153       err = agent_show_message (ctrl, desc, _("Enter new passphrase"));
 154       if (!err)
 155         err = gpg_error (GPG_ERR_CANCELED);
 156     }
 157   else
 158     err = agent_get_confirmation (ctrl, desc,
 159                                   anyway_btn, _("Enter new passphrase"), 0);
 160   return err;
 161 }
 162
 163
 164 static int
 165 take_this_one_anyway (ctrl_t ctrl, const char *desc)
 166 {
 167   return take_this_one_anyway2 (ctrl, desc, _("Take this one anyway"));
 168 }
 169
 170
 171 /* Check whether the passphrase PW is suitable. Returns 0 if the
 172    passphrase is suitable and true if it is not and the user should be
 173    asked to provide a different one.  If SILENT is set, no message are
 174    displayed.  */
 175 int
 176 check_passphrase_constraints (ctrl_t ctrl, const char *pw, int silent)
 177 {
 178   gpg_error_t err;
 179   unsigned int minlen = opt.min_passphrase_len;
 180   unsigned int minnonalpha = opt.min_passphrase_nonalpha;
 181
 182   if (!pw)
 183     pw = "";
 184
 185   if (utf8_charcount (pw) < minlen )
 186     {
 187       char *desc;
 188
 189       if (silent)
 190         return gpg_error (GPG_ERR_INV_PASSPHRASE);
 191
 192       desc = xtryasprintf
 193         ( ngettext ("Warning: You have entered an insecure passphrase.%%0A"
 194                     "A passphrase should be at least %u character long.",
 195                     "Warning: You have entered an insecure passphrase.%%0A"
 196                     "A passphrase should be at least %u characters long.",
 197                     minlen), minlen );
 198       if (!desc)
 199         return gpg_error_from_syserror ();
 200       err = take_this_one_anyway (ctrl, desc);
 201       xfree (desc);
 202       if (err)
 203         return err;
 204     }
 205
 206   if (nonalpha_count (pw) < minnonalpha )
 207     {
 208       char *desc;
 209
 210       if (silent)
 211         return gpg_error (GPG_ERR_INV_PASSPHRASE);
 212
 213       desc = xtryasprintf
 214         ( ngettext ("Warning: You have entered an insecure passphrase.%%0A"
 215                     "A passphrase should contain at least %u digit or%%0A"
 216                     "special character.",
 217                     "Warning: You have entered an insecure passphrase.%%0A"
 218                     "A passphrase should contain at least %u digits or%%0A"
 219                     "special characters.",
 220                     minnonalpha), minnonalpha );
 221       if (!desc)
 222         return gpg_error_from_syserror ();
 223       err = take_this_one_anyway (ctrl, desc);
 224       xfree (desc);
 225       if (err)
 226         return err;
 227     }
 228
 229   /* If configured check the passphrase against a list of know words
 230      and pattern.  The actual test is done by an external program.
 231      The warning message is generic to give the user no hint on how to
 232      circumvent this list.  */
 233   if (*pw && opt.check_passphrase_pattern &&
 234       check_passphrase_pattern (ctrl, pw))
 235     {
 236       const char *desc =
 237         /* */     _("Warning: You have entered an insecure passphrase.%%0A"
 238                     "A passphrase may not be a known term or match%%0A"
 239                     "certain pattern.");
 240
 241       if (silent)
 242         return gpg_error (GPG_ERR_INV_PASSPHRASE);
 243
 244       err = take_this_one_anyway (ctrl, desc);
 245       if (err)
 246         return err;
 247     }
 248
 249   /* The final check is to warn about an empty passphrase. */
 250   if (!*pw)
 251     {
 252       const char *desc = (opt.enforce_passphrase_constraints?
 253                           _("You have not entered a passphrase!%0A"
 254                             "An empty passphrase is not allowed.") :
 255                           _("You have not entered a passphrase - "
 256                             "this is in general a bad idea!%0A"
 257                             "Please confirm that you do not want to "
 258                             "have any protection on your key."));
 259
 260       if (silent)
 261         return gpg_error (GPG_ERR_INV_PASSPHRASE);
 262
 263       err = take_this_one_anyway2 (ctrl, desc,
 264                                    _("Yes, protection is not needed"));
 265       if (err)
 266         return err;
 267     }
 268
 269   return 0;
 270 }
 271
 272
 273 /* Callback function to compare the first entered PIN with the one
 274    currently being entered. */
 275 static int
 276 reenter_compare_cb (struct pin_entry_info_s *pi)
 277 {
 278   const char *pin1 = pi->check_cb_arg;
 279
 280   if (!strcmp (pin1, pi->pin))
 281     return 0; /* okay */
 282   return -1;
 283 }
 284
 285
 286
 287 /* Generate a new keypair according to the parameters given in
 288    KEYPARAM */
 289 int
 290 agent_genkey (ctrl_t ctrl, const char *keyparam, size_t keyparamlen,
 291               membuf_t *outbuf)
 292 {
 293   gcry_sexp_t s_keyparam, s_key, s_private, s_public;
 294   struct pin_entry_info_s *pi, *pi2;
 295   int rc;
 296   size_t len;
 297   char *buf;
 298
 299   rc = gcry_sexp_sscan (&s_keyparam, NULL, keyparam, keyparamlen);
 300   if (rc)
 301     {
 302       log_error ("failed to convert keyparam: %s\n", gpg_strerror (rc));
 303       return gpg_error (GPG_ERR_INV_DATA);
 304     }
 305
 306   /* Get the passphrase now, cause key generation may take a while. */
 307   {
 308     const char *text1 = _("Please enter the passphrase to%0A"
 309                                "to protect your new key");
 310     const char *text2 = _("Please re-enter this passphrase");
 311     const char *initial_errtext = NULL;
 312
 313     pi = gcry_calloc_secure (2, sizeof (*pi) + 100);
 314     pi2 = pi + (sizeof *pi + 100);
 315     pi->max_length = 100;
 316     pi->max_tries = 3;
 317     pi->with_qualitybar = 1;
 318     pi2->max_length = 100;
 319     pi2->max_tries = 3;
 320     pi2->check_cb = reenter_compare_cb;
 321     pi2->check_cb_arg = pi->pin;
 322
 323   next_try:
 324     rc = agent_askpin (ctrl, text1, NULL, initial_errtext, pi);
 325     initial_errtext = NULL;
 326     if (!rc)
 327       {
 328         if (check_passphrase_constraints (ctrl, pi->pin, 0))
 329           {
 330             pi->failed_tries = 0;
 331             pi2->failed_tries = 0;
 332             goto next_try;
 333           }
 334         if (pi->pin && *pi->pin)
 335           {
 336             rc = agent_askpin (ctrl, text2, NULL, NULL, pi2);
 337             if (rc == -1)
 338               { /* The re-entered one did not match and the user did not
 339                    hit cancel. */
 340                 initial_errtext = _("does not match - try again");
 341                 goto next_try;
 342               }
 343           }
 344       }
 345     if (rc)
 346       {
 347         xfree (pi);
 348         return rc;
 349       }
 350
 351     if (!*pi->pin)
 352       {
 353         xfree (pi);
 354         pi = NULL; /* User does not want a passphrase. */
 355       }
 356   }
 357
 358   rc = gcry_pk_genkey (&s_key, s_keyparam );
 359   gcry_sexp_release (s_keyparam);
 360   if (rc)
 361     {
 362       log_error ("key generation failed: %s\n", gpg_strerror (rc));
 363       xfree (pi);
 364       return rc;
 365     }
 366
 367   /* break out the parts */
 368   s_private = gcry_sexp_find_token (s_key, "private-key", 0);
 369   if (!s_private)
 370     {
 371       log_error ("key generation failed: invalid return value\n");
 372       gcry_sexp_release (s_key);
 373       xfree (pi);
 374       return gpg_error (GPG_ERR_INV_DATA);
 375     }
 376   s_public = gcry_sexp_find_token (s_key, "public-key", 0);
 377   if (!s_public)
 378     {
 379       log_error ("key generation failed: invalid return value\n");
 380       gcry_sexp_release (s_private);
 381       gcry_sexp_release (s_key);
 382       xfree (pi);
 383       return gpg_error (GPG_ERR_INV_DATA);
 384     }
 385   gcry_sexp_release (s_key); s_key = NULL;
 386
 387   /* store the secret key */
 388   if (DBG_CRYPTO)
 389     log_debug ("storing private key\n");
 390   rc = store_key (s_private, pi? pi->pin:NULL, 0);
 391   xfree (pi); pi = NULL;
 392   gcry_sexp_release (s_private);
 393   if (rc)
 394     {
 395       gcry_sexp_release (s_public);
 396       return rc;
 397     }
 398
 399   /* return the public key */
 400   if (DBG_CRYPTO)
 401     log_debug ("returning public key\n");
 402   len = gcry_sexp_sprint (s_public, GCRYSEXP_FMT_CANON, NULL, 0);
 403   assert (len);
 404   buf = xtrymalloc (len);
 405   if (!buf)
 406     {
 407       gpg_error_t tmperr = out_of_core ();
 408       gcry_sexp_release (s_private);
 409       gcry_sexp_release (s_public);
 410       return tmperr;
 411     }
 412   len = gcry_sexp_sprint (s_public, GCRYSEXP_FMT_CANON, buf, len);
 413   assert (len);
 414   put_membuf (outbuf, buf, len);
 415   gcry_sexp_release (s_public);
 416   xfree (buf);
 417
 418   return 0;
 419 }
 420
 421
 422 \f
 423 /* Apply a new passpahrse to the key S_SKEY and store it. */
 424 int
 425 agent_protect_and_store (ctrl_t ctrl, gcry_sexp_t s_skey)
 426 {
 427   struct pin_entry_info_s *pi, *pi2;
 428   int rc;
 429
 430   {
 431     const char *text1 = _("Please enter the new passphrase");
 432     const char *text2 = _("Please re-enter this passphrase");
 433     const char *initial_errtext = NULL;
 434
 435     pi = gcry_calloc_secure (2, sizeof (*pi) + 100);
 436     pi2 = pi + (sizeof *pi + 100);
 437     pi->max_length = 100;
 438     pi->max_tries = 3;
 439     pi->with_qualitybar = 1;
 440     pi2->max_length = 100;
 441     pi2->max_tries = 3;
 442     pi2->check_cb = reenter_compare_cb;
 443     pi2->check_cb_arg = pi->pin;
 444
 445   next_try:
 446     rc = agent_askpin (ctrl, text1, NULL, initial_errtext, pi);
 447     initial_errtext = NULL;
 448     if (!rc)
 449       {
 450         if (check_passphrase_constraints (ctrl, pi->pin, 0))
 451           {
 452             pi->failed_tries = 0;
 453             pi2->failed_tries = 0;
 454             goto next_try;
 455           }
 456         /* Unless the passphrase is empty, ask to confirm it.  */
 457         if (pi->pin && *pi->pin)
 458           {
 459             rc = agent_askpin (ctrl, text2, NULL, NULL, pi2);
 460             if (rc == -1)
 461               { /* The re-entered one did not match and the user did not
 462                    hit cancel. */
 463                 initial_errtext = _("does not match - try again");
 464                 goto next_try;
 465               }
 466           }
 467       }
 468     if (rc)
 469       {
 470         xfree (pi);
 471         return rc;
 472       }
 473
 474     if (!*pi->pin)
 475       {
 476         xfree (pi);
 477         pi = NULL; /* User does not want a passphrase. */
 478       }
 479   }
 480
 481   rc = store_key (s_skey, pi? pi->pin:NULL, 1);
 482   xfree (pi);
 483   return rc;
 484 }