2 * Copyright 1995-2020 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);
75 static int rsa_multiprime_keygen(RSA *rsa, int bits, int primes,
76 BIGNUM *e_value, BN_GENCB *cb)
78 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *tmp, *prime;
79 int n = 0, bitsr[RSA_MAX_PRIME_NUM], bitse = 0;
80 int i = 0, quo = 0, rmd = 0, adj = 0, retries = 0;
81 RSA_PRIME_INFO *pinfo = NULL;
82 STACK_OF(RSA_PRIME_INFO) *prime_infos = NULL;
85 unsigned long error = 0;
88 if (bits < RSA_MIN_MODULUS_BITS) {
89 ok = 0; /* we set our own err */
90 RSAerr(0, RSA_R_KEY_SIZE_TOO_SMALL);
94 /* A bad value for e can cause infinite loops */
95 if (e_value != NULL && !ossl_rsa_check_public_exponent(e_value)) {
96 RSAerr(0, RSA_R_PUB_EXPONENT_OUT_OF_RANGE);
100 if (primes < RSA_DEFAULT_PRIME_NUM || primes > rsa_multip_cap(bits)) {
101 ok = 0; /* we set our own err */
102 RSAerr(0, RSA_R_KEY_PRIME_NUM_INVALID);
110 r0 = BN_CTX_get(ctx);
111 r1 = BN_CTX_get(ctx);
112 r2 = BN_CTX_get(ctx);
116 /* divide bits into 'primes' pieces evenly */
120 for (i = 0; i < primes; i++)
121 bitsr[i] = (i < rmd) ? quo + 1 : quo;
125 /* We need the RSA components non-NULL */
126 if (!rsa->n && ((rsa->n = BN_new()) == NULL))
128 if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
130 BN_set_flags(rsa->d, BN_FLG_CONSTTIME);
131 if (!rsa->e && ((rsa->e = BN_new()) == NULL))
133 if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
135 BN_set_flags(rsa->p, BN_FLG_CONSTTIME);
136 if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
138 BN_set_flags(rsa->q, BN_FLG_CONSTTIME);
139 if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL))
141 BN_set_flags(rsa->dmp1, BN_FLG_CONSTTIME);
142 if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL))
144 BN_set_flags(rsa->dmq1, BN_FLG_CONSTTIME);
145 if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
147 BN_set_flags(rsa->iqmp, BN_FLG_CONSTTIME);
149 /* initialize multi-prime components */
150 if (primes > RSA_DEFAULT_PRIME_NUM) {
151 rsa->version = RSA_ASN1_VERSION_MULTI;
152 prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2);
153 if (prime_infos == NULL)
155 if (rsa->prime_infos != NULL) {
156 /* could this happen? */
157 sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, rsa_multip_info_free);
159 rsa->prime_infos = prime_infos;
161 /* prime_info from 2 to |primes| -1 */
162 for (i = 2; i < primes; i++) {
163 pinfo = rsa_multip_info_new();
166 (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo);
170 if (BN_copy(rsa->e, e_value) == NULL)
173 /* generate p, q and other primes (if any) */
174 for (i = 0; i < primes; i++) {
183 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
186 BN_set_flags(prime, BN_FLG_CONSTTIME);
190 if (!BN_generate_prime_ex(prime, bitsr[i] + adj, 0, NULL, NULL, cb))
193 * prime should not be equal to p, q, r_3...
194 * (those primes prior to this one)
199 for (j = 0; j < i; j++) {
207 prev_prime = sk_RSA_PRIME_INFO_value(prime_infos,
210 if (!BN_cmp(prime, prev_prime)) {
215 if (!BN_sub(r2, prime, BN_value_one()))
218 BN_set_flags(r2, BN_FLG_CONSTTIME);
219 if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) {
220 /* GCD == 1 since inverse exists */
223 error = ERR_peek_last_error();
224 if (ERR_GET_LIB(error) == ERR_LIB_BN
225 && ERR_GET_REASON(error) == BN_R_NO_INVERSE) {
231 if (!BN_GENCB_call(cb, 2, n++))
237 /* calculate n immediately to see if it's sufficient */
239 /* we get at least 2 primes */
240 if (!BN_mul(r1, rsa->p, rsa->q, ctx))
243 /* modulus n = p * q * r_3 * r_4 ... */
244 if (!BN_mul(r1, rsa->n, prime, ctx))
247 /* i == 0, do nothing */
248 if (!BN_GENCB_call(cb, 3, i))
253 * if |r1|, product of factors so far, is not as long as expected
254 * (by checking the first 4 bits are less than 0x9 or greater than
255 * 0xF). If so, re-generate the last prime.
257 * NOTE: This actually can't happen in two-prime case, because of
258 * the way factors are generated.
260 * Besides, another consideration is, for multi-prime case, even the
261 * length modulus is as long as expected, the modulus could start at
262 * 0x8, which could be utilized to distinguish a multi-prime private
263 * key by using the modulus in a certificate. This is also covered
264 * by checking the length should not be less than 0x9.
266 if (!BN_rshift(r2, r1, bitse - 4))
268 bitst = BN_get_word(r2);
270 if (bitst < 0x9 || bitst > 0xF) {
272 * For keys with more than 4 primes, we attempt longer factor to
273 * meet length requirement.
275 * Otherwise, we just re-generate the prime with the same length.
277 * This strategy has the following goals:
279 * 1. 1024-bit factors are efficient when using 3072 and 4096-bit key
280 * 2. stay the same logic with normal 2-prime key
283 if (!BN_GENCB_call(cb, 2, n++))
290 } else if (retries == 4) {
292 * re-generate all primes from scratch, mainly used
293 * in 4 prime case to avoid long loop. Max retry times
303 /* save product of primes for further use, for multi-prime only */
304 if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL)
306 if (BN_copy(rsa->n, r1) == NULL)
308 if (!BN_GENCB_call(cb, 3, i))
312 if (BN_cmp(rsa->p, rsa->q) < 0) {
321 if (!BN_sub(r1, rsa->p, BN_value_one()))
324 if (!BN_sub(r2, rsa->q, BN_value_one()))
327 if (!BN_mul(r0, r1, r2, ctx))
330 for (i = 2; i < primes; i++) {
331 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
332 /* save r_i - 1 to pinfo->d temporarily */
333 if (!BN_sub(pinfo->d, pinfo->r, BN_value_one()))
335 if (!BN_mul(r0, r0, pinfo->d, ctx))
340 BIGNUM *pr0 = BN_new();
345 BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
346 if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) {
350 /* We MUST free pr0 before any further use of r0 */
355 BIGNUM *d = BN_new();
360 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
362 /* calculate d mod (p-1) and d mod (q - 1) */
363 if (!BN_mod(rsa->dmp1, d, r1, ctx)
364 || !BN_mod(rsa->dmq1, d, r2, ctx)) {
369 /* calculate CRT exponents */
370 for (i = 2; i < primes; i++) {
371 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
372 /* pinfo->d == r_i - 1 */
373 if (!BN_mod(pinfo->d, d, pinfo->d, ctx)) {
379 /* We MUST free d before any further use of rsa->d */
384 BIGNUM *p = BN_new();
388 BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
390 /* calculate inverse of q mod p */
391 if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) {
396 /* calculate CRT coefficient for other primes */
397 for (i = 2; i < primes; i++) {
398 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
399 BN_with_flags(p, pinfo->r, BN_FLG_CONSTTIME);
400 if (!BN_mod_inverse(pinfo->t, pinfo->pp, p, ctx)) {
406 /* We MUST free p before any further use of rsa->p */
413 RSAerr(0, ERR_LIB_BN);
420 #endif /* FIPS_MODULE */
422 static int rsa_keygen(OSSL_LIB_CTX *libctx, RSA *rsa, int bits, int primes,
423 BIGNUM *e_value, BN_GENCB *cb, int pairwise_test)
428 * Only multi-prime keys or insecure keys with a small key length will use
429 * the older rsa_multiprime_keygen().
431 if (primes == 2 && bits >= 2048)
432 ok = ossl_rsa_sp800_56b_generate_key(rsa, bits, e_value, cb);
435 ok = rsa_multiprime_keygen(rsa, bits, primes, e_value, cb);
436 #endif /* FIPS_MODULE */
439 pairwise_test = 1; /* FIPS MODE needs to always run the pairwise test */
441 if (pairwise_test && ok > 0) {
442 OSSL_CALLBACK *stcb = NULL;
443 void *stcbarg = NULL;
445 OSSL_SELF_TEST_get_callback(libctx, &stcb, &stcbarg);
446 ok = rsa_keygen_pairwise_test(rsa, stcb, stcbarg);
448 ossl_set_error_state(OSSL_SELF_TEST_TYPE_PCT);
449 /* Clear intermediate results */
450 BN_clear_free(rsa->d);
451 BN_clear_free(rsa->p);
452 BN_clear_free(rsa->q);
453 BN_clear_free(rsa->dmp1);
454 BN_clear_free(rsa->dmq1);
455 BN_clear_free(rsa->iqmp);
468 * For RSA key generation it is not known whether the key pair will be used
469 * for key transport or signatures. FIPS 140-2 IG 9.9 states that in this case
470 * either a signature verification OR an encryption operation may be used to
471 * perform the pairwise consistency check. The simpler encrypt/decrypt operation
472 * has been chosen for this case.
474 static int rsa_keygen_pairwise_test(RSA *rsa, OSSL_CALLBACK *cb, void *cbarg)
477 unsigned int ciphertxt_len;
478 unsigned char *ciphertxt = NULL;
479 const unsigned char plaintxt[16] = {0};
480 unsigned char decoded[256];
481 unsigned int decoded_len;
482 unsigned int plaintxt_len = (unsigned int)sizeof(plaintxt_len);
483 int padding = RSA_PKCS1_PADDING;
484 OSSL_SELF_TEST *st = NULL;
486 st = OSSL_SELF_TEST_new(cb, cbarg);
489 OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT,
490 OSSL_SELF_TEST_DESC_PCT_RSA_PKCS1);
492 ciphertxt_len = RSA_size(rsa);
493 ciphertxt = OPENSSL_zalloc(ciphertxt_len);
494 if (ciphertxt == NULL)
497 ciphertxt_len = RSA_public_encrypt(plaintxt_len, plaintxt, ciphertxt, rsa,
499 if (ciphertxt_len <= 0)
501 if (ciphertxt_len == plaintxt_len
502 && memcmp(ciphertxt, plaintxt, plaintxt_len) == 0)
505 OSSL_SELF_TEST_oncorrupt_byte(st, ciphertxt);
507 decoded_len = RSA_private_decrypt(ciphertxt_len, ciphertxt, decoded, rsa,
509 if (decoded_len != plaintxt_len
510 || memcmp(decoded, plaintxt, decoded_len) != 0)
515 OSSL_SELF_TEST_onend(st, ret);
516 OSSL_SELF_TEST_free(st);
517 OPENSSL_free(ciphertxt);