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/*
* Copyright (c) 2021, [Ribose Inc](https://www.ribose.com).
* All rights reserved.
*
* 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 above 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER 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.
*/
#include <cstdlib>
#include <string>
#include <cassert>
#include "bn.h"
#include "dl_ossl.h"
#include "utils.h"
#include <openssl/dh.h>
#include <openssl/err.h>
#include <openssl/evp.h>
EVP_PKEY *
dl_load_key(const pgp_mpi_t &mp,
const pgp_mpi_t *mq,
const pgp_mpi_t &mg,
const pgp_mpi_t &my,
const pgp_mpi_t *mx)
{
DH * dh = NULL;
EVP_PKEY *evpkey = NULL;
bignum_t *p = mpi2bn(&mp);
bignum_t *q = mq ? mpi2bn(mq) : NULL;
bignum_t *g = mpi2bn(&mg);
bignum_t *y = mpi2bn(&my);
bignum_t *x = mx ? mpi2bn(mx) : NULL;
if (!p || (mq && !q) || !g || !y || (mx && !x)) {
RNP_LOG("out of memory");
goto done;
}
dh = DH_new();
if (!dh) {
RNP_LOG("out of memory");
goto done;
}
int res;
/* line below must not fail */
res = DH_set0_pqg(dh, p, q, g);
assert(res == 1);
if (res < 1) {
goto done;
}
p = NULL;
q = NULL;
g = NULL;
/* line below must not fail */
res = DH_set0_key(dh, y, x);
assert(res == 1);
if (res < 1) {
goto done;
}
y = NULL;
x = NULL;
evpkey = EVP_PKEY_new();
if (!evpkey) {
RNP_LOG("allocation failed");
goto done;
}
if (EVP_PKEY_set1_DH(evpkey, dh) <= 0) {
RNP_LOG("Failed to set key: %lu", ERR_peek_last_error());
EVP_PKEY_free(evpkey);
evpkey = NULL;
}
done:
DH_free(dh);
bn_free(p);
bn_free(q);
bn_free(g);
bn_free(y);
bn_free(x);
return evpkey;
}
static rnp_result_t
dl_validate_secret_key(EVP_PKEY *dlkey, const pgp_mpi_t &mx)
{
const DH *dh = EVP_PKEY_get0_DH(dlkey);
assert(dh);
const bignum_t *p = DH_get0_p(dh);
const bignum_t *q = DH_get0_q(dh);
const bignum_t *g = DH_get0_g(dh);
const bignum_t *y = DH_get0_pub_key(dh);
assert(p && g && y);
bignum_t *p1 = NULL;
rnp_result_t ret = RNP_ERROR_GENERIC;
BN_CTX * ctx = BN_CTX_new();
bignum_t *x = mpi2bn(&mx);
bignum_t *cy = bn_new();
if (!x || !cy || !ctx) {
RNP_LOG("Allocation failed");
goto done;
}
if (!q) {
/* if q is NULL then group order is (p - 1) / 2 */
p1 = BN_dup(p);
if (!p1) {
RNP_LOG("Allocation failed");
goto done;
}
int res;
res = BN_rshift(p1, p1, 1);
assert(res == 1);
if (res < 1) {
RNP_LOG("BN_rshift failed.");
goto done;
}
q = p1;
}
if (BN_cmp(x, q) != -1) {
RNP_LOG("x is too large.");
goto done;
}
if (BN_mod_exp_mont_consttime(cy, g, x, p, ctx, NULL) < 1) {
RNP_LOG("Exponentiation failed");
goto done;
}
if (BN_cmp(cy, y) == 0) {
ret = RNP_SUCCESS;
}
done:
BN_CTX_free(ctx);
bn_free(x);
bn_free(cy);
bn_free(p1);
return ret;
}
rnp_result_t
dl_validate_key(EVP_PKEY *pkey, const pgp_mpi_t *x)
{
rnp_result_t ret = RNP_ERROR_GENERIC;
EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new(pkey, NULL);
if (!ctx) {
RNP_LOG("Context allocation failed: %lu", ERR_peek_last_error());
goto done;
}
int res;
res = EVP_PKEY_param_check(ctx);
if (res < 0) {
RNP_LOG("Param validation error: %lu (%s)",
ERR_peek_last_error(),
ERR_reason_error_string(ERR_peek_last_error()));
}
if (res < 1) {
/* ElGamal specification doesn't seem to restrict P to the safe prime */
auto err = ERR_peek_last_error();
DHerr(DH_F_DH_CHECK_EX, DH_R_CHECK_P_NOT_SAFE_PRIME);
if ((ERR_GET_REASON(err) == DH_R_CHECK_P_NOT_SAFE_PRIME)) {
RNP_LOG("Warning! P is not a safe prime.");
} else {
goto done;
}
}
res = EVP_PKEY_public_check(ctx);
if (res < 0) {
RNP_LOG("Key validation error: %lu", ERR_peek_last_error());
}
if (res < 1) {
goto done;
}
/* There is no private key check in OpenSSL yet, so need to check x vs y manually */
if (!x) {
ret = RNP_SUCCESS;
goto done;
}
ret = dl_validate_secret_key(pkey, *x);
done:
EVP_PKEY_CTX_free(ctx);
return ret;
}
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