1 /* $OpenBSD: ssh-rsa.c,v 1.78 2022/10/28 02:47:04 djm 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 "compat.h" 27 #include "ssherr.h" 28 #define SSHKEY_INTERNAL 29 #include "sshkey.h" 30 #include "digest.h" 31 #include "log.h" 32 33 static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *); 34 35 static u_int 36 ssh_rsa_size(const struct sshkey *key) 37 { 38 const BIGNUM *rsa_n; 39 40 if (key->rsa == NULL) 41 return 0; 42 RSA_get0_key(key->rsa, &rsa_n, NULL, NULL); 43 return BN_num_bits(rsa_n); 44 } 45 46 static int 47 ssh_rsa_alloc(struct sshkey *k) 48 { 49 if ((k->rsa = RSA_new()) == NULL) 50 return SSH_ERR_ALLOC_FAIL; 51 return 0; 52 } 53 54 static void 55 ssh_rsa_cleanup(struct sshkey *k) 56 { 57 RSA_free(k->rsa); 58 k->rsa = NULL; 59 } 60 61 static int 62 ssh_rsa_equal(const struct sshkey *a, const struct sshkey *b) 63 { 64 const BIGNUM *rsa_e_a, *rsa_n_a; 65 const BIGNUM *rsa_e_b, *rsa_n_b; 66 67 if (a->rsa == NULL || b->rsa == NULL) 68 return 0; 69 RSA_get0_key(a->rsa, &rsa_n_a, &rsa_e_a, NULL); 70 RSA_get0_key(b->rsa, &rsa_n_b, &rsa_e_b, NULL); 71 if (rsa_e_a == NULL || rsa_e_b == NULL) 72 return 0; 73 if (rsa_n_a == NULL || rsa_n_b == NULL) 74 return 0; 75 if (BN_cmp(rsa_e_a, rsa_e_b) != 0) 76 return 0; 77 if (BN_cmp(rsa_n_a, rsa_n_b) != 0) 78 return 0; 79 return 1; 80 } 81 82 static int 83 ssh_rsa_serialize_public(const struct sshkey *key, struct sshbuf *b, 84 enum sshkey_serialize_rep opts) 85 { 86 int r; 87 const BIGNUM *rsa_n, *rsa_e; 88 89 if (key->rsa == NULL) 90 return SSH_ERR_INVALID_ARGUMENT; 91 RSA_get0_key(key->rsa, &rsa_n, &rsa_e, NULL); 92 if ((r = sshbuf_put_bignum2(b, rsa_e)) != 0 || 93 (r = sshbuf_put_bignum2(b, rsa_n)) != 0) 94 return r; 95 96 return 0; 97 } 98 99 static int 100 ssh_rsa_serialize_private(const struct sshkey *key, struct sshbuf *b, 101 enum sshkey_serialize_rep opts) 102 { 103 int r; 104 const BIGNUM *rsa_n, *rsa_e, *rsa_d, *rsa_iqmp, *rsa_p, *rsa_q; 105 106 RSA_get0_key(key->rsa, &rsa_n, &rsa_e, &rsa_d); 107 RSA_get0_factors(key->rsa, &rsa_p, &rsa_q); 108 RSA_get0_crt_params(key->rsa, NULL, NULL, &rsa_iqmp); 109 110 if (!sshkey_is_cert(key)) { 111 /* Note: can't reuse ssh_rsa_serialize_public: e, n vs. n, e */ 112 if ((r = sshbuf_put_bignum2(b, rsa_n)) != 0 || 113 (r = sshbuf_put_bignum2(b, rsa_e)) != 0) 114 return r; 115 } 116 if ((r = sshbuf_put_bignum2(b, rsa_d)) != 0 || 117 (r = sshbuf_put_bignum2(b, rsa_iqmp)) != 0 || 118 (r = sshbuf_put_bignum2(b, rsa_p)) != 0 || 119 (r = sshbuf_put_bignum2(b, rsa_q)) != 0) 120 return r; 121 122 return 0; 123 } 124 125 static int 126 ssh_rsa_generate(struct sshkey *k, int bits) 127 { 128 RSA *private = NULL; 129 BIGNUM *f4 = NULL; 130 int ret = SSH_ERR_INTERNAL_ERROR; 131 132 if (bits < SSH_RSA_MINIMUM_MODULUS_SIZE || 133 bits > SSHBUF_MAX_BIGNUM * 8) 134 return SSH_ERR_KEY_LENGTH; 135 if ((private = RSA_new()) == NULL || (f4 = BN_new()) == NULL) { 136 ret = SSH_ERR_ALLOC_FAIL; 137 goto out; 138 } 139 if (!BN_set_word(f4, RSA_F4) || 140 !RSA_generate_key_ex(private, bits, f4, NULL)) { 141 ret = SSH_ERR_LIBCRYPTO_ERROR; 142 goto out; 143 } 144 k->rsa = private; 145 private = NULL; 146 ret = 0; 147 out: 148 RSA_free(private); 149 BN_free(f4); 150 return ret; 151 } 152 153 static int 154 ssh_rsa_copy_public(const struct sshkey *from, struct sshkey *to) 155 { 156 const BIGNUM *rsa_n, *rsa_e; 157 BIGNUM *rsa_n_dup = NULL, *rsa_e_dup = NULL; 158 int r = SSH_ERR_INTERNAL_ERROR; 159 160 RSA_get0_key(from->rsa, &rsa_n, &rsa_e, NULL); 161 if ((rsa_n_dup = BN_dup(rsa_n)) == NULL || 162 (rsa_e_dup = BN_dup(rsa_e)) == NULL) { 163 r = SSH_ERR_ALLOC_FAIL; 164 goto out; 165 } 166 if (!RSA_set0_key(to->rsa, rsa_n_dup, rsa_e_dup, NULL)) { 167 r = SSH_ERR_LIBCRYPTO_ERROR; 168 goto out; 169 } 170 rsa_n_dup = rsa_e_dup = NULL; /* transferred */ 171 /* success */ 172 r = 0; 173 out: 174 BN_clear_free(rsa_n_dup); 175 BN_clear_free(rsa_e_dup); 176 return r; 177 } 178 179 static int 180 ssh_rsa_deserialize_public(const char *ktype, struct sshbuf *b, 181 struct sshkey *key) 182 { 183 int ret = SSH_ERR_INTERNAL_ERROR; 184 BIGNUM *rsa_n = NULL, *rsa_e = NULL; 185 186 if (sshbuf_get_bignum2(b, &rsa_e) != 0 || 187 sshbuf_get_bignum2(b, &rsa_n) != 0) { 188 ret = SSH_ERR_INVALID_FORMAT; 189 goto out; 190 } 191 if (!RSA_set0_key(key->rsa, rsa_n, rsa_e, NULL)) { 192 ret = SSH_ERR_LIBCRYPTO_ERROR; 193 goto out; 194 } 195 rsa_n = rsa_e = NULL; /* transferred */ 196 if ((ret = sshkey_check_rsa_length(key, 0)) != 0) 197 goto out; 198 #ifdef DEBUG_PK 199 RSA_print_fp(stderr, key->rsa, 8); 200 #endif 201 /* success */ 202 ret = 0; 203 out: 204 BN_clear_free(rsa_n); 205 BN_clear_free(rsa_e); 206 return ret; 207 } 208 209 static int 210 ssh_rsa_deserialize_private(const char *ktype, struct sshbuf *b, 211 struct sshkey *key) 212 { 213 int r; 214 BIGNUM *rsa_n = NULL, *rsa_e = NULL, *rsa_d = NULL; 215 BIGNUM *rsa_iqmp = NULL, *rsa_p = NULL, *rsa_q = NULL; 216 217 /* Note: can't reuse ssh_rsa_deserialize_public: e, n vs. n, e */ 218 if (!sshkey_is_cert(key)) { 219 if ((r = sshbuf_get_bignum2(b, &rsa_n)) != 0 || 220 (r = sshbuf_get_bignum2(b, &rsa_e)) != 0) 221 goto out; 222 if (!RSA_set0_key(key->rsa, rsa_n, rsa_e, NULL)) { 223 r = SSH_ERR_LIBCRYPTO_ERROR; 224 goto out; 225 } 226 rsa_n = rsa_e = NULL; /* transferred */ 227 } 228 if ((r = sshbuf_get_bignum2(b, &rsa_d)) != 0 || 229 (r = sshbuf_get_bignum2(b, &rsa_iqmp)) != 0 || 230 (r = sshbuf_get_bignum2(b, &rsa_p)) != 0 || 231 (r = sshbuf_get_bignum2(b, &rsa_q)) != 0) 232 goto out; 233 if (!RSA_set0_key(key->rsa, NULL, NULL, rsa_d)) { 234 r = SSH_ERR_LIBCRYPTO_ERROR; 235 goto out; 236 } 237 rsa_d = NULL; /* transferred */ 238 if (!RSA_set0_factors(key->rsa, rsa_p, rsa_q)) { 239 r = SSH_ERR_LIBCRYPTO_ERROR; 240 goto out; 241 } 242 rsa_p = rsa_q = NULL; /* transferred */ 243 if ((r = sshkey_check_rsa_length(key, 0)) != 0) 244 goto out; 245 if ((r = ssh_rsa_complete_crt_parameters(key, rsa_iqmp)) != 0) 246 goto out; 247 if (RSA_blinding_on(key->rsa, NULL) != 1) { 248 r = SSH_ERR_LIBCRYPTO_ERROR; 249 goto out; 250 } 251 /* success */ 252 r = 0; 253 out: 254 BN_clear_free(rsa_n); 255 BN_clear_free(rsa_e); 256 BN_clear_free(rsa_d); 257 BN_clear_free(rsa_p); 258 BN_clear_free(rsa_q); 259 BN_clear_free(rsa_iqmp); 260 return r; 261 } 262 263 static const char * 264 rsa_hash_alg_ident(int hash_alg) 265 { 266 switch (hash_alg) { 267 case SSH_DIGEST_SHA1: 268 return "ssh-rsa"; 269 case SSH_DIGEST_SHA256: 270 return "rsa-sha2-256"; 271 case SSH_DIGEST_SHA512: 272 return "rsa-sha2-512"; 273 } 274 return NULL; 275 } 276 277 /* 278 * Returns the hash algorithm ID for a given algorithm identifier as used 279 * inside the signature blob, 280 */ 281 static int 282 rsa_hash_id_from_ident(const char *ident) 283 { 284 if (strcmp(ident, "ssh-rsa") == 0) 285 return SSH_DIGEST_SHA1; 286 if (strcmp(ident, "rsa-sha2-256") == 0) 287 return SSH_DIGEST_SHA256; 288 if (strcmp(ident, "rsa-sha2-512") == 0) 289 return SSH_DIGEST_SHA512; 290 return -1; 291 } 292 293 /* 294 * Return the hash algorithm ID for the specified key name. This includes 295 * all the cases of rsa_hash_id_from_ident() but also the certificate key 296 * types. 297 */ 298 static int 299 rsa_hash_id_from_keyname(const char *alg) 300 { 301 int r; 302 303 if ((r = rsa_hash_id_from_ident(alg)) != -1) 304 return r; 305 if (strcmp(alg, "ssh-rsa-cert-v01@openssh.com") == 0) 306 return SSH_DIGEST_SHA1; 307 if (strcmp(alg, "rsa-sha2-256-cert-v01@openssh.com") == 0) 308 return SSH_DIGEST_SHA256; 309 if (strcmp(alg, "rsa-sha2-512-cert-v01@openssh.com") == 0) 310 return SSH_DIGEST_SHA512; 311 return -1; 312 } 313 314 static int 315 rsa_hash_alg_nid(int type) 316 { 317 switch (type) { 318 case SSH_DIGEST_SHA1: 319 return NID_sha1; 320 case SSH_DIGEST_SHA256: 321 return NID_sha256; 322 case SSH_DIGEST_SHA512: 323 return NID_sha512; 324 default: 325 return -1; 326 } 327 } 328 329 int 330 ssh_rsa_complete_crt_parameters(struct sshkey *key, const BIGNUM *iqmp) 331 { 332 const BIGNUM *rsa_p, *rsa_q, *rsa_d; 333 BIGNUM *aux = NULL, *d_consttime = NULL; 334 BIGNUM *rsa_dmq1 = NULL, *rsa_dmp1 = NULL, *rsa_iqmp = NULL; 335 BN_CTX *ctx = NULL; 336 int r; 337 338 if (key == NULL || key->rsa == NULL || 339 sshkey_type_plain(key->type) != KEY_RSA) 340 return SSH_ERR_INVALID_ARGUMENT; 341 342 RSA_get0_key(key->rsa, NULL, NULL, &rsa_d); 343 RSA_get0_factors(key->rsa, &rsa_p, &rsa_q); 344 345 if ((ctx = BN_CTX_new()) == NULL) 346 return SSH_ERR_ALLOC_FAIL; 347 if ((aux = BN_new()) == NULL || 348 (rsa_dmq1 = BN_new()) == NULL || 349 (rsa_dmp1 = BN_new()) == NULL) 350 return SSH_ERR_ALLOC_FAIL; 351 if ((d_consttime = BN_dup(rsa_d)) == NULL || 352 (rsa_iqmp = BN_dup(iqmp)) == NULL) { 353 r = SSH_ERR_ALLOC_FAIL; 354 goto out; 355 } 356 BN_set_flags(aux, BN_FLG_CONSTTIME); 357 BN_set_flags(d_consttime, BN_FLG_CONSTTIME); 358 359 if ((BN_sub(aux, rsa_q, BN_value_one()) == 0) || 360 (BN_mod(rsa_dmq1, d_consttime, aux, ctx) == 0) || 361 (BN_sub(aux, rsa_p, BN_value_one()) == 0) || 362 (BN_mod(rsa_dmp1, d_consttime, aux, ctx) == 0)) { 363 r = SSH_ERR_LIBCRYPTO_ERROR; 364 goto out; 365 } 366 if (!RSA_set0_crt_params(key->rsa, rsa_dmp1, rsa_dmq1, rsa_iqmp)) { 367 r = SSH_ERR_LIBCRYPTO_ERROR; 368 goto out; 369 } 370 rsa_dmp1 = rsa_dmq1 = rsa_iqmp = NULL; /* transferred */ 371 /* success */ 372 r = 0; 373 out: 374 BN_clear_free(aux); 375 BN_clear_free(d_consttime); 376 BN_clear_free(rsa_dmp1); 377 BN_clear_free(rsa_dmq1); 378 BN_clear_free(rsa_iqmp); 379 BN_CTX_free(ctx); 380 return r; 381 } 382 383 /* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */ 384 static int 385 ssh_rsa_sign(struct sshkey *key, 386 u_char **sigp, size_t *lenp, 387 const u_char *data, size_t datalen, 388 const char *alg, const char *sk_provider, const char *sk_pin, u_int compat) 389 { 390 const BIGNUM *rsa_n; 391 u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL; 392 size_t slen = 0; 393 u_int hlen, len; 394 int nid, hash_alg, ret = SSH_ERR_INTERNAL_ERROR; 395 struct sshbuf *b = NULL; 396 397 if (lenp != NULL) 398 *lenp = 0; 399 if (sigp != NULL) 400 *sigp = NULL; 401 402 if (alg == NULL || strlen(alg) == 0) 403 hash_alg = SSH_DIGEST_SHA1; 404 else 405 hash_alg = rsa_hash_id_from_keyname(alg); 406 if (key == NULL || key->rsa == NULL || hash_alg == -1 || 407 sshkey_type_plain(key->type) != KEY_RSA) 408 return SSH_ERR_INVALID_ARGUMENT; 409 RSA_get0_key(key->rsa, &rsa_n, NULL, NULL); 410 if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE) 411 return SSH_ERR_KEY_LENGTH; 412 slen = RSA_size(key->rsa); 413 if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM) 414 return SSH_ERR_INVALID_ARGUMENT; 415 416 /* hash the data */ 417 nid = rsa_hash_alg_nid(hash_alg); 418 if ((hlen = ssh_digest_bytes(hash_alg)) == 0) 419 return SSH_ERR_INTERNAL_ERROR; 420 if ((ret = ssh_digest_memory(hash_alg, data, datalen, 421 digest, sizeof(digest))) != 0) 422 goto out; 423 424 if ((sig = malloc(slen)) == NULL) { 425 ret = SSH_ERR_ALLOC_FAIL; 426 goto out; 427 } 428 429 if (RSA_sign(nid, digest, hlen, sig, &len, key->rsa) != 1) { 430 ret = SSH_ERR_LIBCRYPTO_ERROR; 431 goto out; 432 } 433 if (len < slen) { 434 size_t diff = slen - len; 435 memmove(sig + diff, sig, len); 436 explicit_bzero(sig, diff); 437 } else if (len > slen) { 438 ret = SSH_ERR_INTERNAL_ERROR; 439 goto out; 440 } 441 /* encode signature */ 442 if ((b = sshbuf_new()) == NULL) { 443 ret = SSH_ERR_ALLOC_FAIL; 444 goto out; 445 } 446 if ((ret = sshbuf_put_cstring(b, rsa_hash_alg_ident(hash_alg))) != 0 || 447 (ret = sshbuf_put_string(b, sig, slen)) != 0) 448 goto out; 449 len = sshbuf_len(b); 450 if (sigp != NULL) { 451 if ((*sigp = malloc(len)) == NULL) { 452 ret = SSH_ERR_ALLOC_FAIL; 453 goto out; 454 } 455 memcpy(*sigp, sshbuf_ptr(b), len); 456 } 457 if (lenp != NULL) 458 *lenp = len; 459 ret = 0; 460 out: 461 explicit_bzero(digest, sizeof(digest)); 462 freezero(sig, slen); 463 sshbuf_free(b); 464 return ret; 465 } 466 467 static int 468 ssh_rsa_verify(const struct sshkey *key, 469 const u_char *sig, size_t siglen, 470 const u_char *data, size_t dlen, const char *alg, u_int compat, 471 struct sshkey_sig_details **detailsp) 472 { 473 const BIGNUM *rsa_n; 474 char *sigtype = NULL; 475 int hash_alg, want_alg, ret = SSH_ERR_INTERNAL_ERROR; 476 size_t len = 0, diff, modlen, hlen; 477 struct sshbuf *b = NULL; 478 u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL; 479 480 if (key == NULL || key->rsa == NULL || 481 sshkey_type_plain(key->type) != KEY_RSA || 482 sig == NULL || siglen == 0) 483 return SSH_ERR_INVALID_ARGUMENT; 484 RSA_get0_key(key->rsa, &rsa_n, NULL, NULL); 485 if (BN_num_bits(rsa_n) < SSH_RSA_MINIMUM_MODULUS_SIZE) 486 return SSH_ERR_KEY_LENGTH; 487 488 if ((b = sshbuf_from(sig, siglen)) == NULL) 489 return SSH_ERR_ALLOC_FAIL; 490 if (sshbuf_get_cstring(b, &sigtype, NULL) != 0) { 491 ret = SSH_ERR_INVALID_FORMAT; 492 goto out; 493 } 494 if ((hash_alg = rsa_hash_id_from_ident(sigtype)) == -1) { 495 ret = SSH_ERR_KEY_TYPE_MISMATCH; 496 goto out; 497 } 498 /* 499 * Allow ssh-rsa-cert-v01 certs to generate SHA2 signatures for 500 * legacy reasons, but otherwise the signature type should match. 501 */ 502 if (alg != NULL && strcmp(alg, "ssh-rsa-cert-v01@openssh.com") != 0) { 503 if ((want_alg = rsa_hash_id_from_keyname(alg)) == -1) { 504 ret = SSH_ERR_INVALID_ARGUMENT; 505 goto out; 506 } 507 if (hash_alg != want_alg) { 508 ret = SSH_ERR_SIGNATURE_INVALID; 509 goto out; 510 } 511 } 512 if (sshbuf_get_string(b, &sigblob, &len) != 0) { 513 ret = SSH_ERR_INVALID_FORMAT; 514 goto out; 515 } 516 if (sshbuf_len(b) != 0) { 517 ret = SSH_ERR_UNEXPECTED_TRAILING_DATA; 518 goto out; 519 } 520 /* RSA_verify expects a signature of RSA_size */ 521 modlen = RSA_size(key->rsa); 522 if (len > modlen) { 523 ret = SSH_ERR_KEY_BITS_MISMATCH; 524 goto out; 525 } else if (len < modlen) { 526 diff = modlen - len; 527 osigblob = sigblob; 528 if ((sigblob = realloc(sigblob, modlen)) == NULL) { 529 sigblob = osigblob; /* put it back for clear/free */ 530 ret = SSH_ERR_ALLOC_FAIL; 531 goto out; 532 } 533 memmove(sigblob + diff, sigblob, len); 534 explicit_bzero(sigblob, diff); 535 len = modlen; 536 } 537 if ((hlen = ssh_digest_bytes(hash_alg)) == 0) { 538 ret = SSH_ERR_INTERNAL_ERROR; 539 goto out; 540 } 541 if ((ret = ssh_digest_memory(hash_alg, data, dlen, 542 digest, sizeof(digest))) != 0) 543 goto out; 544 545 ret = openssh_RSA_verify(hash_alg, digest, hlen, sigblob, len, 546 key->rsa); 547 out: 548 freezero(sigblob, len); 549 free(sigtype); 550 sshbuf_free(b); 551 explicit_bzero(digest, sizeof(digest)); 552 return ret; 553 } 554 555 /* 556 * See: 557 * http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/ 558 * ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn 559 */ 560 561 /* 562 * id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3) 563 * oiw(14) secsig(3) algorithms(2) 26 } 564 */ 565 static const u_char id_sha1[] = { 566 0x30, 0x21, /* type Sequence, length 0x21 (33) */ 567 0x30, 0x09, /* type Sequence, length 0x09 */ 568 0x06, 0x05, /* type OID, length 0x05 */ 569 0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */ 570 0x05, 0x00, /* NULL */ 571 0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */ 572 }; 573 574 /* 575 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html 576 * id-sha256 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) 577 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2) 578 * id-sha256(1) } 579 */ 580 static const u_char id_sha256[] = { 581 0x30, 0x31, /* type Sequence, length 0x31 (49) */ 582 0x30, 0x0d, /* type Sequence, length 0x0d (13) */ 583 0x06, 0x09, /* type OID, length 0x09 */ 584 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01, /* id-sha256 */ 585 0x05, 0x00, /* NULL */ 586 0x04, 0x20 /* Octet string, length 0x20 (32), followed by sha256 hash */ 587 }; 588 589 /* 590 * See http://csrc.nist.gov/groups/ST/crypto_apps_infra/csor/algorithms.html 591 * id-sha512 OBJECT IDENTIFIER ::= { joint-iso-itu-t(2) country(16) us(840) 592 * organization(1) gov(101) csor(3) nistAlgorithm(4) hashAlgs(2) 593 * id-sha256(3) } 594 */ 595 static const u_char id_sha512[] = { 596 0x30, 0x51, /* type Sequence, length 0x51 (81) */ 597 0x30, 0x0d, /* type Sequence, length 0x0d (13) */ 598 0x06, 0x09, /* type OID, length 0x09 */ 599 0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03, /* id-sha512 */ 600 0x05, 0x00, /* NULL */ 601 0x04, 0x40 /* Octet string, length 0x40 (64), followed by sha512 hash */ 602 }; 603 604 static int 605 rsa_hash_alg_oid(int hash_alg, const u_char **oidp, size_t *oidlenp) 606 { 607 switch (hash_alg) { 608 case SSH_DIGEST_SHA1: 609 *oidp = id_sha1; 610 *oidlenp = sizeof(id_sha1); 611 break; 612 case SSH_DIGEST_SHA256: 613 *oidp = id_sha256; 614 *oidlenp = sizeof(id_sha256); 615 break; 616 case SSH_DIGEST_SHA512: 617 *oidp = id_sha512; 618 *oidlenp = sizeof(id_sha512); 619 break; 620 default: 621 return SSH_ERR_INVALID_ARGUMENT; 622 } 623 return 0; 624 } 625 626 static int 627 openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen, 628 u_char *sigbuf, size_t siglen, RSA *rsa) 629 { 630 size_t rsasize = 0, oidlen = 0, hlen = 0; 631 int ret, len, oidmatch, hashmatch; 632 const u_char *oid = NULL; 633 u_char *decrypted = NULL; 634 635 if ((ret = rsa_hash_alg_oid(hash_alg, &oid, &oidlen)) != 0) 636 return ret; 637 ret = SSH_ERR_INTERNAL_ERROR; 638 hlen = ssh_digest_bytes(hash_alg); 639 if (hashlen != hlen) { 640 ret = SSH_ERR_INVALID_ARGUMENT; 641 goto done; 642 } 643 rsasize = RSA_size(rsa); 644 if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM || 645 siglen == 0 || siglen > rsasize) { 646 ret = SSH_ERR_INVALID_ARGUMENT; 647 goto done; 648 } 649 if ((decrypted = malloc(rsasize)) == NULL) { 650 ret = SSH_ERR_ALLOC_FAIL; 651 goto done; 652 } 653 if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa, 654 RSA_PKCS1_PADDING)) < 0) { 655 ret = SSH_ERR_LIBCRYPTO_ERROR; 656 goto done; 657 } 658 if (len < 0 || (size_t)len != hlen + oidlen) { 659 ret = SSH_ERR_INVALID_FORMAT; 660 goto done; 661 } 662 oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0; 663 hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0; 664 if (!oidmatch || !hashmatch) { 665 ret = SSH_ERR_SIGNATURE_INVALID; 666 goto done; 667 } 668 ret = 0; 669 done: 670 freezero(decrypted, rsasize); 671 return ret; 672 } 673 674 static const struct sshkey_impl_funcs sshkey_rsa_funcs = { 675 /* .size = */ ssh_rsa_size, 676 /* .alloc = */ ssh_rsa_alloc, 677 /* .cleanup = */ ssh_rsa_cleanup, 678 /* .equal = */ ssh_rsa_equal, 679 /* .ssh_serialize_public = */ ssh_rsa_serialize_public, 680 /* .ssh_deserialize_public = */ ssh_rsa_deserialize_public, 681 /* .ssh_serialize_private = */ ssh_rsa_serialize_private, 682 /* .ssh_deserialize_private = */ ssh_rsa_deserialize_private, 683 /* .generate = */ ssh_rsa_generate, 684 /* .copy_public = */ ssh_rsa_copy_public, 685 /* .sign = */ ssh_rsa_sign, 686 /* .verify = */ ssh_rsa_verify, 687 }; 688 689 const struct sshkey_impl sshkey_rsa_impl = { 690 /* .name = */ "ssh-rsa", 691 /* .shortname = */ "RSA", 692 /* .sigalg = */ NULL, 693 /* .type = */ KEY_RSA, 694 /* .nid = */ 0, 695 /* .cert = */ 0, 696 /* .sigonly = */ 0, 697 /* .keybits = */ 0, 698 /* .funcs = */ &sshkey_rsa_funcs, 699 }; 700 701 const struct sshkey_impl sshkey_rsa_cert_impl = { 702 /* .name = */ "ssh-rsa-cert-v01@openssh.com", 703 /* .shortname = */ "RSA-CERT", 704 /* .sigalg = */ NULL, 705 /* .type = */ KEY_RSA_CERT, 706 /* .nid = */ 0, 707 /* .cert = */ 1, 708 /* .sigonly = */ 0, 709 /* .keybits = */ 0, 710 /* .funcs = */ &sshkey_rsa_funcs, 711 }; 712 713 /* SHA2 signature algorithms */ 714 715 const struct sshkey_impl sshkey_rsa_sha256_impl = { 716 /* .name = */ "rsa-sha2-256", 717 /* .shortname = */ "RSA", 718 /* .sigalg = */ NULL, 719 /* .type = */ KEY_RSA, 720 /* .nid = */ 0, 721 /* .cert = */ 0, 722 /* .sigonly = */ 1, 723 /* .keybits = */ 0, 724 /* .funcs = */ &sshkey_rsa_funcs, 725 }; 726 727 const struct sshkey_impl sshkey_rsa_sha512_impl = { 728 /* .name = */ "rsa-sha2-512", 729 /* .shortname = */ "RSA", 730 /* .sigalg = */ NULL, 731 /* .type = */ KEY_RSA, 732 /* .nid = */ 0, 733 /* .cert = */ 0, 734 /* .sigonly = */ 1, 735 /* .keybits = */ 0, 736 /* .funcs = */ &sshkey_rsa_funcs, 737 }; 738 739 const struct sshkey_impl sshkey_rsa_sha256_cert_impl = { 740 /* .name = */ "rsa-sha2-256-cert-v01@openssh.com", 741 /* .shortname = */ "RSA-CERT", 742 /* .sigalg = */ "rsa-sha2-256", 743 /* .type = */ KEY_RSA_CERT, 744 /* .nid = */ 0, 745 /* .cert = */ 1, 746 /* .sigonly = */ 1, 747 /* .keybits = */ 0, 748 /* .funcs = */ &sshkey_rsa_funcs, 749 }; 750 751 const struct sshkey_impl sshkey_rsa_sha512_cert_impl = { 752 /* .name = */ "rsa-sha2-512-cert-v01@openssh.com", 753 /* .shortname = */ "RSA-CERT", 754 /* .sigalg = */ "rsa-sha2-512", 755 /* .type = */ KEY_RSA_CERT, 756 /* .nid = */ 0, 757 /* .cert = */ 1, 758 /* .sigonly = */ 1, 759 /* .keybits = */ 0, 760 /* .funcs = */ &sshkey_rsa_funcs, 761 }; 762