| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Catcrypt key-encapsulation |
| 4 | * |
| 5 | * (c) 2004 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 9 | * |
| 10 | * This file is part of Catacomb. |
| 11 | * |
| 12 | * Catacomb is free software; you can redistribute it and/or modify |
| 13 | * it under the terms of the GNU Library General Public License as |
| 14 | * published by the Free Software Foundation; either version 2 of the |
| 15 | * License, or (at your option) any later version. |
| 16 | * |
| 17 | * Catacomb 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 Library General Public License for more details. |
| 21 | * |
| 22 | * You should have received a copy of the GNU Library General Public |
| 23 | * License along with Catacomb; if not, write to the Free |
| 24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 25 | * MA 02111-1307, USA. |
| 26 | */ |
| 27 | |
| 28 | /*----- Header files ------------------------------------------------------*/ |
| 29 | |
| 30 | #define _FILE_OFFSET_BITS 64 |
| 31 | |
| 32 | #include <stdlib.h> |
| 33 | |
| 34 | #include <mLib/alloc.h> |
| 35 | #include <mLib/dstr.h> |
| 36 | #include <mLib/macros.h> |
| 37 | #include <mLib/report.h> |
| 38 | #include <mLib/sub.h> |
| 39 | |
| 40 | #include "gaead.h" |
| 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 | #include "x25519.h" |
| 49 | #include "x448.h" |
| 50 | |
| 51 | #include "rmd160.h" |
| 52 | #include "blowfish-cbc.h" |
| 53 | #include "chacha20-poly1305.h" |
| 54 | #include "poly1305.h" |
| 55 | #include "salsa20.h" |
| 56 | #include "chacha.h" |
| 57 | |
| 58 | #include "cc.h" |
| 59 | |
| 60 | /*----- Bulk crypto -------------------------------------------------------*/ |
| 61 | |
| 62 | /* --- Authenticated encryption schemes --- */ |
| 63 | |
| 64 | typedef struct aead_encctx { |
| 65 | bulk b; |
| 66 | const gcaead *aec; |
| 67 | gaead_key *key; |
| 68 | union { gaead_enc *enc; gaead_dec *dec; } ed; |
| 69 | octet *t; |
| 70 | size_t nsz, tsz; |
| 71 | } aead_encctx; |
| 72 | |
| 73 | static bulk *aead_internalinit(key *k, const gcaead *aec) |
| 74 | { |
| 75 | aead_encctx *ctx = CREATE(aead_encctx); |
| 76 | |
| 77 | ctx->key = 0; |
| 78 | ctx->aec = aec; |
| 79 | if ((ctx->nsz = keysz_pad(4, aec->noncesz)) == 0) |
| 80 | die(EXIT_FAILURE, "no suitable nonce size for `%s'", aec->name); |
| 81 | ctx->tsz = keysz(0, ctx->aec->tagsz); |
| 82 | |
| 83 | return (&ctx->b); |
| 84 | } |
| 85 | |
| 86 | static bulk *aead_init(key *k, const char *calg, const char *halg) |
| 87 | { |
| 88 | const gcaead *aec; |
| 89 | const char *q; |
| 90 | dstr t = DSTR_INIT; |
| 91 | |
| 92 | key_fulltag(k, &t); |
| 93 | |
| 94 | if ((q = key_getattr(0, k, "cipher")) != 0) calg = q; |
| 95 | if (!calg) aec = &chacha20_poly1305; |
| 96 | else if ((aec = gaead_byname(calg)) == 0) |
| 97 | die(EXIT_FAILURE, "AEAD scheme `%s' not found in key `%s'", |
| 98 | calg, t.buf); |
| 99 | |
| 100 | dstr_destroy(&t); |
| 101 | return (aead_internalinit(k, aec)); |
| 102 | } |
| 103 | |
| 104 | static int aead_commonsetup(aead_encctx *ctx, gcipher *cx) |
| 105 | { |
| 106 | size_t ksz, n; |
| 107 | |
| 108 | n = ksz = keysz(0, ctx->aec->keysz); |
| 109 | if (n < ctx->nsz) n = ctx->nsz; |
| 110 | if (n < ctx->tsz) n = ctx->tsz; |
| 111 | ctx->t = xmalloc(n); |
| 112 | |
| 113 | GC_ENCRYPT(cx, 0, ctx->t, ksz); |
| 114 | ctx->key = GAEAD_KEY(ctx->aec, ctx->t, ksz); |
| 115 | return (0); |
| 116 | } |
| 117 | |
| 118 | static size_t aead_overhead(bulk *b) |
| 119 | { aead_encctx *ctx = (aead_encctx *)b; return (ctx->aec->ohd + ctx->tsz); } |
| 120 | |
| 121 | static void aead_commondestroy(aead_encctx *ctx) |
| 122 | { |
| 123 | if (ctx->key) GAEAD_DESTROY(ctx->key); |
| 124 | xfree(ctx->t); |
| 125 | DESTROY(ctx); |
| 126 | } |
| 127 | |
| 128 | static int aead_encsetup(bulk *b, gcipher *cx) |
| 129 | { |
| 130 | aead_encctx *ctx = (aead_encctx *)b; |
| 131 | ctx->ed.enc = 0; return (aead_commonsetup(ctx, cx)); |
| 132 | } |
| 133 | |
| 134 | static const char *aead_encdoit(bulk *b, uint32 seq, buf *bb, |
| 135 | const void *p, size_t sz) |
| 136 | { |
| 137 | aead_encctx *ctx = (aead_encctx *)b; |
| 138 | octet *t; |
| 139 | int rc; |
| 140 | |
| 141 | memset(ctx->t + 4, 0, ctx->nsz - 4); STORE32_B(ctx->t, seq); |
| 142 | if (!ctx->ed.enc) |
| 143 | ctx->ed.enc = GAEAD_ENC(ctx->key, ctx->t, ctx->nsz, 0, sz, ctx->tsz); |
| 144 | else |
| 145 | GAEAD_REINIT(ctx->ed.enc, ctx->t, ctx->nsz, 0, sz, ctx->tsz); |
| 146 | t = buf_get(bb, ctx->tsz); assert(t); |
| 147 | rc = GAEAD_ENCRYPT(ctx->ed.enc, p, sz, bb); assert(rc >= 0); |
| 148 | rc = GAEAD_DONE(ctx->ed.enc, 0, bb, t, ctx->tsz); assert(rc >= 0); |
| 149 | return (0); |
| 150 | } |
| 151 | |
| 152 | static void aead_encdestroy(bulk *b) |
| 153 | { |
| 154 | aead_encctx *ctx = (aead_encctx *)b; |
| 155 | if (ctx->ed.enc) GAEAD_DESTROY(ctx->ed.enc); |
| 156 | aead_commondestroy(ctx); |
| 157 | } |
| 158 | |
| 159 | static int aead_decsetup(bulk *b, gcipher *cx) |
| 160 | { |
| 161 | aead_encctx *ctx = (aead_encctx *)b; |
| 162 | ctx->ed.dec = 0; return (aead_commonsetup(ctx, cx)); |
| 163 | } |
| 164 | |
| 165 | static const char *aead_decdoit(bulk *b, uint32 seq, buf *bb, |
| 166 | const void *p, size_t sz) |
| 167 | { |
| 168 | aead_encctx *ctx = (aead_encctx *)b; |
| 169 | buf bin; |
| 170 | const octet *t; |
| 171 | int rc; |
| 172 | |
| 173 | memset(ctx->t + 4, 0, ctx->nsz - 4); STORE32_B(ctx->t, seq); |
| 174 | if (!ctx->ed.dec) |
| 175 | ctx->ed.dec = GAEAD_DEC(ctx->key, ctx->t, ctx->nsz, 0, sz, ctx->tsz); |
| 176 | else |
| 177 | GAEAD_REINIT(ctx->ed.enc, ctx->t, ctx->nsz, 0, sz, ctx->tsz); |
| 178 | |
| 179 | buf_init(&bin, (/*unconst*/ void *)p, sz); |
| 180 | t = buf_get(&bin, ctx->tsz); if (!t) return ("no tag"); |
| 181 | rc = GAEAD_DECRYPT(ctx->ed.dec, BCUR(&bin), BLEFT(&bin), bb); |
| 182 | assert(rc >= 0); |
| 183 | rc = GAEAD_DONE(ctx->ed.dec, 0, bb, t, ctx->tsz); assert(rc >= 0); |
| 184 | if (!rc) return ("authentication failure"); |
| 185 | return (0); |
| 186 | } |
| 187 | |
| 188 | static void aead_decdestroy(bulk *b) |
| 189 | { |
| 190 | aead_encctx *ctx = (aead_encctx *)b; |
| 191 | if (ctx->ed.dec) GAEAD_DESTROY(ctx->ed.dec); |
| 192 | aead_commondestroy(ctx); |
| 193 | } |
| 194 | |
| 195 | static const struct bulkops aead_encops = { |
| 196 | aead_init, aead_encsetup, aead_overhead, |
| 197 | aead_encdoit, aead_encdestroy |
| 198 | }, aead_decops = { |
| 199 | aead_init, aead_decsetup, aead_overhead, |
| 200 | aead_decdoit, aead_decdestroy |
| 201 | }; |
| 202 | |
| 203 | /* --- NaCl `secretbox' in terms of AEAD --- */ |
| 204 | |
| 205 | static bulk *naclbox_init(key *k, const char *calg, const char *halg) |
| 206 | { |
| 207 | const gcaead *aec; |
| 208 | dstr t = DSTR_INIT; |
| 209 | const char *q; |
| 210 | |
| 211 | key_fulltag(k, &t); |
| 212 | |
| 213 | if ((q = key_getattr(0, k, "cipher")) != 0) calg = q; |
| 214 | if (!calg || STRCMP(calg, ==, "salsa20")) aec = &salsa20_naclbox; |
| 215 | else if (STRCMP(calg, ==, "salsa20/12")) aec = &salsa2012_naclbox; |
| 216 | else if (STRCMP(calg, ==, "salsa20/8")) aec = &salsa208_naclbox; |
| 217 | else if (STRCMP(calg, ==, "chacha20")) aec = &chacha20_naclbox; |
| 218 | else if (STRCMP(calg, ==, "chacha12")) aec = &chacha12_naclbox; |
| 219 | else if (STRCMP(calg, ==, "chacha8")) aec = &chacha8_naclbox; |
| 220 | else { |
| 221 | die(EXIT_FAILURE, |
| 222 | "unknown or inappropriate encryption scheme `%s' in key `%s'", |
| 223 | calg, t.buf); |
| 224 | } |
| 225 | |
| 226 | dstr_destroy(&t); |
| 227 | return (aead_internalinit(k, aec)); |
| 228 | } |
| 229 | |
| 230 | static const bulkops naclbox_encops = { |
| 231 | naclbox_init, aead_encsetup, aead_overhead, |
| 232 | aead_encdoit, aead_encdestroy |
| 233 | }, naclbox_decops = { |
| 234 | naclbox_init, aead_decsetup, aead_overhead, |
| 235 | aead_decdoit, aead_decdestroy |
| 236 | }; |
| 237 | |
| 238 | /* --- Generic composition --- */ |
| 239 | |
| 240 | typedef struct gencomp_encctx { |
| 241 | bulk b; |
| 242 | const gccipher *cc; |
| 243 | const gcmac *mc; |
| 244 | gcipher *c, *cx; |
| 245 | gmac *m; |
| 246 | octet *t; size_t tsz; |
| 247 | } gencomp_encctx; |
| 248 | |
| 249 | static bulk *gencomp_init(key *k, const char *calg, const char *halg) |
| 250 | { |
| 251 | gencomp_encctx *ctx = CREATE(gencomp_encctx); |
| 252 | const char *q; |
| 253 | dstr d = DSTR_INIT, t = DSTR_INIT; |
| 254 | |
| 255 | key_fulltag(k, &t); |
| 256 | |
| 257 | if ((q = key_getattr(0, k, "cipher")) != 0) calg = q; |
| 258 | if (!calg) ctx->cc = &blowfish_cbc; |
| 259 | else if ((ctx->cc = gcipher_byname(calg)) == 0) { |
| 260 | die(EXIT_FAILURE, "encryption scheme `%s' not found in key `%s'", |
| 261 | calg, t.buf); |
| 262 | } |
| 263 | |
| 264 | dstr_reset(&d); |
| 265 | if ((q = key_getattr(0, k, "mac")) == 0) { |
| 266 | dstr_putf(&d, "%s-hmac", halg); |
| 267 | q = d.buf; |
| 268 | } |
| 269 | if ((ctx->mc = gmac_byname(q)) == 0) { |
| 270 | die(EXIT_FAILURE, |
| 271 | "message authentication code `%s' not found in key `%s'", |
| 272 | q, t.buf); |
| 273 | } |
| 274 | |
| 275 | return (&ctx->b); |
| 276 | } |
| 277 | |
| 278 | static int gencomp_setup(bulk *b, gcipher *cx) |
| 279 | { |
| 280 | gencomp_encctx *ctx = (gencomp_encctx *)b; |
| 281 | size_t cn, mn, n; |
| 282 | octet *kd; |
| 283 | |
| 284 | ctx->cx = cx; |
| 285 | n = ctx->cc->blksz; |
| 286 | cn = keysz(0, ctx->cc->keysz); if (cn > n) n = cn; |
| 287 | mn = keysz(0, ctx->mc->keysz); if (mn > n) n = mn; |
| 288 | ctx->t = kd = xmalloc(n); ctx->tsz = n; |
| 289 | GC_ENCRYPT(cx, 0, kd, cn); |
| 290 | ctx->c = GC_INIT(ctx->cc, kd, cn); |
| 291 | GC_ENCRYPT(cx, 0, kd, mn); |
| 292 | ctx->m = GM_KEY(ctx->mc, kd, mn); |
| 293 | return (0); |
| 294 | } |
| 295 | |
| 296 | static size_t gencomp_overhead(bulk *b) |
| 297 | { |
| 298 | gencomp_encctx *ctx = (gencomp_encctx *)b; |
| 299 | return (ctx->cc->blksz + ctx->mc->hashsz); } |
| 300 | |
| 301 | static void gencomp_destroy(bulk *b) |
| 302 | { |
| 303 | gencomp_encctx *ctx = (gencomp_encctx *)b; |
| 304 | |
| 305 | GC_DESTROY(ctx->c); |
| 306 | GC_DESTROY(ctx->m); |
| 307 | xfree(ctx->t); |
| 308 | DESTROY(ctx); |
| 309 | } |
| 310 | |
| 311 | static const char *gencomp_encdoit(bulk *b, uint32 seq, buf *bb, |
| 312 | const void *p, size_t sz) |
| 313 | { |
| 314 | gencomp_encctx *ctx = (gencomp_encctx *)b; |
| 315 | octet *tag, *ct; |
| 316 | ghash *h = GM_INIT(ctx->m); |
| 317 | |
| 318 | GH_HASHU32(h, seq); |
| 319 | if (ctx->cc->blksz) { |
| 320 | GC_ENCRYPT(ctx->cx, 0, ctx->t, ctx->cc->blksz); |
| 321 | GC_SETIV(ctx->c, ctx->t); |
| 322 | } |
| 323 | tag = buf_get(bb, ctx->mc->hashsz); assert(tag); |
| 324 | ct = buf_get(bb, sz); assert(ct); |
| 325 | GC_ENCRYPT(ctx->c, p, ct, sz); |
| 326 | GH_HASH(h, ct, sz); |
| 327 | GH_DONE(h, tag); |
| 328 | GH_DESTROY(h); |
| 329 | return (0); |
| 330 | } |
| 331 | |
| 332 | static const char *gencomp_decdoit(bulk *b, uint32 seq, buf *bb, |
| 333 | const void *p, size_t sz) |
| 334 | { |
| 335 | gencomp_encctx *ctx = (gencomp_encctx *)b; |
| 336 | buf bin; |
| 337 | const octet *tag, *ct; |
| 338 | octet *pt; |
| 339 | ghash *h; |
| 340 | int ok; |
| 341 | |
| 342 | buf_init(&bin, (/*unconst*/ void *)p, sz); |
| 343 | if ((tag = buf_get(&bin, ctx->mc->hashsz)) == 0) return ("no tag"); |
| 344 | ct = BCUR(&bin); sz = BLEFT(&bin); |
| 345 | pt = buf_get(bb, sz); assert(pt); |
| 346 | |
| 347 | h = GM_INIT(ctx->m); |
| 348 | GH_HASHU32(h, seq); |
| 349 | GH_HASH(h, ct, sz); |
| 350 | ok = ct_memeq(tag, GH_DONE(h, 0), ctx->mc->hashsz); |
| 351 | GH_DESTROY(h); |
| 352 | if (!ok) return ("authentication failure"); |
| 353 | |
| 354 | if (ctx->cc->blksz) { |
| 355 | GC_ENCRYPT(ctx->cx, 0, ctx->t, ctx->cc->blksz); |
| 356 | GC_SETIV(ctx->c, ctx->t); |
| 357 | } |
| 358 | GC_DECRYPT(ctx->c, ct, pt, sz); |
| 359 | return (0); |
| 360 | } |
| 361 | |
| 362 | static const bulkops gencomp_encops = { |
| 363 | gencomp_init, gencomp_setup, gencomp_overhead, |
| 364 | gencomp_encdoit, gencomp_destroy |
| 365 | }, gencomp_decops = { |
| 366 | gencomp_init, gencomp_setup, gencomp_overhead, |
| 367 | gencomp_decdoit, gencomp_destroy |
| 368 | }; |
| 369 | |
| 370 | const struct bulktab bulktab[] = { |
| 371 | { "gencomp", &gencomp_encops, &gencomp_decops }, |
| 372 | { "naclbox", &naclbox_encops, &naclbox_decops }, |
| 373 | { "aead", &aead_encops, &aead_decops }, |
| 374 | { 0, 0, 0 } |
| 375 | }; |
| 376 | |
| 377 | /*----- Key encapsulation -------------------------------------------------*/ |
| 378 | |
| 379 | /* --- RSA --- */ |
| 380 | |
| 381 | typedef struct rsa_encctx { |
| 382 | kem k; |
| 383 | rsa_pubctx rp; |
| 384 | } rsa_encctx; |
| 385 | |
| 386 | static kem *rsa_encinit(key *k, void *kd) |
| 387 | { |
| 388 | rsa_encctx *re = CREATE(rsa_encctx); |
| 389 | rsa_pubcreate(&re->rp, kd); |
| 390 | return (&re->k); |
| 391 | } |
| 392 | |
| 393 | static int rsa_encdoit(kem *k, dstr *d, ghash *h) |
| 394 | { |
| 395 | rsa_encctx *re = (rsa_encctx *)k; |
| 396 | mp *x = mprand_range(MP_NEW, re->rp.rp->n, &rand_global, 0); |
| 397 | mp *y = rsa_pubop(&re->rp, MP_NEW, x); |
| 398 | size_t n = mp_octets(re->rp.rp->n); |
| 399 | dstr_ensure(d, n); |
| 400 | mp_storeb(x, d->buf, n); |
| 401 | GH_HASH(h, d->buf, n); |
| 402 | mp_storeb(y, d->buf, n); |
| 403 | d->len += n; |
| 404 | mp_drop(x); |
| 405 | mp_drop(y); |
| 406 | return (0); |
| 407 | } |
| 408 | |
| 409 | static const char *rsa_lengthcheck(mp *n) |
| 410 | { |
| 411 | if (mp_bits(n) < 1020) return ("key too short"); |
| 412 | return (0); |
| 413 | } |
| 414 | |
| 415 | static const char *rsa_enccheck(kem *k) |
| 416 | { |
| 417 | rsa_encctx *re = (rsa_encctx *)k; |
| 418 | const char *e; |
| 419 | if ((e = rsa_lengthcheck(re->rp.rp->n)) != 0) return (e); |
| 420 | return (0); |
| 421 | } |
| 422 | |
| 423 | static void rsa_encdestroy(kem *k) |
| 424 | { |
| 425 | rsa_encctx *re = (rsa_encctx *)k; |
| 426 | rsa_pubdestroy(&re->rp); |
| 427 | DESTROY(re); |
| 428 | } |
| 429 | |
| 430 | static const kemops rsa_encops = { |
| 431 | rsa_pubfetch, sizeof(rsa_pub), |
| 432 | rsa_encinit, rsa_encdoit, rsa_enccheck, rsa_encdestroy |
| 433 | }; |
| 434 | |
| 435 | typedef struct rsa_decctx { |
| 436 | kem k; |
| 437 | rsa_privctx rp; |
| 438 | } rsa_decctx; |
| 439 | |
| 440 | static kem *rsa_decinit(key *k, void *kd) |
| 441 | { |
| 442 | rsa_decctx *rd = CREATE(rsa_decctx); |
| 443 | rsa_privcreate(&rd->rp, kd, &rand_global); |
| 444 | return (&rd->k); |
| 445 | } |
| 446 | |
| 447 | static int rsa_decdoit(kem *k, dstr *d, ghash *h) |
| 448 | { |
| 449 | rsa_decctx *rd = (rsa_decctx *)k; |
| 450 | mp *x = mp_loadb(MP_NEW, d->buf, d->len); |
| 451 | size_t n; |
| 452 | char *p; |
| 453 | |
| 454 | if (MP_CMP(x, >=, rd->rp.rp->n)) { |
| 455 | mp_drop(x); |
| 456 | return (-1); |
| 457 | } |
| 458 | n = mp_octets(rd->rp.rp->n); |
| 459 | p = xmalloc(n); |
| 460 | x = rsa_privop(&rd->rp, x, x); |
| 461 | mp_storeb(x, p, n); |
| 462 | GH_HASH(h, p, n); |
| 463 | mp_drop(x); |
| 464 | xfree(p); |
| 465 | return (0); |
| 466 | } |
| 467 | |
| 468 | static const char *rsa_deccheck(kem *k) |
| 469 | { |
| 470 | rsa_decctx *rd = (rsa_decctx *)k; |
| 471 | const char *e; |
| 472 | if ((e = rsa_lengthcheck(rd->rp.rp->n)) != 0) return (e); |
| 473 | return (0); |
| 474 | } |
| 475 | |
| 476 | static void rsa_decdestroy(kem *k) |
| 477 | { |
| 478 | rsa_decctx *rd = (rsa_decctx *)k; |
| 479 | rsa_privdestroy(&rd->rp); |
| 480 | DESTROY(rd); |
| 481 | } |
| 482 | |
| 483 | static const kemops rsa_decops = { |
| 484 | rsa_privfetch, sizeof(rsa_priv), |
| 485 | rsa_decinit, rsa_decdoit, rsa_deccheck, rsa_decdestroy |
| 486 | }; |
| 487 | |
| 488 | /* --- DH and EC --- */ |
| 489 | |
| 490 | typedef struct dh_encctx { |
| 491 | kem k; |
| 492 | group *g; |
| 493 | mp *x; |
| 494 | ge *y; |
| 495 | } dh_encctx; |
| 496 | |
| 497 | static dh_encctx *dh_doinit(key *k, const gprime_param *gp, mp *y, |
| 498 | group *(*makegroup)(const gprime_param *), |
| 499 | const char *what) |
| 500 | { |
| 501 | dh_encctx *de = CREATE(dh_encctx); |
| 502 | dstr t = DSTR_INIT; |
| 503 | |
| 504 | key_fulltag(k, &t); |
| 505 | if ((de->g = makegroup(gp)) == 0) |
| 506 | die(EXIT_FAILURE, "bad %s group in key `%s'", what, t.buf); |
| 507 | de->x = MP_NEW; |
| 508 | de->y = G_CREATE(de->g); |
| 509 | if (G_FROMINT(de->g, de->y, y)) |
| 510 | die(EXIT_FAILURE, "bad public key `%s'", t.buf); |
| 511 | dstr_destroy(&t); |
| 512 | return (de); |
| 513 | } |
| 514 | |
| 515 | static dh_encctx *ec_doinit(key *k, const char *cstr, const ec *y) |
| 516 | { |
| 517 | dh_encctx *de = CREATE(dh_encctx); |
| 518 | ec_info ei; |
| 519 | const char *e; |
| 520 | dstr t = DSTR_INIT; |
| 521 | |
| 522 | key_fulltag(k, &t); |
| 523 | if ((e = ec_getinfo(&ei, cstr)) != 0 || |
| 524 | (de->g = group_ec(&ei)) == 0) |
| 525 | die(EXIT_FAILURE, "bad elliptic curve spec in key `%s': %s", t.buf, e); |
| 526 | de->x = MP_NEW; |
| 527 | de->y = G_CREATE(de->g); |
| 528 | if (G_FROMEC(de->g, de->y, y)) |
| 529 | die(EXIT_FAILURE, "bad public curve point `%s'", t.buf); |
| 530 | dstr_destroy(&t); |
| 531 | return (de); |
| 532 | } |
| 533 | |
| 534 | static kem *dh_encinit(key *k, void *kd) |
| 535 | { |
| 536 | dh_pub *dp = kd; |
| 537 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y, group_prime, "prime"); |
| 538 | return (&de->k); |
| 539 | } |
| 540 | |
| 541 | static kem *bindh_encinit(key *k, void *kd) |
| 542 | { |
| 543 | dh_pub *dp = kd; |
| 544 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y, group_binary, "binary"); |
| 545 | return (&de->k); |
| 546 | } |
| 547 | |
| 548 | static kem *ec_encinit(key *k, void *kd) |
| 549 | { |
| 550 | ec_pub *ep = kd; |
| 551 | dh_encctx *de = ec_doinit(k, ep->cstr, &ep->p); |
| 552 | return (&de->k); |
| 553 | } |
| 554 | |
| 555 | static int dh_encdoit(kem *k, dstr *d, ghash *h) |
| 556 | { |
| 557 | dh_encctx *de = (dh_encctx *)k; |
| 558 | mp *r = mprand_range(MP_NEW, de->g->r, &rand_global, 0); |
| 559 | ge *x = G_CREATE(de->g); |
| 560 | ge *y = G_CREATE(de->g); |
| 561 | size_t n = de->g->noctets; |
| 562 | buf b; |
| 563 | |
| 564 | G_EXP(de->g, x, de->g->g, r); |
| 565 | G_EXP(de->g, y, de->y, r); |
| 566 | dstr_ensure(d, n); |
| 567 | buf_init(&b, d->buf, n); |
| 568 | G_TORAW(de->g, &b, y); |
| 569 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
| 570 | buf_init(&b, d->buf, n); |
| 571 | G_TORAW(de->g, &b, x); |
| 572 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
| 573 | d->len += BLEN(&b); |
| 574 | mp_drop(r); |
| 575 | G_DESTROY(de->g, x); |
| 576 | G_DESTROY(de->g, y); |
| 577 | return (0); |
| 578 | } |
| 579 | |
| 580 | static const char *dh_enccheck(kem *k) |
| 581 | { |
| 582 | dh_encctx *de = (dh_encctx *)k; |
| 583 | const char *e; |
| 584 | if ((e = G_CHECK(de->g, &rand_global)) != 0) |
| 585 | return (0); |
| 586 | if (group_check(de->g, de->y)) |
| 587 | return ("public key not in subgroup"); |
| 588 | return (0); |
| 589 | } |
| 590 | |
| 591 | static void dh_encdestroy(kem *k) |
| 592 | { |
| 593 | dh_encctx *de = (dh_encctx *)k; |
| 594 | G_DESTROY(de->g, de->y); |
| 595 | mp_drop(de->x); |
| 596 | G_DESTROYGROUP(de->g); |
| 597 | DESTROY(de); |
| 598 | } |
| 599 | |
| 600 | static const kemops dh_encops = { |
| 601 | dh_pubfetch, sizeof(dh_pub), |
| 602 | dh_encinit, dh_encdoit, dh_enccheck, dh_encdestroy |
| 603 | }; |
| 604 | |
| 605 | static const kemops bindh_encops = { |
| 606 | dh_pubfetch, sizeof(dh_pub), |
| 607 | bindh_encinit, dh_encdoit, dh_enccheck, dh_encdestroy |
| 608 | }; |
| 609 | |
| 610 | static const kemops ec_encops = { |
| 611 | ec_pubfetch, sizeof(ec_pub), |
| 612 | ec_encinit, dh_encdoit, dh_enccheck, dh_encdestroy |
| 613 | }; |
| 614 | |
| 615 | static kem *dh_decinit(key *k, void *kd) |
| 616 | { |
| 617 | dh_priv *dp = kd; |
| 618 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y, group_prime, "prime"); |
| 619 | de->x = MP_COPY(dp->x); |
| 620 | return (&de->k); |
| 621 | } |
| 622 | |
| 623 | static kem *bindh_decinit(key *k, void *kd) |
| 624 | { |
| 625 | dh_priv *dp = kd; |
| 626 | dh_encctx *de = dh_doinit(k, &dp->dp, dp->y, group_binary, "binary"); |
| 627 | de->x = MP_COPY(dp->x); |
| 628 | return (&de->k); |
| 629 | } |
| 630 | |
| 631 | static kem *ec_decinit(key *k, void *kd) |
| 632 | { |
| 633 | ec_priv *ep = kd; |
| 634 | dh_encctx *de = ec_doinit(k, ep->cstr, &ep->p); |
| 635 | de->x = MP_COPY(ep->x); |
| 636 | return (&de->k); |
| 637 | } |
| 638 | |
| 639 | static int dh_decdoit(kem *k, dstr *d, ghash *h) |
| 640 | { |
| 641 | dh_encctx *de = (dh_encctx *)k; |
| 642 | ge *x = G_CREATE(de->g); |
| 643 | size_t n = de->g->noctets; |
| 644 | void *p = xmalloc(n); |
| 645 | buf b; |
| 646 | int rc = -1; |
| 647 | |
| 648 | buf_init(&b, d->buf, d->len); |
| 649 | if (G_FROMRAW(de->g, &b, x) || group_check(de->g, x)) |
| 650 | goto done; |
| 651 | G_EXP(de->g, x, x, de->x); |
| 652 | buf_init(&b, p, n); |
| 653 | G_TORAW(de->g, &b, x); |
| 654 | GH_HASH(h, BBASE(&b), BLEN(&b)); |
| 655 | GH_HASH(h, d->buf, d->len); |
| 656 | rc = 0; |
| 657 | done: |
| 658 | G_DESTROY(de->g, x); |
| 659 | xfree(p); |
| 660 | return (rc); |
| 661 | } |
| 662 | |
| 663 | static const kemops dh_decops = { |
| 664 | dh_privfetch, sizeof(dh_priv), |
| 665 | dh_decinit, dh_decdoit, dh_enccheck, dh_encdestroy |
| 666 | }; |
| 667 | |
| 668 | static const kemops bindh_decops = { |
| 669 | dh_privfetch, sizeof(dh_priv), |
| 670 | bindh_decinit, dh_decdoit, dh_enccheck, dh_encdestroy |
| 671 | }; |
| 672 | |
| 673 | static const kemops ec_decops = { |
| 674 | ec_privfetch, sizeof(ec_priv), |
| 675 | ec_decinit, dh_decdoit, dh_enccheck, dh_encdestroy |
| 676 | }; |
| 677 | |
| 678 | /* --- X25519 and similar schemes --- */ |
| 679 | |
| 680 | #define XDHS(_) \ |
| 681 | _(x25519, X25519) \ |
| 682 | _(x448, X448) |
| 683 | |
| 684 | #define XDHDEF(xdh, XDH) \ |
| 685 | \ |
| 686 | static kem *xdh##_encinit(key *k, void *kd) { return (CREATE(kem)); } \ |
| 687 | static void xdh##_encdestroy(kem *k) { DESTROY(k); } \ |
| 688 | \ |
| 689 | static const char *xdh##_enccheck(kem *k) \ |
| 690 | { \ |
| 691 | xdh##_pub *kd = k->kd; \ |
| 692 | \ |
| 693 | if (kd->pub.sz != XDH##_PUBSZ) \ |
| 694 | return ("incorrect " #XDH "public key length"); \ |
| 695 | return (0); \ |
| 696 | } \ |
| 697 | \ |
| 698 | static int xdh##_encdoit(kem *k, dstr *d, ghash *h) \ |
| 699 | { \ |
| 700 | octet t[XDH##_KEYSZ], z[XDH##_OUTSZ]; \ |
| 701 | xdh##_pub *kd = k->kd; \ |
| 702 | \ |
| 703 | rand_get(RAND_GLOBAL, t, sizeof(t)); \ |
| 704 | dstr_ensure(d, XDH##_PUBSZ); \ |
| 705 | xdh((octet *)d->buf, t, xdh##_base); \ |
| 706 | xdh(z, t, kd->pub.k); \ |
| 707 | d->len += XDH##_PUBSZ; \ |
| 708 | GH_HASH(h, d->buf, XDH##_PUBSZ); \ |
| 709 | GH_HASH(h, z, XDH##_OUTSZ); \ |
| 710 | return (0); \ |
| 711 | } \ |
| 712 | \ |
| 713 | static const char *xdh##_deccheck(kem *k) \ |
| 714 | { \ |
| 715 | xdh##_priv *kd = k->kd; \ |
| 716 | \ |
| 717 | if (kd->priv.sz != XDH##_KEYSZ) \ |
| 718 | return ("incorrect " #XDH " private key length"); \ |
| 719 | if (kd->pub.sz != XDH##_PUBSZ) \ |
| 720 | return ("incorrect " #XDH " public key length"); \ |
| 721 | return (0); \ |
| 722 | } \ |
| 723 | \ |
| 724 | static int xdh##_decdoit(kem *k, dstr *d, ghash *h) \ |
| 725 | { \ |
| 726 | octet z[XDH##_OUTSZ]; \ |
| 727 | xdh##_priv *kd = k->kd; \ |
| 728 | int rc = -1; \ |
| 729 | \ |
| 730 | if (d->len != XDH##_PUBSZ) goto done; \ |
| 731 | xdh(z, kd->priv.k, (const octet *)d->buf); \ |
| 732 | GH_HASH(h, d->buf, XDH##_PUBSZ); \ |
| 733 | GH_HASH(h, z, XDH##_OUTSZ); \ |
| 734 | rc = 0; \ |
| 735 | done: \ |
| 736 | return (rc); \ |
| 737 | } \ |
| 738 | \ |
| 739 | static const kemops xdh##_encops = { \ |
| 740 | xdh##_pubfetch, sizeof(xdh##_pub), \ |
| 741 | xdh##_encinit, xdh##_encdoit, xdh##_enccheck, xdh##_encdestroy \ |
| 742 | }; \ |
| 743 | \ |
| 744 | static const kemops xdh##_decops = { \ |
| 745 | xdh##_privfetch, sizeof(xdh##_priv), \ |
| 746 | xdh##_encinit, xdh##_decdoit, xdh##_deccheck, xdh##_encdestroy \ |
| 747 | }; |
| 748 | |
| 749 | XDHS(XDHDEF) |
| 750 | #undef XDHDEF |
| 751 | |
| 752 | /* --- Symmetric --- */ |
| 753 | |
| 754 | typedef struct symm_ctx { |
| 755 | kem k; |
| 756 | key_packdef kp; |
| 757 | key_bin kb; |
| 758 | } symm_ctx; |
| 759 | |
| 760 | static kem *symm_init(key *k, void *kd) |
| 761 | { |
| 762 | symm_ctx *s; |
| 763 | dstr d = DSTR_INIT; |
| 764 | int err; |
| 765 | |
| 766 | s = CREATE(symm_ctx); |
| 767 | |
| 768 | key_fulltag(k, &d); |
| 769 | s->kp.e = KENC_BINARY; |
| 770 | s->kp.p = &s->kb; |
| 771 | s->kp.kd = 0; |
| 772 | |
| 773 | if ((err = key_unpack(&s->kp, kd, &d)) != 0) { |
| 774 | die(EXIT_FAILURE, "failed to unpack symmetric key `%s': %s", |
| 775 | d.buf, key_strerror(err)); |
| 776 | } |
| 777 | dstr_destroy(&d); |
| 778 | return (&s->k); |
| 779 | } |
| 780 | |
| 781 | static int symm_decdoit(kem *k, dstr *d, ghash *h) |
| 782 | { |
| 783 | symm_ctx *s = (symm_ctx *)k; |
| 784 | |
| 785 | GH_HASH(h, s->kb.k, s->kb.sz); |
| 786 | GH_HASH(h, d->buf, d->len); |
| 787 | return (0); |
| 788 | } |
| 789 | |
| 790 | static int symm_encdoit(kem *k, dstr *d, ghash *h) |
| 791 | { |
| 792 | dstr_ensure(d, h->ops->c->hashsz); |
| 793 | d->len += h->ops->c->hashsz; |
| 794 | rand_get(RAND_GLOBAL, d->buf, d->len); |
| 795 | return (symm_decdoit(k, d, h)); |
| 796 | } |
| 797 | |
| 798 | static const char *symm_check(kem *k) { return (0); } |
| 799 | |
| 800 | static void symm_destroy(kem *k) |
| 801 | { symm_ctx *s = (symm_ctx *)k; key_unpackdone(&s->kp); } |
| 802 | |
| 803 | static const kemops symm_encops = { |
| 804 | 0, 0, |
| 805 | symm_init, symm_encdoit, symm_check, symm_destroy |
| 806 | }; |
| 807 | |
| 808 | static const kemops symm_decops = { |
| 809 | 0, 0, |
| 810 | symm_init, symm_decdoit, symm_check, symm_destroy |
| 811 | }; |
| 812 | |
| 813 | /* --- The switch table --- */ |
| 814 | |
| 815 | const struct kemtab kemtab[] = { |
| 816 | { "rsa", &rsa_encops, &rsa_decops }, |
| 817 | { "dh", &dh_encops, &dh_decops }, |
| 818 | { "bindh", &bindh_encops, &bindh_decops }, |
| 819 | { "ec", &ec_encops, &ec_decops }, |
| 820 | #define XDHTAB(xdh, XDH) \ |
| 821 | { #xdh, &xdh##_encops, &xdh##_decops }, |
| 822 | XDHS(XDHTAB) |
| 823 | #undef XDHTAB |
| 824 | { "symm", &symm_encops, &symm_decops }, |
| 825 | { 0, 0, 0 } |
| 826 | }; |
| 827 | |
| 828 | /* --- @getkem@ --- * |
| 829 | * |
| 830 | * Arguments: @key *k@ = the key to load |
| 831 | * @const char *app@ = application name |
| 832 | * @int wantpriv@ = nonzero if we want to decrypt |
| 833 | * @bulk **bc@ = bulk crypto context to set up |
| 834 | * |
| 835 | * Returns: A key-encapsulating thing. |
| 836 | * |
| 837 | * Use: Loads a key. |
| 838 | */ |
| 839 | |
| 840 | kem *getkem(key *k, const char *app, int wantpriv, bulk **bc) |
| 841 | { |
| 842 | const char *kalg, *halg = 0, *balg = 0; |
| 843 | dstr d = DSTR_INIT; |
| 844 | dstr t = DSTR_INIT; |
| 845 | size_t n; |
| 846 | char *p = 0; |
| 847 | const char *q; |
| 848 | kem *kk; |
| 849 | const struct kemtab *kt; |
| 850 | const kemops *ko; |
| 851 | const struct bulktab *bt; |
| 852 | const bulkops *bo; |
| 853 | void *kd; |
| 854 | int e; |
| 855 | key_packdef *kp; |
| 856 | |
| 857 | /* --- Setup stuff --- */ |
| 858 | |
| 859 | key_fulltag(k, &t); |
| 860 | |
| 861 | /* --- Get the KEM name --- * |
| 862 | * |
| 863 | * Take the attribute if it's there; otherwise use the key type. |
| 864 | */ |
| 865 | |
| 866 | n = strlen(app); |
| 867 | if ((q = key_getattr(0, k, "kem")) != 0) { |
| 868 | dstr_puts(&d, q); |
| 869 | p = d.buf; |
| 870 | } else if (STRNCMP(k->type, ==, app, n) && k->type[n] == '-') { |
| 871 | dstr_puts(&d, k->type); |
| 872 | p = d.buf + n + 1; |
| 873 | } else |
| 874 | die(EXIT_FAILURE, "no KEM for key `%s'", t.buf); |
| 875 | kalg = p; |
| 876 | |
| 877 | /* --- Grab the bulk encryption scheme --- * |
| 878 | * |
| 879 | * Grab it from the KEM if it's there, but override it from the attribute. |
| 880 | */ |
| 881 | |
| 882 | if (p && (p = strchr(p, '/')) != 0) { |
| 883 | *p++ = 0; |
| 884 | balg = p; |
| 885 | } |
| 886 | if ((q = key_getattr(0, k, "bulk")) != 0) |
| 887 | balg = q; |
| 888 | |
| 889 | /* --- Grab the hash function --- */ |
| 890 | |
| 891 | if (p && (p = strchr(p, '/')) != 0) { |
| 892 | *p++ = 0; |
| 893 | halg = p; |
| 894 | } |
| 895 | if ((q = key_getattr(0, k, "hash")) != 0) |
| 896 | halg = q; |
| 897 | |
| 898 | /* --- Instantiate the KEM --- */ |
| 899 | |
| 900 | for (kt = kemtab; kt->name; kt++) { |
| 901 | if (STRCMP(kt->name, ==, kalg)) |
| 902 | goto k_found; |
| 903 | } |
| 904 | die(EXIT_FAILURE, "key encapsulation mechanism `%s' not found in key `%s'", |
| 905 | kalg, t.buf); |
| 906 | k_found:; |
| 907 | ko = wantpriv ? kt->decops : kt->encops; |
| 908 | if (!ko->kf) { |
| 909 | kd = k->k; |
| 910 | key_incref(kd); |
| 911 | kp = 0; |
| 912 | } else { |
| 913 | kd = xmalloc(ko->kdsz); |
| 914 | kp = key_fetchinit(ko->kf, 0, kd); |
| 915 | if ((e = key_fetch(kp, k)) != 0) { |
| 916 | die(EXIT_FAILURE, "error fetching key `%s': %s", |
| 917 | t.buf, key_strerror(e)); |
| 918 | } |
| 919 | } |
| 920 | kk = ko->init(k, kd); |
| 921 | kk->kp = kp; |
| 922 | kk->ops = ko; |
| 923 | kk->kd = kd; |
| 924 | |
| 925 | /* --- Set up the bulk crypto --- */ |
| 926 | |
| 927 | if (!halg) |
| 928 | kk->hc = &rmd160; |
| 929 | else if ((kk->hc = ghash_byname(halg)) == 0) { |
| 930 | die(EXIT_FAILURE, "hash algorithm `%s' not found in key `%s'", |
| 931 | halg, t.buf); |
| 932 | } |
| 933 | |
| 934 | if (!balg) |
| 935 | bt = bulktab; |
| 936 | else { |
| 937 | for (bt = bulktab, bo = 0; bt->name; bt++) { |
| 938 | if (STRCMP(balg, ==, bt->name)) |
| 939 | { balg = 0; goto b_found; } |
| 940 | n = strlen(bt->name); |
| 941 | if (STRNCMP(balg, ==, bt->name, n) && balg[n] == '-') |
| 942 | { balg += n + 1; goto b_found; } |
| 943 | } |
| 944 | bt = bulktab; |
| 945 | b_found:; |
| 946 | } |
| 947 | bo = wantpriv ? bt->decops : bt->encops; |
| 948 | *bc = bo->init(k, balg, kk->hc->name); |
| 949 | (*bc)->ops = bo; |
| 950 | |
| 951 | dstr_reset(&d); |
| 952 | if ((q = key_getattr(0, k, "kdf")) == 0) { |
| 953 | dstr_putf(&d, "%s-mgf", kk->hc->name); |
| 954 | q = d.buf; |
| 955 | } |
| 956 | if ((kk->cxc = gcipher_byname(q)) == 0) { |
| 957 | die(EXIT_FAILURE, "encryption scheme (KDF) `%s' not found in key `%s'", |
| 958 | q, t.buf); |
| 959 | } |
| 960 | |
| 961 | /* --- Tidy up --- */ |
| 962 | |
| 963 | dstr_destroy(&d); |
| 964 | dstr_destroy(&t); |
| 965 | return (kk); |
| 966 | } |
| 967 | |
| 968 | /* --- @setupkem@ --- * |
| 969 | * |
| 970 | * Arguments: @kem *k@ = key-encapsulation thing |
| 971 | * @dstr *d@ = key-encapsulation data |
| 972 | * @bulk *bc@ = bulk crypto context to set up |
| 973 | * |
| 974 | * Returns: Zero on success, nonzero on failure. |
| 975 | * |
| 976 | * Use: Initializes all the various symmetric things from a KEM. |
| 977 | */ |
| 978 | |
| 979 | int setupkem(kem *k, dstr *d, bulk *bc) |
| 980 | { |
| 981 | octet *kd; |
| 982 | size_t n; |
| 983 | ghash *h; |
| 984 | int rc = -1; |
| 985 | |
| 986 | h = GH_INIT(k->hc); |
| 987 | if (k->ops->doit(k, d, h)) |
| 988 | goto done; |
| 989 | n = keysz(GH_CLASS(h)->hashsz, k->cxc->keysz); |
| 990 | if (!n) |
| 991 | goto done; |
| 992 | kd = GH_DONE(h, 0); |
| 993 | k->cx = GC_INIT(k->cxc, kd, n); |
| 994 | bc->ops->setup(bc, k->cx); |
| 995 | |
| 996 | rc = 0; |
| 997 | done: |
| 998 | GH_DESTROY(h); |
| 999 | return (rc); |
| 1000 | } |
| 1001 | |
| 1002 | /* --- @freekem@ --- * |
| 1003 | * |
| 1004 | * Arguments: @kem *k@ = key-encapsulation thing |
| 1005 | * |
| 1006 | * Returns: --- |
| 1007 | * |
| 1008 | * Use: Frees up a key-encapsulation thing. |
| 1009 | */ |
| 1010 | |
| 1011 | void freekem(kem *k) |
| 1012 | { |
| 1013 | if (!k->ops->kf) |
| 1014 | key_drop(k->kd); |
| 1015 | else { |
| 1016 | key_fetchdone(k->kp); |
| 1017 | xfree(k->kd); |
| 1018 | } |
| 1019 | GC_DESTROY(k->cx); |
| 1020 | k->ops->destroy(k); |
| 1021 | } |
| 1022 | |
| 1023 | /*----- That's all, folks -------------------------------------------------*/ |