1 /* $OpenBSD: ssh-rsa.c,v 1.79 2023/03/05 05:34:09 dtucker Exp $ */ 2 /* 3 * Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include <sys/types.h> 19 20 #include <openssl/evp.h> 21 #include <openssl/err.h> 22 23 #include <string.h> 24 25 #include "sshbuf.h" 26 #include "ssherr.h" 27 #define SSHKEY_INTERNAL 28 #include "sshkey.h" 29 #include "digest.h" 30 #include "log.h" 31 32 static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *); 33 34 static u_int 35 ssh_rsa_size(const struct sshkey *key) 36 { 37 const BIGNUM *rsa_n; 38 39 if (key->rsa == NULL) 40 return 0; 41 RSA_get0_key(key->rsa, &rsa_n, NULL, NULL); 42 return BN_num_bits(rsa_n); 43 } 44 45 static int 46 ssh_rsa_alloc(struct sshkey *k) 47 { 48 if ((k->rsa = RSA_new()) == NULL) 49 return SSH_ERR_ALLOC_FAIL; 50 return 0; 51 } 52 53 static void 54 ssh_rsa_cleanup(struct sshkey *k) 55 { 56 RSA_free(k->rsa); 57 k->rsa = NULL; 58 } 59 60 static int 61 ssh_rsa_equal(const struct sshkey *a, const struct sshkey *b) 62 { 63 const BIGNUM *rsa_e_a, *rsa_n_a; 64 const BIGNUM *rsa_e_b, *rsa_n_b; 65 66 if (a->rsa == NULL || b->rsa == NULL) 67 return 0; 68 RSA_get0_key(a->rsa, &rsa_n_a, &rsa_e_a, NULL); 69 RSA_get0_key(b->rsa, &rsa_n_b, &rsa_e_b, NULL); 70 if (rsa_e_a == NULL || rsa_e_b == NULL) 71 return 0; 72 if (rsa_n_a == NULL || rsa_n_b == NULL) 73 return 0; 74 if (BN_cmp(rsa_e_a, rsa_e_b) != 0) 75 return 0; 76 if (BN_cmp(rsa_n_a, rsa_n_b) != 0) 77 return 0; 78 return 1; 79 } 80 81 static int 82 ssh_rsa_serialize_public(const struct sshkey *key, struct sshbuf *b, 83 enum sshkey_serialize_rep opts) 84 { 85 int r; 86 const BIGNUM *rsa_n, *rsa_e; 87 88 if (key->rsa == NULL) 89 return SSH_ERR_INVALID_ARGUMENT; 90 RSA_get0_key(key->rsa, &rsa_n, &rsa_e, NULL); 91 if ((r = sshbuf_put_bignum2(b, rsa_e)) != 0 || 92 (r = sshbuf_put_bignum2(b, rsa_n)) != 0) 93 return r; 94 95 return 0; 96 } 97 98 static int 99 ssh_rsa_serialize_private(const struct sshkey *key, struct sshbuf *b, 100 enum sshkey_serialize_rep opts) 101 { 102 int r; 103 const BIGNUM *rsa_n, *rsa_e, *rsa_d, *rsa_iqmp, *rsa_p, *rsa_q; 104 105 RSA_get0_key(key->rsa, &rsa_n, &rsa_e, &rsa_d); 106 RSA_get0_factors(key->rsa, &rsa_p, &rsa_q); 107 RSA_get0_crt_params(key->rsa, NULL, NULL, &rsa_iqmp); 108 109 if (!sshkey_is_cert(key)) { 110 /* Note: can't reuse ssh_rsa_serialize_public: e, n vs. n, e */ 111 if ((r = sshbuf_put_bignum2(b, rsa_n)) != 0 || 112 (r = sshbuf_put_bignum2(b, rsa_e)) != 0) 113 return r; 114 } 115 if ((r = sshbuf_put_bignum2(b, rsa_d)) != 0 || 116 (r = sshbuf_put_bignum2(b, rsa_iqmp)) != 0 || 117 (r = sshbuf_put_bignum2(b, rsa_p)) != 0 || 118 (r = sshbuf_put_bignum2(b, rsa_q)) != 0) 119 return r; 120 121 return 0; 122 } 123 124 static int 125 ssh_rsa_generate(struct sshkey *k, int bits) 126 { 127 RSA *private = NULL; 128 BIGNUM *f4 = NULL; 129 int ret = SSH_ERR_INTERNAL_ERROR; 130 131 if (bits < SSH_RSA_MINIMUM_MODULUS_SIZE || 132 bits > SSHBUF_MAX_BIGNUM * 8) 133 return SSH_ERR_KEY_LENGTH; 134 if ((private = RSA_new()) == NULL || (f4 = BN_new()) == NULL) { 135 ret = SSH_ERR_ALLOC_FAIL; 136 goto out; 137 } 138 if (!BN_set_word(f4, RSA_F4) || 139 !RSA_generate_key_ex(private, bits, f4, NULL)) { 140 ret = SSH_ERR_LIBCRYPTO_ERROR; 141 goto out; 142 } 143 k->rsa = private; 144 private = NULL; 145 ret = 0; 146 out: 147 RSA_free(private); 148 BN_free(f4); 149 return ret; 150 } 151 152 static int 153 ssh_rsa_copy_public(const struct sshkey *from, struct sshkey *to) 154 { 155 const BIGNUM *rsa_n, *rsa_e; 156 BIGNUM *rsa_n_dup = NULL, *rsa_e_dup = NULL; 157 int r = SSH_ERR_INTERNAL_ERROR; 158 159 RSA_get0_key(from->rsa, &rsa_n, &rsa_e, NULL); 160 if ((rsa_n_dup = BN_dup(rsa_n)) == NULL || 161 (rsa_e_dup = BN_dup(rsa_e)) == NULL) { 162 r = SSH_ERR_ALLOC_FAIL; 163 goto out; 164 } 165 if (!RSA_set0_key(to->rsa, rsa_n_dup, rsa_e_dup, NULL)) { 166 r = SSH_ERR_LIBCRYPTO_ERROR; 167 goto out; 168 } 169 rsa_n_dup = rsa_e_dup = NULL; /* transferred */ 170 /* success */ 171 r = 0; 172 out: 173 BN_clear_free(rsa_n_dup); 174 BN_clear_free(rsa_e_dup); 175 return r; 176 } 177 178 static int 179 ssh_rsa_deserialize_public(const char *ktype, struct sshbuf *b, 180 struct sshkey *key) 181 { 182 int ret = SSH_ERR_INTERNAL_ERROR; 183 BIGNUM *rsa_n = NULL, *rsa_e = NULL; 184 185 if (sshbuf_get_bignum2(b, &rsa_e) != 0 || 186 sshbuf_get_bignum2(b, &rsa_n) != 0) { 187 ret = SSH_ERR_INVALID_FORMAT; 188 goto out; 189 } 190 if (!RSA_set0_key(key->rsa, rsa_n, rsa_e, NULL)) { 191 ret = SSH_ERR_LIBCRYPTO_ERROR; 192 goto out; 193 } 194 rsa_n = rsa_e = NULL; /* transferred */ 195 if ((ret = sshkey_check_rsa_length(key, 0)) != 0) 196 goto out; 197 #ifdef DEBUG_PK 198 RSA_print_fp(stderr, key->rsa, 8); 199 #endif 200 /* success */ 201 ret = 0; 202 out: 203 BN_clear_free(rsa_n); 204 BN_clear_free(rsa_e); 205 return ret; 206 } 207 208 static int 209 ssh_rsa_deserialize_private(const char *ktype, struct sshbuf *b, 210 struct sshkey *key) 211 { 212 int r; 213 BIGNUM *rsa_n = NULL, *rsa_e = NULL, *rsa_d = NULL; 214 BIGNUM *rsa_iqmp = NULL, *rsa_p = NULL, *rsa_q = NULL; 215 216 /* Note: can't reuse ssh_rsa_deserialize_public: e, n vs. n, e */ 217 if (!sshkey_is_cert(key)) { 218 if ((r = sshbuf_get_bignum2(b, &rsa_n)) != 0 || 219 (r = sshbuf_get_bignum2(b, &rsa_e)) != 0) 220 goto out; 221 if (!RSA_set0_key(key->rsa, rsa_n, rsa_e, NULL)) { 222 r = SSH_ERR_LIBCRYPTO_ERROR; 223 goto out; 224 } 225 rsa_n = rsa_e = NULL; /* transferred */ 226 } 227 if ((r = sshbuf_get_bignum2(b, &rsa_d)) != 0 || 228 (r = sshbuf_get_bignum2(b, &rsa_iqmp)) != 0 || 229 (r = sshbuf_get_bignum2(b, &rsa_p)) != 0 || 230 (r = sshbuf_get_bignum2(b, &rsa_q)) != 0) 231 goto out; 232 if (!RSA_set0_key(key->rsa, NULL, NULL, rsa_d)) { 233 r = SSH_ERR_LIBCRYPTO_ERROR; 234 goto out; 235 } 236 rsa_d = NULL; /* transferred */ 237 if (!RSA_set0_factors(key->rsa, rsa_p, rsa_q)) { 238 r = SSH_ERR_LIBCRYPTO_ERROR; 239 goto out; 240 } 241 rsa_p = rsa_q = NULL; /* transferred */ 242 if ((r = sshkey_check_rsa_length(key, 0)) != 0) 243 goto out; 244 if ((r = ssh_rsa_complete_crt_parameters(key, rsa_iqmp)) != 0) 245 goto out; 246 if (RSA_blinding_on(key->rsa, NULL) != 1) { 247 r = SSH_ERR_LIBCRYPTO_ERROR; 248 goto out; 249 } 250 /* success */ 251 r = 0; 252 out: 253 BN_clear_free(rsa_n); 254 BN_clear_free(rsa_e); 255 BN_clear_free(rsa_d); 256 BN_clear_free(rsa_p); 257 BN_clear_free(rsa_q); 258 BN_clear_free(rsa_iqmp); 259 return r; 260 } 261 262 static const char * 263 rsa_hash_alg_ident(int hash_alg) 264 { 265 switch (hash_alg) { 266 case SSH_DIGEST_SHA1: 267 return "ssh-rsa"; 268 case SSH_DIGEST_SHA256: 269 return "rsa-sha2-256"; 270 case SSH_DIGEST_SHA512: 271 return "rsa-sha2-512"; 272 } 273 return NULL; 274 } 275 276 /* 277 * Returns the hash algorithm ID for a given algorithm identifier as used 278 * inside the signature blob, 279 */ 280 static int 281 rsa_hash_id_from_ident(const char *ident) 282 { 283 if (strcmp(ident, "ssh-rsa") == 0) 284 return SSH_DIGEST_SHA1; 285 if (strcmp(ident, "rsa-sha2-256") == 0) 286 return SSH_DIGEST_SHA256; 287 if (strcmp(ident, "rsa-sha2-512") == 0) 288 return SSH_DIGEST_SHA512; 289 return -1; 290 } 291 292 /* 293 * Return the hash algorithm ID for the specified key name. This includes 294 * all the cases of rsa_hash_id_from_ident() but also the certificate key 295 * types. 296 */ 297 static int 298 rsa_hash_id_from_keyname(const char *alg) 299 { 300 int r; 301 302 if ((r = rsa_hash_id_from_ident(alg)) != -1) 303 return r; 304 if (strcmp(alg, "ssh-rsa-cert-v01@openssh.com") == 0) 305 return SSH_DIGEST_SHA1; 306 if (strcmp(alg, "rsa-sha2-256-cert-v01@openssh.com") == 0) 307 return SSH_DIGEST_SHA256; 308 if (strcmp(alg, "rsa-sha2-512-cert-v01@openssh.com") == 0) 309 return SSH_DIGEST_SHA512; 310 return -1; 311 } 312 313 static int 314 rsa_hash_alg_nid(int type) 315 { 316 switch (type) { 317 case SSH_DIGEST_SHA1: 318 return NID_sha1; 319 case SSH_DIGEST_SHA256: 320 return NID_sha256; 321 case SSH_DIGEST_SHA512: 322 return NID_sha512; 323 default: 324 return -1; 325 } 326 } 327 328 int 329 ssh_rsa_complete_crt_parameters(struct sshkey *key, const BIGNUM *iqmp) 330 { 331 const BIGNUM *rsa_p, *rsa_q, *rsa_d; 332 BIGNUM *aux = NULL, *d_consttime = NULL; 333 BIGNUM *rsa_dmq1 = NULL, *rsa_dmp1 = NULL, *rsa_iqmp = NULL; 334 BN_CTX *ctx = NULL; 335 int r; 336 337 if (key == NULL || key->rsa == NULL || 338 sshkey_type_plain(key->type) != KEY_RSA) 339 return SSH_ERR_INVALID_ARGUMENT; 340 341 RSA_get0_key(key->rsa, NULL, NULL, &rsa_d); 342 RSA_get0_factors(key->rsa, &rsa_p, &rsa_q); 343 344 if ((ctx = BN_CTX_new()) == NULL) 345 return SSH_ERR_ALLOC_FAIL; 346 if ((aux = BN_new()) == NULL || 347 (rsa_dmq1 = BN_new()) == NULL || 348 (rsa_dmp1 = BN_new()) == NULL) 349 return SSH_ERR_ALLOC_FAIL; 350 if ((d_consttime = BN_dup(rsa_d)) == NULL || 351 (rsa_iqmp = BN_dup(iqmp)) == NULL) { 352 r = SSH_ERR_ALLOC_FAIL; 353 goto out; 354 } 355 BN_set_flags(aux, BN_FLG_CONSTTIME); 356 BN_set_flags(d_consttime, BN_FLG_CONSTTIME); 357 358 if ((BN_sub(aux, rsa_q, BN_value_one()) == 0) || 359 (BN_mod(rsa_dmq1, d_consttime, aux, ctx) == 0) || 360 (BN_sub(aux, rsa_p, BN_value_one()) == 0) || 361 (BN_mod(rsa_dmp1, d_consttime, aux, ctx) == 0)) { 362 r = SSH_ERR_LIBCRYPTO_ERROR; 363 goto out; 364 } 365 if (!RSA_set0_crt_params(key->rsa, rsa_dmp1, rsa_dmq1, rsa_iqmp)) { 366 r = SSH_ERR_LIBCRYPTO_ERROR; 367 goto out; 368 } 369 rsa_dmp1 = rsa_dmq1 = rsa_iqmp = NULL; /* transferred */ 370 /* success */ 371 r = 0; 372 out: 373 BN_clear_free(aux); 374 BN_clear_free(d_consttime); 375 BN_clear_free(rsa_dmp1); 376 BN_clear_free(rsa_dmq1); 377 BN_clear_free(rsa_iqmp); 378 BN_CTX_free(ctx); 379 return r; 380 } 381 382 /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */ 383 static int 384 ssh_rsa_sign(struct sshkey *key, 385 u_char **sigp, size_t *lenp, 386 const u_char *data, size_t datalen, 387 const char *alg, const char *sk_provider, const char *sk_pin, u_int compat) 388 { 389 const BIGNUM *rsa_n; 390 u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL; 391 size_t slen = 0; 392 u_int hlen, len; 393 int nid, hash_alg, ret = SSH_ERR_INTERNAL_ERROR; 394 struct sshbuf *b = NULL; 395 396 if (lenp != NULL) 397 *lenp = 0; 398 if (sigp != NULL) 399 *sigp = NULL; 400 401 if (alg == NULL || strlen(alg) == 0) 402 hash_alg = SSH_DIGEST_SHA1; 403 else 404 hash_alg = rsa_hash_id_from_keyname(alg); 405 if (key == NULL || key->rsa == NULL || hash_alg == -1 || 406 sshkey_type_plain(key->type) != KEY_RSA) 407 return SSH_ERR_INVALID_ARGUMENT; 408 RSA_get0_key(key->rsa, &rsa_n, NULL, NULL); 409 if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE) 410 return SSH_ERR_KEY_LENGTH; 411 slen = RSA_size(key->rsa); 412 if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM) 413 return SSH_ERR_INVALID_ARGUMENT; 414 415 /* hash the data */ 416 nid = rsa_hash_alg_nid(hash_alg); 417 if ((hlen = ssh_digest_bytes(hash_alg)) == 0) 418 return SSH_ERR_INTERNAL_ERROR; 419 if ((ret = ssh_digest_memory(hash_alg, data, datalen, 420 digest, sizeof(digest))) != 0) 421 goto out; 422 423 if ((sig = malloc(slen)) == NULL) { 424 ret = SSH_ERR_ALLOC_FAIL; 425 goto out; 426 } 427 428 if (RSA_sign(nid, digest, hlen, sig, &len, key->rsa) != 1) { 429 ret = SSH_ERR_LIBCRYPTO_ERROR; 430 goto out; 431 } 432 if (len < slen) { 433 size_t diff = slen - len; 434 memmove(sig + diff, sig, len); 435 explicit_bzero(sig, diff); 436 } else if (len > slen) { 437 ret = SSH_ERR_INTERNAL_ERROR; 438 goto out; 439 } 440 /* encode signature */ 441 if ((b = sshbuf_new()) == NULL) { 442 ret = SSH_ERR_ALLOC_FAIL; 443 goto out; 444 } 445 if ((ret = sshbuf_put_cstring(b, rsa_hash_alg_ident(hash_alg))) != 0 || 446 (ret = sshbuf_put_string(b, sig, slen)) != 0) 447 goto out; 448 len = sshbuf_len(b); 449 if (sigp != NULL) { 450 if ((*sigp = malloc(len)) == NULL) { 451 ret = SSH_ERR_ALLOC_FAIL; 452 goto out; 453 } 454 memcpy(*sigp, sshbuf_ptr(b), len); 455 } 456 if (lenp != NULL) 457 *lenp = len; 458 ret = 0; 459 out: 460 explicit_bzero(digest, sizeof(digest)); 461 freezero(sig, slen); 462 sshbuf_free(b); 463 return ret; 464 } 465 466 static int 467 ssh_rsa_verify(const struct sshkey *key, 468 const u_char *sig, size_t siglen, 469 const u_char *data, size_t dlen, const char *alg, u_int compat, 470 struct sshkey_sig_details **detailsp) 471 { 472 const BIGNUM *rsa_n; 473 char *sigtype = NULL; 474 int hash_alg, want_alg, ret = SSH_ERR_INTERNAL_ERROR; 475 size_t len = 0, diff, modlen, hlen; 476 struct sshbuf *b = NULL; 477 u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL; 478 479 if (key == NULL || key->rsa == NULL || 480 sshkey_type_plain(key->type) != KEY_RSA || 481 sig == NULL || siglen == 0) 482 return SSH_ERR_INVALID_ARGUMENT; 483 RSA_get0_key(key->rsa, &rsa_n, NULL, NULL); 484 if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE) 485 return SSH_ERR_KEY_LENGTH; 486 487 if ((b = sshbuf_from(sig, siglen)) == NULL) 488 return SSH_ERR_ALLOC_FAIL; 489 if (sshbuf_get_cstring(b, &sigtype, NULL) != 0) { 490 ret = SSH_ERR_INVALID_FORMAT; 491 goto out; 492 } 493 if ((hash_alg = rsa_hash_id_from_ident(sigtype)) == -1) { 494 ret = SSH_ERR_KEY_TYPE_MISMATCH; 495 goto out; 496 } 497 /* 498 * Allow ssh-rsa-cert-v01 certs to generate SHA2 signatures for 499 * legacy reasons, but otherwise the signature type should match. 500 */ 501 if (alg != NULL && strcmp(alg, "ssh-rsa-cert-v01@openssh.com") != 0) { 502 if ((want_alg = rsa_hash_id_from_keyname(alg)) == -1) { 503 ret = SSH_ERR_INVALID_ARGUMENT; 504 goto out; 505 } 506 if (hash_alg != want_alg) { 507 ret = SSH_ERR_SIGNATURE_INVALID; 508 goto out; 509 } 510 } 511 if (sshbuf_get_string(b, &sigblob, &len) != 0) { 512 ret = SSH_ERR_INVALID_FORMAT; 513 goto out; 514 } 515 if (sshbuf_len(b) != 0) { 516 ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; 517 goto out; 518 } 519 /* RSA_verify expects a signature of RSA_size */ 520 modlen = RSA_size(key->rsa); 521 if (len > modlen) { 522 ret = SSH_ERR_KEY_BITS_MISMATCH; 523 goto out; 524 } else if (len < modlen) { 525 diff = modlen - len; 526 osigblob = sigblob; 527 if ((sigblob = realloc(sigblob, modlen)) == NULL) { 528 sigblob = osigblob; /* put it back for clear/free */ 529 ret = SSH_ERR_ALLOC_FAIL; 530 goto out; 531 } 532 memmove(sigblob + diff, sigblob, len); 533 explicit_bzero(sigblob, diff); 534 len = modlen; 535 } 536 if ((hlen = ssh_digest_bytes(hash_alg)) == 0) { 537 ret = SSH_ERR_INTERNAL_ERROR; 538 goto out; 539 } 540 if ((ret = ssh_digest_memory(hash_alg, data, dlen, 541 digest, sizeof(digest))) != 0) 542 goto out; 543 544 ret = openssh_RSA_verify(hash_alg, digest, hlen, sigblob, len, 545 key->rsa); 546 out: 547 freezero(sigblob, len); 548 free(sigtype); 549 sshbuf_free(b); 550 explicit_bzero(digest, sizeof(digest)); 551 return ret; 552 } 553 554 /* 555 * See: 556 * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/ 557 * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn 558 */ 559 560 /* 561 * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) 562 * oiw(14) secsig(3) algorithms(2) 26 } 563 */ 564 static const u_char id_sha1[] = { 565 0x30, 0x21, /* type Sequence, length 0x21 (33) */ 566 0x30, 0x09, /* type Sequence, length 0x09 */ 567 0x06, 0x05, /* type OID, length 0x05 */ 568 0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */ 569 0x05, 0x00, /* NULL */ 570 0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */ 571 }; 572 573 /* 574 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html 575 * id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) 576 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2) 577 * id-sha256(1) } 578 */ 579 static const u_char id_sha256[] = { 580 0x30, 0x31, /* type Sequence, length 0x31 (49) */ 581 0x30, 0x0d, /* type Sequence, length 0x0d (13) */ 582 0x06, 0x09, /* type OID, length 0x09 */ 583 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, /* id-sha256 */ 584 0x05, 0x00, /* NULL */ 585 0x04, 0x20 /* Octet string, length 0x20 (32), followed by sha256 hash */ 586 }; 587 588 /* 589 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html 590 * id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) 591 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2) 592 * id-sha256(3) } 593 */ 594 static const u_char id_sha512[] = { 595 0x30, 0x51, /* type Sequence, length 0x51 (81) */ 596 0x30, 0x0d, /* type Sequence, length 0x0d (13) */ 597 0x06, 0x09, /* type OID, length 0x09 */ 598 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, /* id-sha512 */ 599 0x05, 0x00, /* NULL */ 600 0x04, 0x40 /* Octet string, length 0x40 (64), followed by sha512 hash */ 601 }; 602 603 static int 604 rsa_hash_alg_oid(int hash_alg, const u_char **oidp, size_t *oidlenp) 605 { 606 switch (hash_alg) { 607 case SSH_DIGEST_SHA1: 608 *oidp = id_sha1; 609 *oidlenp = sizeof(id_sha1); 610 break; 611 case SSH_DIGEST_SHA256: 612 *oidp = id_sha256; 613 *oidlenp = sizeof(id_sha256); 614 break; 615 case SSH_DIGEST_SHA512: 616 *oidp = id_sha512; 617 *oidlenp = sizeof(id_sha512); 618 break; 619 default: 620 return SSH_ERR_INVALID_ARGUMENT; 621 } 622 return 0; 623 } 624 625 static int 626 openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen, 627 u_char *sigbuf, size_t siglen, RSA *rsa) 628 { 629 size_t rsasize = 0, oidlen = 0, hlen = 0; 630 int ret, len, oidmatch, hashmatch; 631 const u_char *oid = NULL; 632 u_char *decrypted = NULL; 633 634 if ((ret = rsa_hash_alg_oid(hash_alg, &oid, &oidlen)) != 0) 635 return ret; 636 ret = SSH_ERR_INTERNAL_ERROR; 637 hlen = ssh_digest_bytes(hash_alg); 638 if (hashlen != hlen) { 639 ret = SSH_ERR_INVALID_ARGUMENT; 640 goto done; 641 } 642 rsasize = RSA_size(rsa); 643 if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM || 644 siglen == 0 || siglen > rsasize) { 645 ret = SSH_ERR_INVALID_ARGUMENT; 646 goto done; 647 } 648 if ((decrypted = malloc(rsasize)) == NULL) { 649 ret = SSH_ERR_ALLOC_FAIL; 650 goto done; 651 } 652 if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa, 653 RSA_PKCS1_PADDING)) < 0) { 654 ret = SSH_ERR_LIBCRYPTO_ERROR; 655 goto done; 656 } 657 if (len < 0 || (size_t)len != hlen + oidlen) { 658 ret = SSH_ERR_INVALID_FORMAT; 659 goto done; 660 } 661 oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0; 662 hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0; 663 if (!oidmatch || !hashmatch) { 664 ret = SSH_ERR_SIGNATURE_INVALID; 665 goto done; 666 } 667 ret = 0; 668 done: 669 freezero(decrypted, rsasize); 670 return ret; 671 } 672 673 static const struct sshkey_impl_funcs sshkey_rsa_funcs = { 674 /* .size = */ ssh_rsa_size, 675 /* .alloc = */ ssh_rsa_alloc, 676 /* .cleanup = */ ssh_rsa_cleanup, 677 /* .equal = */ ssh_rsa_equal, 678 /* .ssh_serialize_public = */ ssh_rsa_serialize_public, 679 /* .ssh_deserialize_public = */ ssh_rsa_deserialize_public, 680 /* .ssh_serialize_private = */ ssh_rsa_serialize_private, 681 /* .ssh_deserialize_private = */ ssh_rsa_deserialize_private, 682 /* .generate = */ ssh_rsa_generate, 683 /* .copy_public = */ ssh_rsa_copy_public, 684 /* .sign = */ ssh_rsa_sign, 685 /* .verify = */ ssh_rsa_verify, 686 }; 687 688 const struct sshkey_impl sshkey_rsa_impl = { 689 /* .name = */ "ssh-rsa", 690 /* .shortname = */ "RSA", 691 /* .sigalg = */ NULL, 692 /* .type = */ KEY_RSA, 693 /* .nid = */ 0, 694 /* .cert = */ 0, 695 /* .sigonly = */ 0, 696 /* .keybits = */ 0, 697 /* .funcs = */ &sshkey_rsa_funcs, 698 }; 699 700 const struct sshkey_impl sshkey_rsa_cert_impl = { 701 /* .name = */ "ssh-rsa-cert-v01@openssh.com", 702 /* .shortname = */ "RSA-CERT", 703 /* .sigalg = */ NULL, 704 /* .type = */ KEY_RSA_CERT, 705 /* .nid = */ 0, 706 /* .cert = */ 1, 707 /* .sigonly = */ 0, 708 /* .keybits = */ 0, 709 /* .funcs = */ &sshkey_rsa_funcs, 710 }; 711 712 /* SHA2 signature algorithms */ 713 714 const struct sshkey_impl sshkey_rsa_sha256_impl = { 715 /* .name = */ "rsa-sha2-256", 716 /* .shortname = */ "RSA", 717 /* .sigalg = */ NULL, 718 /* .type = */ KEY_RSA, 719 /* .nid = */ 0, 720 /* .cert = */ 0, 721 /* .sigonly = */ 1, 722 /* .keybits = */ 0, 723 /* .funcs = */ &sshkey_rsa_funcs, 724 }; 725 726 const struct sshkey_impl sshkey_rsa_sha512_impl = { 727 /* .name = */ "rsa-sha2-512", 728 /* .shortname = */ "RSA", 729 /* .sigalg = */ NULL, 730 /* .type = */ KEY_RSA, 731 /* .nid = */ 0, 732 /* .cert = */ 0, 733 /* .sigonly = */ 1, 734 /* .keybits = */ 0, 735 /* .funcs = */ &sshkey_rsa_funcs, 736 }; 737 738 const struct sshkey_impl sshkey_rsa_sha256_cert_impl = { 739 /* .name = */ "rsa-sha2-256-cert-v01@openssh.com", 740 /* .shortname = */ "RSA-CERT", 741 /* .sigalg = */ "rsa-sha2-256", 742 /* .type = */ KEY_RSA_CERT, 743 /* .nid = */ 0, 744 /* .cert = */ 1, 745 /* .sigonly = */ 1, 746 /* .keybits = */ 0, 747 /* .funcs = */ &sshkey_rsa_funcs, 748 }; 749 750 const struct sshkey_impl sshkey_rsa_sha512_cert_impl = { 751 /* .name = */ "rsa-sha2-512-cert-v01@openssh.com", 752 /* .shortname = */ "RSA-CERT", 753 /* .sigalg = */ "rsa-sha2-512", 754 /* .type = */ KEY_RSA_CERT, 755 /* .nid = */ 0, 756 /* .cert = */ 1, 757 /* .sigonly = */ 1, 758 /* .keybits = */ 0, 759 /* .funcs = */ &sshkey_rsa_funcs, 760 }; 761