yuezonghe | 824eb0c | 2024-06-27 02:32:26 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved. |
| 3 | * |
| 4 | * Licensed under the OpenSSL license (the "License"). You may not use |
| 5 | * this file except in compliance with the License. You can obtain a copy |
| 6 | * in the file LICENSE in the source distribution or at |
| 7 | * https://www.openssl.org/source/license.html |
| 8 | */ |
| 9 | |
| 10 | /* |
| 11 | * NB: these functions have been "upgraded", the deprecated versions (which |
| 12 | * are compatibility wrappers using these functions) are in rsa_depr.c. - |
| 13 | * Geoff |
| 14 | */ |
| 15 | |
| 16 | #include <stdio.h> |
| 17 | #include <time.h> |
| 18 | #include "internal/cryptlib.h" |
| 19 | #include <openssl/bn.h> |
| 20 | #include "rsa_local.h" |
| 21 | |
| 22 | static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value, |
| 23 | BN_GENCB *cb); |
| 24 | |
| 25 | /* |
| 26 | * NB: this wrapper would normally be placed in rsa_lib.c and the static |
| 27 | * implementation would probably be in rsa_eay.c. Nonetheless, is kept here |
| 28 | * so that we don't introduce a new linker dependency. Eg. any application |
| 29 | * that wasn't previously linking object code related to key-generation won't |
| 30 | * have to now just because key-generation is part of RSA_METHOD. |
| 31 | */ |
| 32 | int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb) |
| 33 | { |
| 34 | if (rsa->meth->rsa_keygen != NULL) |
| 35 | return rsa->meth->rsa_keygen(rsa, bits, e_value, cb); |
| 36 | |
| 37 | return RSA_generate_multi_prime_key(rsa, bits, RSA_DEFAULT_PRIME_NUM, |
| 38 | e_value, cb); |
| 39 | } |
| 40 | |
| 41 | int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, |
| 42 | BIGNUM *e_value, BN_GENCB *cb) |
| 43 | { |
| 44 | /* multi-prime is only supported with the builtin key generation */ |
| 45 | if (rsa->meth->rsa_multi_prime_keygen != NULL) { |
| 46 | return rsa->meth->rsa_multi_prime_keygen(rsa, bits, primes, |
| 47 | e_value, cb); |
| 48 | } else if (rsa->meth->rsa_keygen != NULL) { |
| 49 | /* |
| 50 | * However, if rsa->meth implements only rsa_keygen, then we |
| 51 | * have to honour it in 2-prime case and assume that it wouldn't |
| 52 | * know what to do with multi-prime key generated by builtin |
| 53 | * subroutine... |
| 54 | */ |
| 55 | if (primes == 2) |
| 56 | return rsa->meth->rsa_keygen(rsa, bits, e_value, cb); |
| 57 | else |
| 58 | return 0; |
| 59 | } |
| 60 | |
| 61 | return rsa_builtin_keygen(rsa, bits, primes, e_value, cb); |
| 62 | } |
| 63 | |
| 64 | static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value, |
| 65 | BN_GENCB *cb) |
| 66 | { |
| 67 | BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *tmp, *prime; |
| 68 | int ok = -1, n = 0, bitsr[RSA_MAX_PRIME_NUM], bitse = 0; |
| 69 | int i = 0, quo = 0, rmd = 0, adj = 0, retries = 0; |
| 70 | RSA_PRIME_INFO *pinfo = NULL; |
| 71 | STACK_OF(RSA_PRIME_INFO) *prime_infos = NULL; |
| 72 | BN_CTX *ctx = NULL; |
| 73 | BN_ULONG bitst = 0; |
| 74 | unsigned long error = 0; |
| 75 | |
| 76 | if (bits < RSA_MIN_MODULUS_BITS) { |
| 77 | ok = 0; /* we set our own err */ |
| 78 | RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL); |
| 79 | goto err; |
| 80 | } |
| 81 | |
| 82 | if (primes < RSA_DEFAULT_PRIME_NUM || primes > rsa_multip_cap(bits)) { |
| 83 | ok = 0; /* we set our own err */ |
| 84 | RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_PRIME_NUM_INVALID); |
| 85 | goto err; |
| 86 | } |
| 87 | |
| 88 | ctx = BN_CTX_new(); |
| 89 | if (ctx == NULL) |
| 90 | goto err; |
| 91 | BN_CTX_start(ctx); |
| 92 | r0 = BN_CTX_get(ctx); |
| 93 | r1 = BN_CTX_get(ctx); |
| 94 | r2 = BN_CTX_get(ctx); |
| 95 | if (r2 == NULL) |
| 96 | goto err; |
| 97 | |
| 98 | /* divide bits into 'primes' pieces evenly */ |
| 99 | quo = bits / primes; |
| 100 | rmd = bits % primes; |
| 101 | |
| 102 | for (i = 0; i < primes; i++) |
| 103 | bitsr[i] = (i < rmd) ? quo + 1 : quo; |
| 104 | |
| 105 | /* We need the RSA components non-NULL */ |
| 106 | if (!rsa->n && ((rsa->n = BN_new()) == NULL)) |
| 107 | goto err; |
| 108 | if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL)) |
| 109 | goto err; |
| 110 | if (!rsa->e && ((rsa->e = BN_new()) == NULL)) |
| 111 | goto err; |
| 112 | if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL)) |
| 113 | goto err; |
| 114 | if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL)) |
| 115 | goto err; |
| 116 | if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL)) |
| 117 | goto err; |
| 118 | if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL)) |
| 119 | goto err; |
| 120 | if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL)) |
| 121 | goto err; |
| 122 | |
| 123 | /* initialize multi-prime components */ |
| 124 | if (primes > RSA_DEFAULT_PRIME_NUM) { |
| 125 | rsa->version = RSA_ASN1_VERSION_MULTI; |
| 126 | prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2); |
| 127 | if (prime_infos == NULL) |
| 128 | goto err; |
| 129 | if (rsa->prime_infos != NULL) { |
| 130 | /* could this happen? */ |
| 131 | sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, rsa_multip_info_free); |
| 132 | } |
| 133 | rsa->prime_infos = prime_infos; |
| 134 | |
| 135 | /* prime_info from 2 to |primes| -1 */ |
| 136 | for (i = 2; i < primes; i++) { |
| 137 | pinfo = rsa_multip_info_new(); |
| 138 | if (pinfo == NULL) |
| 139 | goto err; |
| 140 | (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo); |
| 141 | } |
| 142 | } |
| 143 | |
| 144 | if (BN_copy(rsa->e, e_value) == NULL) |
| 145 | goto err; |
| 146 | |
| 147 | /* generate p, q and other primes (if any) */ |
| 148 | for (i = 0; i < primes; i++) { |
| 149 | adj = 0; |
| 150 | retries = 0; |
| 151 | |
| 152 | if (i == 0) { |
| 153 | prime = rsa->p; |
| 154 | } else if (i == 1) { |
| 155 | prime = rsa->q; |
| 156 | } else { |
| 157 | pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); |
| 158 | prime = pinfo->r; |
| 159 | } |
| 160 | BN_set_flags(prime, BN_FLG_CONSTTIME); |
| 161 | |
| 162 | for (;;) { |
| 163 | redo: |
| 164 | if (!BN_generate_prime_ex(prime, bitsr[i] + adj, 0, NULL, NULL, cb)) |
| 165 | goto err; |
| 166 | /* |
| 167 | * prime should not be equal to p, q, r_3... |
| 168 | * (those primes prior to this one) |
| 169 | */ |
| 170 | { |
| 171 | int j; |
| 172 | |
| 173 | for (j = 0; j < i; j++) { |
| 174 | BIGNUM *prev_prime; |
| 175 | |
| 176 | if (j == 0) |
| 177 | prev_prime = rsa->p; |
| 178 | else if (j == 1) |
| 179 | prev_prime = rsa->q; |
| 180 | else |
| 181 | prev_prime = sk_RSA_PRIME_INFO_value(prime_infos, |
| 182 | j - 2)->r; |
| 183 | |
| 184 | if (!BN_cmp(prime, prev_prime)) { |
| 185 | goto redo; |
| 186 | } |
| 187 | } |
| 188 | } |
| 189 | if (!BN_sub(r2, prime, BN_value_one())) |
| 190 | goto err; |
| 191 | ERR_set_mark(); |
| 192 | BN_set_flags(r2, BN_FLG_CONSTTIME); |
| 193 | if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) { |
| 194 | /* GCD == 1 since inverse exists */ |
| 195 | break; |
| 196 | } |
| 197 | error = ERR_peek_last_error(); |
| 198 | if (ERR_GET_LIB(error) == ERR_LIB_BN |
| 199 | && ERR_GET_REASON(error) == BN_R_NO_INVERSE) { |
| 200 | /* GCD != 1 */ |
| 201 | ERR_pop_to_mark(); |
| 202 | } else { |
| 203 | goto err; |
| 204 | } |
| 205 | if (!BN_GENCB_call(cb, 2, n++)) |
| 206 | goto err; |
| 207 | } |
| 208 | |
| 209 | bitse += bitsr[i]; |
| 210 | |
| 211 | /* calculate n immediately to see if it's sufficient */ |
| 212 | if (i == 1) { |
| 213 | /* we get at least 2 primes */ |
| 214 | if (!BN_mul(r1, rsa->p, rsa->q, ctx)) |
| 215 | goto err; |
| 216 | } else if (i != 0) { |
| 217 | /* modulus n = p * q * r_3 * r_4 ... */ |
| 218 | if (!BN_mul(r1, rsa->n, prime, ctx)) |
| 219 | goto err; |
| 220 | } else { |
| 221 | /* i == 0, do nothing */ |
| 222 | if (!BN_GENCB_call(cb, 3, i)) |
| 223 | goto err; |
| 224 | continue; |
| 225 | } |
| 226 | /* |
| 227 | * if |r1|, product of factors so far, is not as long as expected |
| 228 | * (by checking the first 4 bits are less than 0x9 or greater than |
| 229 | * 0xF). If so, re-generate the last prime. |
| 230 | * |
| 231 | * NOTE: This actually can't happen in two-prime case, because of |
| 232 | * the way factors are generated. |
| 233 | * |
| 234 | * Besides, another consideration is, for multi-prime case, even the |
| 235 | * length modulus is as long as expected, the modulus could start at |
| 236 | * 0x8, which could be utilized to distinguish a multi-prime private |
| 237 | * key by using the modulus in a certificate. This is also covered |
| 238 | * by checking the length should not be less than 0x9. |
| 239 | */ |
| 240 | if (!BN_rshift(r2, r1, bitse - 4)) |
| 241 | goto err; |
| 242 | bitst = BN_get_word(r2); |
| 243 | |
| 244 | if (bitst < 0x9 || bitst > 0xF) { |
| 245 | /* |
| 246 | * For keys with more than 4 primes, we attempt longer factor to |
| 247 | * meet length requirement. |
| 248 | * |
| 249 | * Otherwise, we just re-generate the prime with the same length. |
| 250 | * |
| 251 | * This strategy has the following goals: |
| 252 | * |
| 253 | * 1. 1024-bit factors are efficient when using 3072 and 4096-bit key |
| 254 | * 2. stay the same logic with normal 2-prime key |
| 255 | */ |
| 256 | bitse -= bitsr[i]; |
| 257 | if (!BN_GENCB_call(cb, 2, n++)) |
| 258 | goto err; |
| 259 | if (primes > 4) { |
| 260 | if (bitst < 0x9) |
| 261 | adj++; |
| 262 | else |
| 263 | adj--; |
| 264 | } else if (retries == 4) { |
| 265 | /* |
| 266 | * re-generate all primes from scratch, mainly used |
| 267 | * in 4 prime case to avoid long loop. Max retry times |
| 268 | * is set to 4. |
| 269 | */ |
| 270 | i = -1; |
| 271 | bitse = 0; |
| 272 | continue; |
| 273 | } |
| 274 | retries++; |
| 275 | goto redo; |
| 276 | } |
| 277 | /* save product of primes for further use, for multi-prime only */ |
| 278 | if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL) |
| 279 | goto err; |
| 280 | if (BN_copy(rsa->n, r1) == NULL) |
| 281 | goto err; |
| 282 | if (!BN_GENCB_call(cb, 3, i)) |
| 283 | goto err; |
| 284 | } |
| 285 | |
| 286 | if (BN_cmp(rsa->p, rsa->q) < 0) { |
| 287 | tmp = rsa->p; |
| 288 | rsa->p = rsa->q; |
| 289 | rsa->q = tmp; |
| 290 | } |
| 291 | |
| 292 | /* calculate d */ |
| 293 | |
| 294 | /* p - 1 */ |
| 295 | if (!BN_sub(r1, rsa->p, BN_value_one())) |
| 296 | goto err; |
| 297 | /* q - 1 */ |
| 298 | if (!BN_sub(r2, rsa->q, BN_value_one())) |
| 299 | goto err; |
| 300 | /* (p - 1)(q - 1) */ |
| 301 | if (!BN_mul(r0, r1, r2, ctx)) |
| 302 | goto err; |
| 303 | /* multi-prime */ |
| 304 | for (i = 2; i < primes; i++) { |
| 305 | pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); |
| 306 | /* save r_i - 1 to pinfo->d temporarily */ |
| 307 | if (!BN_sub(pinfo->d, pinfo->r, BN_value_one())) |
| 308 | goto err; |
| 309 | if (!BN_mul(r0, r0, pinfo->d, ctx)) |
| 310 | goto err; |
| 311 | } |
| 312 | |
| 313 | { |
| 314 | BIGNUM *pr0 = BN_new(); |
| 315 | |
| 316 | if (pr0 == NULL) |
| 317 | goto err; |
| 318 | |
| 319 | BN_with_flags(pr0, r0, BN_FLG_CONSTTIME); |
| 320 | if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) { |
| 321 | BN_free(pr0); |
| 322 | goto err; /* d */ |
| 323 | } |
| 324 | /* We MUST free pr0 before any further use of r0 */ |
| 325 | BN_free(pr0); |
| 326 | } |
| 327 | |
| 328 | { |
| 329 | BIGNUM *d = BN_new(); |
| 330 | |
| 331 | if (d == NULL) |
| 332 | goto err; |
| 333 | |
| 334 | BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME); |
| 335 | |
| 336 | /* calculate d mod (p-1) and d mod (q - 1) */ |
| 337 | if (!BN_mod(rsa->dmp1, d, r1, ctx) |
| 338 | || !BN_mod(rsa->dmq1, d, r2, ctx)) { |
| 339 | BN_free(d); |
| 340 | goto err; |
| 341 | } |
| 342 | |
| 343 | /* calculate CRT exponents */ |
| 344 | for (i = 2; i < primes; i++) { |
| 345 | pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); |
| 346 | /* pinfo->d == r_i - 1 */ |
| 347 | if (!BN_mod(pinfo->d, d, pinfo->d, ctx)) { |
| 348 | BN_free(d); |
| 349 | goto err; |
| 350 | } |
| 351 | } |
| 352 | |
| 353 | /* We MUST free d before any further use of rsa->d */ |
| 354 | BN_free(d); |
| 355 | } |
| 356 | |
| 357 | { |
| 358 | BIGNUM *p = BN_new(); |
| 359 | |
| 360 | if (p == NULL) |
| 361 | goto err; |
| 362 | BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME); |
| 363 | |
| 364 | /* calculate inverse of q mod p */ |
| 365 | if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) { |
| 366 | BN_free(p); |
| 367 | goto err; |
| 368 | } |
| 369 | |
| 370 | /* calculate CRT coefficient for other primes */ |
| 371 | for (i = 2; i < primes; i++) { |
| 372 | pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); |
| 373 | BN_with_flags(p, pinfo->r, BN_FLG_CONSTTIME); |
| 374 | if (!BN_mod_inverse(pinfo->t, pinfo->pp, p, ctx)) { |
| 375 | BN_free(p); |
| 376 | goto err; |
| 377 | } |
| 378 | } |
| 379 | |
| 380 | /* We MUST free p before any further use of rsa->p */ |
| 381 | BN_free(p); |
| 382 | } |
| 383 | |
| 384 | ok = 1; |
| 385 | err: |
| 386 | if (ok == -1) { |
| 387 | RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN); |
| 388 | ok = 0; |
| 389 | } |
| 390 | BN_CTX_end(ctx); |
| 391 | BN_CTX_free(ctx); |
| 392 | return ok; |
| 393 | } |