2 * Copyright 1995-2024 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. -
17 * RSA low level APIs are deprecated for public use, but still ok for
20 #include "internal/deprecated.h"
24 #include "internal/cryptlib.h"
25 #include <openssl/bn.h>
26 #include <openssl/self_test.h>
27 #include "prov/providercommon.h"
28 #include "rsa_local.h"
30 static int rsa_keygen_pairwise_test(RSA *rsa, OSSL_CALLBACK *cb, void *cbarg);
31 static int rsa_keygen(OSSL_LIB_CTX *libctx, RSA *rsa, int bits, int primes,
32 BIGNUM *e_value, BN_GENCB *cb, int pairwise_test);
35 * NB: this wrapper would normally be placed in rsa_lib.c and the static
36 * implementation would probably be in rsa_eay.c. Nonetheless, is kept here
37 * so that we don't introduce a new linker dependency. Eg. any application
38 * that wasn't previously linking object code related to key-generation won't
39 * have to now just because key-generation is part of RSA_METHOD.
41 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
43 if (rsa->meth->rsa_keygen != NULL)
44 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
46 return RSA_generate_multi_prime_key(rsa, bits, RSA_DEFAULT_PRIME_NUM,
50 int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes,
51 BIGNUM *e_value, BN_GENCB *cb)
54 /* multi-prime is only supported with the builtin key generation */
55 if (rsa->meth->rsa_multi_prime_keygen != NULL) {
56 return rsa->meth->rsa_multi_prime_keygen(rsa, bits, primes,
58 } else if (rsa->meth->rsa_keygen != NULL) {
60 * However, if rsa->meth implements only rsa_keygen, then we
61 * have to honour it in 2-prime case and assume that it wouldn't
62 * know what to do with multi-prime key generated by builtin
66 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
70 #endif /* FIPS_MODULE */
71 return rsa_keygen(rsa->libctx, rsa, bits, primes, e_value, cb, 0);
74 DEFINE_STACK_OF(BIGNUM)
77 * Given input values, q, p, n, d and e, derive the exponents
78 * and coefficients for each prime in this key, placing the result
79 * on their respective exps and coeffs stacks
82 int ossl_rsa_multiprime_derive(RSA *rsa, int bits, int primes,
84 STACK_OF(BIGNUM) *factors,
85 STACK_OF(BIGNUM) *exps,
86 STACK_OF(BIGNUM) *coeffs)
88 STACK_OF(BIGNUM) *pplist = NULL, *pdlist = NULL;
89 BIGNUM *factor = NULL, *newpp = NULL, *newpd = NULL;
90 BIGNUM *dval = NULL, *newexp = NULL, *newcoeff = NULL;
91 BIGNUM *p = NULL, *q = NULL;
92 BIGNUM *dmp1 = NULL, *dmq1 = NULL, *iqmp = NULL;
93 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL;
99 ctx = BN_CTX_new_ex(rsa->libctx);
105 pplist = sk_BIGNUM_new_null();
109 pdlist = sk_BIGNUM_new_null();
113 r0 = BN_CTX_get(ctx);
114 r1 = BN_CTX_get(ctx);
115 r2 = BN_CTX_get(ctx);
120 BN_set_flags(r0, BN_FLG_CONSTTIME);
121 BN_set_flags(r1, BN_FLG_CONSTTIME);
122 BN_set_flags(r2, BN_FLG_CONSTTIME);
124 if (BN_copy(r1, rsa->n) == NULL)
127 p = sk_BIGNUM_value(factors, 0);
128 q = sk_BIGNUM_value(factors, 1);
130 /* Build list of partial products of primes */
131 for (i = 0; i < sk_BIGNUM_num(factors); i++) {
134 /* our first prime, p */
135 if (!BN_sub(r2, p, BN_value_one()))
137 BN_set_flags(r2, BN_FLG_CONSTTIME);
138 if (BN_mod_inverse(r1, r2, rsa->e, ctx) == NULL)
143 if (!BN_mul(r1, p, q, ctx))
148 if (!sk_BIGNUM_insert(pplist, tmp, sk_BIGNUM_num(pplist)))
152 factor = sk_BIGNUM_value(factors, i);
153 /* all other primes */
154 if (!BN_mul(r1, r1, factor, ctx))
159 if (!sk_BIGNUM_insert(pplist, tmp, sk_BIGNUM_num(pplist)))
165 /* build list of relative d values */
167 if (!BN_sub(r1, p, BN_value_one()))
169 if (!BN_sub(r2, q, BN_value_one()))
171 if (!BN_mul(r0, r1, r2, ctx))
173 for (i = 2; i < sk_BIGNUM_num(factors); i++) {
174 factor = sk_BIGNUM_value(factors, i);
178 BN_set_flags(dval, BN_FLG_CONSTTIME);
179 if (!BN_sub(dval, factor, BN_value_one()))
181 if (!BN_mul(r0, r0, dval, ctx))
183 if (!sk_BIGNUM_insert(pdlist, dval, sk_BIGNUM_num(pdlist)))
187 /* Calculate dmp1, dmq1 and additional exponents */
188 dmp1 = BN_secure_new();
191 dmq1 = BN_secure_new();
195 if (!BN_mod(dmp1, rsa->d, r1, ctx))
197 if (!sk_BIGNUM_insert(exps, dmp1, sk_BIGNUM_num(exps)))
201 if (!BN_mod(dmq1, rsa->d, r2, ctx))
203 if (!sk_BIGNUM_insert(exps, dmq1, sk_BIGNUM_num(exps)))
207 for (i = 2; i < sk_BIGNUM_num(factors); i++) {
208 newpd = sk_BIGNUM_value(pdlist, i - 2);
212 if (!BN_mod(newexp, rsa->d, newpd, ctx)) {
216 if (!sk_BIGNUM_insert(exps, newexp, sk_BIGNUM_num(exps)))
220 /* Calculate iqmp and additional coefficients */
225 if (BN_mod_inverse(iqmp, sk_BIGNUM_value(factors, 1),
226 sk_BIGNUM_value(factors, 0), ctx) == NULL)
228 if (!sk_BIGNUM_insert(coeffs, iqmp, sk_BIGNUM_num(coeffs)))
232 for (i = 2; i < sk_BIGNUM_num(factors); i++) {
233 newpp = sk_BIGNUM_value(pplist, i - 2);
235 if (newcoeff == NULL)
237 if (BN_mod_inverse(newcoeff, newpp, sk_BIGNUM_value(factors, i),
242 if (!sk_BIGNUM_insert(coeffs, newcoeff, sk_BIGNUM_num(coeffs)))
248 sk_BIGNUM_pop_free(pplist, BN_free);
249 sk_BIGNUM_pop_free(pdlist, BN_free);
258 static int rsa_multiprime_keygen(RSA *rsa, int bits, int primes,
259 BIGNUM *e_value, BN_GENCB *cb)
261 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *tmp, *tmp2, *prime;
262 int n = 0, bitsr[RSA_MAX_PRIME_NUM], bitse = 0;
263 int i = 0, quo = 0, rmd = 0, adj = 0, retries = 0;
264 RSA_PRIME_INFO *pinfo = NULL;
265 STACK_OF(RSA_PRIME_INFO) *prime_infos = NULL;
266 STACK_OF(BIGNUM) *factors = NULL;
267 STACK_OF(BIGNUM) *exps = NULL;
268 STACK_OF(BIGNUM) *coeffs = NULL;
271 unsigned long error = 0;
274 if (bits < RSA_MIN_MODULUS_BITS) {
275 ERR_raise(ERR_LIB_RSA, RSA_R_KEY_SIZE_TOO_SMALL);
278 if (e_value == NULL) {
279 ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE);
282 /* A bad value for e can cause infinite loops */
283 if (!ossl_rsa_check_public_exponent(e_value)) {
284 ERR_raise(ERR_LIB_RSA, RSA_R_PUB_EXPONENT_OUT_OF_RANGE);
288 if (primes < RSA_DEFAULT_PRIME_NUM || primes > ossl_rsa_multip_cap(bits)) {
289 ERR_raise(ERR_LIB_RSA, RSA_R_KEY_PRIME_NUM_INVALID);
293 factors = sk_BIGNUM_new_null();
297 exps = sk_BIGNUM_new_null();
301 coeffs = sk_BIGNUM_new_null();
305 ctx = BN_CTX_new_ex(rsa->libctx);
309 r0 = BN_CTX_get(ctx);
310 r1 = BN_CTX_get(ctx);
311 r2 = BN_CTX_get(ctx);
315 /* divide bits into 'primes' pieces evenly */
319 for (i = 0; i < primes; i++)
320 bitsr[i] = (i < rmd) ? quo + 1 : quo;
324 /* We need the RSA components non-NULL */
325 if (!rsa->n && ((rsa->n = BN_new()) == NULL))
327 if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
329 BN_set_flags(rsa->d, BN_FLG_CONSTTIME);
330 if (!rsa->e && ((rsa->e = BN_new()) == NULL))
332 if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
334 BN_set_flags(rsa->p, BN_FLG_CONSTTIME);
335 if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
337 BN_set_flags(rsa->q, BN_FLG_CONSTTIME);
339 /* initialize multi-prime components */
340 if (primes > RSA_DEFAULT_PRIME_NUM) {
341 rsa->version = RSA_ASN1_VERSION_MULTI;
342 prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2);
343 if (prime_infos == NULL)
345 if (rsa->prime_infos != NULL) {
346 /* could this happen? */
347 sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos,
348 ossl_rsa_multip_info_free);
350 rsa->prime_infos = prime_infos;
352 /* prime_info from 2 to |primes| -1 */
353 for (i = 2; i < primes; i++) {
354 pinfo = ossl_rsa_multip_info_new();
357 (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo);
361 if (BN_copy(rsa->e, e_value) == NULL)
364 /* generate p, q and other primes (if any) */
365 for (i = 0; i < primes; i++) {
374 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
377 BN_set_flags(prime, BN_FLG_CONSTTIME);
381 if (!BN_generate_prime_ex2(prime, bitsr[i] + adj, 0, NULL, NULL,
385 * prime should not be equal to p, q, r_3...
386 * (those primes prior to this one)
391 for (j = 0; j < i; j++) {
399 prev_prime = sk_RSA_PRIME_INFO_value(prime_infos,
402 if (!BN_cmp(prime, prev_prime)) {
407 if (!BN_sub(r2, prime, BN_value_one()))
410 BN_set_flags(r2, BN_FLG_CONSTTIME);
411 if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) {
412 /* GCD == 1 since inverse exists */
415 error = ERR_peek_last_error();
416 if (ERR_GET_LIB(error) == ERR_LIB_BN
417 && ERR_GET_REASON(error) == BN_R_NO_INVERSE) {
423 if (!BN_GENCB_call(cb, 2, n++))
429 /* calculate n immediately to see if it's sufficient */
431 /* we get at least 2 primes */
432 if (!BN_mul(r1, rsa->p, rsa->q, ctx))
435 /* modulus n = p * q * r_3 * r_4 ... */
436 if (!BN_mul(r1, rsa->n, prime, ctx))
439 /* i == 0, do nothing */
440 if (!BN_GENCB_call(cb, 3, i))
445 if (!sk_BIGNUM_insert(factors, tmp, sk_BIGNUM_num(factors)))
451 * if |r1|, product of factors so far, is not as long as expected
452 * (by checking the first 4 bits are less than 0x9 or greater than
453 * 0xF). If so, re-generate the last prime.
455 * NOTE: This actually can't happen in two-prime case, because of
456 * the way factors are generated.
458 * Besides, another consideration is, for multi-prime case, even the
459 * length modulus is as long as expected, the modulus could start at
460 * 0x8, which could be utilized to distinguish a multi-prime private
461 * key by using the modulus in a certificate. This is also covered
462 * by checking the length should not be less than 0x9.
464 if (!BN_rshift(r2, r1, bitse - 4))
466 bitst = BN_get_word(r2);
468 if (bitst < 0x9 || bitst > 0xF) {
470 * For keys with more than 4 primes, we attempt longer factor to
471 * meet length requirement.
473 * Otherwise, we just re-generate the prime with the same length.
475 * This strategy has the following goals:
477 * 1. 1024-bit factors are efficient when using 3072 and 4096-bit key
478 * 2. stay the same logic with normal 2-prime key
481 if (!BN_GENCB_call(cb, 2, n++))
488 } else if (retries == 4) {
490 * re-generate all primes from scratch, mainly used
491 * in 4 prime case to avoid long loop. Max retry times
496 sk_BIGNUM_pop_free(factors, BN_clear_free);
497 factors = sk_BIGNUM_new_null();
505 /* save product of primes for further use, for multi-prime only */
506 if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL)
508 if (BN_copy(rsa->n, r1) == NULL)
510 if (!BN_GENCB_call(cb, 3, i))
515 if (!sk_BIGNUM_insert(factors, tmp, sk_BIGNUM_num(factors)))
519 if (BN_cmp(rsa->p, rsa->q) < 0) {
523 /* mirror this in our factor stack */
524 if (!sk_BIGNUM_insert(factors, sk_BIGNUM_delete(factors, 0), 1))
531 if (!BN_sub(r1, rsa->p, BN_value_one()))
534 if (!BN_sub(r2, rsa->q, BN_value_one()))
537 if (!BN_mul(r0, r1, r2, ctx))
540 for (i = 2; i < primes; i++) {
541 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
542 /* save r_i - 1 to pinfo->d temporarily */
543 if (!BN_sub(pinfo->d, pinfo->r, BN_value_one()))
545 if (!BN_mul(r0, r0, pinfo->d, ctx))
550 BN_set_flags(r0, BN_FLG_CONSTTIME);
551 if (BN_mod_inverse(rsa->d, rsa->e, r0, ctx) == NULL) {
555 /* derive any missing exponents and coefficients */
556 if (!ossl_rsa_multiprime_derive(rsa, bits, primes, e_value,
557 factors, exps, coeffs))
561 * first 2 factors/exps are already tracked in p/q/dmq1/dmp1
562 * and the first coeff is in iqmp, so pop those off the stack
563 * Note, the first 2 factors/exponents are already tracked by p and q
564 * assign dmp1/dmq1 and iqmp
565 * the remaining pinfo values are separately allocated, so copy and delete
568 BN_clear_free(sk_BIGNUM_delete(factors, 0));
569 BN_clear_free(sk_BIGNUM_delete(factors, 0));
570 rsa->dmp1 = sk_BIGNUM_delete(exps, 0);
571 rsa->dmq1 = sk_BIGNUM_delete(exps, 0);
572 rsa->iqmp = sk_BIGNUM_delete(coeffs, 0);
573 for (i = 2; i < primes; i++) {
574 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
575 tmp = sk_BIGNUM_delete(factors, 0);
576 BN_copy(pinfo->r, tmp);
578 tmp = sk_BIGNUM_delete(exps, 0);
579 tmp2 = BN_copy(pinfo->d, tmp);
583 tmp = sk_BIGNUM_delete(coeffs, 0);
584 tmp2 = BN_copy(pinfo->t, tmp);
591 sk_BIGNUM_free(factors);
592 sk_BIGNUM_free(exps);
593 sk_BIGNUM_free(coeffs);
595 ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
602 #endif /* FIPS_MODULE */
604 static int rsa_keygen(OSSL_LIB_CTX *libctx, RSA *rsa, int bits, int primes,
605 BIGNUM *e_value, BN_GENCB *cb, int pairwise_test)
610 ok = ossl_rsa_sp800_56b_generate_key(rsa, bits, e_value, cb);
611 pairwise_test = 1; /* FIPS MODE needs to always run the pairwise test */
614 * Only multi-prime keys or insecure keys with a small key length or a
615 * public exponent <= 2^16 will use the older rsa_multiprime_keygen().
619 && (e_value == NULL || BN_num_bits(e_value) > 16))
620 ok = ossl_rsa_sp800_56b_generate_key(rsa, bits, e_value, cb);
622 ok = rsa_multiprime_keygen(rsa, bits, primes, e_value, cb);
623 #endif /* FIPS_MODULE */
625 if (pairwise_test && ok > 0) {
626 OSSL_CALLBACK *stcb = NULL;
627 void *stcbarg = NULL;
629 OSSL_SELF_TEST_get_callback(libctx, &stcb, &stcbarg);
630 ok = rsa_keygen_pairwise_test(rsa, stcb, stcbarg);
632 ossl_set_error_state(OSSL_SELF_TEST_TYPE_PCT);
633 /* Clear intermediate results */
634 BN_clear_free(rsa->d);
635 BN_clear_free(rsa->p);
636 BN_clear_free(rsa->q);
637 BN_clear_free(rsa->dmp1);
638 BN_clear_free(rsa->dmq1);
639 BN_clear_free(rsa->iqmp);
652 * For RSA key generation it is not known whether the key pair will be used
653 * for key transport or signatures. FIPS 140-2 IG 9.9 states that in this case
654 * either a signature verification OR an encryption operation may be used to
655 * perform the pairwise consistency check. The simpler encrypt/decrypt operation
656 * has been chosen for this case.
658 static int rsa_keygen_pairwise_test(RSA *rsa, OSSL_CALLBACK *cb, void *cbarg)
661 unsigned int ciphertxt_len;
662 unsigned char *ciphertxt = NULL;
663 const unsigned char plaintxt[16] = {0};
664 unsigned char *decoded = NULL;
665 unsigned int decoded_len;
666 unsigned int plaintxt_len = (unsigned int)sizeof(plaintxt_len);
667 int padding = RSA_PKCS1_PADDING;
668 OSSL_SELF_TEST *st = NULL;
670 st = OSSL_SELF_TEST_new(cb, cbarg);
673 OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT,
674 OSSL_SELF_TEST_DESC_PCT_RSA_PKCS1);
676 ciphertxt_len = RSA_size(rsa);
678 * RSA_private_encrypt() and RSA_private_decrypt() requires the 'to'
679 * parameter to be a maximum of RSA_size() - allocate space for both.
681 ciphertxt = OPENSSL_zalloc(ciphertxt_len * 2);
682 if (ciphertxt == NULL)
684 decoded = ciphertxt + ciphertxt_len;
686 ciphertxt_len = RSA_public_encrypt(plaintxt_len, plaintxt, ciphertxt, rsa,
688 if (ciphertxt_len <= 0)
690 if (ciphertxt_len == plaintxt_len
691 && memcmp(ciphertxt, plaintxt, plaintxt_len) == 0)
694 OSSL_SELF_TEST_oncorrupt_byte(st, ciphertxt);
696 decoded_len = RSA_private_decrypt(ciphertxt_len, ciphertxt, decoded, rsa,
698 if (decoded_len != plaintxt_len
699 || memcmp(decoded, plaintxt, decoded_len) != 0)
704 OSSL_SELF_TEST_onend(st, ret);
705 OSSL_SELF_TEST_free(st);
706 OPENSSL_free(ciphertxt);