1 /* $OpenBSD: dsa_lib.c,v 1.48 2024/03/27 01:49:31 tb Exp $ */ 2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 3 * All rights reserved. 4 * 5 * This package is an SSL implementation written 6 * by Eric Young (eay@cryptsoft.com). 7 * The implementation was written so as to conform with Netscapes SSL. 8 * 9 * This library is free for commercial and non-commercial use as long as 10 * the following conditions are aheared to. The following conditions 11 * apply to all code found in this distribution, be it the RC4, RSA, 12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 13 * included with this distribution is covered by the same copyright terms 14 * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15 * 16 * Copyright remains Eric Young's, and as such any Copyright notices in 17 * the code are not to be removed. 18 * If this package is used in a product, Eric Young should be given attribution 19 * as the author of the parts of the library used. 20 * This can be in the form of a textual message at program startup or 21 * in documentation (online or textual) provided with the package. 22 * 23 * Redistribution and use in source and binary forms, with or without 24 * modification, are permitted provided that the following conditions 25 * are met: 26 * 1. Redistributions of source code must retain the copyright 27 * notice, this list of conditions and the following disclaimer. 28 * 2. Redistributions in binary form must reproduce the above copyright 29 * notice, this list of conditions and the following disclaimer in the 30 * documentation and/or other materials provided with the distribution. 31 * 3. All advertising materials mentioning features or use of this software 32 * must display the following acknowledgement: 33 * "This product includes cryptographic software written by 34 * Eric Young (eay@cryptsoft.com)" 35 * The word 'cryptographic' can be left out if the rouines from the library 36 * being used are not cryptographic related :-). 37 * 4. If you include any Windows specific code (or a derivative thereof) from 38 * the apps directory (application code) you must include an acknowledgement: 39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40 * 41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 51 * SUCH DAMAGE. 52 * 53 * The licence and distribution terms for any publically available version or 54 * derivative of this code cannot be changed. i.e. this code cannot simply be 55 * copied and put under another distribution licence 56 * [including the GNU Public Licence.] 57 */ 58 59 /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */ 60 61 #include <stdio.h> 62 63 #include <openssl/opensslconf.h> 64 65 #include <openssl/asn1.h> 66 #include <openssl/bn.h> 67 #include <openssl/dsa.h> 68 #include <openssl/err.h> 69 70 #ifndef OPENSSL_NO_DH 71 #include <openssl/dh.h> 72 #endif 73 74 #include "dh_local.h" 75 #include "dsa_local.h" 76 77 static const DSA_METHOD *default_DSA_method = NULL; 78 79 void 80 DSA_set_default_method(const DSA_METHOD *meth) 81 { 82 default_DSA_method = meth; 83 } 84 LCRYPTO_ALIAS(DSA_set_default_method); 85 86 const DSA_METHOD * 87 DSA_get_default_method(void) 88 { 89 if (!default_DSA_method) 90 default_DSA_method = DSA_OpenSSL(); 91 return default_DSA_method; 92 } 93 LCRYPTO_ALIAS(DSA_get_default_method); 94 95 DSA * 96 DSA_new(void) 97 { 98 return DSA_new_method(NULL); 99 } 100 LCRYPTO_ALIAS(DSA_new); 101 102 int 103 DSA_set_method(DSA *dsa, const DSA_METHOD *meth) 104 { 105 /* 106 * NB: The caller is specifically setting a method, so it's not up to us 107 * to deal with which ENGINE it comes from. 108 */ 109 const DSA_METHOD *mtmp; 110 mtmp = dsa->meth; 111 if (mtmp->finish) 112 mtmp->finish(dsa); 113 dsa->meth = meth; 114 if (meth->init) 115 meth->init(dsa); 116 return 1; 117 } 118 LCRYPTO_ALIAS(DSA_set_method); 119 120 DSA * 121 DSA_new_method(ENGINE *engine) 122 { 123 DSA *dsa; 124 125 if ((dsa = calloc(1, sizeof(DSA))) == NULL) { 126 DSAerror(ERR_R_MALLOC_FAILURE); 127 goto err; 128 } 129 130 dsa->meth = DSA_get_default_method(); 131 dsa->flags = dsa->meth->flags & ~DSA_FLAG_NON_FIPS_ALLOW; 132 dsa->references = 1; 133 134 if (!CRYPTO_new_ex_data(CRYPTO_EX_INDEX_DSA, dsa, &dsa->ex_data)) 135 goto err; 136 if (dsa->meth->init != NULL && !dsa->meth->init(dsa)) 137 goto err; 138 139 return dsa; 140 141 err: 142 DSA_free(dsa); 143 144 return NULL; 145 } 146 LCRYPTO_ALIAS(DSA_new_method); 147 148 void 149 DSA_free(DSA *dsa) 150 { 151 if (dsa == NULL) 152 return; 153 154 if (CRYPTO_add(&dsa->references, -1, CRYPTO_LOCK_DSA) > 0) 155 return; 156 157 if (dsa->meth != NULL && dsa->meth->finish != NULL) 158 dsa->meth->finish(dsa); 159 160 CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DSA, dsa, &dsa->ex_data); 161 162 BN_free(dsa->p); 163 BN_free(dsa->q); 164 BN_free(dsa->g); 165 BN_free(dsa->pub_key); 166 BN_free(dsa->priv_key); 167 BN_free(dsa->kinv); 168 BN_free(dsa->r); 169 free(dsa); 170 } 171 LCRYPTO_ALIAS(DSA_free); 172 173 int 174 DSA_up_ref(DSA *dsa) 175 { 176 return CRYPTO_add(&dsa->references, 1, CRYPTO_LOCK_DSA) > 1; 177 } 178 LCRYPTO_ALIAS(DSA_up_ref); 179 180 int 181 DSA_size(const DSA *dsa) 182 { 183 DSA_SIG signature; 184 int ret = 0; 185 186 signature.r = dsa->q; 187 signature.s = dsa->q; 188 189 if ((ret = i2d_DSA_SIG(&signature, NULL)) < 0) 190 ret = 0; 191 192 return ret; 193 } 194 LCRYPTO_ALIAS(DSA_size); 195 196 int 197 DSA_get_ex_new_index(long argl, void *argp, CRYPTO_EX_new *new_func, 198 CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func) 199 { 200 return CRYPTO_get_ex_new_index(CRYPTO_EX_INDEX_DSA, argl, argp, 201 new_func, dup_func, free_func); 202 } 203 LCRYPTO_ALIAS(DSA_get_ex_new_index); 204 205 int 206 DSA_set_ex_data(DSA *dsa, int idx, void *arg) 207 { 208 return CRYPTO_set_ex_data(&dsa->ex_data, idx, arg); 209 } 210 LCRYPTO_ALIAS(DSA_set_ex_data); 211 212 void * 213 DSA_get_ex_data(DSA *dsa, int idx) 214 { 215 return CRYPTO_get_ex_data(&dsa->ex_data, idx); 216 } 217 LCRYPTO_ALIAS(DSA_get_ex_data); 218 219 int 220 DSA_security_bits(const DSA *dsa) 221 { 222 if (dsa->p == NULL || dsa->q == NULL) 223 return -1; 224 225 return BN_security_bits(BN_num_bits(dsa->p), BN_num_bits(dsa->q)); 226 } 227 LCRYPTO_ALIAS(DSA_security_bits); 228 229 #ifndef OPENSSL_NO_DH 230 DH * 231 DSA_dup_DH(const DSA *dsa) 232 { 233 /* 234 * DSA has p, q, g, optional pub_key, optional priv_key. 235 * DH has p, optional length, g, optional pub_key, optional priv_key, 236 * optional q. 237 */ 238 DH *dh = NULL; 239 240 if (dsa == NULL) 241 goto err; 242 243 if ((dh = DH_new()) == NULL) 244 goto err; 245 246 if (dsa->p != NULL) { 247 if ((dh->p = BN_dup(dsa->p)) == NULL) 248 goto err; 249 } 250 if (dsa->q != NULL) { 251 dh->length = BN_num_bits(dsa->q); 252 if ((dh->q = BN_dup(dsa->q)) == NULL) 253 goto err; 254 } 255 if (dsa->g != NULL) { 256 if ((dh->g = BN_dup(dsa->g)) == NULL) 257 goto err; 258 } 259 if (dsa->pub_key != NULL) { 260 if ((dh->pub_key = BN_dup(dsa->pub_key)) == NULL) 261 goto err; 262 } 263 if (dsa->priv_key != NULL) { 264 if ((dh->priv_key = BN_dup(dsa->priv_key)) == NULL) 265 goto err; 266 } 267 268 return dh; 269 270 err: 271 DH_free(dh); 272 return NULL; 273 } 274 LCRYPTO_ALIAS(DSA_dup_DH); 275 #endif 276 277 void 278 DSA_get0_pqg(const DSA *dsa, const BIGNUM **p, const BIGNUM **q, const BIGNUM **g) 279 { 280 if (p != NULL) 281 *p = dsa->p; 282 if (q != NULL) 283 *q = dsa->q; 284 if (g != NULL) 285 *g = dsa->g; 286 } 287 LCRYPTO_ALIAS(DSA_get0_pqg); 288 289 int 290 DSA_set0_pqg(DSA *dsa, BIGNUM *p, BIGNUM *q, BIGNUM *g) 291 { 292 if ((dsa->p == NULL && p == NULL) || (dsa->q == NULL && q == NULL) || 293 (dsa->g == NULL && g == NULL)) 294 return 0; 295 296 if (p != NULL) { 297 BN_free(dsa->p); 298 dsa->p = p; 299 } 300 if (q != NULL) { 301 BN_free(dsa->q); 302 dsa->q = q; 303 } 304 if (g != NULL) { 305 BN_free(dsa->g); 306 dsa->g = g; 307 } 308 309 return 1; 310 } 311 LCRYPTO_ALIAS(DSA_set0_pqg); 312 313 void 314 DSA_get0_key(const DSA *dsa, const BIGNUM **pub_key, const BIGNUM **priv_key) 315 { 316 if (pub_key != NULL) 317 *pub_key = dsa->pub_key; 318 if (priv_key != NULL) 319 *priv_key = dsa->priv_key; 320 } 321 LCRYPTO_ALIAS(DSA_get0_key); 322 323 int 324 DSA_set0_key(DSA *dsa, BIGNUM *pub_key, BIGNUM *priv_key) 325 { 326 if (dsa->pub_key == NULL && pub_key == NULL) 327 return 0; 328 329 if (pub_key != NULL) { 330 BN_free(dsa->pub_key); 331 dsa->pub_key = pub_key; 332 } 333 if (priv_key != NULL) { 334 BN_free(dsa->priv_key); 335 dsa->priv_key = priv_key; 336 } 337 338 return 1; 339 } 340 LCRYPTO_ALIAS(DSA_set0_key); 341 342 const BIGNUM * 343 DSA_get0_p(const DSA *dsa) 344 { 345 return dsa->p; 346 } 347 LCRYPTO_ALIAS(DSA_get0_p); 348 349 const BIGNUM * 350 DSA_get0_q(const DSA *dsa) 351 { 352 return dsa->q; 353 } 354 LCRYPTO_ALIAS(DSA_get0_q); 355 356 const BIGNUM * 357 DSA_get0_g(const DSA *dsa) 358 { 359 return dsa->g; 360 } 361 LCRYPTO_ALIAS(DSA_get0_g); 362 363 const BIGNUM * 364 DSA_get0_pub_key(const DSA *dsa) 365 { 366 return dsa->pub_key; 367 } 368 LCRYPTO_ALIAS(DSA_get0_pub_key); 369 370 const BIGNUM * 371 DSA_get0_priv_key(const DSA *dsa) 372 { 373 return dsa->priv_key; 374 } 375 LCRYPTO_ALIAS(DSA_get0_priv_key); 376 377 void 378 DSA_clear_flags(DSA *dsa, int flags) 379 { 380 dsa->flags &= ~flags; 381 } 382 LCRYPTO_ALIAS(DSA_clear_flags); 383 384 int 385 DSA_test_flags(const DSA *dsa, int flags) 386 { 387 return dsa->flags & flags; 388 } 389 LCRYPTO_ALIAS(DSA_test_flags); 390 391 void 392 DSA_set_flags(DSA *dsa, int flags) 393 { 394 dsa->flags |= flags; 395 } 396 LCRYPTO_ALIAS(DSA_set_flags); 397 398 ENGINE * 399 DSA_get0_engine(DSA *dsa) 400 { 401 return NULL; 402 } 403 LCRYPTO_ALIAS(DSA_get0_engine); 404 405 int 406 DSA_bits(const DSA *dsa) 407 { 408 return BN_num_bits(dsa->p); 409 } 410 LCRYPTO_ALIAS(DSA_bits); 411 412 int 413 dsa_check_key(const DSA *dsa) 414 { 415 int p_bits, q_bits; 416 417 if (dsa->p == NULL || dsa->q == NULL || dsa->g == NULL) { 418 DSAerror(DSA_R_MISSING_PARAMETERS); 419 return 0; 420 } 421 422 /* Checking that p and q are primes is expensive. Check they are odd. */ 423 if (!BN_is_odd(dsa->p) || !BN_is_odd(dsa->q)) { 424 DSAerror(DSA_R_INVALID_PARAMETERS); 425 return 0; 426 } 427 428 /* FIPS 186-4: 1 < g < p. */ 429 if (BN_cmp(dsa->g, BN_value_one()) <= 0 || 430 BN_cmp(dsa->g, dsa->p) >= 0) { 431 DSAerror(DSA_R_INVALID_PARAMETERS); 432 return 0; 433 } 434 435 /* We know p and g are positive. The next two checks imply q > 0. */ 436 if (BN_is_negative(dsa->q)) { 437 DSAerror(DSA_R_BAD_Q_VALUE); 438 return 0; 439 } 440 441 /* FIPS 186-4 only allows three sizes for q. */ 442 q_bits = BN_num_bits(dsa->q); 443 if (q_bits != 160 && q_bits != 224 && q_bits != 256) { 444 DSAerror(DSA_R_BAD_Q_VALUE); 445 return 0; 446 } 447 448 /* 449 * XXX - FIPS 186-4 only allows 1024, 2048, and 3072 bits for p. 450 * Cap the size to reduce DoS risks. Poor defaults make keys with 451 * incorrect p sizes >= 512 bits common, so only enforce a weak 452 * lower bound. 453 */ 454 p_bits = BN_num_bits(dsa->p); 455 if (p_bits > OPENSSL_DSA_MAX_MODULUS_BITS) { 456 DSAerror(DSA_R_MODULUS_TOO_LARGE); 457 return 0; 458 } 459 if (p_bits < 512) { 460 DSAerror(DSA_R_INVALID_PARAMETERS); 461 return 0; 462 } 463 464 /* The public key must be in the multiplicative group (mod p). */ 465 if (dsa->pub_key != NULL) { 466 if (BN_cmp(dsa->pub_key, BN_value_one()) <= 0 || 467 BN_cmp(dsa->pub_key, dsa->p) >= 0) { 468 DSAerror(DSA_R_INVALID_PARAMETERS); 469 return 0; 470 } 471 } 472 473 /* The private key must be nonzero and in GF(q). */ 474 if (dsa->priv_key != NULL) { 475 if (BN_cmp(dsa->priv_key, BN_value_one()) < 0 || 476 BN_cmp(dsa->priv_key, dsa->q) >= 0) { 477 DSAerror(DSA_R_INVALID_PARAMETERS); 478 return 0; 479 } 480 } 481 482 return 1; 483 } 484