git.distorted.org.uk Git - u/mdw/catacomb/blob - cc-sig.c

   1 /* -*-c-*-
   2  *
   3  * $Id$
   4  *
   5  * Catcrypt signatures
   6  *
   7  * (c) 2004 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Header files ------------------------------------------------------*/
  31
  32 #include <stdlib.h>
  33
  34 #include <mLib/report.h>
  35
  36 #include "rand.h"
  37 #include "sha.h"
  38 #include "has160.h"
  39
  40 #include "ec.h"
  41 #include "ec-keys.h"
  42 #include "dh.h"
  43 #include "gdsa.h"
  44 #include "gkcdsa.h"
  45 #include "rsa.h"
  46
  47 #include "cc.h"
  48
  49 /*----- Main code ---------------------------------------------------------*/
  50
  51 /* --- RSA PKCS1 --- */
  52
  53 typedef struct rsap1_sigctx {
  54   sig s;
  55   rsa_privctx rp;
  56   pkcs1 p1;
  57 } rsap1_sigctx;
  58
  59 static sig *rsap1_siginit(key *k, void *kd, const gchash *hc)
  60 {
  61   rsap1_sigctx *rs = CREATE(rsap1_sigctx);
  62   rsa_privcreate(&rs->rp, kd, &rand_global);
  63   rs->p1.r = &rand_global;
  64   rs->p1.ep = hc->name;
  65   rs->p1.epsz = strlen(hc->name) + 1;
  66   rs->s.h = 0;
  67   return (&rs->s);
  68 }
  69
  70 static int rsap1_sigdoit(sig *s, dstr *d)
  71 {
  72   rsap1_sigctx *rs = (rsap1_sigctx *)s;
  73   size_t n;
  74   mp *m = rsa_sign(&rs->rp, MP_NEW,
  75                    GH_DONE(s->h, 0), GH_CLASS(s->h)->hashsz,
  76                    pkcs1_sigencode, &rs->p1);
  77   if (!m) return (-1);
  78   n = mp_octets(rs->rp.rp->n); dstr_ensure(d, n); mp_storeb(m, d->buf, n);
  79   d->len += n; mp_drop(m);
  80   return (0);
  81 }
  82
  83 static const char *rsa_lengthcheck(mp *n)
  84 {
  85   if (mp_bits(n) < 1024) return ("key too short");
  86   return (0);
  87 }
  88
  89 static const char *rsap1_sigcheck(sig *s)
  90 {
  91   rsap1_sigctx *rs = (rsap1_sigctx *)s;
  92   const char *e;
  93   if ((e = rsa_lengthcheck(rs->rp.rp->n)) != 0) return (e);
  94   return (0);
  95 }
  96
  97 static void rsap1_sigdestroy(sig *s)
  98 {
  99   rsap1_sigctx *rs = (rsap1_sigctx *)s;
 100   rsa_privdestroy(&rs->rp);
 101   DESTROY(rs);
 102 }
 103
 104 static const sigops rsap1_sig = {
 105   rsa_privfetch, sizeof(rsa_priv),
 106   rsap1_siginit, rsap1_sigdoit, rsap1_sigcheck, rsap1_sigdestroy
 107 };
 108
 109 typedef struct rsap1_vrfctx {
 110   sig s;
 111   rsa_pubctx rp;
 112   pkcs1 p1;
 113 } rsap1_vrfctx;
 114
 115 static sig *rsap1_vrfinit(key *k, void *kd, const gchash *hc)
 116 {
 117   rsap1_vrfctx *rv = CREATE(rsap1_vrfctx);
 118   rsa_pubcreate(&rv->rp, kd);
 119   rv->p1.r = &rand_global;
 120   rv->p1.ep = hc->name;
 121   rv->p1.epsz = strlen(hc->name) + 1;
 122   rv->s.h = 0;
 123   return (&rv->s);
 124 }
 125
 126 static int rsap1_vrfdoit(sig *s, dstr *d)
 127 {
 128   rsap1_vrfctx *rv = (rsap1_vrfctx *)s;
 129   mp *m = mp_loadb(MP_NEW, d->buf, d->len);
 130   int rc = rsa_verify(&rv->rp, m,
 131                       GH_DONE(s->h, 0), GH_CLASS(s->h)->hashsz,
 132                       0, pkcs1_sigdecode, &rv->p1);
 133   mp_drop(m);
 134   return (rc);
 135 }
 136
 137 static const char *rsap1_vrfcheck(sig *s)
 138 {
 139   rsap1_vrfctx *rv = (rsap1_vrfctx *)s;
 140   const char *e;
 141   if ((e = rsa_lengthcheck(rv->rp.rp->n)) != 0) return (e);
 142   return (0);
 143 }
 144
 145 static void rsap1_vrfdestroy(sig *s)
 146 {
 147   rsap1_vrfctx *rv = (rsap1_vrfctx *)s;
 148   rsa_pubdestroy(&rv->rp);
 149   DESTROY(rv);
 150 }
 151
 152 static const sigops rsap1_vrf = {
 153   rsa_pubfetch, sizeof(rsa_pub),
 154   rsap1_vrfinit, rsap1_vrfdoit, rsap1_vrfcheck, rsap1_vrfdestroy
 155 };
 156
 157 /* --- RSA PSS --- */
 158
 159 static const gccipher *getmgf(key *k, const gchash *hc)
 160 {
 161   dstr d = DSTR_INIT;
 162   const gccipher *gc;
 163   const char *mm;
 164
 165   if ((mm = key_getattr(0, k, "mgf")) == 0) {
 166     dstr_putf(&d, "%s-mgf", hc->name);
 167     mm = d.buf;
 168   }
 169   if ((gc = gcipher_byname(mm)) == 0)
 170     die(EXIT_FAILURE, "unknown encryption scheme `%s'", mm);
 171   dstr_destroy(&d);
 172   return (gc);
 173 }
 174
 175 typedef struct rsapss_sigctx {
 176   sig s;
 177   rsa_privctx rp;
 178   pss p;
 179 } rsapss_sigctx;
 180
 181 static sig *rsapss_siginit(key *k, void *kd, const gchash *hc)
 182 {
 183   rsapss_sigctx *rs = CREATE(rsapss_sigctx);
 184   rsa_privcreate(&rs->rp, kd, &rand_global);
 185   rs->p.r = &rand_global;
 186   rs->p.cc = getmgf(k, hc);
 187   rs->p.ch = hc;
 188   rs->p.ssz = hc->hashsz;
 189   rsa_privdestroy(&rs->rp);
 190   return (&rs->s);
 191 }
 192
 193 static int rsapss_sigdoit(sig *s, dstr *d)
 194 {
 195   rsapss_sigctx *rs = (rsapss_sigctx *)s;
 196   size_t n;
 197   mp *m = rsa_sign(&rs->rp, MP_NEW,
 198                    GH_DONE(s->h, 0), GH_CLASS(s->h)->hashsz,
 199                    pss_encode, &rs->p);
 200   if (!m) return (-1);
 201   n = mp_octets(rs->rp.rp->n); dstr_ensure(d, n); mp_storeb(m, d->buf, n);
 202   d->len += n;  mp_drop(m);
 203   return (0);
 204 }
 205
 206 static const char *rsapss_sigcheck(sig *s)
 207 {
 208   rsapss_sigctx *rs = (rsapss_sigctx *)s;
 209   const char *e;
 210   if ((e = rsa_lengthcheck(rs->rp.rp->n)) != 0) return (e);
 211   return (0);
 212 }
 213
 214 static void rsapss_sigdestroy(sig *s)
 215 {
 216   rsapss_sigctx *rs = (rsapss_sigctx *)s;
 217   rsa_privdestroy(&rs->rp);
 218   DESTROY(rs);
 219 }
 220
 221 static const sigops rsapss_sig = {
 222   rsa_privfetch, sizeof(rsa_priv),
 223   rsapss_siginit, rsapss_sigdoit, rsapss_sigcheck, rsapss_sigdestroy
 224 };
 225
 226 typedef struct rsapss_vrfctx {
 227   sig s;
 228   rsa_pubctx rp;
 229   pss p;
 230 } rsapss_vrfctx;
 231
 232 static sig *rsapss_vrfinit(key *k, void *kd, const gchash *hc)
 233 {
 234   rsapss_vrfctx *rv = CREATE(rsapss_vrfctx);
 235   rsa_pubcreate(&rv->rp, kd);
 236   rv->p.r = &rand_global;
 237   rv->p.cc = getmgf(k, hc);
 238   rv->p.ch = hc;
 239   rv->p.ssz = hc->hashsz;
 240   return (&rv->s);
 241 }
 242
 243 static int rsapss_vrfdoit(sig *s, dstr *d)
 244 {
 245   rsapss_vrfctx *rv = (rsapss_vrfctx *)s;
 246   mp *m = mp_loadb(MP_NEW, d->buf, d->len);
 247   int rc = rsa_verify(&rv->rp, m,
 248                       GH_DONE(s->h, 0), GH_CLASS(s->h)->hashsz,
 249                       0, pss_decode, &rv->p);
 250   mp_drop(m);
 251   return (rc);
 252 }
 253
 254 static const char *rsapss_vrfcheck(sig *s)
 255 {
 256   rsapss_vrfctx *rv = (rsapss_vrfctx *)s;
 257   const char *e;
 258   if ((e = rsa_lengthcheck(rv->rp.rp->n)) != 0) return (e);
 259   return (0);
 260 }
 261
 262 static void rsapss_vrfdestroy(sig *s)
 263 {
 264   rsapss_vrfctx *rv = (rsapss_vrfctx *)s;
 265   rsa_pubdestroy(&rv->rp);
 266   DESTROY(rv);
 267 }
 268
 269 static const sigops rsapss_vrf = {
 270   rsa_pubfetch, sizeof(rsa_pub),
 271   rsapss_vrfinit, rsapss_vrfdoit, rsapss_vrfcheck, rsapss_vrfdestroy
 272 };
 273
 274 /* --- DSA and ECDSA --- */
 275
 276 typedef struct dsa_sigctx {
 277   sig s;
 278   gdsa g;
 279 } dsa_sigctx;
 280
 281 static void dsa_initcommon(dsa_sigctx *ds, const gchash *hc,
 282                            const char *ktag)
 283 {
 284   ds->g.r = &rand_global;
 285   ds->g.h = hc;
 286   ds->g.u = MP_NEW;
 287   ds->s.h = 0;
 288 }
 289
 290 static dsa_sigctx *dsa_doinit(key *k, const gprime_param *gp,
 291                               mp *y, const gchash *hc,
 292                               group *(*makegroup)(const gprime_param *),
 293                               const char *what)
 294 {
 295   dsa_sigctx *ds = CREATE(dsa_sigctx);
 296   dstr t = DSTR_INIT;
 297
 298   key_fulltag(k, &t);
 299   if ((ds->g.g = makegroup(gp)) == 0)
 300     die(EXIT_FAILURE, "bad %s group in key `%s'", what, t.buf);
 301   ds->g.p = G_CREATE(ds->g.g);
 302   if (G_FROMINT(ds->g.g, ds->g.p, y))
 303     die(EXIT_FAILURE, "bad public key in key `%s'", t.buf);
 304   dsa_initcommon(ds, hc, t.buf);
 305   dstr_destroy(&t);
 306   return (ds);
 307 }
 308
 309 static dsa_sigctx *ecdsa_doinit(key *k, const char *cstr,
 310                                 ec *y, const gchash *hc)
 311 {
 312   dsa_sigctx *ds = CREATE(dsa_sigctx);
 313   ec_info ei;
 314   const char *e;
 315   dstr t = DSTR_INIT;
 316
 317   key_fulltag(k, &t);
 318   if ((e = ec_getinfo(&ei, cstr)) != 0)
 319     die(EXIT_FAILURE, "bad curve in key `%s': %s", t.buf, e);
 320   ds->g.g = group_ec(&ei);
 321   ds->g.p = G_CREATE(ds->g.g);
 322   if (G_FROMEC(ds->g.g, ds->g.p, y))
 323     die(EXIT_FAILURE, "bad public key in key `%s'", t.buf);
 324   dsa_initcommon(ds, hc, t.buf);
 325   dstr_destroy(&t);
 326   return (ds);
 327 }
 328
 329 static sig *dsa_siginit(key *k, void *kd, const gchash *hc)
 330 {
 331   dh_priv *dp = kd;
 332   dsa_sigctx *ds = dsa_doinit(k, &dp->dp, dp->y, hc, group_prime, "prime");
 333   ds->g.u = MP_COPY(dp->x);
 334   return (&ds->s);
 335 }
 336
 337 static sig *bindsa_siginit(key *k, void *kd, const gchash *hc)
 338 {
 339   dh_priv *dp = kd;
 340   dsa_sigctx *ds = dsa_doinit(k, &dp->dp, dp->y, hc, group_binary, "binary");
 341   ds->g.u = MP_COPY(dp->x);
 342   return (&ds->s);
 343 }
 344
 345 static sig *ecdsa_siginit(key *k, void *kd, const gchash *hc)
 346 {
 347   ec_priv *ep = kd;
 348   dsa_sigctx *ds = ecdsa_doinit(k, ep->cstr, &ep->p, hc);
 349   ds->g.u = MP_COPY(ep->x);
 350   return (&ds->s);
 351 }
 352
 353 static int dsa_sigdoit(sig *s, dstr *d)
 354 {
 355   dsa_sigctx *ds = (dsa_sigctx *)s;
 356   gdsa_sig ss = GDSA_SIG_INIT;
 357   size_t n = mp_octets(ds->g.g->r);
 358
 359   gdsa_sign(&ds->g, &ss, GH_DONE(ds->s.h, 0), 0);
 360   dstr_ensure(d, 2 * n);
 361   mp_storeb(ss.r, d->buf, n);
 362   mp_storeb(ss.s, d->buf + n, n);
 363   d->len += 2 * n;
 364   mp_drop(ss.r); mp_drop(ss.s);
 365   return (0);
 366 }
 367
 368 static const char *dsa_sigcheck(sig *s)
 369 {
 370   dsa_sigctx *ds = (dsa_sigctx *)s;
 371   const char *e;
 372   if ((e = G_CHECK(ds->g.g, &rand_global)) != 0)
 373     return (0);
 374   if (group_check(ds->g.g, ds->g.p))
 375     return ("public key not in subgroup");
 376   return (0);
 377 }
 378
 379 static void dsa_sigdestroy(sig *s)
 380 {
 381   dsa_sigctx *ds = (dsa_sigctx *)s;
 382   G_DESTROY(ds->g.g, ds->g.p);
 383   mp_drop(ds->g.u);
 384   G_DESTROYGROUP(ds->g.g);
 385 }
 386
 387 static const sigops dsa_sig = {
 388   dh_privfetch, sizeof(dh_priv),
 389   dsa_siginit, dsa_sigdoit, dsa_sigcheck, dsa_sigdestroy
 390 };
 391
 392 static const sigops bindsa_sig = {
 393   dh_privfetch, sizeof(dh_priv),
 394   bindsa_siginit, dsa_sigdoit, dsa_sigcheck, dsa_sigdestroy
 395 };
 396
 397 static const sigops ecdsa_sig = {
 398   ec_privfetch, sizeof(ec_priv),
 399   ecdsa_siginit, dsa_sigdoit, dsa_sigcheck, dsa_sigdestroy
 400 };
 401
 402 static sig *dsa_vrfinit(key *k, void *kd, const gchash *hc)
 403 {
 404   dh_pub *dp = kd;
 405   dsa_sigctx *ds = dsa_doinit(k, &dp->dp, dp->y, hc, group_prime, "prime");
 406   return (&ds->s);
 407 }
 408
 409 static sig *bindsa_vrfinit(key *k, void *kd, const gchash *hc)
 410 {
 411   dh_pub *dp = kd;
 412   dsa_sigctx *ds = dsa_doinit(k, &dp->dp, dp->y, hc, group_binary, "binary");
 413   return (&ds->s);
 414 }
 415
 416 static sig *ecdsa_vrfinit(key *k, void *kd, const gchash *hc)
 417 {
 418   ec_pub *ep = kd;
 419   dsa_sigctx *ds = ecdsa_doinit(k, ep->cstr, &ep->p, hc);
 420   return (&ds->s);
 421 }
 422
 423 static int dsa_vrfdoit(sig *s, dstr *d)
 424 {
 425   dsa_sigctx *ds = (dsa_sigctx *)s;
 426   gdsa_sig ss;
 427   size_t n = d->len/2;
 428   int rc;
 429
 430   ss.r = mp_loadb(MP_NEW, d->buf, n);
 431   ss.s = mp_loadb(MP_NEW, d->buf + n, d->len - n);
 432   rc = gdsa_verify(&ds->g, &ss, GH_DONE(ds->s.h, 0));
 433   mp_drop(ss.r); mp_drop(ss.s);
 434   return (rc);
 435 }
 436
 437 static const sigops dsa_vrf = {
 438   dh_pubfetch, sizeof(dh_pub),
 439   dsa_vrfinit, dsa_vrfdoit, dsa_sigcheck, dsa_sigdestroy
 440 };
 441
 442 static const sigops bindsa_vrf = {
 443   dh_pubfetch, sizeof(dh_pub),
 444   bindsa_vrfinit, dsa_vrfdoit, dsa_sigcheck, dsa_sigdestroy
 445 };
 446
 447 static const sigops ecdsa_vrf = {
 448   ec_pubfetch, sizeof(ec_pub),
 449   ecdsa_vrfinit, dsa_vrfdoit, dsa_sigcheck, dsa_sigdestroy
 450 };
 451
 452 /* --- KCDSA and ECKCDSA --- */
 453
 454 static void kcdsa_privkey(dsa_sigctx *ds, mp *x)
 455   { ds->g.u = mp_modinv(MP_NEW, x, ds->g.g->r); }
 456
 457 static void kcdsa_sethash(dsa_sigctx *ds, const gchash *hc)
 458   { ds->s.h = gkcdsa_beginhash(&ds->g); }
 459
 460 static sig *kcdsa_siginit(key *k, void *kd, const gchash *hc)
 461 {
 462   dh_priv *dp = kd;
 463   dsa_sigctx *ds = dsa_doinit(k, &dp->dp, dp->y, hc, group_prime, "prime");
 464   kcdsa_privkey(ds, dp->x);
 465   kcdsa_sethash(ds, hc);
 466   return (&ds->s);
 467 }
 468
 469 static sig *binkcdsa_siginit(key *k, void *kd, const gchash *hc)
 470 {
 471   dh_priv *dp = kd;
 472   dsa_sigctx *ds = dsa_doinit(k, &dp->dp, dp->y, hc, group_binary, "binary");
 473   kcdsa_privkey(ds, dp->x);
 474   kcdsa_sethash(ds, hc);
 475   return (&ds->s);
 476 }
 477
 478 static sig *eckcdsa_siginit(key *k, void *kd, const gchash *hc)
 479 {
 480   ec_priv *ep = kd;
 481   dsa_sigctx *ds = ecdsa_doinit(k, ep->cstr, &ep->p, hc);
 482   kcdsa_privkey(ds, ep->x);
 483   kcdsa_sethash(ds, hc);
 484   return (&ds->s);
 485 }
 486
 487 static int kcdsa_sigdoit(sig *s, dstr *d)
 488 {
 489   dsa_sigctx *ds = (dsa_sigctx *)s;
 490   gkcdsa_sig ss = GKCDSA_SIG_INIT;
 491   size_t hsz = ds->g.h->hashsz, n = mp_octets(ds->g.g->r);
 492
 493   gkcdsa_sign(&ds->g, &ss, GH_DONE(ds->s.h, 0), 0);
 494   dstr_ensure(d, hsz + n);
 495   memcpy(d->buf, ss.r, hsz);
 496   mp_storeb(ss.s, d->buf + hsz, n);
 497   d->len += hsz + n;
 498   xfree(ss.r); mp_drop(ss.s);
 499   return (0);
 500 }
 501
 502 static const sigops kcdsa_sig = {
 503   dh_privfetch, sizeof(dh_priv),
 504   kcdsa_siginit, kcdsa_sigdoit, dsa_sigcheck, dsa_sigdestroy
 505 };
 506
 507 static const sigops binkcdsa_sig = {
 508   dh_privfetch, sizeof(dh_priv),
 509   binkcdsa_siginit, kcdsa_sigdoit, dsa_sigcheck, dsa_sigdestroy
 510 };
 511
 512 static const sigops eckcdsa_sig = {
 513   ec_privfetch, sizeof(ec_priv),
 514   eckcdsa_siginit, kcdsa_sigdoit, dsa_sigcheck, dsa_sigdestroy
 515 };
 516
 517 static sig *kcdsa_vrfinit(key *k, void *kd, const gchash *hc)
 518 {
 519   dh_pub *dp = kd;
 520   dsa_sigctx *ds = dsa_doinit(k, &dp->dp, dp->y, hc, group_prime, "prime");
 521   kcdsa_sethash(ds, hc);
 522   return (&ds->s);
 523 }
 524
 525 static sig *binkcdsa_vrfinit(key *k, void *kd, const gchash *hc)
 526 {
 527   dh_pub *dp = kd;
 528   dsa_sigctx *ds = dsa_doinit(k, &dp->dp, dp->y, hc, group_binary, "binary");
 529   kcdsa_sethash(ds, hc);
 530   return (&ds->s);
 531 }
 532
 533 static sig *eckcdsa_vrfinit(key *k, void *kd, const gchash *hc)
 534 {
 535   ec_pub *ep = kd;
 536   dsa_sigctx *ds = ecdsa_doinit(k, ep->cstr, &ep->p, hc);
 537   kcdsa_sethash(ds, hc);
 538   return (&ds->s);
 539 }
 540
 541 static int kcdsa_vrfdoit(sig *s, dstr *d)
 542 {
 543   dsa_sigctx *ds = (dsa_sigctx *)s;
 544   gkcdsa_sig ss;
 545   size_t hsz = ds->g.h->hashsz, n = d->len - hsz;
 546   int rc;
 547
 548   if (d->len < hsz)
 549     return (-1);
 550   ss.r = (octet *)d->buf;
 551   ss.s = mp_loadb(MP_NEW, d->buf + hsz, n);
 552   rc = gkcdsa_verify(&ds->g, &ss, GH_DONE(ds->s.h, 0));
 553   mp_drop(ss.s);
 554   return (rc);
 555 }
 556
 557 static const sigops kcdsa_vrf = {
 558   dh_pubfetch, sizeof(dh_pub),
 559   kcdsa_vrfinit, kcdsa_vrfdoit, dsa_sigcheck, dsa_sigdestroy
 560 };
 561
 562 static const sigops binkcdsa_vrf = {
 563   dh_pubfetch, sizeof(dh_pub),
 564   binkcdsa_vrfinit, kcdsa_vrfdoit, dsa_sigcheck, dsa_sigdestroy
 565 };
 566
 567 static const sigops eckcdsa_vrf = {
 568   ec_pubfetch, sizeof(ec_pub),
 569   eckcdsa_vrfinit, kcdsa_vrfdoit, dsa_sigcheck, dsa_sigdestroy
 570 };
 571
 572 /* --- The switch table --- */
 573
 574 const struct sigtab sigtab[] = {
 575   { "rsapkcs1", &rsap1_sig,     &rsap1_vrf,     &sha },
 576   { "rsapss",   &rsapss_sig,    &rsapss_vrf,    &sha },
 577   { "dsa",      &dsa_sig,       &dsa_vrf,       &sha },
 578   { "bindsa",   &bindsa_sig,    &bindsa_vrf,    &sha },
 579   { "ecdsa",    &ecdsa_sig,     &ecdsa_vrf,     &sha },
 580   { "kcdsa",    &kcdsa_sig,     &kcdsa_vrf,     &has160 },
 581   { "binkcdsa", &binkcdsa_sig,  &binkcdsa_vrf,  &has160 },
 582   { "eckcdsa",  &eckcdsa_sig,   &eckcdsa_vrf,   &has160 },
 583   { 0,          0,              0 }
 584 };
 585
 586 /* --- @getsig@ --- *
 587  *
 588  * Arguments:   @key *k@ = the key to load
 589  *              @const char *app@ = application name
 590  *              @int wantpriv@ = nonzero if we want to sign
 591  *
 592  * Returns:     A signature-making thing.
 593  *
 594  * Use:         Loads a key and starts hashing.
 595  */
 596
 597 sig *getsig(key *k, const char *app, int wantpriv)
 598 {
 599   const char *salg, *halg = 0;
 600   dstr d = DSTR_INIT;
 601   dstr t = DSTR_INIT;
 602   char *p = 0;
 603   const char *q;
 604   sig *s;
 605   size_t n;
 606   const struct sigtab *st;
 607   const sigops *so;
 608   const gchash *ch;
 609   void *kd;
 610   int e;
 611   key_packdef *kp;
 612
 613   /* --- Setup stuff --- */
 614
 615   key_fulltag(k, &t);
 616
 617   /* --- Get the signature algorithm --- *
 618    *
 619    * Take the attribute if it's there; otherwise use the key type.
 620    */
 621
 622   n = strlen(app);
 623   if ((q = key_getattr(0, k, "sig")) != 0) {
 624     dstr_puts(&d, q);
 625     p = d.buf;
 626   } else if (strncmp(k->type, app, n) == 0 && k->type[n] == '-') {
 627     dstr_puts(&d, k->type);
 628     p = d.buf + n + 1;
 629   } else
 630     die(EXIT_FAILURE, "no signature algorithm for key `%s'", t.buf);
 631
 632   /* --- Grab the hash algorithm --- *
 633    *
 634    * Grab it from the signature algorithm if it's there.  But override that
 635    * from the attribute.
 636    */
 637
 638   salg = p;
 639   if ((p = strchr(p, '/')) != 0) {
 640     *p++ = 0;
 641     halg = p;
 642   }
 643   if ((q = key_getattr(0, k, "hash")) != 0)
 644     halg = q;
 645
 646   /* --- Look up the algorithms in the table --- */
 647
 648   for (st = sigtab; st->name; st++) {
 649     if (strcmp(st->name, salg) == 0)
 650       goto s_found;
 651   }
 652   die(EXIT_FAILURE, "signature algorithm `%s' not found in key `%s'",
 653       salg, t.buf);
 654 s_found:;
 655   if (!halg)
 656     ch = st->ch;
 657   else {
 658     if ((ch = ghash_byname(halg)) == 0) {
 659       die(EXIT_FAILURE, "hash algorithm `%s' not found in key `%s'",
 660           halg, t.buf);
 661     }
 662   }
 663   so = wantpriv ? st->signops : st->verifyops;
 664
 665   /* --- Load the key --- */
 666
 667   kd = xmalloc(so->kdsz);
 668   kp = key_fetchinit(so->kf, 0, kd);
 669   if ((e = key_fetch(kp, k)) != 0)
 670     die(EXIT_FAILURE, "error fetching key `%s': %s", t.buf, key_strerror(e));
 671   s = so->init(k, kd, ch);
 672   if (!s->h)
 673     s->h = GH_INIT(ch);
 674   s->kp = kp;
 675   s->ops = so;
 676   s->kd = kd;
 677
 678   /* --- Free stuff up --- */
 679
 680   dstr_destroy(&d);
 681   dstr_destroy(&t);
 682   return (s);
 683 }
 684
 685 /* --- @freesig@ --- *
 686  *
 687  * Arguments:   @sig *s@ = signature-making thing
 688  *
 689  * Returns:     ---
 690  *
 691  * Use:         Frees up a signature-making thing
 692  */
 693
 694 void freesig(sig *s)
 695 {
 696   GH_DESTROY(s->h);
 697   key_fetchdone(s->kp);
 698   xfree(s->kd);
 699   s->ops->destroy(s);
 700 }
 701
 702 /*----- That's all, folks -------------------------------------------------*/