2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (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)
45 /* multi-prime is only supported with the builtin key generation */
46 if (rsa->meth->rsa_multi_prime_keygen != NULL) {
47 return rsa->meth->rsa_multi_prime_keygen(rsa, bits, primes,
49 } else if (rsa->meth->rsa_keygen != NULL) {
51 * However, if rsa->meth implements only rsa_keygen, then we
52 * have to honour it in 2-prime case and assume that it wouldn't
53 * know what to do with multi-prime key generated by builtin
57 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
61 #endif /* FIPS_MODE */
62 return rsa_builtin_keygen(rsa, bits, primes, e_value, cb);
65 static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value,
71 return rsa_sp800_56b_generate_key(rsa, bits, e_value, cb);
73 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *tmp, *prime;
74 int ok = -1, n = 0, bitsr[RSA_MAX_PRIME_NUM], bitse = 0;
75 int i = 0, quo = 0, rmd = 0, adj = 0, retries = 0;
76 RSA_PRIME_INFO *pinfo = NULL;
77 STACK_OF(RSA_PRIME_INFO) *prime_infos = NULL;
80 unsigned long error = 0;
82 if (bits < RSA_MIN_MODULUS_BITS) {
83 ok = 0; /* we set our own err */
84 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
88 if (primes < RSA_DEFAULT_PRIME_NUM || primes > rsa_multip_cap(bits)) {
89 ok = 0; /* we set our own err */
90 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_PRIME_NUM_INVALID);
100 r2 = BN_CTX_get(ctx);
104 /* divide bits into 'primes' pieces evenly */
108 for (i = 0; i < primes; i++)
109 bitsr[i] = (i < rmd) ? quo + 1 : quo;
111 /* We need the RSA components non-NULL */
112 if (!rsa->n && ((rsa->n = BN_new()) == NULL))
114 if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
116 if (!rsa->e && ((rsa->e = BN_new()) == NULL))
118 if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
120 if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
122 if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL))
124 if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL))
126 if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
129 /* initialize multi-prime components */
130 if (primes > RSA_DEFAULT_PRIME_NUM) {
131 rsa->version = RSA_ASN1_VERSION_MULTI;
132 prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2);
133 if (prime_infos == NULL)
135 if (rsa->prime_infos != NULL) {
136 /* could this happen? */
137 sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, rsa_multip_info_free);
139 rsa->prime_infos = prime_infos;
141 /* prime_info from 2 to |primes| -1 */
142 for (i = 2; i < primes; i++) {
143 pinfo = rsa_multip_info_new();
146 (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo);
150 if (BN_copy(rsa->e, e_value) == NULL)
153 /* generate p, q and other primes (if any) */
154 for (i = 0; i < primes; i++) {
163 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
166 BN_set_flags(prime, BN_FLG_CONSTTIME);
170 if (!BN_generate_prime_ex(prime, bitsr[i] + adj, 0, NULL, NULL, cb))
173 * prime should not be equal to p, q, r_3...
174 * (those primes prior to this one)
179 for (j = 0; j < i; j++) {
187 prev_prime = sk_RSA_PRIME_INFO_value(prime_infos,
190 if (!BN_cmp(prime, prev_prime)) {
195 if (!BN_sub(r2, prime, BN_value_one()))
198 BN_set_flags(r2, BN_FLG_CONSTTIME);
199 if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) {
200 /* GCD == 1 since inverse exists */
203 error = ERR_peek_last_error();
204 if (ERR_GET_LIB(error) == ERR_LIB_BN
205 && ERR_GET_REASON(error) == BN_R_NO_INVERSE) {
211 if (!BN_GENCB_call(cb, 2, n++))
217 /* calculate n immediately to see if it's sufficient */
219 /* we get at least 2 primes */
220 if (!BN_mul(r1, rsa->p, rsa->q, ctx))
223 /* modulus n = p * q * r_3 * r_4 ... */
224 if (!BN_mul(r1, rsa->n, prime, ctx))
227 /* i == 0, do nothing */
228 if (!BN_GENCB_call(cb, 3, i))
233 * if |r1|, product of factors so far, is not as long as expected
234 * (by checking the first 4 bits are less than 0x9 or greater than
235 * 0xF). If so, re-generate the last prime.
237 * NOTE: This actually can't happen in two-prime case, because of
238 * the way factors are generated.
240 * Besides, another consideration is, for multi-prime case, even the
241 * length modulus is as long as expected, the modulus could start at
242 * 0x8, which could be utilized to distinguish a multi-prime private
243 * key by using the modulus in a certificate. This is also covered
244 * by checking the length should not be less than 0x9.
246 if (!BN_rshift(r2, r1, bitse - 4))
248 bitst = BN_get_word(r2);
250 if (bitst < 0x9 || bitst > 0xF) {
252 * For keys with more than 4 primes, we attempt longer factor to
253 * meet length requirement.
255 * Otherwise, we just re-generate the prime with the same length.
257 * This strategy has the following goals:
259 * 1. 1024-bit factors are efficient when using 3072 and 4096-bit key
260 * 2. stay the same logic with normal 2-prime key
263 if (!BN_GENCB_call(cb, 2, n++))
270 } else if (retries == 4) {
272 * re-generate all primes from scratch, mainly used
273 * in 4 prime case to avoid long loop. Max retry times
283 /* save product of primes for further use, for multi-prime only */
284 if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL)
286 if (BN_copy(rsa->n, r1) == NULL)
288 if (!BN_GENCB_call(cb, 3, i))
292 if (BN_cmp(rsa->p, rsa->q) < 0) {
301 if (!BN_sub(r1, rsa->p, BN_value_one()))
304 if (!BN_sub(r2, rsa->q, BN_value_one()))
307 if (!BN_mul(r0, r1, r2, ctx))
310 for (i = 2; i < primes; i++) {
311 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
312 /* save r_i - 1 to pinfo->d temporarily */
313 if (!BN_sub(pinfo->d, pinfo->r, BN_value_one()))
315 if (!BN_mul(r0, r0, pinfo->d, ctx))
320 BIGNUM *pr0 = BN_new();
325 BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
326 if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) {
330 /* We MUST free pr0 before any further use of r0 */
335 BIGNUM *d = BN_new();
340 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
342 /* calculate d mod (p-1) and d mod (q - 1) */
343 if (!BN_mod(rsa->dmp1, d, r1, ctx)
344 || !BN_mod(rsa->dmq1, d, r2, ctx)) {
349 /* calculate CRT exponents */
350 for (i = 2; i < primes; i++) {
351 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
352 /* pinfo->d == r_i - 1 */
353 if (!BN_mod(pinfo->d, d, pinfo->d, ctx)) {
359 /* We MUST free d before any further use of rsa->d */
364 BIGNUM *p = BN_new();
368 BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
370 /* calculate inverse of q mod p */
371 if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) {
376 /* calculate CRT coefficient for other primes */
377 for (i = 2; i < primes; i++) {
378 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
379 BN_with_flags(p, pinfo->r, BN_FLG_CONSTTIME);
380 if (!BN_mod_inverse(pinfo->t, pinfo->pp, p, ctx)) {
386 /* We MUST free p before any further use of rsa->p */
393 RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);
399 #endif /* FIPS_MODE */