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- /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
- * 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.] */
-
- #include <openssl/dh.h>
-
- #include <string.h>
-
- #include <openssl/bn.h>
- #include <openssl/buf.h>
- #include <openssl/err.h>
- #include <openssl/ex_data.h>
- #include <openssl/mem.h>
- #include <openssl/thread.h>
-
- #include "../internal.h"
-
-
- #define OPENSSL_DH_MAX_MODULUS_BITS 10000
-
- static CRYPTO_EX_DATA_CLASS g_ex_data_class = CRYPTO_EX_DATA_CLASS_INIT;
-
- DH *DH_new(void) {
- DH *dh = OPENSSL_malloc(sizeof(DH));
- if (dh == NULL) {
- OPENSSL_PUT_ERROR(DH, ERR_R_MALLOC_FAILURE);
- return NULL;
- }
-
- OPENSSL_memset(dh, 0, sizeof(DH));
-
- CRYPTO_MUTEX_init(&dh->method_mont_p_lock);
-
- dh->references = 1;
- CRYPTO_new_ex_data(&dh->ex_data);
-
- return dh;
- }
-
- void DH_free(DH *dh) {
- if (dh == NULL) {
- return;
- }
-
- if (!CRYPTO_refcount_dec_and_test_zero(&dh->references)) {
- return;
- }
-
- CRYPTO_free_ex_data(&g_ex_data_class, dh, &dh->ex_data);
-
- BN_MONT_CTX_free(dh->method_mont_p);
- BN_clear_free(dh->p);
- BN_clear_free(dh->g);
- BN_clear_free(dh->q);
- BN_clear_free(dh->j);
- OPENSSL_free(dh->seed);
- BN_clear_free(dh->counter);
- BN_clear_free(dh->pub_key);
- BN_clear_free(dh->priv_key);
- CRYPTO_MUTEX_cleanup(&dh->method_mont_p_lock);
-
- OPENSSL_free(dh);
- }
-
- void DH_get0_key(const DH *dh, const BIGNUM **out_pub_key,
- const BIGNUM **out_priv_key) {
- if (out_pub_key != NULL) {
- *out_pub_key = dh->pub_key;
- }
- if (out_priv_key != NULL) {
- *out_priv_key = dh->priv_key;
- }
- }
-
- void DH_get0_pqg(const DH *dh, const BIGNUM **out_p, const BIGNUM **out_q,
- const BIGNUM **out_g) {
- if (out_p != NULL) {
- *out_p = dh->p;
- }
- if (out_q != NULL) {
- *out_q = dh->q;
- }
- if (out_g != NULL) {
- *out_g = dh->g;
- }
- }
-
- int DH_generate_parameters_ex(DH *dh, int prime_bits, int generator, BN_GENCB *cb) {
- // We generate DH parameters as follows
- // find a prime q which is prime_bits/2 bits long.
- // p=(2*q)+1 or (p-1)/2 = q
- // For this case, g is a generator if
- // g^((p-1)/q) mod p != 1 for values of q which are the factors of p-1.
- // Since the factors of p-1 are q and 2, we just need to check
- // g^2 mod p != 1 and g^q mod p != 1.
- //
- // Having said all that,
- // there is another special case method for the generators 2, 3 and 5.
- // for 2, p mod 24 == 11
- // for 3, p mod 12 == 5 <<<<< does not work for safe primes.
- // for 5, p mod 10 == 3 or 7
- //
- // Thanks to Phil Karn <karn@qualcomm.com> for the pointers about the
- // special generators and for answering some of my questions.
- //
- // I've implemented the second simple method :-).
- // Since DH should be using a safe prime (both p and q are prime),
- // this generator function can take a very very long time to run.
-
- // Actually there is no reason to insist that 'generator' be a generator.
- // It's just as OK (and in some sense better) to use a generator of the
- // order-q subgroup.
-
- BIGNUM *t1, *t2;
- int g, ok = 0;
- BN_CTX *ctx = NULL;
-
- ctx = BN_CTX_new();
- if (ctx == NULL) {
- goto err;
- }
- BN_CTX_start(ctx);
- t1 = BN_CTX_get(ctx);
- t2 = BN_CTX_get(ctx);
- if (t1 == NULL || t2 == NULL) {
- goto err;
- }
-
- // Make sure |dh| has the necessary elements
- if (dh->p == NULL) {
- dh->p = BN_new();
- if (dh->p == NULL) {
- goto err;
- }
- }
- if (dh->g == NULL) {
- dh->g = BN_new();
- if (dh->g == NULL) {
- goto err;
- }
- }
-
- if (generator <= 1) {
- OPENSSL_PUT_ERROR(DH, DH_R_BAD_GENERATOR);
- goto err;
- }
- if (generator == DH_GENERATOR_2) {
- if (!BN_set_word(t1, 24)) {
- goto err;
- }
- if (!BN_set_word(t2, 11)) {
- goto err;
- }
- g = 2;
- } else if (generator == DH_GENERATOR_5) {
- if (!BN_set_word(t1, 10)) {
- goto err;
- }
- if (!BN_set_word(t2, 3)) {
- goto err;
- }
- // BN_set_word(t3,7); just have to miss
- // out on these ones :-(
- g = 5;
- } else {
- // in the general case, don't worry if 'generator' is a
- // generator or not: since we are using safe primes,
- // it will generate either an order-q or an order-2q group,
- // which both is OK
- if (!BN_set_word(t1, 2)) {
- goto err;
- }
- if (!BN_set_word(t2, 1)) {
- goto err;
- }
- g = generator;
- }
-
- if (!BN_generate_prime_ex(dh->p, prime_bits, 1, t1, t2, cb)) {
- goto err;
- }
- if (!BN_GENCB_call(cb, 3, 0)) {
- goto err;
- }
- if (!BN_set_word(dh->g, g)) {
- goto err;
- }
- ok = 1;
-
- err:
- if (!ok) {
- OPENSSL_PUT_ERROR(DH, ERR_R_BN_LIB);
- }
-
- if (ctx != NULL) {
- BN_CTX_end(ctx);
- BN_CTX_free(ctx);
- }
- return ok;
- }
-
- int DH_generate_key(DH *dh) {
- int ok = 0;
- int generate_new_key = 0;
- BN_CTX *ctx = NULL;
- BIGNUM *pub_key = NULL, *priv_key = NULL;
-
- if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
- OPENSSL_PUT_ERROR(DH, DH_R_MODULUS_TOO_LARGE);
- goto err;
- }
-
- 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 (!BN_MONT_CTX_set_locked(&dh->method_mont_p, &dh->method_mont_p_lock,
- dh->p, ctx)) {
- goto err;
- }
-
- if (generate_new_key) {
- if (dh->q) {
- if (!BN_rand_range_ex(priv_key, 2, dh->q)) {
- goto err;
- }
- } else {
- // secret exponent length
- unsigned priv_bits = dh->priv_length;
- if (priv_bits == 0) {
- const unsigned p_bits = BN_num_bits(dh->p);
- if (p_bits == 0) {
- goto err;
- }
-
- priv_bits = p_bits - 1;
- }
-
- if (!BN_rand(priv_key, priv_bits, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY)) {
- goto err;
- }
- }
- }
-
- if (!BN_mod_exp_mont_consttime(pub_key, dh->g, priv_key, dh->p, ctx,
- dh->method_mont_p)) {
- goto err;
- }
-
- dh->pub_key = pub_key;
- dh->priv_key = priv_key;
- ok = 1;
-
- err:
- if (ok != 1) {
- OPENSSL_PUT_ERROR(DH, ERR_R_BN_LIB);
- }
-
- if (dh->pub_key == NULL) {
- BN_free(pub_key);
- }
- if (dh->priv_key == NULL) {
- BN_free(priv_key);
- }
- BN_CTX_free(ctx);
- return ok;
- }
-
- int DH_compute_key(unsigned char *out, const BIGNUM *peers_key, DH *dh) {
- BN_CTX *ctx = NULL;
- BIGNUM *shared_key;
- int ret = -1;
- int check_result;
-
- if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
- OPENSSL_PUT_ERROR(DH, DH_R_MODULUS_TOO_LARGE);
- goto err;
- }
-
- ctx = BN_CTX_new();
- if (ctx == NULL) {
- goto err;
- }
- BN_CTX_start(ctx);
- shared_key = BN_CTX_get(ctx);
- if (shared_key == NULL) {
- goto err;
- }
-
- if (dh->priv_key == NULL) {
- OPENSSL_PUT_ERROR(DH, DH_R_NO_PRIVATE_VALUE);
- goto err;
- }
-
- if (!BN_MONT_CTX_set_locked(&dh->method_mont_p, &dh->method_mont_p_lock,
- dh->p, ctx)) {
- goto err;
- }
-
- if (!DH_check_pub_key(dh, peers_key, &check_result) || check_result) {
- OPENSSL_PUT_ERROR(DH, DH_R_INVALID_PUBKEY);
- goto err;
- }
-
- if (!BN_mod_exp_mont_consttime(shared_key, peers_key, dh->priv_key, dh->p,
- ctx, dh->method_mont_p)) {
- OPENSSL_PUT_ERROR(DH, ERR_R_BN_LIB);
- goto err;
- }
-
- ret = BN_bn2bin(shared_key, out);
-
- err:
- if (ctx != NULL) {
- BN_CTX_end(ctx);
- BN_CTX_free(ctx);
- }
-
- return ret;
- }
-
- int DH_size(const DH *dh) { return BN_num_bytes(dh->p); }
-
- unsigned DH_num_bits(const DH *dh) { return BN_num_bits(dh->p); }
-
- int DH_up_ref(DH *dh) {
- CRYPTO_refcount_inc(&dh->references);
- return 1;
- }
-
- static int int_dh_bn_cpy(BIGNUM **dst, const BIGNUM *src) {
- BIGNUM *a = NULL;
-
- if (src) {
- a = BN_dup(src);
- if (!a) {
- return 0;
- }
- }
-
- BN_free(*dst);
- *dst = a;
- return 1;
- }
-
- static int int_dh_param_copy(DH *to, const DH *from, int is_x942) {
- if (is_x942 == -1) {
- is_x942 = !!from->q;
- }
- if (!int_dh_bn_cpy(&to->p, from->p) ||
- !int_dh_bn_cpy(&to->g, from->g)) {
- return 0;
- }
-
- if (!is_x942) {
- return 1;
- }
-
- if (!int_dh_bn_cpy(&to->q, from->q) ||
- !int_dh_bn_cpy(&to->j, from->j)) {
- return 0;
- }
-
- OPENSSL_free(to->seed);
- to->seed = NULL;
- to->seedlen = 0;
-
- if (from->seed) {
- to->seed = BUF_memdup(from->seed, from->seedlen);
- if (!to->seed) {
- return 0;
- }
- to->seedlen = from->seedlen;
- }
-
- return 1;
- }
-
- DH *DHparams_dup(const DH *dh) {
- DH *ret = DH_new();
- if (!ret) {
- return NULL;
- }
-
- if (!int_dh_param_copy(ret, dh, -1)) {
- DH_free(ret);
- return NULL;
- }
-
- return ret;
- }
-
- int DH_get_ex_new_index(long argl, void *argp, CRYPTO_EX_unused *unused,
- CRYPTO_EX_dup *dup_unused, CRYPTO_EX_free *free_func) {
- int index;
- if (!CRYPTO_get_ex_new_index(&g_ex_data_class, &index, argl, argp,
- free_func)) {
- return -1;
- }
- return index;
- }
-
- int DH_set_ex_data(DH *d, int idx, void *arg) {
- return CRYPTO_set_ex_data(&d->ex_data, idx, arg);
- }
-
- void *DH_get_ex_data(DH *d, int idx) {
- return CRYPTO_get_ex_data(&d->ex_data, idx);
- }
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