| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id$ |
| 4 | * |
| 5 | * Catcrypt key-encapsulation |
| 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 | #define _FILE_OFFSET_BITS 64 |
| 33 | |
| 34 | #include <stdlib.h> |
| 35 | |
| 36 | #include <mLib/alloc.h> |
| 37 | #include <mLib/dstr.h> |
| 38 | #include <mLib/report.h> |
| 39 | #include <mLib/sub.h> |
| 40 | |
| 41 | #include "mprand.h" |
| 42 | #include "rand.h" |
| 43 | |
| 44 | #include "ec.h" |
| 45 | #include "ec-keys.h" |
| 46 | #include "dh.h" |
| 47 | #include "rsa.h" |
| 48 | |
| 49 | #include "rmd160.h" |
| 50 | #include "blowfish-cbc.h" |
| 51 | |
| 52 | #include "cc.h" |
| 53 | |
| 54 | /*----- Key encapsulation -------------------------------------------------*/ |
| 55 | |
| 56 | /* --- RSA --- */ |
| 57 | |
| 58 | typedef struct rsa_encctx { |
| 59 | kem k; |
| 60 | rsa_pubctx rp; |
| 61 | } rsa_encctx; |
| 62 | |
| 63 | static kem *rsa_encinit(key *k, void *kd) |
| 64 | { |
| 65 | rsa_encctx *re = CREATE(rsa_encctx); |
| 66 | rsa_pubcreate(&re->rp, kd); |
| 67 | return (&re->k); |
| 68 | } |
| 69 | |
| 70 | static int rsa_encdoit(kem *k, dstr *d, ghash *h) |
| 71 | { |
| 72 | rsa_encctx *re = (rsa_encctx *)k; |
| 73 | mp *x = mprand_range(MP_NEW, re->rp.rp->n, &rand_global, 0); |
| 74 | mp *y = rsa_pubop(&re->rp, MP_NEW, x); |
| 75 | size_t n = mp_octets(re->rp.rp->n); |
| 76 | dstr_ensure(d, n); |
| 77 | mp_storeb(x, d->buf, n); |
| 78 | GH_HASH(h, d->buf, n); |
| 79 | mp_storeb(y, d->buf, n); |
| 80 | d->len += n; |
| 81 | mp_drop(x); |
| 82 | mp_drop(y); |
| 83 | return (0); |
| 84 | } |
| 85 | |
| 86 | static const char *rsa_lengthcheck(mp *n) |
| 87 | { |
| 88 | if (mp_bits(n) < 1020) return ("key too short"); |
| 89 | return (0); |
| 90 | } |
| 91 | |
| 92 | static const char *rsa_enccheck(kem *k) |
| 93 | { |
| 94 | rsa_encctx *re = (rsa_encctx *)k; |
| 95 | const char *e; |
| 96 | if ((e = rsa_lengthcheck(re->rp.rp->n)) != 0) return (e); |
| 97 | return (0); |
| 98 | } |
| 99 | |
| 100 | static void rsa_encdestroy(kem *k) |
| 101 | { |
| 102 | rsa_encctx *re = (rsa_encctx *)k; |
| 103 | rsa_pubdestroy(&re->rp); |
| 104 | DESTROY(re); |
| 105 | } |
| 106 | |
| 107 | static const kemops rsa_encops = { |
| 108 | rsa_pubfetch, sizeof(rsa_pub), |
| 109 | rsa_encinit, rsa_encdoit, rsa_enccheck, rsa_encdestroy |
| 110 | }; |
| 111 | |
| 112 | typedef struct rsa_decctx { |
| 113 | kem k; |
| 114 | rsa_privctx rp; |
| 115 | } rsa_decctx; |
| 116 | |
| 117 | static kem *rsa_decinit(key *k, void *kd) |
| 118 | { |
| 119 | rsa_decctx *rd = CREATE(rsa_decctx); |
| 120 | rsa_privcreate(&rd->rp, kd, &rand_global); |
| 121 | return (&rd->k); |
| 122 | } |
| 123 | |
| 124 | static int rsa_decdoit(kem *k, dstr *d, ghash *h) |
| 125 | { |
| 126 | rsa_decctx *rd = (rsa_decctx *)k; |
| 127 | mp *x = mp_loadb(MP_NEW, d->buf, d->len); |
| 128 | size_t n; |
| 129 | char *p; |
| 130 | |
| 131 | if (MP_CMP(x, >=, rd->rp.rp->n)) { |
| 132 | mp_drop(x); |
| 133 | return (-1); |
| 134 | } |
| 135 | n = mp_octets(rd->rp.rp->n); |
| 136 | p = xmalloc(n); |
| 137 | x = rsa_privop(&rd->rp, x, x); |
| 138 | mp_storeb(x, p, n); |
| 139 | GH_HASH(h, p, n); |
| 140 | mp_drop(x); |
| 141 | xfree(p); |
| 142 | return (0); |
| 143 | } |
| 144 | |
| 145 | static const char *rsa_deccheck(kem *k) |
| 146 | { |
| 147 | rsa_decctx *rd = (rsa_decctx *)k; |
| 148 | const char *e; |
| 149 | if ((e = rsa_lengthcheck(rd->rp.rp->n)) != 0) return (e); |
| 150 | return (0); |
| 151 | } |
| 152 | |
| 153 | static void rsa_decdestroy(kem *k) |
| 154 | { |
| 155 | rsa_decctx *rd = (rsa_decctx *)k; |
| 156 | rsa_privdestroy(&rd->rp); |
| 157 | DESTROY(rd); |
| 158 | } |
| 159 | |
| 160 | static const kemops rsa_decops = { |
| 161 | rsa_privfetch, sizeof(rsa_priv), |
| 162 | rsa_decinit, rsa_decdoit, rsa_deccheck, rsa_decdestroy |
| 163 | }; |
| 164 | |
| 165 | /* --- DH and EC --- */ |
| 166 | |
| 167 | typedef struct dh_encctx { |
| 168 | kem k; |
| 169 | group *g; |
| 170 | mp *x; |
| 171 | ge *y; |
| 172 | } dh_encctx; |
| 173 | |
| 174 | static dh_encctx *dh_doinit(key *k, const gprime_param *gp, mp *y, |
| 175 | group *(*makegroup)(const gprime_param *), |
| 176 | const char *what) |
| 177 | { |
| 178 | dh_encctx *de = CREATE(dh_encctx); |
| 179 | dstr t = DSTR_INIT; |
| 180 | |
| 181 | key_fulltag(k, &t); |
| 182 | if ((de->g = makegroup(gp)) == 0) |
| 183 | die(EXIT_FAILURE, "bad %s group in key `%s'", what, t.buf); |
| 184 | de->x = MP_NEW; |
| 185 | de->y = G_CREATE(de->g); |
| 186 | if (G_FROMINT(de->g, de->y, y)) |
| 187 | die(EXIT_FAILURE, "bad public key `%s'", t.buf); |
| 188 | dstr_destroy(&t); |
| 189 | return (de); |
| 190 | } |
| 191 | |
| 192 | static dh_encctx *ec_doinit(key *k, const char *cstr, const ec *y) |
| 193 | { |
| 194 | dh_encctx *de = CREATE(dh_encctx); |
| 195 | ec_info ei; |
| 196 | const char *e; |
| 197 | dstr t = DSTR_INIT; |
| 198 | |
| 199 | key_fulltag(k, &t); |
| 200 | if ((e = ec_getinfo(&ei, cstr)) != 0 || |
| 201 | (de->g = group_ec(&ei)) == 0) |
| 202 | die(EXIT_FAILURE, "bad elliptic curve spec in key `%s': %s", t.buf, e); |
| 203 | de->x = MP_NEW; |
| 204 | de->y = G_CREATE(de->g); |
| 205 | if (G_FROMEC(de->g, de->y, y)) |
| 206 | die(EXIT_FAILURE, "bad public curve point `%s'", t.buf); |
| 207 | dstr_destroy(&t); |
| 208 | return (de); |
| 209 | } |
| 210 | |
| 211 | static kem *dh_encinit(key *k, void *kd) |
| 212 | { |
| 213 | dh_pub *dp = kd; |
| 214 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y, group_prime, "prime"); |
| 215 | return (&de->k); |
| 216 | } |
| 217 | |
| 218 | static kem *bindh_encinit(key *k, void *kd) |
| 219 | { |
| 220 | dh_pub *dp = kd; |
| 221 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y, group_binary, "binary"); |
| 222 | return (&de->k); |
| 223 | } |
| 224 | |
| 225 | static kem *ec_encinit(key *k, void *kd) |
| 226 | { |
| 227 | ec_pub *ep = kd; |
| 228 | dh_encctx *de = ec_doinit(k, ep->cstr, &ep->p); |
| 229 | return (&de->k); |
| 230 | } |
| 231 | |
| 232 | static int dh_encdoit(kem *k, dstr *d, ghash *h) |
| 233 | { |
| 234 | dh_encctx *de = (dh_encctx *)k; |
| 235 | mp *r = mprand_range(MP_NEW, de->g->r, &rand_global, 0); |
| 236 | ge *x = G_CREATE(de->g); |
| 237 | ge *y = G_CREATE(de->g); |
| 238 | size_t n = de->g->noctets; |
| 239 | buf b; |
| 240 | |
| 241 | G_EXP(de->g, x, de->g->g, r); |
| 242 | G_EXP(de->g, y, de->y, r); |
| 243 | dstr_ensure(d, n); |
| 244 | buf_init(&b, d->buf, n); |
| 245 | G_TORAW(de->g, &b, y); |
| 246 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
| 247 | buf_init(&b, d->buf, n); |
| 248 | G_TORAW(de->g, &b, x); |
| 249 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
| 250 | d->len += BLEN(&b); |
| 251 | mp_drop(r); |
| 252 | G_DESTROY(de->g, x); |
| 253 | G_DESTROY(de->g, y); |
| 254 | return (0); |
| 255 | } |
| 256 | |
| 257 | static const char *dh_enccheck(kem *k) |
| 258 | { |
| 259 | dh_encctx *de = (dh_encctx *)k; |
| 260 | const char *e; |
| 261 | if ((e = G_CHECK(de->g, &rand_global)) != 0) |
| 262 | return (0); |
| 263 | if (group_check(de->g, de->y)) |
| 264 | return ("public key not in subgroup"); |
| 265 | return (0); |
| 266 | } |
| 267 | |
| 268 | static void dh_encdestroy(kem *k) |
| 269 | { |
| 270 | dh_encctx *de = (dh_encctx *)k; |
| 271 | G_DESTROY(de->g, de->y); |
| 272 | mp_drop(de->x); |
| 273 | G_DESTROYGROUP(de->g); |
| 274 | DESTROY(de); |
| 275 | } |
| 276 | |
| 277 | static const kemops dh_encops = { |
| 278 | dh_pubfetch, sizeof(dh_pub), |
| 279 | dh_encinit, dh_encdoit, dh_enccheck, dh_encdestroy |
| 280 | }; |
| 281 | |
| 282 | static const kemops bindh_encops = { |
| 283 | dh_pubfetch, sizeof(dh_pub), |
| 284 | bindh_encinit, dh_encdoit, dh_enccheck, dh_encdestroy |
| 285 | }; |
| 286 | |
| 287 | static const kemops ec_encops = { |
| 288 | ec_pubfetch, sizeof(ec_pub), |
| 289 | ec_encinit, dh_encdoit, dh_enccheck, dh_encdestroy |
| 290 | }; |
| 291 | |
| 292 | static kem *dh_decinit(key *k, void *kd) |
| 293 | { |
| 294 | dh_priv *dp = kd; |
| 295 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y, group_prime, "prime"); |
| 296 | de->x = MP_COPY(dp->x); |
| 297 | return (&de->k); |
| 298 | } |
| 299 | |
| 300 | static kem *bindh_decinit(key *k, void *kd) |
| 301 | { |
| 302 | dh_priv *dp = kd; |
| 303 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y, group_binary, "binary"); |
| 304 | de->x = MP_COPY(dp->x); |
| 305 | return (&de->k); |
| 306 | } |
| 307 | |
| 308 | static kem *ec_decinit(key *k, void *kd) |
| 309 | { |
| 310 | ec_priv *ep = kd; |
| 311 | dh_encctx *de = ec_doinit(k, ep->cstr, &ep->p); |
| 312 | de->x = MP_COPY(ep->x); |
| 313 | return (&de->k); |
| 314 | } |
| 315 | |
| 316 | static int dh_decdoit(kem *k, dstr *d, ghash *h) |
| 317 | { |
| 318 | dh_encctx *de = (dh_encctx *)k; |
| 319 | ge *x = G_CREATE(de->g); |
| 320 | size_t n = de->g->noctets; |
| 321 | void *p = xmalloc(n); |
| 322 | buf b; |
| 323 | int rc = -1; |
| 324 | |
| 325 | buf_init(&b, d->buf, d->len); |
| 326 | if (G_FROMRAW(de->g, &b, x) || group_check(de->g, x)) |
| 327 | goto done; |
| 328 | G_EXP(de->g, x, x, de->x); |
| 329 | buf_init(&b, p, n); |
| 330 | G_TORAW(de->g, &b, x); |
| 331 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
| 332 | GH_HASH(h, d->buf, d->len); |
| 333 | rc = 0; |
| 334 | done: |
| 335 | G_DESTROY(de->g, x); |
| 336 | xfree(p); |
| 337 | return (rc); |
| 338 | } |
| 339 | |
| 340 | static const kemops dh_decops = { |
| 341 | dh_privfetch, sizeof(dh_priv), |
| 342 | dh_decinit, dh_decdoit, dh_enccheck, dh_encdestroy |
| 343 | }; |
| 344 | |
| 345 | static const kemops bindh_decops = { |
| 346 | dh_privfetch, sizeof(dh_priv), |
| 347 | bindh_decinit, dh_decdoit, dh_enccheck, dh_encdestroy |
| 348 | }; |
| 349 | |
| 350 | static const kemops ec_decops = { |
| 351 | ec_privfetch, sizeof(ec_priv), |
| 352 | ec_decinit, dh_decdoit, dh_enccheck, dh_encdestroy |
| 353 | }; |
| 354 | |
| 355 | /* --- Symmetric --- */ |
| 356 | |
| 357 | typedef struct symm_ctx { |
| 358 | kem k; |
| 359 | key_packdef kp; |
| 360 | key_bin kb; |
| 361 | } symm_ctx; |
| 362 | |
| 363 | static kem *symm_init(key *k, void *kd) |
| 364 | { |
| 365 | symm_ctx *s; |
| 366 | dstr d = DSTR_INIT; |
| 367 | int err; |
| 368 | |
| 369 | s = CREATE(symm_ctx); |
| 370 | |
| 371 | key_fulltag(k, &d); |
| 372 | s->kp.e = KENC_BINARY; |
| 373 | s->kp.p = &s->kb; |
| 374 | s->kp.kd = 0; |
| 375 | |
| 376 | if ((err = key_unpack(&s->kp, kd, &d)) != 0) { |
| 377 | die(EXIT_FAILURE, "failed to unpack symmetric key `%s': %s", |
| 378 | d.buf, key_strerror(err)); |
| 379 | } |
| 380 | dstr_destroy(&d); |
| 381 | return (&s->k); |
| 382 | } |
| 383 | |
| 384 | static int symm_decdoit(kem *k, dstr *d, ghash *h) |
| 385 | { |
| 386 | symm_ctx *s = (symm_ctx *)k; |
| 387 | |
| 388 | GH_HASH(h, s->kb.k, s->kb.sz); |
| 389 | GH_HASH(h, d->buf, d->len); |
| 390 | return (0); |
| 391 | } |
| 392 | |
| 393 | static int symm_encdoit(kem *k, dstr *d, ghash *h) |
| 394 | { |
| 395 | dstr_ensure(d, h->ops->c->hashsz); |
| 396 | d->len += h->ops->c->hashsz; |
| 397 | rand_get(RAND_GLOBAL, d->buf, d->len); |
| 398 | return (symm_decdoit(k, d, h)); |
| 399 | } |
| 400 | |
| 401 | static const char *symm_check(kem *k) { return (0); } |
| 402 | |
| 403 | static void symm_destroy(kem *k) |
| 404 | { symm_ctx *s = (symm_ctx *)k; key_unpackdone(&s->kp); } |
| 405 | |
| 406 | static const kemops symm_encops = { |
| 407 | 0, 0, |
| 408 | symm_init, symm_encdoit, symm_check, symm_destroy |
| 409 | }; |
| 410 | |
| 411 | static const kemops symm_decops = { |
| 412 | 0, 0, |
| 413 | symm_init, symm_decdoit, symm_check, symm_destroy |
| 414 | }; |
| 415 | |
| 416 | /* --- The switch table --- */ |
| 417 | |
| 418 | const struct kemtab kemtab[] = { |
| 419 | { "rsa", &rsa_encops, &rsa_decops }, |
| 420 | { "dh", &dh_encops, &dh_decops }, |
| 421 | { "bindh", &bindh_encops, &bindh_decops }, |
| 422 | { "ec", &ec_encops, &ec_decops }, |
| 423 | { "symm", &symm_encops, &symm_decops }, |
| 424 | { 0, 0, 0 } |
| 425 | }; |
| 426 | |
| 427 | /* --- @getkem@ --- * |
| 428 | * |
| 429 | * Arguments: @key *k@ = the key to load |
| 430 | * @const char *app@ = application name |
| 431 | * @int wantpriv@ = nonzero if we want to decrypt |
| 432 | * |
| 433 | * Returns: A key-encapsulating thing. |
| 434 | * |
| 435 | * Use: Loads a key. |
| 436 | */ |
| 437 | |
| 438 | kem *getkem(key *k, const char *app, int wantpriv) |
| 439 | { |
| 440 | const char *kalg, *halg = 0, *calg = 0; |
| 441 | dstr d = DSTR_INIT; |
| 442 | dstr t = DSTR_INIT; |
| 443 | size_t n; |
| 444 | char *p = 0; |
| 445 | const char *q; |
| 446 | kem *kk; |
| 447 | const struct kemtab *kt; |
| 448 | const kemops *ko; |
| 449 | void *kd; |
| 450 | int e; |
| 451 | key_packdef *kp; |
| 452 | |
| 453 | /* --- Setup stuff --- */ |
| 454 | |
| 455 | key_fulltag(k, &t); |
| 456 | |
| 457 | /* --- Get the KEM name --- * |
| 458 | * |
| 459 | * Take the attribute if it's there; otherwise use the key type. |
| 460 | */ |
| 461 | |
| 462 | n = strlen(app); |
| 463 | if ((q = key_getattr(0, k, "kem")) != 0) { |
| 464 | dstr_puts(&d, q); |
| 465 | p = d.buf; |
| 466 | } else if (strncmp(k->type, app, n) == 0 && k->type[n] == '-') { |
| 467 | dstr_puts(&d, k->type); |
| 468 | p = d.buf + n + 1; |
| 469 | } else |
| 470 | die(EXIT_FAILURE, "no KEM for key `%s'", t.buf); |
| 471 | kalg = p; |
| 472 | |
| 473 | /* --- Grab the encryption scheme --- * |
| 474 | * |
| 475 | * Grab it from the KEM if it's there, but override it from the attribute. |
| 476 | */ |
| 477 | |
| 478 | if (p && (p = strchr(p, '/')) != 0) { |
| 479 | *p++ = 0; |
| 480 | calg = p; |
| 481 | } |
| 482 | if ((q = key_getattr(0, k, "cipher")) != 0) |
| 483 | calg = q; |
| 484 | |
| 485 | /* --- Grab the hash function --- */ |
| 486 | |
| 487 | if (p && (p = strchr(p, '/')) != 0) { |
| 488 | *p++ = 0; |
| 489 | halg = p; |
| 490 | } |
| 491 | if ((q = key_getattr(0, k, "hash")) != 0) |
| 492 | halg = q; |
| 493 | |
| 494 | /* --- Instantiate the KEM --- */ |
| 495 | |
| 496 | for (kt = kemtab; kt->name; kt++) { |
| 497 | if (strcmp(kt->name, kalg) == 0) |
| 498 | goto k_found; |
| 499 | } |
| 500 | die(EXIT_FAILURE, "key encapsulation mechanism `%s' not found in key `%s'", |
| 501 | kalg, t.buf); |
| 502 | k_found:; |
| 503 | ko = wantpriv ? kt->decops : kt->encops; |
| 504 | if (!ko->kf) { |
| 505 | kd = k->k; |
| 506 | key_incref(kd); |
| 507 | kp = 0; |
| 508 | } else { |
| 509 | kd = xmalloc(ko->kdsz); |
| 510 | kp = key_fetchinit(ko->kf, 0, kd); |
| 511 | if ((e = key_fetch(kp, k)) != 0) { |
| 512 | die(EXIT_FAILURE, "error fetching key `%s': %s", |
| 513 | t.buf, key_strerror(e)); |
| 514 | } |
| 515 | } |
| 516 | kk = ko->init(k, kd); |
| 517 | kk->kp = kp; |
| 518 | kk->ops = ko; |
| 519 | kk->kd = kd; |
| 520 | |
| 521 | /* --- Set up the algorithms --- */ |
| 522 | |
| 523 | if (!halg) |
| 524 | kk->h = &rmd160; |
| 525 | else if ((kk->h = ghash_byname(halg)) == 0) { |
| 526 | die(EXIT_FAILURE, "hash algorithm `%s' not found in key `%s'", |
| 527 | halg, t.buf); |
| 528 | } |
| 529 | |
| 530 | if (!calg) |
| 531 | kk->c = &blowfish_cbc; |
| 532 | else if ((kk->c = gcipher_byname(calg)) == 0) { |
| 533 | die(EXIT_FAILURE, "encryption scheme `%s' not found in key `%s'", |
| 534 | calg, t.buf); |
| 535 | } |
| 536 | |
| 537 | dstr_reset(&d); |
| 538 | if ((q = key_getattr(0, k, "kdf")) == 0) { |
| 539 | dstr_putf(&d, "%s-mgf", kk->h->name); |
| 540 | q = d.buf; |
| 541 | } |
| 542 | if ((kk->cx = gcipher_byname(q)) == 0) { |
| 543 | die(EXIT_FAILURE, "encryption scheme (KDF) `%s' not found in key `%s'", |
| 544 | q, t.buf); |
| 545 | } |
| 546 | |
| 547 | dstr_reset(&d); |
| 548 | if ((q = key_getattr(0, k, "mac")) == 0) { |
| 549 | dstr_putf(&d, "%s-hmac", kk->h->name); |
| 550 | q = d.buf; |
| 551 | } |
| 552 | if ((kk->m = gmac_byname(q)) == 0) { |
| 553 | die(EXIT_FAILURE, |
| 554 | "message authentication code `%s' not found in key `%s'", |
| 555 | q, t.buf); |
| 556 | } |
| 557 | |
| 558 | /* --- Tidy up --- */ |
| 559 | |
| 560 | dstr_destroy(&d); |
| 561 | dstr_destroy(&t); |
| 562 | return (kk); |
| 563 | } |
| 564 | |
| 565 | /* --- @setupkem@ --- * |
| 566 | * |
| 567 | * Arguments: @kem *k@ = key-encapsulation thing |
| 568 | * @dstr *d@ = key-encapsulation data |
| 569 | * @gcipher **cx@ = key-expansion function (for IVs) |
| 570 | * @gcipher **c@ = where to put initialized encryption scheme |
| 571 | * @gmac **m@ = where to put initialized MAC |
| 572 | * |
| 573 | * Returns: Zero on success, nonzero on failure. |
| 574 | * |
| 575 | * Use: Initializes all the various symmetric things from a KEM. |
| 576 | */ |
| 577 | |
| 578 | int setupkem(kem *k, dstr *d, gcipher **cx, gcipher **c, gmac **m) |
| 579 | { |
| 580 | octet *kd; |
| 581 | size_t n, cn, mn; |
| 582 | ghash *h; |
| 583 | int rc = -1; |
| 584 | |
| 585 | h = GH_INIT(k->h); |
| 586 | if (k->ops->doit(k, d, h)) |
| 587 | goto done; |
| 588 | n = keysz(GH_CLASS(h)->hashsz, k->cx->keysz); |
| 589 | if (!n) |
| 590 | goto done; |
| 591 | kd = GH_DONE(h, 0); |
| 592 | *cx = GC_INIT(k->cx, kd, n); |
| 593 | |
| 594 | cn = keysz(0, k->c->keysz); n = cn; |
| 595 | mn = keysz(0, k->m->keysz); if (mn > n) n = mn; |
| 596 | kd = xmalloc(n); |
| 597 | GC_ENCRYPT(*cx, 0, kd, cn); |
| 598 | *c = GC_INIT(k->c, kd, cn); |
| 599 | GC_ENCRYPT(*cx, 0, kd, mn); |
| 600 | *m = GM_KEY(k->m, kd, mn); |
| 601 | xfree(kd); |
| 602 | |
| 603 | rc = 0; |
| 604 | done: |
| 605 | GH_DESTROY(h); |
| 606 | return (rc); |
| 607 | } |
| 608 | |
| 609 | /* --- @freekem@ --- * |
| 610 | * |
| 611 | * Arguments: @kem *k@ = key-encapsulation thing |
| 612 | * |
| 613 | * Returns: --- |
| 614 | * |
| 615 | * Use: Frees up a key-encapsulation thing. |
| 616 | */ |
| 617 | |
| 618 | void freekem(kem *k) |
| 619 | { |
| 620 | if (!k->ops->kf) |
| 621 | key_drop(k->kd); |
| 622 | else { |
| 623 | key_fetchdone(k->kp); |
| 624 | xfree(k->kd); |
| 625 | } |
| 626 | k->ops->destroy(k); |
| 627 | } |
| 628 | |
| 629 | /*----- That's all, folks -------------------------------------------------*/ |