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/*
* Copyright (C) 2018 René Korthaus
* Copyright (C) 2018 Konstantinos Kolelis
* Rohde & Schwarz Cybersecurity GmbH
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "botan_diffie_hellman.h"
#include <botan/build.h>
#ifdef BOTAN_HAS_DIFFIE_HELLMAN
#include "botan_util.h"
#include <botan/ffi.h>
#include <utils/debug.h>
typedef struct private_botan_diffie_hellman_t private_botan_diffie_hellman_t;
/**
* Private data of an botan_diffie_hellman_t object.
*/
struct private_botan_diffie_hellman_t {
/**
* Public botan_diffie_hellman_t interface
*/
botan_diffie_hellman_t public;
/**
* Diffie Hellman group number
*/
diffie_hellman_group_t group;
/**
* Private key
*/
botan_privkey_t dh_key;
/**
* Diffie hellman shared secret
*/
chunk_t shared_secret;
/**
* Generator value
*/
botan_mp_t g;
/**
* Modulus
*/
botan_mp_t p;
};
/**
* Load a DH private key
*/
bool load_private_key(private_botan_diffie_hellman_t *this, chunk_t value)
{
botan_mp_t xa;
if (!chunk_to_botan_mp(value, &xa))
{
return FALSE;
}
if (botan_privkey_destroy(this->dh_key) ||
botan_privkey_load_dh(&this->dh_key, this->p, this->g, xa))
{
botan_mp_destroy(xa);
return FALSE;
}
botan_mp_destroy(xa);
return TRUE;
}
METHOD(diffie_hellman_t, set_other_public_value, bool,
private_botan_diffie_hellman_t *this, chunk_t value)
{
if (!diffie_hellman_verify_value(this->group, value))
{
return FALSE;
}
chunk_clear(&this->shared_secret);
return botan_dh_key_derivation(this->dh_key, value, &this->shared_secret);
}
METHOD(diffie_hellman_t, get_my_public_value, bool,
private_botan_diffie_hellman_t *this, chunk_t *value)
{
*value = chunk_empty;
/* get key size of public key first */
if (botan_pk_op_key_agreement_export_public(this->dh_key, NULL, &value->len)
!= BOTAN_FFI_ERROR_INSUFFICIENT_BUFFER_SPACE)
{
return FALSE;
}
*value = chunk_alloc(value->len);
if (botan_pk_op_key_agreement_export_public(this->dh_key, value->ptr,
&value->len))
{
chunk_clear(value);
return FALSE;
}
return TRUE;
}
METHOD(diffie_hellman_t, set_private_value, bool,
private_botan_diffie_hellman_t *this, chunk_t value)
{
chunk_clear(&this->shared_secret);
return load_private_key(this, value);
}
METHOD(diffie_hellman_t, get_shared_secret, bool,
private_botan_diffie_hellman_t *this, chunk_t *secret)
{
if (!this->shared_secret.len)
{
return FALSE;
}
*secret = chunk_clone(this->shared_secret);
return TRUE;
}
METHOD(diffie_hellman_t, get_dh_group, diffie_hellman_group_t,
private_botan_diffie_hellman_t *this)
{
return this->group;
}
METHOD(diffie_hellman_t, destroy, void,
private_botan_diffie_hellman_t *this)
{
botan_mp_destroy(this->p);
botan_mp_destroy(this->g);
botan_privkey_destroy(this->dh_key);
chunk_clear(&this->shared_secret);
free(this);
}
/*
* Generic internal constructor
*/
static botan_diffie_hellman_t *create_generic(diffie_hellman_group_t group,
chunk_t g, chunk_t p, size_t exp_len)
{
private_botan_diffie_hellman_t *this;
chunk_t random;
rng_t *rng;
INIT(this,
.public = {
.dh = {
.get_shared_secret = _get_shared_secret,
.set_other_public_value = _set_other_public_value,
.get_my_public_value = _get_my_public_value,
.set_private_value = _set_private_value,
.get_dh_group = _get_dh_group,
.destroy = _destroy,
},
},
.group = group,
);
if (!chunk_to_botan_mp(p, &this->p))
{
destroy(this);
return NULL;
}
if (!chunk_to_botan_mp(g, &this->g))
{
destroy(this);
return NULL;
}
rng = lib->crypto->create_rng(lib->crypto, RNG_STRONG);
if (!rng || !rng->allocate_bytes(rng, exp_len, &random))
{
DESTROY_IF(rng);
destroy(this);
return NULL;
}
rng->destroy(rng);
if (!load_private_key(this, random))
{
chunk_clear(&random);
destroy(this);
return NULL;
}
chunk_clear(&random);
return &this->public;
}
/*
* Described in header.
*/
botan_diffie_hellman_t *botan_diffie_hellman_create(
diffie_hellman_group_t group, ...)
{
diffie_hellman_params_t *params;
chunk_t g, p;
if (group == MODP_CUSTOM)
{
VA_ARGS_GET(group, g, p);
return create_generic(group, g, p, p.len);
}
params = diffie_hellman_get_params(group);
if (!params)
{
return NULL;
}
return create_generic(group, params->generator, params->prime,
params->exp_len);
}
#endif
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