2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
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
11 * NB: these functions have been "upgraded", the deprecated versions (which
12 * are compatibility wrappers using these functions) are in rsa_depr.c. -
18 #include "internal/cryptlib.h"
19 #include <openssl/bn.h>
22 static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value,
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.
32 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
34 if (rsa->meth->rsa_keygen != NULL)
35 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
37 return RSA_generate_multi_prime_key(rsa, bits, RSA_DEFAULT_PRIME_NUM,
41 int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes,
42 BIGNUM *e_value, BN_GENCB *cb)
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,
48 } else if (rsa->meth->rsa_keygen != NULL) {
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
56 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
61 return rsa_builtin_keygen(rsa, bits, primes, e_value, cb);
64 static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value,
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;
74 unsigned long error = 0;
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);
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);
98 /* divide bits into 'primes' pieces evenly */
102 for (i = 0; i < primes; i++)
103 bitsr[i] = (i < rmd) ? quo + 1 : quo;
105 /* We need the RSA components non-NULL */
106 if (!rsa->n && ((rsa->n = BN_new()) == NULL))
108 if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
110 if (!rsa->e && ((rsa->e = BN_new()) == NULL))
112 if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
114 if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
116 if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL))
118 if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL))
120 if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
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)
129 if (rsa->prime_infos != NULL) {
130 /* could this happen? */
131 sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, rsa_multip_info_free);
133 rsa->prime_infos = prime_infos;
135 /* prime_info from 2 to |primes| -1 */
136 for (i = 2; i < primes; i++) {
137 pinfo = rsa_multip_info_new();
140 (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo);
144 if (BN_copy(rsa->e, e_value) == NULL)
147 /* generate p, q and other primes (if any) */
148 for (i = 0; i < primes; i++) {
157 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
160 BN_set_flags(prime, BN_FLG_CONSTTIME);
164 if (!BN_generate_prime_ex(prime, bitsr[i] + adj, 0, NULL, NULL, cb))
167 * prime should not be equal to p, q, r_3...
168 * (those primes prior to this one)
173 for (j = 0; j < i; j++) {
181 prev_prime = sk_RSA_PRIME_INFO_value(prime_infos,
184 if (!BN_cmp(prime, prev_prime)) {
189 if (!BN_sub(r2, prime, BN_value_one()))
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 */
197 error = ERR_peek_last_error();
198 if (ERR_GET_LIB(error) == ERR_LIB_BN
199 && ERR_GET_REASON(error) == BN_R_NO_INVERSE) {
205 if (!BN_GENCB_call(cb, 2, n++))
211 /* calculate n immediately to see if it's sufficient */
213 /* we get at least 2 primes */
214 if (!BN_mul(r1, rsa->p, rsa->q, ctx))
217 /* modulus n = p * q * r_3 * r_4 ... */
218 if (!BN_mul(r1, rsa->n, prime, ctx))
221 /* i == 0, do nothing */
222 if (!BN_GENCB_call(cb, 3, i))
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.
231 * NOTE: This actually can't happen in two-prime case, because of
232 * the way factors are generated.
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.
240 if (!BN_rshift(r2, r1, bitse - 4))
242 bitst = BN_get_word(r2);
244 if (bitst < 0x9 || bitst > 0xF) {
246 * For keys with more than 4 primes, we attempt longer factor to
247 * meet length requirement.
249 * Otherwise, we just re-generate the prime with the same length.
251 * This strategy has the following goals:
253 * 1. 1024-bit factors are effcient when using 3072 and 4096-bit key
254 * 2. stay the same logic with normal 2-prime key
257 if (!BN_GENCB_call(cb, 2, n++))
264 } else if (retries == 4) {
266 * re-generate all primes from scratch, mainly used
267 * in 4 prime case to avoid long loop. Max retry times
277 /* save product of primes for further use, for multi-prime only */
278 if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL)
280 if (BN_copy(rsa->n, r1) == NULL)
282 if (!BN_GENCB_call(cb, 3, i))
286 if (BN_cmp(rsa->p, rsa->q) < 0) {
295 if (!BN_sub(r1, rsa->p, BN_value_one()))
298 if (!BN_sub(r2, rsa->q, BN_value_one()))
301 if (!BN_mul(r0, r1, r2, ctx))
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()))
309 if (!BN_mul(r0, r0, pinfo->d, ctx))
314 BIGNUM *pr0 = BN_new();
319 BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
320 if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) {
324 /* We MUST free pr0 before any further use of r0 */
329 BIGNUM *d = BN_new();
334 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
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)) {
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)) {
353 /* We MUST free d before any further use of rsa->d */
358 BIGNUM *p = BN_new();
362 BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
364 /* calculate inverse of q mod p */
365 if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) {
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)) {
380 /* We MUST free p before any further use of rsa->p */
387 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);