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/*
* Copyright (C) 2015 Martin Willi
* Copyright (C) 2015 revosec AG
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include <string.h>
#include <stdint.h>
#include "curve25519_dh.h"
#include "curve25519_drv.h"
typedef struct private_curve25519_dh_t private_curve25519_dh_t;
/**
* Private data of an curve25519_dh_t object.
*/
struct private_curve25519_dh_t {
/**
* Public curve25519_dh_t interface.
*/
curve25519_dh_t public;
/**
* Shared key, if computed
*/
u_char shared[CURVE25519_KEY_SIZE];
/**
* TRUE if shared secret is computed
*/
bool computed;
/**
* Curve25519 backend
*/
curve25519_drv_t *drv;
};
/**
* Generate a valid Curve25519 key
*/
static bool generate_key(private_curve25519_dh_t *this)
{
u_char key[CURVE25519_KEY_SIZE];
rng_t *rng;
rng = lib->crypto->create_rng(lib->crypto, RNG_STRONG);
if (!rng)
{
DBG1(DBG_LIB, "no RNG found for quality %N",
rng_quality_names, RNG_STRONG);
return FALSE;
}
if (!rng->get_bytes(rng, CURVE25519_KEY_SIZE, key))
{
rng->destroy(rng);
return FALSE;
}
rng->destroy(rng);
return this->drv->set_key(this->drv, key);
}
METHOD(diffie_hellman_t, set_other_public_value, bool,
private_curve25519_dh_t *this, chunk_t value)
{
if (value.len == CURVE25519_KEY_SIZE)
{
if (this->drv->curve25519(this->drv, value.ptr, this->shared))
{
this->computed = TRUE;
return TRUE;
}
}
return FALSE;
}
METHOD(diffie_hellman_t, get_my_public_value, bool,
private_curve25519_dh_t *this, chunk_t *value)
{
u_char basepoint[CURVE25519_KEY_SIZE] = { 9 };
*value = chunk_alloc(CURVE25519_KEY_SIZE);
if (this->drv->curve25519(this->drv, basepoint, value->ptr))
{
return TRUE;
}
free(value->ptr);
return FALSE;
}
METHOD(diffie_hellman_t, set_private_value, bool,
private_curve25519_dh_t *this, chunk_t value)
{
if (value.len != CURVE25519_KEY_SIZE)
{
return FALSE;
}
return this->drv->set_key(this->drv, value.ptr);
}
METHOD(diffie_hellman_t, get_shared_secret, bool,
private_curve25519_dh_t *this, chunk_t *secret)
{
if (!this->computed)
{
return FALSE;
}
*secret = chunk_clone(chunk_from_thing(this->shared));
return TRUE;
}
METHOD(diffie_hellman_t, get_dh_group, diffie_hellman_group_t,
private_curve25519_dh_t *this)
{
return CURVE_25519;
}
METHOD(diffie_hellman_t, destroy, void,
private_curve25519_dh_t *this)
{
this->drv->destroy(this->drv);
free(this);
}
/*
* Described in header.
*/
curve25519_dh_t *curve25519_dh_create(diffie_hellman_group_t group)
{
private_curve25519_dh_t *this;
if (group != CURVE_25519)
{
return FALSE;
}
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,
},
},
.drv = curve25519_drv_probe(),
);
if (!this->drv)
{
free(this);
return NULL;
}
if (!generate_key(this))
{
destroy(this);
return NULL;
}
return &this->public;
}
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