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/*
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* Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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c4476c |
* this file except in compliance with the License. You can obtain a copy
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c4476c |
* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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c4476c |
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#include <stdio.h>
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#include "internal/cryptlib.h"
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#include "dh_local.h"
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#include "crypto/bn.h"
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#ifdef OPENSSL_FIPS
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# include <openssl/fips.h>
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#endif
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static int generate_key(DH *dh);
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static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh);
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static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
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c4476c |
const BIGNUM *a, const BIGNUM *p,
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c4476c |
const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
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static int dh_init(DH *dh);
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static int dh_finish(DH *dh);
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int DH_generate_key(DH *dh)
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{
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#ifdef OPENSSL_FIPS
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if (FIPS_mode() && !(dh->meth->flags & DH_FLAG_FIPS_METHOD)
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&& !(dh->flags & DH_FLAG_NON_FIPS_ALLOW)) {
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DHerr(DH_F_DH_GENERATE_KEY, DH_R_NON_FIPS_METHOD);
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return 0;
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}
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#endif
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return dh->meth->generate_key(dh);
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}
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int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
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{
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#ifdef OPENSSL_FIPS
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if (FIPS_mode() && !(dh->meth->flags & DH_FLAG_FIPS_METHOD)
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c4476c |
&& !(dh->flags & DH_FLAG_NON_FIPS_ALLOW)) {
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DHerr(DH_F_DH_COMPUTE_KEY, DH_R_NON_FIPS_METHOD);
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return 0;
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}
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#endif
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return dh->meth->compute_key(key, pub_key, dh);
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}
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int DH_compute_key_padded(unsigned char *key, const BIGNUM *pub_key, DH *dh)
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{
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c4476c |
int rv, pad;
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c4476c |
rv = DH_compute_key(key, pub_key, dh);
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if (rv <= 0)
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return rv;
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pad = BN_num_bytes(dh->p) - rv;
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c4476c |
if (pad > 0) {
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memmove(key + pad, key, rv);
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memset(key, 0, pad);
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}
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return rv + pad;
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}
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static DH_METHOD dh_ossl = {
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"OpenSSL DH Method",
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generate_key,
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compute_key,
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dh_bn_mod_exp,
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dh_init,
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dh_finish,
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DH_FLAG_FIPS_METHOD,
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NULL,
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NULL
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};
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static const DH_METHOD *default_DH_method = &dh_ossl;
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const DH_METHOD *DH_OpenSSL(void)
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c4476c |
{
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return &dh_ossl;
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c4476c |
}
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void DH_set_default_method(const DH_METHOD *meth)
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c4476c |
{
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c4476c |
default_DH_method = meth;
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c4476c |
}
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const DH_METHOD *DH_get_default_method(void)
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c4476c |
{
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return default_DH_method;
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}
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static int generate_key(DH *dh)
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{
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int ok = 0;
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c4476c |
int generate_new_key = 0;
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unsigned l;
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c4476c |
BN_CTX *ctx = NULL;
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BN_MONT_CTX *mont = NULL;
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BIGNUM *pub_key = NULL, *priv_key = NULL;
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#ifdef OPENSSL_FIPS
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if (FIPS_mode()) {
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if (BN_num_bits(dh->p) < OPENSSL_DH_FIPS_MIN_MODULUS_BITS) {
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DHerr(DH_F_GENERATE_KEY, DH_R_KEY_SIZE_TOO_SMALL);
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return 0;
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}
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if (dh->nid == NID_undef)
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dh_cache_nid(dh);
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if (dh->nid == NID_undef || dh->length > BN_num_bits(dh->p) - 2
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c4476c |
|| dh->length < 224) {
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c4476c |
DHerr(DH_F_GENERATE_KEY, DH_R_NON_FIPS_METHOD);
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return 0;
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}
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}
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#endif
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if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
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DHerr(DH_F_GENERATE_KEY, DH_R_MODULUS_TOO_LARGE);
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c4476c |
return 0;
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c4476c |
}
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c4476c |
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c4476c |
ctx = BN_CTX_new();
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c4476c |
if (ctx == NULL)
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c4476c |
goto err;
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c4476c |
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c4476c |
if (dh->priv_key == NULL) {
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c4476c |
priv_key = BN_secure_new();
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c4476c |
if (priv_key == NULL)
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c4476c |
goto err;
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c4476c |
generate_new_key = 1;
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c4476c |
} else
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priv_key = dh->priv_key;
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c4476c |
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c4476c |
if (dh->pub_key == NULL) {
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c4476c |
pub_key = BN_new();
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c4476c |
if (pub_key == NULL)
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c4476c |
goto err;
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c4476c |
} else
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c4476c |
pub_key = dh->pub_key;
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c4476c |
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c4476c |
if (dh->flags & DH_FLAG_CACHE_MONT_P) {
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c4476c |
mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
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c4476c |
dh->lock, dh->p, ctx);
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c4476c |
if (!mont)
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c4476c |
goto err;
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c4476c |
}
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c4476c |
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c4476c |
if (generate_new_key) {
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c4476c |
if (FIPS_mode()) {
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c4476c |
do {
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c4476c |
if (!BN_priv_rand(priv_key, dh->length, BN_RAND_TOP_ANY, BN_RAND_BOTTOM_ANY))
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c4476c |
goto err;
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Packit |
c4476c |
if (!BN_add_word(priv_key, 1))
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c4476c |
goto err;
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c4476c |
}
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c4476c |
while (BN_num_bits(priv_key) > dh->length);
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c4476c |
} else if (dh->q) {
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c4476c |
do {
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c4476c |
if (!BN_priv_rand_range(priv_key, dh->q))
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c4476c |
goto err;
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Packit |
c4476c |
}
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Packit |
c4476c |
while (BN_is_zero(priv_key) || BN_is_one(priv_key));
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c4476c |
} else {
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c4476c |
/* secret exponent length */
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c4476c |
l = dh->length ? dh->length : BN_num_bits(dh->p) - 1;
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Packit |
c4476c |
if (!BN_priv_rand(priv_key, l, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY))
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c4476c |
goto err;
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Packit |
c4476c |
/*
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Packit |
c4476c |
* We handle just one known case where g is a quadratic non-residue:
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c4476c |
* for g = 2: p % 8 == 3
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c4476c |
*/
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c4476c |
if (BN_is_word(dh->g, DH_GENERATOR_2) && !BN_is_bit_set(dh->p, 2)) {
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Packit |
c4476c |
/* clear bit 0, since it won't be a secret anyway */
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Packit |
c4476c |
if (!BN_clear_bit(priv_key, 0))
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Packit |
c4476c |
goto err;
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Packit |
c4476c |
}
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Packit |
c4476c |
}
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Packit |
c4476c |
}
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c4476c |
|
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c4476c |
{
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c4476c |
BIGNUM *prk = BN_new();
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c4476c |
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Packit |
c4476c |
if (prk == NULL)
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c4476c |
goto err;
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c4476c |
BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
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Packit |
c4476c |
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Packit |
c4476c |
if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) {
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Packit |
c4476c |
BN_clear_free(prk);
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Packit |
c4476c |
goto err;
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Packit |
c4476c |
}
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Packit |
c4476c |
/* We MUST free prk before any further use of priv_key */
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c4476c |
BN_clear_free(prk);
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c4476c |
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Packit |
c4476c |
if (FIPS_mode()) {
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Packit |
c4476c |
int check_result;
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c4476c |
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Packit |
c4476c |
if (!dh_check_pub_key_full(dh, pub_key, &check_result) || check_result) {
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Packit |
c4476c |
DHerr(DH_F_GENERATE_KEY, DH_R_INVALID_PUBKEY);
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Packit |
c4476c |
goto err;
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Packit |
c4476c |
}
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Packit |
c4476c |
}
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Packit |
c4476c |
}
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c4476c |
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c4476c |
dh->pub_key = pub_key;
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c4476c |
dh->priv_key = priv_key;
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c4476c |
ok = 1;
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Packit |
c4476c |
err:
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Packit |
c4476c |
if (ok != 1)
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Packit |
c4476c |
DHerr(DH_F_GENERATE_KEY, ERR_R_BN_LIB);
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Packit |
c4476c |
|
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Packit |
c4476c |
if (pub_key != dh->pub_key)
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Packit |
c4476c |
BN_free(pub_key);
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Packit |
c4476c |
if (priv_key != dh->priv_key)
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Packit |
c4476c |
BN_free(priv_key);
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Packit |
c4476c |
BN_CTX_free(ctx);
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Packit |
c4476c |
return ok;
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c4476c |
}
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c4476c |
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c4476c |
static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh)
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Packit |
c4476c |
{
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Packit |
c4476c |
BN_CTX *ctx = NULL;
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Packit |
c4476c |
BN_MONT_CTX *mont = NULL;
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Packit |
c4476c |
BIGNUM *tmp;
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Packit |
c4476c |
BIGNUM *p1;
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Packit |
c4476c |
int ret = -1;
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Packit |
c4476c |
int check_result;
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Packit |
c4476c |
|
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Packit |
c4476c |
if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) {
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Packit |
c4476c |
DHerr(DH_F_COMPUTE_KEY, DH_R_MODULUS_TOO_LARGE);
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Packit |
c4476c |
goto err;
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Packit |
c4476c |
}
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Packit |
c4476c |
#ifdef OPENSSL_FIPS
|
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Packit |
c4476c |
if (FIPS_mode()
|
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Packit |
c4476c |
&& (BN_num_bits(dh->p) < OPENSSL_DH_FIPS_MIN_MODULUS_BITS)) {
|
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Packit |
c4476c |
DHerr(DH_F_COMPUTE_KEY, DH_R_KEY_SIZE_TOO_SMALL);
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Packit |
c4476c |
goto err;
|
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Packit |
c4476c |
}
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Packit |
c4476c |
#endif
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Packit |
c4476c |
|
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Packit |
c4476c |
ctx = BN_CTX_new();
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Packit |
c4476c |
if (ctx == NULL)
|
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Packit |
c4476c |
goto err;
|
|
Packit |
c4476c |
BN_CTX_start(ctx);
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Packit |
c4476c |
tmp = BN_CTX_get(ctx);
|
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Packit |
c4476c |
if (tmp == NULL)
|
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Packit |
c4476c |
goto err;
|
|
Packit |
c4476c |
|
|
Packit |
c4476c |
if (dh->priv_key == NULL) {
|
|
Packit |
c4476c |
DHerr(DH_F_COMPUTE_KEY, DH_R_NO_PRIVATE_VALUE);
|
|
Packit |
c4476c |
goto err;
|
|
Packit |
c4476c |
}
|
|
Packit |
c4476c |
|
|
Packit |
c4476c |
if (dh->flags & DH_FLAG_CACHE_MONT_P) {
|
|
Packit |
c4476c |
mont = BN_MONT_CTX_set_locked(&dh->method_mont_p,
|
|
Packit |
c4476c |
dh->lock, dh->p, ctx);
|
|
Packit |
c4476c |
BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME);
|
|
Packit |
c4476c |
if (!mont)
|
|
Packit |
c4476c |
goto err;
|
|
Packit |
c4476c |
}
|
|
Packit |
c4476c |
|
|
Packit |
c4476c |
if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) {
|
|
Packit |
c4476c |
DHerr(DH_F_COMPUTE_KEY, DH_R_INVALID_PUBKEY);
|
|
Packit |
c4476c |
goto err;
|
|
Packit |
c4476c |
}
|
|
Packit |
c4476c |
|
|
Packit |
c4476c |
if (!dh->
|
|
Packit |
c4476c |
meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key, dh->p, ctx, mont)) {
|
|
Packit |
c4476c |
DHerr(DH_F_COMPUTE_KEY, ERR_R_BN_LIB);
|
|
Packit |
c4476c |
goto err;
|
|
Packit |
c4476c |
}
|
|
Packit |
c4476c |
|
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Packit |
c4476c |
if (BN_is_zero(tmp) || BN_is_one(tmp) || BN_is_negative(tmp)) {
|
|
Packit |
c4476c |
DHerr(DH_F_COMPUTE_KEY, ERR_R_BN_LIB);
|
|
Packit |
c4476c |
goto err;
|
|
Packit |
c4476c |
}
|
|
Packit |
c4476c |
|
|
Packit |
c4476c |
if ((p1 = BN_CTX_get(ctx)) == NULL
|
|
Packit |
c4476c |
|| !BN_sub(p1, dh->p, BN_value_one())
|
|
Packit |
c4476c |
|| BN_cmp(p1, tmp) <= 0) {
|
|
Packit |
c4476c |
DHerr(DH_F_COMPUTE_KEY, ERR_R_BN_LIB);
|
|
Packit |
c4476c |
goto err;
|
|
Packit |
c4476c |
}
|
|
Packit |
c4476c |
|
|
Packit |
c4476c |
ret = BN_bn2bin(tmp, key);
|
|
Packit |
c4476c |
err:
|
|
Packit |
c4476c |
BN_CTX_end(ctx);
|
|
Packit |
c4476c |
BN_CTX_free(ctx);
|
|
Packit |
c4476c |
return ret;
|
|
Packit |
c4476c |
}
|
|
Packit |
c4476c |
|
|
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c4476c |
static int dh_bn_mod_exp(const DH *dh, BIGNUM *r,
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c4476c |
const BIGNUM *a, const BIGNUM *p,
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c4476c |
const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
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c4476c |
{
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c4476c |
return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
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c4476c |
}
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c4476c |
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c4476c |
static int dh_init(DH *dh)
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c4476c |
{
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c4476c |
#ifdef OPENSSL_FIPS
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c4476c |
FIPS_selftest_check();
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c4476c |
#endif
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c4476c |
dh->flags |= DH_FLAG_CACHE_MONT_P;
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c4476c |
return 1;
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c4476c |
}
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c4476c |
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c4476c |
static int dh_finish(DH *dh)
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c4476c |
{
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c4476c |
BN_MONT_CTX_free(dh->method_mont_p);
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c4476c |
return 1;
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c4476c |
}
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