-/* crypto/dh/dh_key.c */
-/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * All rights reserved.
+/*
+ * Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved.
*
- * This package is an SSL implementation written
- * by Eric Young (eay@cryptsoft.com).
- * The implementation was written so as to conform with Netscapes SSL.
- *
- * This library is free for commercial and non-commercial use as long as
- * the following conditions are aheared to. The following conditions
- * apply to all code found in this distribution, be it the RC4, RSA,
- * lhash, DES, etc., code; not just the SSL code. The SSL documentation
- * included with this distribution is covered by the same copyright terms
- * except that the holder is Tim Hudson (tjh@cryptsoft.com).
- *
- * Copyright remains Eric Young's, and as such any Copyright notices in
- * the code are not to be removed.
- * If this package is used in a product, Eric Young should be given attribution
- * as the author of the parts of the library used.
- * This can be in the form of a textual message at program startup or
- * in documentation (online or textual) provided with the package.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * "This product includes cryptographic software written by
- * Eric Young (eay@cryptsoft.com)"
- * The word 'cryptographic' can be left out if the rouines from the library
- * being used are not cryptographic related :-).
- * 4. If you include any Windows specific code (or a derivative thereof) from
- * the apps directory (application code) you must include an acknowledgement:
- * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
- *
- * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- * The licence and distribution terms for any publically available version or
- * derivative of this code cannot be changed. i.e. this code cannot simply be
- * copied and put under another distribution licence
- * [including the GNU Public Licence.]
+ * 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
*/
+/*
+ * DH low level APIs are deprecated for public use, but still ok for
+ * internal use.
+ */
+#include "internal/deprecated.h"
+
#include <stdio.h>
-#include "cryptlib.h"
-#include <openssl/bn.h>
-#include <openssl/rand.h>
-#include <openssl/dh.h>
-#include <openssl/engine.h>
+#include "internal/cryptlib.h"
+#include "dh_local.h"
+#include "crypto/bn.h"
+#include "crypto/dh.h"
+#include "crypto/security_bits.h"
+
+#ifdef FIPS_MODULE
+# define MIN_STRENGTH 112
+#else
+# define MIN_STRENGTH 80
+#endif
static int generate_key(DH *dh);
-static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
- const BIGNUM *a, const BIGNUM *p,
- const BIGNUM *m, BN_CTX *ctx,
- BN_MONT_CTX *m_ctx);
+ const BIGNUM *a, const BIGNUM *p,
+ const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
static int dh_init(DH *dh);
static int dh_finish(DH *dh);
-int DH_generate_key(DH *dh)
- {
- return ENGINE_get_DH(dh->engine)->generate_key(dh);
- }
+/*
+ * See SP800-56Ar3 Section 5.7.1.1
+ * Finite Field Cryptography Diffie-Hellman (FFC DH) Primitive
+ */
+int ossl_dh_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
+{
+ BN_CTX *ctx = NULL;
+ BN_MONT_CTX *mont = NULL;
+ BIGNUM *z = NULL, *pminus1;
+ int ret = -1;
+
+ if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) {
+ ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
+ goto err;
+ }
+
+ if (dh->params.q != NULL
+ && BN_num_bits(dh->params.q) > OPENSSL_DH_MAX_MODULUS_BITS) {
+ ERR_raise(ERR_LIB_DH, DH_R_Q_TOO_LARGE);
+ goto err;
+ }
+
+ if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
+ ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
+ return 0;
+ }
+
+ ctx = BN_CTX_new_ex(dh->libctx);
+ if (ctx == NULL)
+ goto err;
+ BN_CTX_start(ctx);
+ pminus1 = BN_CTX_get(ctx);
+ z = BN_CTX_get(ctx);
+ if (z == NULL)
+ goto err;
+ if (dh->priv_key == NULL) {
+ ERR_raise(ERR_LIB_DH, DH_R_NO_PRIVATE_VALUE);
+ goto err;
+ }
+
+ if (dh->flags & DH_FLAG_CACHE_MONT_P) {
+ mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
+ dh->lock, dh->params.p, ctx);
+ BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
+ if (!mont)
+ goto err;
+ }
+
+ /* (Step 1) Z = pub_key^priv_key mod p */
+ if (!dh->meth->bn_mod_exp(dh, z, pub_key, dh->priv_key, dh->params.p, ctx,
+ mont)) {
+ ERR_raise(ERR_LIB_DH, ERR_R_BN_LIB);
+ goto err;
+ }
+
+ /* (Step 2) Error if z <= 1 or z = p - 1 */
+ if (BN_copy(pminus1, dh->params.p) == NULL
+ || !BN_sub_word(pminus1, 1)
+ || BN_cmp(z, BN_value_one()) <= 0
+ || BN_cmp(z, pminus1) == 0) {
+ ERR_raise(ERR_LIB_DH, DH_R_INVALID_SECRET);
+ goto err;
+ }
+
+ /* return the padded key, i.e. same number of bytes as the modulus */
+ ret = BN_bn2binpad(z, key, BN_num_bytes(dh->params.p));
+ err:
+ BN_clear(z); /* (Step 2) destroy intermediate values */
+ BN_CTX_end(ctx);
+ BN_CTX_free(ctx);
+ return ret;
+}
+
+/*-
+ * NB: This function is inherently not constant time due to the
+ * RFC 5246 (8.1.2) padding style that strips leading zero bytes.
+ */
int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
- {
- return ENGINE_get_DH(dh->engine)->compute_key(key, pub_key, dh);
- }
+{
+ int ret = 0, i;
+ volatile size_t npad = 0, mask = 1;
+
+ /* compute the key; ret is constant unless compute_key is external */
+#ifdef FIPS_MODULE
+ ret = ossl_dh_compute_key(key, pub_key, dh);
+#else
+ ret = dh->meth->compute_key(key, pub_key, dh);
+#endif
+ if (ret <= 0)
+ return ret;
+
+ /* count leading zero bytes, yet still touch all bytes */
+ for (i = 0; i < ret; i++) {
+ mask &= !key[i];
+ npad += mask;
+ }
+
+ /* unpad key */
+ ret -= npad;
+ /* key-dependent memory access, potentially leaking npad / ret */
+ memmove(key, key + npad, ret);
+ /* key-dependent memory access, potentially leaking npad / ret */
+ memset(key + ret, 0, npad);
+
+ return ret;
+}
+
+int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh)
+{
+ int rv, pad;
+
+ /* rv is constant unless compute_key is external */
+#ifdef FIPS_MODULE
+ rv = ossl_dh_compute_key(key, pub_key, dh);
+#else
+ rv = dh->meth->compute_key(key, pub_key, dh);
+#endif
+ if (rv <= 0)
+ return rv;
+ pad = BN_num_bytes(dh->params.p) - rv;
+ /* pad is constant (zero) unless compute_key is external */
+ if (pad > 0) {
+ memmove(key + pad, key, rv);
+ memset(key, 0, pad);
+ }
+ return rv + pad;
+}
static DH_METHOD dh_ossl = {
-"OpenSSL DH Method",
-generate_key,
-compute_key,
-dh_bn_mod_exp,
-dh_init,
-dh_finish,
-0,
-NULL
+ "OpenSSL DH Method",
+ generate_key,
+ ossl_dh_compute_key,
+ dh_bn_mod_exp,
+ dh_init,
+ dh_finish,
+ DH_FLAG_FIPS_METHOD,
+ NULL,
+ NULL
};
+static const DH_METHOD *default_DH_method = &dh_ossl;
+
const DH_METHOD *DH_OpenSSL(void)
{
- return &dh_ossl;
+ return &dh_ossl;
}
-static int generate_key(DH *dh)
- {
- int ok=0;
- int generate_new_key=0;
- unsigned l;
- BN_CTX *ctx;
- BN_MONT_CTX *mont;
- BIGNUM *pub_key=NULL,*priv_key=NULL;
-
- ctx = BN_CTX_new();
- if (ctx == NULL) goto err;
-
- if (dh->priv_key == NULL)
- {
- priv_key=BN_new();
- if (priv_key == NULL) goto err;
- generate_new_key=1;
- }
- else
- priv_key=dh->priv_key;
-
- if (dh->pub_key == NULL)
- {
- pub_key=BN_new();
- if (pub_key == NULL) goto err;
- }
- else
- pub_key=dh->pub_key;
-
- if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P))
- {
- if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
- if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p,
- dh->p,ctx)) goto err;
- }
- mont=(BN_MONT_CTX *)dh->method_mont_p;
-
- l = dh->length ? dh->length : BN_num_bits(dh->p)-1; /* secret exponent length */
-
- if (generate_new_key)
- {
- if (!BN_rand(priv_key, l, 0, 0)) goto err;
- }
- if (!ENGINE_get_DH(dh->engine)->bn_mod_exp(dh, pub_key, dh->g,
- priv_key,dh->p,ctx,mont)) goto err;
-
- dh->pub_key=pub_key;
- dh->priv_key=priv_key;
- ok=1;
-err:
- if (ok != 1)
- DHerr(DH_F_DH_GENERATE_KEY,ERR_R_BN_LIB);
-
- if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key);
- if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key);
- BN_CTX_free(ctx);
- return(ok);
- }
-
-static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
- {
- BN_CTX *ctx;
- BN_MONT_CTX *mont;
- BIGNUM *tmp;
- int ret= -1;
-
- ctx = BN_CTX_new();
- if (ctx == NULL) goto err;
- BN_CTX_start(ctx);
- tmp = BN_CTX_get(ctx);
-
- if (dh->priv_key == NULL)
- {
- DHerr(DH_F_DH_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE);
- goto err;
- }
- if ((dh->method_mont_p == NULL) && (dh->flags & DH_FLAG_CACHE_MONT_P))
- {
- if ((dh->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
- if (!BN_MONT_CTX_set((BN_MONT_CTX *)dh->method_mont_p,
- dh->p,ctx)) goto err;
- }
-
- mont=(BN_MONT_CTX *)dh->method_mont_p;
- if (!ENGINE_get_DH(dh->engine)->bn_mod_exp(dh, tmp, pub_key,
- dh->priv_key,dh->p,ctx,mont))
- {
- DHerr(DH_F_DH_COMPUTE_KEY,ERR_R_BN_LIB);
- goto err;
- }
-
- ret=BN_bn2bin(tmp,key);
-err:
- BN_CTX_end(ctx);
- BN_CTX_free(ctx);
- return(ret);
- }
+const DH_METHOD *DH_get_default_method(void)
+{
+ return default_DH_method;
+}
static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
- const BIGNUM *a, const BIGNUM *p,
- const BIGNUM *m, BN_CTX *ctx,
- BN_MONT_CTX *m_ctx)
- {
- if (a->top == 1)
- {
- BN_ULONG A = a->d[0];
- return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx);
- }
- else
- return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx);
- }
-
+ const BIGNUM *a, const BIGNUM *p,
+ const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
+{
+#ifdef S390X_MOD_EXP
+ return s390x_mod_exp(r, a, p, m, ctx, m_ctx);
+#else
+ return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
+#endif
+}
static int dh_init(DH *dh)
- {
- dh->flags |= DH_FLAG_CACHE_MONT_P;
- return(1);
- }
+{
+ dh->flags |= DH_FLAG_CACHE_MONT_P;
+ dh->dirty_cnt++;
+ return 1;
+}
static int dh_finish(DH *dh)
- {
- if(dh->method_mont_p)
- BN_MONT_CTX_free((BN_MONT_CTX *)dh->method_mont_p);
- return(1);
- }
+{
+ BN_MONT_CTX_free(dh->method_mont_p);
+ return 1;
+}
+
+#ifndef FIPS_MODULE
+void DH_set_default_method(const DH_METHOD *meth)
+{
+ default_DH_method = meth;
+}
+#endif /* FIPS_MODULE */
+
+int DH_generate_key(DH *dh)
+{
+#ifdef FIPS_MODULE
+ return generate_key(dh);
+#else
+ return dh->meth->generate_key(dh);
+#endif
+}
+
+int ossl_dh_generate_public_key(BN_CTX *ctx, const DH *dh,
+ const BIGNUM *priv_key, BIGNUM *pub_key)
+{
+ int ret = 0;
+ BIGNUM *prk = BN_new();
+ BN_MONT_CTX *mont = NULL;
+
+ if (prk == NULL)
+ return 0;
+
+ if (dh->flags & DH_FLAG_CACHE_MONT_P) {
+ /*
+ * We take the input DH as const, but we lie, because in some cases we
+ * want to get a hold of its Montgomery context.
+ *
+ * We cast to remove the const qualifier in this case, it should be
+ * fine...
+ */
+ BN_MONT_CTX **pmont = (BN_MONT_CTX **)&dh->method_mont_p;
+
+ mont = BN_MONT_CTX_set_locked(pmont, dh->lock, dh->params.p, ctx);
+ if (mont == NULL)
+ goto err;
+ }
+ BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
+
+ /* pub_key = g^priv_key mod p */
+ if (!dh->meth->bn_mod_exp(dh, pub_key, dh->params.g, prk, dh->params.p,
+ ctx, mont))
+ goto err;
+ ret = 1;
+err:
+ BN_clear_free(prk);
+ return ret;
+}
+
+static int generate_key(DH *dh)
+{
+ int ok = 0;
+ int generate_new_key = 0;
+#ifndef FIPS_MODULE
+ unsigned l;
+#endif
+ BN_CTX *ctx = NULL;
+ BIGNUM *pub_key = NULL, *priv_key = NULL;
+
+ if (BN_num_bits(dh->params.p) > OPENSSL_DH_MAX_MODULUS_BITS) {
+ ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_LARGE);
+ return 0;
+ }
+
+ if (dh->params.q != NULL
+ && BN_num_bits(dh->params.q) > OPENSSL_DH_MAX_MODULUS_BITS) {
+ ERR_raise(ERR_LIB_DH, DH_R_Q_TOO_LARGE);
+ return 0;
+ }
+
+ if (BN_num_bits(dh->params.p) < DH_MIN_MODULUS_BITS) {
+ ERR_raise(ERR_LIB_DH, DH_R_MODULUS_TOO_SMALL);
+ return 0;
+ }
+
+ ctx = BN_CTX_new_ex(dh->libctx);
+ if (ctx == NULL)
+ goto err;
+
+ if (dh->priv_key == NULL) {
+ priv_key = BN_secure_new();
+ if (priv_key == NULL)
+ goto err;
+ generate_new_key = 1;
+ } else {
+ priv_key = dh->priv_key;
+ }
+
+ if (dh->pub_key == NULL) {
+ pub_key = BN_new();
+ if (pub_key == NULL)
+ goto err;
+ } else {
+ pub_key = dh->pub_key;
+ }
+ if (generate_new_key) {
+ /* Is it an approved safe prime ?*/
+ if (DH_get_nid(dh) != NID_undef) {
+ int max_strength =
+ ossl_ifc_ffc_compute_security_bits(BN_num_bits(dh->params.p));
+
+ if (dh->params.q == NULL
+ || dh->length > BN_num_bits(dh->params.q))
+ goto err;
+ /* dh->length = maximum bit length of generated private key */
+ if (!ossl_ffc_generate_private_key(ctx, &dh->params, dh->length,
+ max_strength, priv_key))
+ goto err;
+ } else {
+#ifdef FIPS_MODULE
+ if (dh->params.q == NULL)
+ goto err;
+#else
+ if (dh->params.q == NULL) {
+ /* secret exponent length, must satisfy 2^(l-1) <= p */
+ if (dh->length != 0
+ && dh->length >= BN_num_bits(dh->params.p))
+ goto err;
+ l = dh->length ? dh->length : BN_num_bits(dh->params.p) - 1;
+ if (!BN_priv_rand_ex(priv_key, l, BN_RAND_TOP_ONE,
+ BN_RAND_BOTTOM_ANY, 0, ctx))
+ goto err;
+ /*
+ * We handle just one known case where g is a quadratic non-residue:
+ * for g = 2: p % 8 == 3
+ */
+ if (BN_is_word(dh->params.g, DH_GENERATOR_2)
+ && !BN_is_bit_set(dh->params.p, 2)) {
+ /* clear bit 0, since it won't be a secret anyway */
+ if (!BN_clear_bit(priv_key, 0))
+ goto err;
+ }
+ } else
+#endif
+ {
+ /* Do a partial check for invalid p, q, g */
+ if (!ossl_ffc_params_simple_validate(dh->libctx, &dh->params,
+ FFC_PARAM_TYPE_DH, NULL))
+ goto err;
+ /*
+ * For FFC FIPS 186-4 keygen
+ * security strength s = 112,
+ * Max Private key size N = len(q)
+ */
+ if (!ossl_ffc_generate_private_key(ctx, &dh->params,
+ BN_num_bits(dh->params.q),
+ MIN_STRENGTH,
+ priv_key))
+ goto err;
+ }
+ }
+ }
+
+ if (!ossl_dh_generate_public_key(ctx, dh, priv_key, pub_key))
+ goto err;
+
+ dh->pub_key = pub_key;
+ dh->priv_key = priv_key;
+ dh->dirty_cnt++;
+ ok = 1;
+ err:
+ if (ok != 1)
+ ERR_raise(ERR_LIB_DH, ERR_R_BN_LIB);
+
+ if (pub_key != dh->pub_key)
+ BN_free(pub_key);
+ if (priv_key != dh->priv_key)
+ BN_free(priv_key);
+ BN_CTX_free(ctx);
+ return ok;
+}
+
+int ossl_dh_buf2key(DH *dh, const unsigned char *buf, size_t len)
+{
+ int err_reason = DH_R_BN_ERROR;
+ BIGNUM *pubkey = NULL;
+ const BIGNUM *p;
+ int ret;
+
+ if ((pubkey = BN_bin2bn(buf, len, NULL)) == NULL)
+ goto err;
+ DH_get0_pqg(dh, &p, NULL, NULL);
+ if (p == NULL || BN_num_bytes(p) == 0) {
+ err_reason = DH_R_NO_PARAMETERS_SET;
+ goto err;
+ }
+ /* Prevent small subgroup attacks per RFC 8446 Section 4.2.8.1 */
+ if (!ossl_dh_check_pub_key_partial(dh, pubkey, &ret)) {
+ err_reason = DH_R_INVALID_PUBKEY;
+ goto err;
+ }
+ if (DH_set0_key(dh, pubkey, NULL) != 1)
+ goto err;
+ return 1;
+err:
+ ERR_raise(ERR_LIB_DH, err_reason);
+ BN_free(pubkey);
+ return 0;
+}
+
+size_t ossl_dh_key2buf(const DH *dh, unsigned char **pbuf_out, size_t size,
+ int alloc)
+{
+ const BIGNUM *pubkey;
+ unsigned char *pbuf = NULL;
+ const BIGNUM *p;
+ int p_size;
+
+ DH_get0_pqg(dh, &p, NULL, NULL);
+ DH_get0_key(dh, &pubkey, NULL);
+ if (p == NULL || pubkey == NULL
+ || (p_size = BN_num_bytes(p)) == 0
+ || BN_num_bytes(pubkey) == 0) {
+ ERR_raise(ERR_LIB_DH, DH_R_INVALID_PUBKEY);
+ return 0;
+ }
+ if (pbuf_out != NULL && (alloc || *pbuf_out != NULL)) {
+ if (!alloc) {
+ if (size >= (size_t)p_size)
+ pbuf = *pbuf_out;
+ if (pbuf == NULL)
+ ERR_raise(ERR_LIB_DH, DH_R_INVALID_SIZE);
+ } else {
+ pbuf = OPENSSL_malloc(p_size);
+ }
+
+ /* Errors raised above */
+ if (pbuf == NULL)
+ return 0;
+ /*
+ * As per Section 4.2.8.1 of RFC 8446 left pad public
+ * key with zeros to the size of p
+ */
+ if (BN_bn2binpad(pubkey, pbuf, p_size) < 0) {
+ if (alloc)
+ OPENSSL_free(pbuf);
+ ERR_raise(ERR_LIB_DH, DH_R_BN_ERROR);
+ return 0;
+ }
+ *pbuf_out = pbuf;
+ }
+ return p_size;
+}
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