mdw@git.distorted.org.uk Git - tripe/blob - server/dh.c

   1 /* -*-c-*-
   2  *
   3  * Diffie--Hellman groups
   4  *
   5  * (c) 2017 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Trivial IP Encryption (TrIPE).
  11  *
  12  * TrIPE is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * TrIPE is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with TrIPE; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 /*----- Header files ------------------------------------------------------*/
  28
  29 #include "tripe.h"
  30
  31 /*----- Common utilities --------------------------------------------------*/
  32
  33 /* --- @KLOAD@ --- *
  34  *
  35  * Arguments:   @pre@ = prefix for defined functions
  36  *              @ty@, @TY@ = key type name (lower- and upper-case)
  37  *              @setgroup@ = code to initialize @kd->g@
  38  *              @setpriv@ = code to initialize @kd->kpriv@
  39  *              @setpub@ = code to initialize @kd->kpub@
  40  *
  41  * Use:         Generates the body of one of the (rather tedious) key loading
  42  *              functions.  See the description of @KEYTYPES@ below for the
  43  *              details.
  44  */
  45
  46 #define KLOAD_HALF(pre, ty, TY, which, WHICH, setgroup, setpriv, setpub) \
  47 static int pre##_ld##which(key_file *kf, key *k, key_data *d,           \
  48                            kdata *kd, dstr *t, dstr *e)                 \
  49 {                                                                       \
  50   key_packstruct kps[TY##_##WHICH##FETCHSZ];                            \
  51   key_packdef *kp;                                                      \
  52   ty##_##which p;                                                       \
  53   int rc;                                                               \
  54                                                                         \
  55   /* --- Initialize things we've not set up yet --- */                  \
  56                                                                         \
  57   kd->grp = 0; kd->k = 0; kd->K = 0;                                    \
  58                                                                         \
  59   /* --- Unpack the key --- */                                          \
  60                                                                         \
  61   kp = key_fetchinit(ty##_##which##fetch, kps, &p);                     \
  62   if ((rc = key_unpack(kp, d, t)) != 0) {                               \
  63     a_format(e, "unpack-failed", "%s", key_strerror(rc), A_END);        \
  64     goto fail;                                                          \
  65   }                                                                     \
  66                                                                         \
  67   /* --- Extract the pieces of the key --- */                           \
  68                                                                         \
  69   setgroup;                                                             \
  70   setpriv;                                                              \
  71   setpub;                                                               \
  72                                                                         \
  73   /* --- We win --- */                                                  \
  74                                                                         \
  75   rc = 0;                                                               \
  76   goto done;                                                            \
  77                                                                         \
  78 fail:                                                                   \
  79   if (kd->grp) {                                                        \
  80     if (kd->K) pre##_freege(kd->grp, kd->K);                            \
  81     if (kd->k) pre##_freesc(kd->grp, kd->k);                            \
  82     pre##_freegrp(kd->grp);                                             \
  83   }                                                                     \
  84   rc = -1;                                                              \
  85                                                                         \
  86 done:                                                                   \
  87   key_fetchdone(kp);                                                    \
  88   return (rc);                                                          \
  89 }
  90
  91 #define KLOAD(pre, ty, TY, setgroup, setpriv, setpub)                   \
  92 static void pre##_freegrp(dhgrp *); \
  93 static void pre##_freesc(const dhgrp *, dhsc *); \
  94 static void pre##_freege(const dhgrp *, dhge *); \
  95   KLOAD_HALF(pre, ty, TY, priv, PRIV, setgroup, setpriv, setpub)        \
  96   KLOAD_HALF(pre, ty, TY, pub, PUB, setgroup, { kd->k = 0; }, setpub)
  97
  98 #ifndef NTRACE
  99 static void setupstr(mptext_stringctx *sc)
 100   { sc->buf = (char *)buf_u; sc->lim = sc->buf + sizeof(buf_u); }
 101
 102 static const char *donestr(mptext_stringctx *sc)
 103   { *sc->buf = 0; return ((const char *)buf_u); }
 104
 105 static void addlitstr(const char *p, mptext_stringctx *sc)
 106   { mptext_stringops.put(p, strlen(p), sc); }
 107
 108 static void addmpstr(mp *x, int radix, mptext_stringctx *sc)
 109 {
 110   char b[12];
 111
 112   if (radix == 16) addlitstr("0x", sc);
 113   else if (radix == 8) addlitstr("0", sc);
 114   else if (radix != 10) { sprintf(b, "%d#", radix); addlitstr(b, sc); }
 115   mp_write(x, radix, &mptext_stringops, sc);
 116 }
 117
 118 static const char *mpstr(mp *x, int radix)
 119 {
 120   mptext_stringctx sc;
 121
 122   setupstr(&sc);
 123   addmpstr(x, radix, &sc);
 124   return (donestr(&sc));
 125 }
 126 #endif
 127
 128 /*----- Schnorr groups ----------------------------------------------------*/
 129
 130 typedef struct intdh_grp {
 131   dhgrp _g;
 132   mpmont mm;
 133   mp *q, *G;
 134   size_t gesz;
 135 } intdh_grp;
 136
 137 typedef struct intdh_sc { mp *x; } intdh_sc;
 138 typedef struct intdh_ge { mp *X; } intdh_ge;
 139
 140 static dhgrp *intdh_mkgroup(const dh_param *dp)
 141 {
 142   intdh_grp *g = CREATE(intdh_grp);
 143   g->_g.scsz = mp_octets(dp->q);
 144   g->gesz = mp_octets(dp->p);
 145   mpmont_create(&g->mm, dp->p);
 146   g->q = MP_COPY(dp->q);
 147   g->G = mpmont_mul(&g->mm, MP_NEW, dp->g, g->mm.r2);
 148   return (&g->_g);
 149 }
 150
 151 static dhsc *intdh_mptosc(const dhgrp *gg, mp *z)
 152 {
 153   const intdh_grp *g = (const intdh_grp *)gg;
 154   intdh_sc *x = CREATE(intdh_sc);
 155   x->x = MP_NEW; mp_div(0, &x->x, z, g->q);
 156   return ((dhsc *)x);
 157 }
 158
 159 static dhge *intdh_mptoge(const dhgrp *gg, mp *z)
 160 {
 161   const intdh_grp *g = (const intdh_grp *)gg;
 162   intdh_ge *Y = CREATE(intdh_ge);
 163   mp *t = MP_NEW; mp_div(0, &t, z, g->mm.m);
 164   Y->X = mpmont_mul(&g->mm, t, t, g->mm.r2);
 165   return ((dhge *)Y);
 166 }
 167
 168 KLOAD(intdh, dh, DH,
 169       { kd->grp = intdh_mkgroup(&p.dp); },
 170       { kd->k = intdh_mptosc(kd->grp, p.x); },
 171       { kd->K = intdh_mptoge(kd->grp, p.y); })
 172
 173 static const char *intdh_checkgrp(const dhgrp *gg)
 174 {
 175   const intdh_grp *g = (const intdh_grp *)gg;
 176   mp *t = MP_NEW;
 177
 178   if (!pgen_primep(g->mm.m, &rand_global)) return ("p is not prime");
 179   if (!pgen_primep(g->q, &rand_global)) return ("q is not prime");
 180   mp_div(0, &t, g->mm.m, g->q);
 181   if (!MP_EQ(t, MP_ONE)) return ("q is not a subgroup order");
 182   t = mpmont_expr(&g->mm, t, g->G, g->q);
 183   if (!MP_EQ(t, g->mm.r)) return ("g not in the subgroup");
 184   return (0);
 185 }
 186
 187 static void intdh_grpinfo(const dhgrp *gg, admin *adm)
 188 {
 189   const intdh_grp *g = (const intdh_grp *)gg;
 190   a_info(adm,
 191          "kx-group=prime",
 192          "kx-group-order-bits=%lu", (unsigned long)mp_bits(g->q),
 193          "kx-group-elt-bits=%lu", (unsigned long)mp_bits(g->mm.m),
 194          A_END);
 195 }
 196
 197 #ifndef NTRACE
 198 static void intdh_tracegrp(const dhgrp *gg)
 199 {
 200   const intdh_grp *g = (const intdh_grp *)gg;
 201   mp *t = MP_NEW;
 202   trace(T_CRYPTO, "crypto: group type `dh'");
 203   trace(T_CRYPTO, "crypto: p = %s", mpstr(g->mm.m, 10));
 204   trace(T_CRYPTO, "crypto: q = %s", mpstr(g->q, 10));
 205   t = mpmont_reduce(&g->mm, t, g->G);
 206   trace(T_CRYPTO, "crypto: g = %s", mpstr(t, 10));
 207   MP_DROP(t);
 208 }
 209 #endif
 210
 211 static int intdh_samegrpp(const dhgrp *gg, const dhgrp *hh)
 212 {
 213   const intdh_grp *g = (const intdh_grp *)gg, *h = (const intdh_grp *)hh;
 214   return (MP_EQ(g->mm.m, h->mm.m) && MP_EQ(g->q, h->q) && MP_EQ(g->G, h->G));
 215 }
 216
 217 static void intdh_freegrp(dhgrp *gg)
 218 {
 219   intdh_grp *g = (intdh_grp *)gg;
 220   mpmont_destroy(&g->mm); MP_DROP(g->q); MP_DROP(g->G);
 221   DESTROY(g);
 222 }
 223
 224 static dhsc *intdh_ldsc(const dhgrp *gg, const void *p, size_t sz)
 225 { const intdh_grp *g = (const intdh_grp *)gg;
 226   intdh_sc *x = CREATE(intdh_sc);
 227   mp *t = mp_loadb(MP_NEW, p, sz);
 228   mp_div(0, &t, t, g->q); x->x = t;
 229   return ((dhsc *)x);
 230 }
 231
 232 static int intdh_stsc(const dhgrp *gg, void *p, size_t sz, const dhsc *xx)
 233 {
 234   const intdh_sc *x = (const intdh_sc *)xx;
 235   mp_storeb(x->x, p, sz);
 236   return (0);
 237 }
 238
 239 static dhsc *intdh_randsc(const dhgrp *gg)
 240 {
 241   const intdh_grp *g = (const intdh_grp *)gg;
 242   intdh_sc *x = CREATE(intdh_sc);
 243   x->x = mprand_range(MP_NEW, g->q, &rand_global, 0);
 244   return ((dhsc *)x);
 245 }
 246
 247 #ifndef NTRACE
 248 static const char *intdh_scstr(const dhgrp *gg, const dhsc *xx)
 249   { const intdh_sc *x = (const intdh_sc *)xx; return (mpstr(x->x, 10)); }
 250 #endif
 251
 252 static void intdh_freesc(const dhgrp *gg, dhsc *xx)
 253 {
 254   intdh_sc *x = (intdh_sc *)xx;
 255   MP_DROP(x->x); DESTROY(x);
 256 }
 257
 258 static dhge *intdh_ldge(const dhgrp *gg, buf *b, int fmt)
 259 {
 260   const intdh_grp *g = (const intdh_grp *)gg;
 261   intdh_ge *Y;
 262   mp *t;
 263   const octet *p;
 264
 265   switch (fmt) {
 266     case DHFMT_VAR: case DHFMT_HASH:
 267       if ((t = buf_getmp(b)) == 0) return (0);
 268       break;
 269     case DHFMT_STD:
 270       if ((p = buf_get(b, g->gesz)) == 0) return (0);
 271       t = mp_loadb(MP_NEW, p, g->gesz);
 272       break;
 273     default:
 274       abort();
 275   }
 276   Y = CREATE(intdh_ge);
 277   mp_div(0, &t, t, g->mm.m);
 278   Y->X = mpmont_mul(&g->mm, t, t, g->mm.r2);
 279   return ((dhge *)Y);
 280 }
 281
 282 static int intdh_stge(const dhgrp *gg, buf *b, const dhge *YY, int fmt)
 283 {
 284   const intdh_grp *g = (const intdh_grp *)gg;
 285   const intdh_ge *Y = (const intdh_ge *)YY;
 286   octet *p;
 287   mp *t;
 288   int rc;
 289
 290   t = mpmont_reduce(&g->mm, MP_NEW, Y->X);
 291   switch (fmt) {
 292     case DHFMT_VAR: case DHFMT_HASH:
 293       rc = buf_putmp(b, t);
 294       break;
 295     case DHFMT_STD:
 296       if ((p = buf_get(b, g->gesz)) == 0)
 297         rc = -1;
 298       else {
 299         mp_storeb(t, p, g->gesz);
 300         rc = 0;
 301       }
 302       break;
 303     default:
 304       abort();
 305   }
 306   MP_DROP(t);
 307   return (rc);
 308 }
 309
 310 static int intdh_checkge(const dhgrp *gg, const dhge *YY)
 311 {
 312   const intdh_grp *g = (const intdh_grp *)gg;
 313   const intdh_ge *Y = (const intdh_ge *)YY;
 314   mp *T;
 315   int rc = 0;
 316
 317   if (MP_EQ(Y->X, g->mm.r)) rc = -1;
 318   T = mpmont_expr(&g->mm, MP_NEW, Y->X, g->q);
 319   if (!MP_EQ(T, g->mm.r)) rc = -1;
 320   MP_DROP(T);
 321   return (rc);
 322 }
 323
 324 static int intdh_eq(const dhgrp *gg, const dhge *YY, const dhge *ZZ)
 325 {
 326   const intdh_ge *Y = (const intdh_ge *)YY, *Z = (const intdh_ge *)ZZ;
 327   return (MP_EQ(Y->X, Z->X));
 328 }
 329
 330 static dhge *intdh_mul(const dhgrp *gg, const dhsc *xx, const dhge *YY)
 331 {
 332   const intdh_grp *g = (const intdh_grp *)gg;
 333   const intdh_sc *x = (const intdh_sc *)xx;
 334   const intdh_ge *Y = (const intdh_ge *)YY;
 335   intdh_ge *Z = CREATE(intdh_ge);
 336
 337   Z->X = mpmont_expr(&g->mm, MP_NEW, Y ? Y->X : g->G, x->x);
 338   return ((dhge *)Z);
 339 }
 340
 341 #ifndef NTRACE
 342 static const char *intdh_gestr(const dhgrp *gg, const dhge *YY)
 343 {
 344   const intdh_grp *g = (const intdh_grp *)gg;
 345   const intdh_ge *Y = (const intdh_ge *)YY;
 346   mp *t = mpmont_reduce(&g->mm, MP_NEW, Y->X);
 347   const char *p = mpstr(t, 10);
 348   MP_DROP(t);
 349   return (p);
 350 }
 351 #endif
 352
 353 static void intdh_freege(const dhgrp *gg, dhge *YY)
 354   { intdh_ge *Y = (intdh_ge *)YY; MP_DROP(Y->X); DESTROY(Y); }
 355
 356 /*----- Elliptic curve groups ---------------------------------------------*/
 357
 358 typedef struct ecdh_grp {
 359   dhgrp _g;
 360   ec_info ei;
 361   ec P;
 362 } ecdh_grp;
 363
 364 typedef struct ecdh_sc { mp *x; } ecdh_sc;
 365 typedef struct ecdh_ge { ec Q; } ecdh_ge;
 366
 367 static dhgrp *ecdh_mkgroup(const char *cstr, dstr *e)
 368 {
 369   ecdh_grp *g;
 370   ec_info ei;
 371   const char *err;
 372
 373   if ((err = ec_getinfo(&ei, cstr)) != 0) {
 374     a_format(e, "decode-failed", "%s", err, A_END);
 375     return (0);
 376   }
 377   g = CREATE(ecdh_grp);
 378   g->ei = ei;
 379   EC_CREATE(&g->P); EC_IN(g->ei.c, &g->P, &g->ei.g);
 380   g->_g.scsz = mp_octets(g->ei.r);
 381   return (&g->_g);
 382 }
 383
 384 static dhsc *ecdh_mptosc(const dhgrp *gg, mp *z)
 385 {
 386   const ecdh_grp *g = (const ecdh_grp *)gg;
 387   ecdh_sc *x = CREATE(ecdh_sc);
 388   x->x = MP_NEW; mp_div(0, &x->x, z, g->ei.r);
 389   return ((dhsc *)x);
 390 }
 391
 392 static dhge *ecdh_ectoge(const dhgrp *gg, ec *Q)
 393 {
 394   const ecdh_grp *g = (const ecdh_grp *)gg;
 395   ecdh_ge *Y = CREATE(ecdh_ge); EC_CREATE(&Y->Q);
 396   EC_IN(g->ei.c, &Y->Q, Q);
 397   if (EC_CHECK(g->ei.c, &Y->Q))
 398     { EC_DESTROY(&Y->Q); DESTROY(Y); return (0); }
 399   return ((dhge *)Y);
 400 }
 401
 402 KLOAD(ecdh, ec, EC,
 403       { if ((kd->grp = ecdh_mkgroup(p.cstr, e)) == 0) goto fail; },
 404       { kd->k = ecdh_mptosc(kd->grp, p.x); },
 405       { if ((kd->K = ecdh_ectoge(kd->grp, &p.p)) == 0) {
 406           a_format(e, "bad-public-vector", A_END);
 407           goto fail;
 408         }
 409       })
 410
 411 static const char *ecdh_checkgrp(const dhgrp *gg)
 412 {
 413   const ecdh_grp *g = (const ecdh_grp *)gg;
 414   return (ec_checkinfo(&g->ei, &rand_global));
 415 }
 416
 417 static void ecdh_grpinfo(const dhgrp *gg, admin *adm)
 418 {
 419   const ecdh_grp *g = (const ecdh_grp *)gg;
 420   a_info(adm,
 421          "kx-group=ec",
 422          "kx-group-order-bits=%lu", (unsigned long)mp_bits(g->ei.r),
 423          "kx-group-elt-bits=%lu", (unsigned long)2*g->ei.c->f->nbits,
 424          A_END);
 425 }
 426
 427 #ifndef NTRACE
 428 static void addfestr(field *f, mp *x, mptext_stringctx *sc)
 429   { addmpstr(x, F_TYPE(f) == FTY_PRIME ? 10 : 16, sc); }
 430
 431 static void addintfestr(field *f, mp *x, mptext_stringctx *sc)
 432   { mp *t = F_OUT(f, MP_NEW, x); addfestr(f, x, sc); MP_DROP(t); }
 433
 434 static const char *intfestr(field *f, mp *x)
 435 {
 436   mptext_stringctx sc;
 437   setupstr(&sc);
 438   addintfestr(f, x, &sc);
 439   return (donestr(&sc));
 440 }
 441
 442 static void ecdh_tracegrp(const dhgrp *gg)
 443 {
 444   const ecdh_grp *g = (const ecdh_grp *)gg;
 445   const ec_curve *c = g->ei.c;
 446   field *f = c->f;
 447
 448   trace(T_CRYPTO, "crypto: group type `ec'");
 449   switch (F_TYPE(f)) {
 450     case FTY_PRIME:
 451       trace(T_CRYPTO, "crypto: prime field `%s'", F_NAME(f));
 452       trace(T_CRYPTO, "crypto: p = %s", mpstr(f->q, 10));
 453       break;
 454     case FTY_BINARY:
 455       trace(T_CRYPTO, "crypto: binary field `%s'", F_NAME(f));
 456       trace(T_CRYPTO, "crypto: degree = %lu", f->nbits - 1);
 457       break;
 458     default:
 459       trace(T_CRYPTO, "crypto: unknown field type! `%s'", F_NAME(f));
 460       break;
 461   }
 462   trace(T_CRYPTO, "crypto: curve type `%s'", EC_NAME(c));
 463   trace(T_CRYPTO, "crypto: curve a = %s", intfestr(f, c->a));
 464   trace(T_CRYPTO, "crypto: curve b = %s", intfestr(f, c->b));
 465   trace(T_CRYPTO, "crypto: n = %s", mpstr(g->ei.r, 10));
 466   trace(T_CRYPTO, "crypto: h = %s", mpstr(g->ei.h, 10));
 467 }
 468 #endif
 469
 470 static int ecdh_samegrpp(const dhgrp *gg, const dhgrp *hh)
 471 {
 472   const ecdh_grp *g = (const ecdh_grp *)gg, *h = (const ecdh_grp *)hh;
 473   return (ec_sameinfop(&g->ei, &h->ei));
 474 }
 475
 476 static void ecdh_freegrp(dhgrp *gg)
 477 {
 478   ecdh_grp *g = (ecdh_grp *)gg;
 479   EC_DESTROY(&g->P); ec_freeinfo(&g->ei);
 480   DESTROY(g);
 481 }
 482
 483 static dhsc *ecdh_ldsc(const dhgrp *gg, const void *p, size_t sz)
 484 {
 485   const ecdh_grp *g = (const ecdh_grp *)gg;
 486   ecdh_sc *x = CREATE(ecdh_sc);
 487   mp *t = mp_loadb(MP_NEW, p, sz);
 488   mp_div(0, &t, t, g->ei.r); x->x = t;
 489   return ((dhsc *)x);
 490 }
 491
 492 static int ecdh_stsc(const dhgrp *gg, void *p, size_t sz, const dhsc *xx)
 493 {
 494   const ecdh_sc *x = (const ecdh_sc *)xx;
 495   mp_storeb(x->x, p, sz);
 496   return (0);
 497 }
 498
 499 static dhsc *ecdh_randsc(const dhgrp *gg)
 500 {
 501   const ecdh_grp *g = (const ecdh_grp *)gg;
 502   ecdh_sc *x = CREATE(ecdh_sc);
 503   x->x = mprand_range(MP_NEW, g->ei.r, &rand_global, 0);
 504   return ((dhsc *)x);
 505 }
 506
 507 #ifndef NTRACE
 508 static const char *ecdh_scstr(const dhgrp *gg, const dhsc *xx)
 509 {
 510   const ecdh_sc *x = (const ecdh_sc *)xx;
 511   return (mpstr(x->x, 10));
 512 }
 513 #endif
 514
 515 static void ecdh_freesc(const dhgrp *gg, dhsc *xx)
 516   { ecdh_sc *x = (ecdh_sc *)xx; MP_DROP(x->x); DESTROY(x); }
 517
 518 static dhge *ecdh_ldge(const dhgrp *gg, buf *b, int fmt)
 519 {
 520   const ecdh_grp *g = (const ecdh_grp *)gg;
 521   ecdh_ge *Y;
 522   ec T = EC_INIT;
 523
 524   switch (fmt) {
 525     case DHFMT_VAR: case DHFMT_HASH: if (buf_getec(b, &T)) return (0); break;
 526     case DHFMT_STD: if (ec_getraw(g->ei.c, b, &T)) return (0); break;
 527     default:
 528       abort();
 529   }
 530   EC_IN(g->ei.c, &T, &T);
 531   Y = CREATE(ecdh_ge); Y->Q = T;
 532   return ((dhge *)Y);
 533 }
 534
 535 static int ecdh_stge(const dhgrp *gg, buf *b, const dhge *YY, int fmt)
 536 {
 537   const ecdh_grp *g = (const ecdh_grp *)gg;
 538   const ecdh_ge *Y = (const ecdh_ge *)YY;
 539   ec T = EC_INIT;
 540   int rc;
 541
 542   EC_OUT(g->ei.c, &T, &Y->Q);
 543   switch (fmt) {
 544     case DHFMT_VAR: case DHFMT_HASH: rc = buf_putec(b, &T); break;
 545     case DHFMT_STD: rc = ec_putraw(g->ei.c, b, &T); break;
 546     default: abort();
 547   }
 548   EC_DESTROY(&T);
 549   return (rc);
 550 }
 551
 552 static int ecdh_checkge(const dhgrp *gg, const dhge *YY)
 553 {
 554   const ecdh_grp *g = (const ecdh_grp *)gg;
 555   const ecdh_ge *Y = (const ecdh_ge *)YY;
 556   ec T = EC_INIT;
 557   int rc = 0;
 558
 559   if (EC_ATINF(&Y->Q)) rc = -1;
 560   ec_imul(g->ei.c, &T, &Y->Q, g->ei.r);
 561   if (!EC_ATINF(&T)) rc = -1;
 562   EC_DESTROY(&T);
 563   return (rc);
 564 }
 565
 566 static int ecdh_eq(const dhgrp *gg, const dhge *YY, const dhge *ZZ)
 567 {
 568   const ecdh_grp *g = (const ecdh_grp *)gg;
 569   const ecdh_ge *Y = (const ecdh_ge *)YY, *Z = (const ecdh_ge *)ZZ;
 570   ec T = EC_INIT, U = EC_INIT; int rc;
 571   EC_FIX(g->ei.c, &T, &Y->Q); EC_FIX(g->ei.c, &U, &Z->Q);
 572   rc = EC_EQ(&T, &U);
 573   EC_DESTROY(&T); EC_DESTROY(&U);
 574   return (rc);
 575 }
 576
 577 static dhge *ecdh_mul(const dhgrp *gg, const dhsc *xx, const dhge *YY)
 578 {
 579   const ecdh_grp *g = (const ecdh_grp *)gg;
 580   const ecdh_sc *x = (const ecdh_sc *)xx;
 581   const ecdh_ge *Y = (const ecdh_ge *)YY;
 582   ecdh_ge *Z = CREATE(ecdh_ge); EC_CREATE(&Z->Q);
 583
 584   ec_imul(g->ei.c, &Z->Q, Y ? &Y->Q : &g->P, x->x);
 585   return ((dhge *)Z);
 586 }
 587
 588 #ifndef NTRACE
 589 static const char *ecdh_gestr(const dhgrp *gg, const dhge *YY)
 590 {
 591   const ecdh_grp *g = (const ecdh_grp *)gg;
 592   const ecdh_ge *Y = (const ecdh_ge *)YY;
 593   ec T = EC_INIT;
 594   field *f = g->ei.c->f;
 595   mptext_stringctx sc;
 596
 597   if (EC_ATINF(&Y->Q)) return ("inf");
 598   setupstr(&sc);
 599   EC_OUT(g->ei.c, &T, &Y->Q);
 600   addfestr(f, T.x, &sc);
 601   addlitstr(", ", &sc);
 602   addfestr(f, T.y, &sc);
 603   EC_DESTROY(&T);
 604   return (donestr(&sc));
 605 }
 606 #endif
 607
 608 static void ecdh_freege(const dhgrp *gg, dhge *YY)
 609   { ecdh_ge *Y = (ecdh_ge *)YY; EC_DESTROY(&Y->Q); DESTROY(Y); }
 610
 611 /*----- Diffie--Hellman group table ---------------------------------------*/
 612
 613 const dhops dhtab[] = {
 614
 615 #define COMMA ,
 616
 617 #define DH(name, pre)                                                   \
 618   { name, pre##_ldpriv, pre##_ldpub, pre##_checkgrp,                    \
 619     pre##_grpinfo, T( pre##_tracegrp COMMA ) pre##_samegrpp,            \
 620     pre##_freegrp,                                                      \
 621     pre##_ldsc, pre##_stsc, pre##_randsc, T( pre##_scstr COMMA )        \
 622     pre##_freesc,                                                       \
 623     pre##_ldge, pre##_stge, pre##_checkge, pre##_eq, pre##_mul,         \
 624     T( pre##_gestr COMMA ) pre##_freege },                              \
 625
 626   DH("dh", intdh)
 627   DH("ec", ecdh)
 628
 629 #undef DH
 630
 631   { 0 }
 632 };
 633
 634 /*----- That's all, folks -------------------------------------------------*/