2 * Copyright 1995-2017 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;
75 if (bits < RSA_MIN_MODULUS_BITS) {
76 ok = 0; /* we set our own err */
77 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
81 if (primes < RSA_DEFAULT_PRIME_NUM || primes > rsa_multip_cap(bits)) {
82 ok = 0; /* we set our own err */
83 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_PRIME_NUM_INVALID);
97 /* divide bits into 'primes' pieces evenly */
101 for (i = 0; i < primes; i++)
102 bitsr[i] = (i < rmd) ? quo + 1 : quo;
104 /* We need the RSA components non-NULL */
105 if (!rsa->n && ((rsa->n = BN_new()) == NULL))
107 if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
109 if (!rsa->e && ((rsa->e = BN_new()) == NULL))
111 if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
113 if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
115 if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL))
117 if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL))
119 if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
122 /* initialize multi-prime components */
123 if (primes > RSA_DEFAULT_PRIME_NUM) {
124 rsa->version = RSA_ASN1_VERSION_MULTI;
125 prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2);
126 if (prime_infos == NULL)
128 if (rsa->prime_infos != NULL) {
129 /* could this happen? */
130 sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, rsa_multip_info_free);
132 rsa->prime_infos = prime_infos;
134 /* prime_info from 2 to |primes| -1 */
135 for (i = 2; i < primes; i++) {
136 pinfo = rsa_multip_info_new();
139 (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo);
143 if (BN_copy(rsa->e, e_value) == NULL)
146 /* generate p, q and other primes (if any) */
147 for (i = 0; i < primes; i++) {
156 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
162 if (!BN_generate_prime_ex(prime, bitsr[i] + adj, 0, NULL, NULL, cb))
165 * prime should not be equal to p, q, r_3...
166 * (those primes prior to this one)
171 for (j = 0; j < i; j++) {
179 prev_prime = sk_RSA_PRIME_INFO_value(prime_infos,
182 if (!BN_cmp(prime, prev_prime)) {
187 if (!BN_sub(r2, prime, BN_value_one()))
189 if (!BN_gcd(r1, r2, rsa->e, ctx))
193 if (!BN_GENCB_call(cb, 2, n++))
199 /* calculate n immediately to see if it's sufficient */
201 /* we get at least 2 primes */
202 if (!BN_mul(r1, rsa->p, rsa->q, ctx))
205 /* modulus n = p * q * r_3 * r_4 ... */
206 if (!BN_mul(r1, rsa->n, prime, ctx))
209 /* i == 0, do nothing */
210 if (!BN_GENCB_call(cb, 3, i))
215 * if |r1|, product of factors so far, is not as long as expected
216 * (by checking the first 4 bits are less than 0x9 or greater than
217 * 0xF). If so, re-generate the last prime.
219 * NOTE: This actually can't happen in two-prime case, because of
220 * the way factors are generated.
222 * Besides, another consideration is, for multi-prime case, even the
223 * length modulus is as long as expected, the modulus could start at
224 * 0x8, which could be utilized to distinguish a multi-prime private
225 * key by using the modulus in a certificate. This is also covered
226 * by checking the length should not be less than 0x9.
228 if (!BN_rshift(r2, r1, bitse - 4))
230 bitst = BN_get_word(r2);
232 if (bitst < 0x9 || bitst > 0xF) {
234 * For keys with more than 4 primes, we attempt longer factor to
235 * meet length requirement.
237 * Otherwise, we just re-generate the prime with the same length.
239 * This strategy has the following goals:
241 * 1. 1024-bit factors are effcient when using 3072 and 4096-bit key
242 * 2. stay the same logic with normal 2-prime key
245 if (!BN_GENCB_call(cb, 2, n++))
252 } else if (retries == 4) {
254 * re-generate all primes from scratch, mainly used
255 * in 4 prime case to avoid long loop. Max retry times
265 /* save product of primes for further use, for multi-prime only */
266 if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL)
268 if (BN_copy(rsa->n, r1) == NULL)
270 if (!BN_GENCB_call(cb, 3, i))
274 if (BN_cmp(rsa->p, rsa->q) < 0) {
283 if (!BN_sub(r1, rsa->p, BN_value_one()))
286 if (!BN_sub(r2, rsa->q, BN_value_one()))
289 if (!BN_mul(r0, r1, r2, ctx))
292 for (i = 2; i < primes; i++) {
293 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
294 /* save r_i - 1 to pinfo->d temporarily */
295 if (!BN_sub(pinfo->d, pinfo->r, BN_value_one()))
297 if (!BN_mul(r0, r0, pinfo->d, ctx))
302 BIGNUM *pr0 = BN_new();
307 BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
308 if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) {
312 /* We MUST free pr0 before any further use of r0 */
317 BIGNUM *d = BN_new();
322 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
324 /* calculate d mod (p-1) and d mod (q - 1) */
325 if (!BN_mod(rsa->dmp1, d, r1, ctx)
326 || !BN_mod(rsa->dmq1, d, r2, ctx)) {
331 /* calculate CRT exponents */
332 for (i = 2; i < primes; i++) {
333 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
334 /* pinfo->d == r_i - 1 */
335 if (!BN_mod(pinfo->d, d, pinfo->d, ctx)) {
341 /* We MUST free d before any further use of rsa->d */
346 BIGNUM *p = BN_new();
350 BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
352 /* calculate inverse of q mod p */
353 if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) {
358 /* calculate CRT coefficient for other primes */
359 for (i = 2; i < primes; i++) {
360 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
361 BN_with_flags(p, pinfo->r, BN_FLG_CONSTTIME);
362 if (!BN_mod_inverse(pinfo->t, pinfo->pp, p, ctx)) {
368 /* We MUST free p before any further use of rsa->p */
375 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);