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 "rsa_local.h"
29 static int rsa_keygen_pairwise_test(RSA *rsa, OSSL_CALLBACK *cb, void *cbarg);
30 static int rsa_keygen(OPENSSL_CTX *libctx, RSA *rsa, int bits, int primes,
31 BIGNUM *e_value, BN_GENCB *cb, int pairwise_test);
34 * NB: this wrapper would normally be placed in rsa_lib.c and the static
35 * implementation would probably be in rsa_eay.c. Nonetheless, is kept here
36 * so that we don't introduce a new linker dependency. Eg. any application
37 * that wasn't previously linking object code related to key-generation won't
38 * have to now just because key-generation is part of RSA_METHOD.
40 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
42 if (rsa->meth->rsa_keygen != NULL)
43 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
45 return RSA_generate_multi_prime_key(rsa, bits, RSA_DEFAULT_PRIME_NUM,
49 int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes,
50 BIGNUM *e_value, BN_GENCB *cb)
53 /* multi-prime is only supported with the builtin key generation */
54 if (rsa->meth->rsa_multi_prime_keygen != NULL) {
55 return rsa->meth->rsa_multi_prime_keygen(rsa, bits, primes,
57 } else if (rsa->meth->rsa_keygen != NULL) {
59 * However, if rsa->meth implements only rsa_keygen, then we
60 * have to honour it in 2-prime case and assume that it wouldn't
61 * know what to do with multi-prime key generated by builtin
65 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
69 #endif /* FIPS_MODUKE */
70 return rsa_keygen(rsa->libctx, rsa, bits, primes, e_value, cb, 0);
74 static int rsa_multiprime_keygen(RSA *rsa, int bits, int primes,
75 BIGNUM *e_value, BN_GENCB *cb)
77 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *tmp, *prime;
78 int n = 0, bitsr[RSA_MAX_PRIME_NUM], bitse = 0;
79 int i = 0, quo = 0, rmd = 0, adj = 0, retries = 0;
80 RSA_PRIME_INFO *pinfo = NULL;
81 STACK_OF(RSA_PRIME_INFO) *prime_infos = NULL;
84 unsigned long error = 0;
87 if (bits < RSA_MIN_MODULUS_BITS) {
88 ok = 0; /* we set our own err */
89 RSAerr(0, RSA_R_KEY_SIZE_TOO_SMALL);
93 /* A bad value for e can cause infinite loops */
94 if (e_value != NULL && !rsa_check_public_exponent(e_value)) {
95 RSAerr(0, RSA_R_PUB_EXPONENT_OUT_OF_RANGE);
99 if (primes < RSA_DEFAULT_PRIME_NUM || primes > rsa_multip_cap(bits)) {
100 ok = 0; /* we set our own err */
101 RSAerr(0, RSA_R_KEY_PRIME_NUM_INVALID);
109 r0 = BN_CTX_get(ctx);
110 r1 = BN_CTX_get(ctx);
111 r2 = BN_CTX_get(ctx);
115 /* divide bits into 'primes' pieces evenly */
119 for (i = 0; i < primes; i++)
120 bitsr[i] = (i < rmd) ? quo + 1 : quo;
124 /* We need the RSA components non-NULL */
125 if (!rsa->n && ((rsa->n = BN_new()) == NULL))
127 if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
129 BN_set_flags(rsa->d, BN_FLG_CONSTTIME);
130 if (!rsa->e && ((rsa->e = BN_new()) == NULL))
132 if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
134 BN_set_flags(rsa->p, BN_FLG_CONSTTIME);
135 if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
137 BN_set_flags(rsa->q, BN_FLG_CONSTTIME);
138 if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL))
140 BN_set_flags(rsa->dmp1, BN_FLG_CONSTTIME);
141 if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL))
143 BN_set_flags(rsa->dmq1, BN_FLG_CONSTTIME);
144 if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
146 BN_set_flags(rsa->iqmp, BN_FLG_CONSTTIME);
148 /* initialize multi-prime components */
149 if (primes > RSA_DEFAULT_PRIME_NUM) {
150 rsa->version = RSA_ASN1_VERSION_MULTI;
151 prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2);
152 if (prime_infos == NULL)
154 if (rsa->prime_infos != NULL) {
155 /* could this happen? */
156 sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, rsa_multip_info_free);
158 rsa->prime_infos = prime_infos;
160 /* prime_info from 2 to |primes| -1 */
161 for (i = 2; i < primes; i++) {
162 pinfo = rsa_multip_info_new();
165 (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo);
169 if (BN_copy(rsa->e, e_value) == NULL)
172 /* generate p, q and other primes (if any) */
173 for (i = 0; i < primes; i++) {
182 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
185 BN_set_flags(prime, BN_FLG_CONSTTIME);
189 if (!BN_generate_prime_ex(prime, bitsr[i] + adj, 0, NULL, NULL, cb))
192 * prime should not be equal to p, q, r_3...
193 * (those primes prior to this one)
198 for (j = 0; j < i; j++) {
206 prev_prime = sk_RSA_PRIME_INFO_value(prime_infos,
209 if (!BN_cmp(prime, prev_prime)) {
214 if (!BN_sub(r2, prime, BN_value_one()))
217 BN_set_flags(r2, BN_FLG_CONSTTIME);
218 if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) {
219 /* GCD == 1 since inverse exists */
222 error = ERR_peek_last_error();
223 if (ERR_GET_LIB(error) == ERR_LIB_BN
224 && ERR_GET_REASON(error) == BN_R_NO_INVERSE) {
230 if (!BN_GENCB_call(cb, 2, n++))
236 /* calculate n immediately to see if it's sufficient */
238 /* we get at least 2 primes */
239 if (!BN_mul(r1, rsa->p, rsa->q, ctx))
242 /* modulus n = p * q * r_3 * r_4 ... */
243 if (!BN_mul(r1, rsa->n, prime, ctx))
246 /* i == 0, do nothing */
247 if (!BN_GENCB_call(cb, 3, i))
252 * if |r1|, product of factors so far, is not as long as expected
253 * (by checking the first 4 bits are less than 0x9 or greater than
254 * 0xF). If so, re-generate the last prime.
256 * NOTE: This actually can't happen in two-prime case, because of
257 * the way factors are generated.
259 * Besides, another consideration is, for multi-prime case, even the
260 * length modulus is as long as expected, the modulus could start at
261 * 0x8, which could be utilized to distinguish a multi-prime private
262 * key by using the modulus in a certificate. This is also covered
263 * by checking the length should not be less than 0x9.
265 if (!BN_rshift(r2, r1, bitse - 4))
267 bitst = BN_get_word(r2);
269 if (bitst < 0x9 || bitst > 0xF) {
271 * For keys with more than 4 primes, we attempt longer factor to
272 * meet length requirement.
274 * Otherwise, we just re-generate the prime with the same length.
276 * This strategy has the following goals:
278 * 1. 1024-bit factors are efficient when using 3072 and 4096-bit key
279 * 2. stay the same logic with normal 2-prime key
282 if (!BN_GENCB_call(cb, 2, n++))
289 } else if (retries == 4) {
291 * re-generate all primes from scratch, mainly used
292 * in 4 prime case to avoid long loop. Max retry times
302 /* save product of primes for further use, for multi-prime only */
303 if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL)
305 if (BN_copy(rsa->n, r1) == NULL)
307 if (!BN_GENCB_call(cb, 3, i))
311 if (BN_cmp(rsa->p, rsa->q) < 0) {
320 if (!BN_sub(r1, rsa->p, BN_value_one()))
323 if (!BN_sub(r2, rsa->q, BN_value_one()))
326 if (!BN_mul(r0, r1, r2, ctx))
329 for (i = 2; i < primes; i++) {
330 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
331 /* save r_i - 1 to pinfo->d temporarily */
332 if (!BN_sub(pinfo->d, pinfo->r, BN_value_one()))
334 if (!BN_mul(r0, r0, pinfo->d, ctx))
339 BIGNUM *pr0 = BN_new();
344 BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
345 if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) {
349 /* We MUST free pr0 before any further use of r0 */
354 BIGNUM *d = BN_new();
359 BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
361 /* calculate d mod (p-1) and d mod (q - 1) */
362 if (!BN_mod(rsa->dmp1, d, r1, ctx)
363 || !BN_mod(rsa->dmq1, d, r2, ctx)) {
368 /* calculate CRT exponents */
369 for (i = 2; i < primes; i++) {
370 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
371 /* pinfo->d == r_i - 1 */
372 if (!BN_mod(pinfo->d, d, pinfo->d, ctx)) {
378 /* We MUST free d before any further use of rsa->d */
383 BIGNUM *p = BN_new();
387 BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
389 /* calculate inverse of q mod p */
390 if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) {
395 /* calculate CRT coefficient for other primes */
396 for (i = 2; i < primes; i++) {
397 pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2);
398 BN_with_flags(p, pinfo->r, BN_FLG_CONSTTIME);
399 if (!BN_mod_inverse(pinfo->t, pinfo->pp, p, ctx)) {
405 /* We MUST free p before any further use of rsa->p */
412 RSAerr(0, ERR_LIB_BN);
419 #endif /* FIPS_MODULE */
421 static int rsa_keygen(OPENSSL_CTX *libctx, RSA *rsa, int bits, int primes,
422 BIGNUM *e_value, BN_GENCB *cb, int pairwise_test)
427 * Only multi-prime keys or insecure keys with a small key length will use
428 * the older rsa_multiprime_keygen().
430 if (primes == 2 && bits >= 2048)
431 ok = rsa_sp800_56b_generate_key(rsa, bits, e_value, cb);
434 ok = rsa_multiprime_keygen(rsa, bits, primes, e_value, cb);
435 #endif /* FIPS_MODULE */
438 pairwise_test = 1; /* FIPS MODE needs to always run the pairwise test */
440 if (pairwise_test && ok > 0) {
441 OSSL_CALLBACK *stcb = NULL;
442 void *stcbarg = NULL;
444 OSSL_SELF_TEST_get_callback(libctx, &stcb, &stcbarg);
445 ok = rsa_keygen_pairwise_test(rsa, stcb, stcbarg);
447 /* Clear intermediate results */
448 BN_clear_free(rsa->d);
449 BN_clear_free(rsa->p);
450 BN_clear_free(rsa->q);
451 BN_clear_free(rsa->dmp1);
452 BN_clear_free(rsa->dmq1);
453 BN_clear_free(rsa->iqmp);
460 * For RSA key generation it is not known whether the key pair will be used
461 * for key transport or signatures. FIPS 140-2 IG 9.9 states that in this case
462 * either a signature verification OR an encryption operation may be used to
463 * perform the pairwise consistency check. The simpler encrypt/decrypt operation
464 * has been chosen for this case.
466 static int rsa_keygen_pairwise_test(RSA *rsa, OSSL_CALLBACK *cb, void *cbarg)
469 unsigned int ciphertxt_len;
470 unsigned char *ciphertxt = NULL;
471 const unsigned char plaintxt[16] = {0};
472 unsigned char decoded[256];
473 unsigned int decoded_len;
474 unsigned int plaintxt_len = (unsigned int)sizeof(plaintxt_len);
475 int padding = RSA_PKCS1_PADDING;
476 OSSL_SELF_TEST *st = NULL;
478 st = OSSL_SELF_TEST_new(cb, cbarg);
481 OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT,
482 OSSL_SELF_TEST_DESC_PCT_RSA_PKCS1);
484 ciphertxt_len = RSA_size(rsa);
485 ciphertxt = OPENSSL_zalloc(ciphertxt_len);
486 if (ciphertxt == NULL)
489 ciphertxt_len = RSA_public_encrypt(plaintxt_len, plaintxt, ciphertxt, rsa,
491 if (ciphertxt_len <= 0)
493 if (ciphertxt_len == plaintxt_len
494 && memcmp(ciphertxt, plaintxt, plaintxt_len) == 0)
497 OSSL_SELF_TEST_oncorrupt_byte(st, ciphertxt);
499 decoded_len = RSA_private_decrypt(ciphertxt_len, ciphertxt, decoded, rsa,
501 if (decoded_len != plaintxt_len
502 || memcmp(decoded, plaintxt, decoded_len) != 0)
507 OSSL_SELF_TEST_onend(st, ret);
508 OSSL_SELF_TEST_free(st);
509 OPENSSL_free(ciphertxt);