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