/* 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_func, CRYPTO_EX_free *free_func) {
int index;
if (!CRYPTO_get_ex_new_index(&g_ex_data_class, &index, argl, argp, dup_func,
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);
}