/* 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_grpc/dh.h>
#include <string.h>
#include <openssl_grpc/bn.h>
#include <openssl_grpc/err.h>
#include <openssl_grpc/digest.h>
#include <openssl_grpc/mem.h>
#include <openssl_grpc/thread.h>
#include "../../internal.h"
#include "../bn/internal.h"
#define OPENSSL_DH_MAX_MODULUS_BITS 10000
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;
return dh;
}
void DH_free(DH *dh) {
if (dh == NULL) {
return;
}
if (!CRYPTO_refcount_dec_and_test_zero(&dh->references)) {
return;
}
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);
}
const BIGNUM *DH_get0_pub_key(const DH *dh) { return dh->pub_key; }
const BIGNUM *DH_get0_priv_key(const DH *dh) { return dh->priv_key; }
const BIGNUM *DH_get0_p(const DH *dh) { return dh->p; }
const BIGNUM *DH_get0_q(const DH *dh) { return dh->q; }
const BIGNUM *DH_get0_g(const DH *dh) { return dh->g; }
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;
}
}
int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key) {
if (pub_key != NULL) {
BN_free(dh->pub_key);
dh->pub_key = pub_key;
}
if (priv_key != NULL) {
BN_free(dh->priv_key);
dh->priv_key = priv_key;
}
return 1;
}
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_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g) {
if ((dh->p == NULL && p == NULL) ||
(dh->g == NULL && g == NULL)) {
return 0;
}
if (p != NULL) {
BN_free(dh->p);
dh->p = p;
}
if (q != NULL) {
BN_free(dh->q);
dh->q = q;
}
if (g != NULL) {
BN_free(dh->g);
dh->g = g;
}
return 1;
}
int DH_set_length(DH *dh, unsigned priv_length) {
dh->priv_length = priv_length;
return 1;
}
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;
}
static int dh_compute_key(DH *dh, BIGNUM *out_shared_key,
const BIGNUM *peers_key, BN_CTX *ctx) {
if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
OPENSSL_PUT_ERROR(DH, DH_R_MODULUS_TOO_LARGE);
return 0;
}
if (dh->priv_key == NULL) {
OPENSSL_PUT_ERROR(DH, DH_R_NO_PRIVATE_VALUE);
return 0;
}
int check_result;
if (!DH_check_pub_key(dh, peers_key, &check_result) || check_result) {
OPENSSL_PUT_ERROR(DH, DH_R_INVALID_PUBKEY);
return 0;
}
int ret = 0;
BN_CTX_start(ctx);
BIGNUM *p_minus_1 = BN_CTX_get(ctx);
if (!p_minus_1 ||
!BN_MONT_CTX_set_locked(&dh->method_mont_p, &dh->method_mont_p_lock,
dh->p, ctx)) {
goto err;
}
if (!BN_mod_exp_mont_consttime(out_shared_key, peers_key, dh->priv_key, dh->p,
ctx, dh->method_mont_p) ||
!BN_copy(p_minus_1, dh->p) ||
!BN_sub_word(p_minus_1, 1)) {
OPENSSL_PUT_ERROR(DH, ERR_R_BN_LIB);
goto err;
}
// This performs the check required by SP 800-56Ar3 section 5.7.1.1 step two.
if (BN_cmp_word(out_shared_key, 1) <= 0 ||
BN_cmp(out_shared_key, p_minus_1) == 0) {
OPENSSL_PUT_ERROR(DH, DH_R_INVALID_PUBKEY);
goto err;
}
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
int DH_compute_key_padded(unsigned char *out, const BIGNUM *peers_key, DH *dh) {
BN_CTX *ctx = BN_CTX_new();
if (ctx == NULL) {
return -1;
}
BN_CTX_start(ctx);
int dh_size = DH_size(dh);
int ret = -1;
BIGNUM *shared_key = BN_CTX_get(ctx);
if (shared_key &&
dh_compute_key(dh, shared_key, peers_key, ctx) &&
BN_bn2bin_padded(out, dh_size, shared_key)) {
ret = dh_size;
}
BN_CTX_end(ctx);
BN_CTX_free(ctx);
return ret;
}
int DH_compute_key(unsigned char *out, const BIGNUM *peers_key, DH *dh) {
BN_CTX *ctx = BN_CTX_new();
if (ctx == NULL) {
return -1;
}
BN_CTX_start(ctx);
int ret = -1;
BIGNUM *shared_key = BN_CTX_get(ctx);
if (shared_key && dh_compute_key(dh, shared_key, peers_key, ctx)) {
ret = BN_bn2bin(shared_key, out);
}
BN_CTX_end(ctx);
BN_CTX_free(ctx);
return ret;
}
int DH_compute_key_hashed(DH *dh, uint8_t *out, size_t *out_len,
size_t max_out_len, const BIGNUM *peers_key,
const EVP_MD *digest) {
*out_len = (size_t)-1;
const size_t digest_len = EVP_MD_size(digest);
if (digest_len > max_out_len) {
return 0;
}
int ret = 0;
const size_t dh_len = DH_size(dh);
uint8_t *shared_bytes = OPENSSL_malloc(dh_len);
unsigned out_len_unsigned;
if (!shared_bytes ||
// SP 800-56A is ambiguous about whether the output should be padded prior
// to revision three. But revision three, section C.1, awkwardly specifies
// padding to the length of p.
//
// Also, padded output avoids side-channels, so is always strongly
// advisable.
DH_compute_key_padded(shared_bytes, peers_key, dh) != (int)dh_len ||
!EVP_Digest(shared_bytes, dh_len, out, &out_len_unsigned, digest, NULL) ||
out_len_unsigned != digest_len) {
goto err;
}
*out_len = digest_len;
ret = 1;
err:
OPENSSL_free(shared_bytes);
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;
}
DH *DH_get_rfc7919_2048(void) {
// This is the prime from https://tools.ietf.org/html/rfc7919#appendix-A.1,
// which is specifically approved for FIPS in appendix D of SP 800-56Ar3.
static const BN_ULONG kFFDHE2048Data[] = {
TOBN(0xffffffff, 0xffffffff), TOBN(0x886b4238, 0x61285c97),
TOBN(0xc6f34a26, 0xc1b2effa), TOBN(0xc58ef183, 0x7d1683b2),
TOBN(0x3bb5fcbc, 0x2ec22005), TOBN(0xc3fe3b1b, 0x4c6fad73),
TOBN(0x8e4f1232, 0xeef28183), TOBN(0x9172fe9c, 0xe98583ff),
TOBN(0xc03404cd, 0x28342f61), TOBN(0x9e02fce1, 0xcdf7e2ec),
TOBN(0x0b07a7c8, 0xee0a6d70), TOBN(0xae56ede7, 0x6372bb19),
TOBN(0x1d4f42a3, 0xde394df4), TOBN(0xb96adab7, 0x60d7f468),
TOBN(0xd108a94b, 0xb2c8e3fb), TOBN(0xbc0ab182, 0xb324fb61),
TOBN(0x30acca4f, 0x483a797a), TOBN(0x1df158a1, 0x36ade735),
TOBN(0xe2a689da, 0xf3efe872), TOBN(0x984f0c70, 0xe0e68b77),
TOBN(0xb557135e, 0x7f57c935), TOBN(0x85636555, 0x3ded1af3),
TOBN(0x2433f51f, 0x5f066ed0), TOBN(0xd3df1ed5, 0xd5fd6561),
TOBN(0xf681b202, 0xaec4617a), TOBN(0x7d2fe363, 0x630c75d8),
TOBN(0xcc939dce, 0x249b3ef9), TOBN(0xa9e13641, 0x146433fb),
TOBN(0xd8b9c583, 0xce2d3695), TOBN(0xafdc5620, 0x273d3cf1),
TOBN(0xadf85458, 0xa2bb4a9a), TOBN(0xffffffff, 0xffffffff),
};
BIGNUM *const ffdhe2048_p = BN_new();
BIGNUM *const ffdhe2048_q = BN_new();
BIGNUM *const ffdhe2048_g = BN_new();
DH *const dh = DH_new();
if (!ffdhe2048_p || !ffdhe2048_q || !ffdhe2048_g || !dh) {
goto err;
}
bn_set_static_words(ffdhe2048_p, kFFDHE2048Data,
OPENSSL_ARRAY_SIZE(kFFDHE2048Data));
if (!BN_rshift1(ffdhe2048_q, ffdhe2048_p) ||
!BN_set_word(ffdhe2048_g, 2) ||
!DH_set0_pqg(dh, ffdhe2048_p, ffdhe2048_q, ffdhe2048_g)) {
goto err;
}
return dh;
err:
BN_free(ffdhe2048_p);
BN_free(ffdhe2048_q);
BN_free(ffdhe2048_g);
DH_free(dh);
return NULL;
}