/* * Copyright 1995-2024 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the Apache License 2.0 (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ /* * NB: these functions have been "upgraded", the deprecated versions (which * are compatibility wrappers using these functions) are in rsa_depr.c. - * Geoff */ /* * RSA low level APIs are deprecated for public use, but still ok for * internal use. */ #include "internal/deprecated.h" #include #include #include "internal/cryptlib.h" #include #include #include "prov/providercommon.h" #include "rsa_local.h" static int rsa_keygen_pairwise_test(RSA *rsa, OSSL_CALLBACK *cb, void *cbarg); static int rsa_keygen(OSSL_LIB_CTX *libctx, RSA *rsa, int bits, int primes, BIGNUM *e_value, BN_GENCB *cb, int pairwise_test); /* * NB: this wrapper would normally be placed in rsa_lib.c and the static * implementation would probably be in rsa_eay.c. Nonetheless, is kept here * so that we don't introduce a new linker dependency. Eg. any application * that wasn't previously linking object code related to key-generation won't * have to now just because key-generation is part of RSA_METHOD. */ int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb) { if (rsa->meth->rsa_keygen != NULL) return rsa->meth->rsa_keygen(rsa, bits, e_value, cb); return RSA_generate_multi_prime_key(rsa, bits, RSA_DEFAULT_PRIME_NUM, e_value, cb); } int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, BIGNUM *e_value, BN_GENCB *cb) { #ifndef FIPS_MODULE /* multi-prime is only supported with the builtin key generation */ if (rsa->meth->rsa_multi_prime_keygen != NULL) { return rsa->meth->rsa_multi_prime_keygen(rsa, bits, primes, e_value, cb); } else if (rsa->meth->rsa_keygen != NULL) { /* * However, if rsa->meth implements only rsa_keygen, then we * have to honour it in 2-prime case and assume that it wouldn't * know what to do with multi-prime key generated by builtin * subroutine... */ if (primes == 2) return rsa->meth->rsa_keygen(rsa, bits, e_value, cb); else return 0; } #endif /* FIPS_MODULE */ return rsa_keygen(rsa->libctx, rsa, bits, primes, e_value, cb, 0); } DEFINE_STACK_OF(BIGNUM) /* * Given input values, q, p, n, d and e, derive the exponents * and coefficients for each prime in this key, placing the result * on their respective exps and coeffs stacks */ #ifndef FIPS_MODULE int ossl_rsa_multiprime_derive(RSA *rsa, int bits, int primes, BIGNUM *e_value, STACK_OF(BIGNUM) *factors, STACK_OF(BIGNUM) *exps, STACK_OF(BIGNUM) *coeffs) { STACK_OF(BIGNUM) *pplist = NULL, *pdlist = NULL; BIGNUM *factor = NULL, *newpp = NULL, *newpd = NULL; BIGNUM *dval = NULL, *newexp = NULL, *newcoeff = NULL; BIGNUM *p = NULL, *q = NULL; BIGNUM *dmp1 = NULL, *dmq1 = NULL, *iqmp = NULL; BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL; BN_CTX *ctx = NULL; BIGNUM *tmp = NULL; int i; int ret = 0; ctx = BN_CTX_new_ex(rsa->libctx); if (ctx == NULL) goto err; BN_CTX_start(ctx); pplist = sk_BIGNUM_new_null(); if (pplist == NULL) goto err; pdlist = sk_BIGNUM_new_null(); if (pdlist == NULL) goto err; r0 = BN_CTX_get(ctx); r1 = BN_CTX_get(ctx); r2 = BN_CTX_get(ctx); if (r2 == NULL) goto err; BN_set_flags(r0, BN_FLG_CONSTTIME); BN_set_flags(r1, BN_FLG_CONSTTIME); BN_set_flags(r2, BN_FLG_CONSTTIME); if (BN_copy(r1, rsa->n) == NULL) goto err; p = sk_BIGNUM_value(factors, 0); q = sk_BIGNUM_value(factors, 1); /* Build list of partial products of primes */ for (i = 0; i < sk_BIGNUM_num(factors); i++) { switch (i) { case 0: /* our first prime, p */ if (!BN_sub(r2, p, BN_value_one())) goto err; BN_set_flags(r2, BN_FLG_CONSTTIME); if (BN_mod_inverse(r1, r2, rsa->e, ctx) == NULL) goto err; break; case 1: /* second prime q */ if (!BN_mul(r1, p, q, ctx)) goto err; tmp = BN_dup(r1); if (tmp == NULL) goto err; if (!sk_BIGNUM_insert(pplist, tmp, sk_BIGNUM_num(pplist))) goto err; break; default: factor = sk_BIGNUM_value(factors, i); /* all other primes */ if (!BN_mul(r1, r1, factor, ctx)) goto err; tmp = BN_dup(r1); if (tmp == NULL) goto err; if (!sk_BIGNUM_insert(pplist, tmp, sk_BIGNUM_num(pplist))) goto err; break; } } /* build list of relative d values */ /* p -1 */ if (!BN_sub(r1, p, BN_value_one())) goto err; if (!BN_sub(r2, q, BN_value_one())) goto err; if (!BN_mul(r0, r1, r2, ctx)) goto err; for (i = 2; i < sk_BIGNUM_num(factors); i++) { factor = sk_BIGNUM_value(factors, i); dval = BN_new(); if (dval == NULL) goto err; BN_set_flags(dval, BN_FLG_CONSTTIME); if (!BN_sub(dval, factor, BN_value_one())) goto err; if (!BN_mul(r0, r0, dval, ctx)) goto err; if (!sk_BIGNUM_insert(pdlist, dval, sk_BIGNUM_num(pdlist))) goto err; } /* Calculate dmp1, dmq1 and additional exponents */ dmp1 = BN_secure_new(); if (dmp1 == NULL) goto err; dmq1 = BN_secure_new(); if (dmq1 == NULL) goto err; if (!BN_mod(dmp1, rsa->d, r1, ctx)) goto err; if (!sk_BIGNUM_insert(exps, dmp1, sk_BIGNUM_num(exps))) goto err; dmp1 = NULL; if (!BN_mod(dmq1, rsa->d, r2, ctx)) goto err; if (!sk_BIGNUM_insert(exps, dmq1, sk_BIGNUM_num(exps))) goto err; dmq1 = NULL; for (i = 2; i < sk_BIGNUM_num(factors); i++) { newpd = sk_BIGNUM_value(pdlist, i - 2); newexp = BN_new(); if (newexp == NULL) goto err; if (!BN_mod(newexp, rsa->d, newpd, ctx)) { BN_free(newexp); goto err; } if (!sk_BIGNUM_insert(exps, newexp, sk_BIGNUM_num(exps))) goto err; } /* Calculate iqmp and additional coefficients */ iqmp = BN_new(); if (iqmp == NULL) goto err; if (BN_mod_inverse(iqmp, sk_BIGNUM_value(factors, 1), sk_BIGNUM_value(factors, 0), ctx) == NULL) goto err; if (!sk_BIGNUM_insert(coeffs, iqmp, sk_BIGNUM_num(coeffs))) goto err; iqmp = NULL; for (i = 2; i < sk_BIGNUM_num(factors); i++) { newpp = sk_BIGNUM_value(pplist, i - 2); newcoeff = BN_new(); if (newcoeff == NULL) goto err; if (BN_mod_inverse(newcoeff, newpp, sk_BIGNUM_value(factors, i), ctx) == NULL) { BN_free(newcoeff); goto err; } if (!sk_BIGNUM_insert(coeffs, newcoeff, sk_BIGNUM_num(coeffs))) goto err; } ret = 1; err: sk_BIGNUM_pop_free(pplist, BN_free); sk_BIGNUM_pop_free(pdlist, BN_free); BN_CTX_end(ctx); BN_CTX_free(ctx); BN_clear_free(dmp1); BN_clear_free(dmq1); BN_clear_free(iqmp); return ret; } static int rsa_multiprime_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value, BN_GENCB *cb) { BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *tmp, *tmp2, *prime; int n = 0, bitsr[RSA_MAX_PRIME_NUM], bitse = 0; int i = 0, quo = 0, rmd = 0, adj = 0, retries = 0; RSA_PRIME_INFO *pinfo = NULL; STACK_OF(RSA_PRIME_INFO) *prime_infos = NULL; STACK_OF(BIGNUM) *factors = NULL; STACK_OF(BIGNUM) *exps = NULL; STACK_OF(BIGNUM) *coeffs = NULL; BN_CTX *ctx = NULL; BN_ULONG bitst = 0; unsigned long error = 0; int ok = -1; if (bits < RSA_MIN_MODULUS_BITS) { ERR_raise(ERR_LIB_RSA, RSA_R_KEY_SIZE_TOO_SMALL); return 0; } if (e_value == NULL) { ERR_raise(ERR_LIB_RSA, RSA_R_BAD_E_VALUE); return 0; } /* A bad value for e can cause infinite loops */ if (!ossl_rsa_check_public_exponent(e_value)) { ERR_raise(ERR_LIB_RSA, RSA_R_PUB_EXPONENT_OUT_OF_RANGE); return 0; } if (primes < RSA_DEFAULT_PRIME_NUM || primes > ossl_rsa_multip_cap(bits)) { ERR_raise(ERR_LIB_RSA, RSA_R_KEY_PRIME_NUM_INVALID); return 0; } factors = sk_BIGNUM_new_null(); if (factors == NULL) return 0; exps = sk_BIGNUM_new_null(); if (exps == NULL) goto err; coeffs = sk_BIGNUM_new_null(); if (coeffs == NULL) goto err; ctx = BN_CTX_new_ex(rsa->libctx); if (ctx == NULL) goto err; BN_CTX_start(ctx); r0 = BN_CTX_get(ctx); r1 = BN_CTX_get(ctx); r2 = BN_CTX_get(ctx); if (r2 == NULL) goto err; /* divide bits into 'primes' pieces evenly */ quo = bits / primes; rmd = bits % primes; for (i = 0; i < primes; i++) bitsr[i] = (i < rmd) ? quo + 1 : quo; rsa->dirty_cnt++; /* We need the RSA components non-NULL */ if (!rsa->n && ((rsa->n = BN_new()) == NULL)) goto err; if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL)) goto err; BN_set_flags(rsa->d, BN_FLG_CONSTTIME); if (!rsa->e && ((rsa->e = BN_new()) == NULL)) goto err; if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL)) goto err; BN_set_flags(rsa->p, BN_FLG_CONSTTIME); if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL)) goto err; BN_set_flags(rsa->q, BN_FLG_CONSTTIME); /* initialize multi-prime components */ if (primes > RSA_DEFAULT_PRIME_NUM) { rsa->version = RSA_ASN1_VERSION_MULTI; prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2); if (prime_infos == NULL) goto err; if (rsa->prime_infos != NULL) { /* could this happen? */ sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, ossl_rsa_multip_info_free); } rsa->prime_infos = prime_infos; /* prime_info from 2 to |primes| -1 */ for (i = 2; i < primes; i++) { pinfo = ossl_rsa_multip_info_new(); if (pinfo == NULL) goto err; (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo); } } if (BN_copy(rsa->e, e_value) == NULL) goto err; /* generate p, q and other primes (if any) */ for (i = 0; i < primes; i++) { adj = 0; retries = 0; if (i == 0) { prime = rsa->p; } else if (i == 1) { prime = rsa->q; } else { pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); prime = pinfo->r; } BN_set_flags(prime, BN_FLG_CONSTTIME); for (;;) { redo: if (!BN_generate_prime_ex2(prime, bitsr[i] + adj, 0, NULL, NULL, cb, ctx)) goto err; /* * prime should not be equal to p, q, r_3... * (those primes prior to this one) */ { int j; for (j = 0; j < i; j++) { BIGNUM *prev_prime; if (j == 0) prev_prime = rsa->p; else if (j == 1) prev_prime = rsa->q; else prev_prime = sk_RSA_PRIME_INFO_value(prime_infos, j - 2)->r; if (!BN_cmp(prime, prev_prime)) { goto redo; } } } if (!BN_sub(r2, prime, BN_value_one())) goto err; ERR_set_mark(); BN_set_flags(r2, BN_FLG_CONSTTIME); if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) { /* GCD == 1 since inverse exists */ break; } error = ERR_peek_last_error(); if (ERR_GET_LIB(error) == ERR_LIB_BN && ERR_GET_REASON(error) == BN_R_NO_INVERSE) { /* GCD != 1 */ ERR_pop_to_mark(); } else { goto err; } if (!BN_GENCB_call(cb, 2, n++)) goto err; } bitse += bitsr[i]; /* calculate n immediately to see if it's sufficient */ if (i == 1) { /* we get at least 2 primes */ if (!BN_mul(r1, rsa->p, rsa->q, ctx)) goto err; } else if (i != 0) { /* modulus n = p * q * r_3 * r_4 ... */ if (!BN_mul(r1, rsa->n, prime, ctx)) goto err; } else { /* i == 0, do nothing */ if (!BN_GENCB_call(cb, 3, i)) goto err; tmp = BN_dup(prime); if (tmp == NULL) goto err; if (!sk_BIGNUM_insert(factors, tmp, sk_BIGNUM_num(factors))) goto err; continue; } /* * if |r1|, product of factors so far, is not as long as expected * (by checking the first 4 bits are less than 0x9 or greater than * 0xF). If so, re-generate the last prime. * * NOTE: This actually can't happen in two-prime case, because of * the way factors are generated. * * Besides, another consideration is, for multi-prime case, even the * length modulus is as long as expected, the modulus could start at * 0x8, which could be utilized to distinguish a multi-prime private * key by using the modulus in a certificate. This is also covered * by checking the length should not be less than 0x9. */ if (!BN_rshift(r2, r1, bitse - 4)) goto err; bitst = BN_get_word(r2); if (bitst < 0x9 || bitst > 0xF) { /* * For keys with more than 4 primes, we attempt longer factor to * meet length requirement. * * Otherwise, we just re-generate the prime with the same length. * * This strategy has the following goals: * * 1. 1024-bit factors are efficient when using 3072 and 4096-bit key * 2. stay the same logic with normal 2-prime key */ bitse -= bitsr[i]; if (!BN_GENCB_call(cb, 2, n++)) goto err; if (primes > 4) { if (bitst < 0x9) adj++; else adj--; } else if (retries == 4) { /* * re-generate all primes from scratch, mainly used * in 4 prime case to avoid long loop. Max retry times * is set to 4. */ i = -1; bitse = 0; sk_BIGNUM_pop_free(factors, BN_clear_free); factors = sk_BIGNUM_new_null(); if (factors == NULL) goto err; continue; } retries++; goto redo; } /* save product of primes for further use, for multi-prime only */ if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL) goto err; if (BN_copy(rsa->n, r1) == NULL) goto err; if (!BN_GENCB_call(cb, 3, i)) goto err; tmp = BN_dup(prime); if (tmp == NULL) goto err; if (!sk_BIGNUM_insert(factors, tmp, sk_BIGNUM_num(factors))) goto err; } if (BN_cmp(rsa->p, rsa->q) < 0) { tmp = rsa->p; rsa->p = rsa->q; rsa->q = tmp; /* mirror this in our factor stack */ if (!sk_BIGNUM_insert(factors, sk_BIGNUM_delete(factors, 0), 1)) goto err; } /* calculate d */ /* p - 1 */ if (!BN_sub(r1, rsa->p, BN_value_one())) goto err; /* q - 1 */ if (!BN_sub(r2, rsa->q, BN_value_one())) goto err; /* (p - 1)(q - 1) */ if (!BN_mul(r0, r1, r2, ctx)) goto err; /* multi-prime */ for (i = 2; i < primes; i++) { pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); /* save r_i - 1 to pinfo->d temporarily */ if (!BN_sub(pinfo->d, pinfo->r, BN_value_one())) goto err; if (!BN_mul(r0, r0, pinfo->d, ctx)) goto err; } BN_set_flags(r0, BN_FLG_CONSTTIME); if (BN_mod_inverse(rsa->d, rsa->e, r0, ctx) == NULL) { goto err; /* d */ } /* derive any missing exponents and coefficients */ if (!ossl_rsa_multiprime_derive(rsa, bits, primes, e_value, factors, exps, coeffs)) goto err; /* * first 2 factors/exps are already tracked in p/q/dmq1/dmp1 * and the first coeff is in iqmp, so pop those off the stack * Note, the first 2 factors/exponents are already tracked by p and q * assign dmp1/dmq1 and iqmp * the remaining pinfo values are separately allocated, so copy and delete * those */ BN_clear_free(sk_BIGNUM_delete(factors, 0)); BN_clear_free(sk_BIGNUM_delete(factors, 0)); rsa->dmp1 = sk_BIGNUM_delete(exps, 0); rsa->dmq1 = sk_BIGNUM_delete(exps, 0); rsa->iqmp = sk_BIGNUM_delete(coeffs, 0); for (i = 2; i < primes; i++) { pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); tmp = sk_BIGNUM_delete(factors, 0); BN_copy(pinfo->r, tmp); BN_clear_free(tmp); tmp = sk_BIGNUM_delete(exps, 0); tmp2 = BN_copy(pinfo->d, tmp); BN_clear_free(tmp); if (tmp2 == NULL) goto err; tmp = sk_BIGNUM_delete(coeffs, 0); tmp2 = BN_copy(pinfo->t, tmp); BN_clear_free(tmp); if (tmp2 == NULL) goto err; } ok = 1; err: sk_BIGNUM_free(factors); sk_BIGNUM_free(exps); sk_BIGNUM_free(coeffs); if (ok == -1) { ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB); ok = 0; } BN_CTX_end(ctx); BN_CTX_free(ctx); return ok; } #endif /* FIPS_MODULE */ static int rsa_keygen(OSSL_LIB_CTX *libctx, RSA *rsa, int bits, int primes, BIGNUM *e_value, BN_GENCB *cb, int pairwise_test) { int ok = 0; #ifdef FIPS_MODULE ok = ossl_rsa_sp800_56b_generate_key(rsa, bits, e_value, cb); pairwise_test = 1; /* FIPS MODE needs to always run the pairwise test */ #else /* * Only multi-prime keys or insecure keys with a small key length or a * public exponent <= 2^16 will use the older rsa_multiprime_keygen(). */ if (primes == 2 && bits >= 2048 && (e_value == NULL || BN_num_bits(e_value) > 16)) ok = ossl_rsa_sp800_56b_generate_key(rsa, bits, e_value, cb); else ok = rsa_multiprime_keygen(rsa, bits, primes, e_value, cb); #endif /* FIPS_MODULE */ if (pairwise_test && ok > 0) { OSSL_CALLBACK *stcb = NULL; void *stcbarg = NULL; OSSL_SELF_TEST_get_callback(libctx, &stcb, &stcbarg); ok = rsa_keygen_pairwise_test(rsa, stcb, stcbarg); if (!ok) { ossl_set_error_state(OSSL_SELF_TEST_TYPE_PCT); /* Clear intermediate results */ BN_clear_free(rsa->d); BN_clear_free(rsa->p); BN_clear_free(rsa->q); BN_clear_free(rsa->dmp1); BN_clear_free(rsa->dmq1); BN_clear_free(rsa->iqmp); rsa->d = NULL; rsa->p = NULL; rsa->q = NULL; rsa->dmp1 = NULL; rsa->dmq1 = NULL; rsa->iqmp = NULL; } } return ok; } /* * AS10.35 (and its VEs/TEs) of the FIPS 140-3 standard requires a PCT for every * generated key pair. There are 3 options: * 1) If the key pair is to be used for key transport (asymmetric cipher), the * PCT consists of encrypting a plaintext, verifying that the result * (ciphertext) is not equal to the plaintext, decrypting the ciphertext, and * verifying that the result is equal to the plaintext. * 2) If the key pair is to be used for digital signatures, the PCT consists of * computing and verifying a signature. * 3) If the key pair is to be used for key agreement, the exact PCT is defined * in the applicable standards. For RSA-based schemes, this is defined in * SP 800-56Br2 (Section 6.4.1.1) as: * "The owner shall perform a pair-wise consistency test by verifying that m * = (m^e)^d mod n for some integer m satisfying 1 < m < (n - 1)." * * OpenSSL implements all three use cases: RSA-OAEP for key transport, * RSA signatures with PKCS#1 v1.5 or PSS padding, and KAS-IFC-SSC (KAS1/KAS2) * using RSASVE. * * According to FIPS 140-3 IG 10.3.A, if at the time when the PCT is performed * the keys' intended usage is not known, then any of the three PCTs described * in AS10.35 shall be performed on this key pair. * * Because of this allowance from the IG, the simplest option is 3, i.e. * RSA_public_encrypt() and RSA_private_decrypt() with RSA_NO_PADDING. */ static int rsa_keygen_pairwise_test(RSA *rsa, OSSL_CALLBACK *cb, void *cbarg) { int ret = 0; unsigned int plaintxt_len; unsigned char *plaintxt = NULL; unsigned int ciphertxt_len; unsigned char *ciphertxt = NULL; unsigned char *decoded = NULL; unsigned int decoded_len; int padding = RSA_NO_PADDING; OSSL_SELF_TEST *st = NULL; st = OSSL_SELF_TEST_new(cb, cbarg); if (st == NULL) goto err; OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_PCT, OSSL_SELF_TEST_DESC_PCT_RSA); /* * For RSA_NO_PADDING, RSA_public_encrypt() and RSA_private_decrypt() * require the 'to' and 'from' parameters to have equal length and a * maximum of RSA_size() - allocate space for plaintxt, ciphertxt, and * decoded. */ plaintxt_len = RSA_size(rsa); plaintxt = OPENSSL_zalloc(plaintxt_len * 3); if (plaintxt == NULL) goto err; ciphertxt = plaintxt + plaintxt_len; decoded = ciphertxt + plaintxt_len; /* SP 800-56Br2 Section 6.4.1.1 requires that plaintext is greater than 1 */ plaintxt[plaintxt_len - 1] = 2; ciphertxt_len = RSA_public_encrypt(plaintxt_len, plaintxt, ciphertxt, rsa, padding); if (ciphertxt_len <= 0) goto err; OSSL_SELF_TEST_oncorrupt_byte(st, ciphertxt); decoded_len = RSA_private_decrypt(ciphertxt_len, ciphertxt, decoded, rsa, padding); if (decoded_len != plaintxt_len || memcmp(decoded, plaintxt, decoded_len) != 0) goto err; ret = 1; err: OSSL_SELF_TEST_onend(st, ret); OSSL_SELF_TEST_free(st); OPENSSL_free(plaintxt); return ret; }