332 lines
7.5 KiB
C
332 lines
7.5 KiB
C
/*
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* Copyright (C) 2013-2014 Andreas Steffen
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* HSR Hochschule fuer Technik Rapperswil
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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 "ntru_ke.h"
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#include "ntru_param_set.h"
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#include "ntru_private_key.h"
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#include "ntru_public_key.h"
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#include <crypto/diffie_hellman.h>
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#include <crypto/drbgs/drbg.h>
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#include <utils/debug.h>
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typedef struct private_ntru_ke_t private_ntru_ke_t;
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/* Best bandwidth and speed, no X9.98 compatibility */
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static const ntru_param_set_id_t param_sets_optimum[] = {
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NTRU_EES401EP2, NTRU_EES439EP1, NTRU_EES593EP1, NTRU_EES743EP1
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};
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/* X9.98/IEEE 1363.1 parameter sets for best speed */
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static const ntru_param_set_id_t param_sets_x9_98_speed[] = {
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NTRU_EES659EP1, NTRU_EES761EP1, NTRU_EES1087EP1, NTRU_EES1499EP1
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};
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/* X9.98/IEEE 1363.1 parameter sets for best bandwidth (smallest size) */
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static const ntru_param_set_id_t param_sets_x9_98_bandwidth[] = {
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NTRU_EES401EP1, NTRU_EES449EP1, NTRU_EES677EP1, NTRU_EES1087EP2
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};
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/* X9.98/IEEE 1363.1 parameter sets balancing speed and bandwidth */
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static const ntru_param_set_id_t param_sets_x9_98_balance[] = {
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NTRU_EES541EP1, NTRU_EES613EP1, NTRU_EES887EP1, NTRU_EES1171EP1
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};
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/**
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* Private data of an ntru_ke_t object.
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*/
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struct private_ntru_ke_t {
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/**
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* Public ntru_ke_t interface.
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*/
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ntru_ke_t public;
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/**
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* Diffie Hellman group number.
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*/
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diffie_hellman_group_t group;
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/**
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* NTRU Parameter Set
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*/
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const ntru_param_set_t *param_set;
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/**
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* Cryptographical strength in bits of the NTRU Parameter Set
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*/
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uint32_t strength;
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/**
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* NTRU Public Key
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*/
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ntru_public_key_t *pubkey;
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/**
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* NTRU Private Key
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*/
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ntru_private_key_t *privkey;
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/**
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* NTRU encrypted shared secret
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*/
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chunk_t ciphertext;
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/**
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* Shared secret
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*/
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chunk_t shared_secret;
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/**
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* True if peer is responder
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*/
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bool responder;
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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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* True Random Generator
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*/
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rng_t *entropy;
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/**
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* Deterministic Random Bit Generator
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*/
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drbg_t *drbg;
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};
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METHOD(diffie_hellman_t, get_my_public_value, bool,
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private_ntru_ke_t *this, chunk_t *value)
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{
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*value = chunk_empty;
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if (this->responder)
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{
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if (this->ciphertext.len)
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{
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*value = chunk_clone(this->ciphertext);
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}
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}
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else
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{
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if (!this->pubkey)
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{
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/* generate a random NTRU public/private key pair */
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this->privkey = ntru_private_key_create(this->drbg, this->param_set);
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if (!this->privkey)
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{
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DBG1(DBG_LIB, "NTRU key pair generation failed");
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return FALSE;
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}
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this->pubkey = this->privkey->get_public_key(this->privkey);
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}
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*value = chunk_clone(this->pubkey->get_encoding(this->pubkey));
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DBG3(DBG_LIB, "NTRU public key: %B", value);
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}
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return TRUE;
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}
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METHOD(diffie_hellman_t, get_shared_secret, bool,
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private_ntru_ke_t *this, chunk_t *secret)
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{
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if (!this->computed || !this->shared_secret.len)
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{
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*secret = chunk_empty;
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return FALSE;
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}
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*secret = chunk_clone(this->shared_secret);
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return TRUE;
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}
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METHOD(diffie_hellman_t, set_other_public_value, bool,
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private_ntru_ke_t *this, chunk_t value)
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{
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if (this->privkey)
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{
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/* initiator decrypting shared secret */
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if (value.len == 0)
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{
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DBG1(DBG_LIB, "empty NTRU ciphertext");
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return FALSE;
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}
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DBG3(DBG_LIB, "NTRU ciphertext: %B", &value);
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/* decrypt the shared secret */
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if (!this->privkey->decrypt(this->privkey, value, &this->shared_secret))
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{
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DBG1(DBG_LIB, "NTRU decryption of shared secret failed");
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return FALSE;
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}
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this->computed = TRUE;
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}
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else
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{
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ntru_public_key_t *pubkey;
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/* responder generating and encrypting the shared secret */
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this->responder = TRUE;
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DBG3(DBG_LIB, "NTRU public key: %B", &value);
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pubkey = ntru_public_key_create_from_data(this->drbg, value);
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if (!pubkey)
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{
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return FALSE;
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}
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if (pubkey->get_id(pubkey) != this->param_set->id)
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{
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DBG1(DBG_LIB, "received NTRU public key with wrong OUI");
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pubkey->destroy(pubkey);
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return FALSE;
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}
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this->pubkey = pubkey;
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/* shared secret size is chosen as twice the cryptographical strength */
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this->shared_secret = chunk_alloc(2 * this->strength / BITS_PER_BYTE);
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/* generate the random shared secret */
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if (!this->drbg->generate(this->drbg, this->shared_secret.len,
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this->shared_secret.ptr))
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{
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DBG1(DBG_LIB, "generation of shared secret failed");
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chunk_free(&this->shared_secret);
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return FALSE;
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}
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this->computed = TRUE;
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/* encrypt the shared secret */
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if (!pubkey->encrypt(pubkey, this->shared_secret, &this->ciphertext))
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{
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DBG1(DBG_LIB, "NTRU encryption of shared secret failed");
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return FALSE;
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}
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DBG3(DBG_LIB, "NTRU ciphertext: %B", &this->ciphertext);
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}
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return this->computed;
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}
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METHOD(diffie_hellman_t, get_dh_group, diffie_hellman_group_t,
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private_ntru_ke_t *this)
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{
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return this->group;
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}
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METHOD(diffie_hellman_t, destroy, void,
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private_ntru_ke_t *this)
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{
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DESTROY_IF(this->privkey);
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DESTROY_IF(this->pubkey);
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this->drbg->destroy(this->drbg);
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chunk_free(&this->ciphertext);
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chunk_clear(&this->shared_secret);
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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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ntru_ke_t *ntru_ke_create(diffie_hellman_group_t group, chunk_t g, chunk_t p)
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{
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private_ntru_ke_t *this;
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const ntru_param_set_id_t *param_sets;
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ntru_param_set_id_t param_set_id;
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rng_t *entropy;
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drbg_t *drbg;
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char *parameter_set;
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uint32_t strength;
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parameter_set = lib->settings->get_str(lib->settings,
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"%s.plugins.ntru.parameter_set", "optimum", lib->ns);
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if (streq(parameter_set, "x9_98_speed"))
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{
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param_sets = param_sets_x9_98_speed;
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}
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else if (streq(parameter_set, "x9_98_bandwidth"))
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{
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param_sets = param_sets_x9_98_bandwidth;
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}
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else if (streq(parameter_set, "x9_98_balance"))
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{
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param_sets = param_sets_x9_98_balance;
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}
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else
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{
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param_sets = param_sets_optimum;
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}
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switch (group)
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{
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case NTRU_112_BIT:
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strength = 112;
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param_set_id = param_sets[0];
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break;
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case NTRU_128_BIT:
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strength = 128;
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param_set_id = param_sets[1];
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break;
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case NTRU_192_BIT:
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strength = 192;
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param_set_id = param_sets[2];
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break;
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case NTRU_256_BIT:
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strength = 256;
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param_set_id = param_sets[3];
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break;
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default:
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return NULL;
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}
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DBG1(DBG_LIB, "%u bit %s NTRU parameter set %N selected", strength,
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parameter_set, ntru_param_set_id_names, param_set_id);
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/* entropy will be owned by drbg */
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entropy = lib->crypto->create_rng(lib->crypto, RNG_TRUE);
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if (!entropy)
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{
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DBG1(DBG_LIB, "could not attach entropy source for DRBG");
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return NULL;
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}
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drbg = lib->crypto->create_drbg(lib->crypto, DRBG_HMAC_SHA256, strength,
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entropy, chunk_from_str("IKE NTRU-KE"));
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if (!drbg)
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{
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DBG1(DBG_LIB, "could not instantiate DRBG at %u bit security", strength);
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entropy->destroy(entropy);
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return NULL;
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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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.get_dh_group = _get_dh_group,
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.destroy = _destroy,
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},
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},
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.group = group,
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.param_set = ntru_param_set_get_by_id(param_set_id),
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.strength = strength,
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.entropy = entropy,
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.drbg = drbg,
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);
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return &this->public;
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}
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