Make the NTRU parameter set configurable

man/strongswan.conf.5.in

@@ -867,6 +867,11 @@ Enable logging of SQL IP pool leases
 .BR libstrongswan.plugins.gcrypt.quick_random " [no]"
 Use faster random numbers in gcrypt; for testing only, produces weak keys!
 .TP
+.BR libstrongswan.plugins.ntru.param_set_selection " [optimum]"
+The following parameter sets are available: 'x9_98_speed', 'x9_98_bandwidth',
+'x9_98_balance' and 'optimum', the last set not being part of the X9.98
+standard but exhibiting the best performance.
+.TP
 .BR libstrongswan.plugins.openssl.engine_id " [pkcs11]"
 ENGINE ID to use in the OpenSSL plugin
 .TP

src/libstrongswan/plugins/ntru/ntru_ke.c

@@ -193,6 +193,7 @@ METHOD(diffie_hellman_t, set_other_public_value, void,
 			chunk_free(&this->shared_secret);
 			return;
 		}
+		this->computed = TRUE;
 
 		/* determine the size of the ciphertext */
 		if (ntru_crypto_ntru_encrypt(this->drbg,
@@ -204,7 +205,6 @@ METHOD(diffie_hellman_t, set_other_public_value, void,
 			return;
 		}
 		this->ciphertext = chunk_alloc(ciphertext_len);
-		this->computed = TRUE;
 
 		/* encrypt the shared secret */
 		if (ntru_crypto_ntru_encrypt(this->drbg,
@@ -247,35 +247,68 @@ ntru_ke_t *ntru_ke_create(diffie_hellman_group_t group, chunk_t g, chunk_t p)
 {
 	private_ntru_ke_t *this;
 	char personalization_str[] = "strongSwan NTRU-KE";
-	NTRU_ENCRYPT_PARAM_SET_ID param_set_id;
+	NTRU_ENCRYPT_PARAM_SET_ID *param_set, param_set_id;
 	DRBG_HANDLE drbg;
+	char *param_set_selection;
 	u_int32_t strength;
 
-	/**
+	/* Best bandwidth and speed, no X9.98 compatibility */
-	 * We are selecting the X9.98 / IEEE 1363.1 parameter sets
+	NTRU_ENCRYPT_PARAM_SET_ID param_set_optimum[] = {
-	 * which balance speed and bandwidth
+		NTRU_EES401EP2, NTRU_EES439EP1, NTRU_EES593EP1, NTRU_EES743EP1
-	 */
+	};
+
+	/* X9.98/IEEE 1363.1 parameter set for best speed */
+	NTRU_ENCRYPT_PARAM_SET_ID param_set_x9_98_speed[] = {
+		NTRU_EES659EP1, NTRU_EES761EP1, NTRU_EES1087EP1, NTRU_EES1499EP1
+	};
+
+	/* X9.98/IEEE 1363.1 parameter set for best bandwidth (smallest size) */
+	NTRU_ENCRYPT_PARAM_SET_ID param_set_x9_98_bandwidth[] = {
+		NTRU_EES401EP1, NTRU_EES449EP1, NTRU_EES677EP1, NTRU_EES1087EP1
+	};
+
+	/* X9.98/IEEE 1363.1 parameter set balancing speed and bandwidth */
+	NTRU_ENCRYPT_PARAM_SET_ID param_set_x9_98_balance[] = {
+		NTRU_EES541EP1, NTRU_EES613EP1, NTRU_EES887EP1, NTRU_EES1171EP1
+	};
+
+	param_set_selection = lib->settings->get_str(lib->settings,
+				"libstrongswan.plugins.ntru.param__set_selection", "optimum");
+
+	if (streq(param_set_selection, "x9_98_speed"))
+	{
+		param_set = param_set_x9_98_speed;
+	}
+	else if (streq(param_set_selection, "x9_98_bandwidth"))
+	{
+		param_set = param_set_x9_98_bandwidth;
+	}
+	else if (streq(param_set_selection, "x9_98_balance"))
+	{
+		param_set = param_set_x9_98_balance;
+	}
+	else
+	{
+		param_set = param_set_optimum;
+	}
+
 	switch (group)
 	{
 		case NTRU_112_BIT:
 			strength = 112;
-			/* param_set_id = NTRU_EES541EP1; */
+			param_set_id = param_set[0];
-			param_set_id = NTRU_EES401EP2;
 			break;
 		case NTRU_128_BIT:
 			strength = 128;
-			/* param_set_id = NTRU_EES613EP1; */
+			param_set_id = param_set[1];
-			param_set_id = NTRU_EES439EP1;
 			break;
 		case NTRU_192_BIT:
 			strength = 192;
-			/* param_set_id = NTRU_EES887EP1; */
+			param_set_id = param_set[2];
-			param_set_id = NTRU_EES593EP1;
 			break;
 		case NTRU_256_BIT:
 			strength = 256;
-			/* param_set_id = NTRU_EES1171EP1; */
+			param_set_id = param_set[3];
-			param_set_id = NTRU_EES743EP1;
 			break;
 		default:
 			return NULL;

src/libstrongswan/tests/suites/test_ntru.c

@@ -28,12 +28,19 @@ static struct {
 	{ NTRU_256_BIT, "NTRU_256" }
 };
 
-START_TEST(test_ke)
+/**
+ * NTRU parameter set selection
+ */
+char *param_set_selection[] = {
+		"x9_98_speed", "x9_98_bandwidth", "x9_98_balance", "optimum"
+};
+
+START_TEST(test_ntru_ke)
 {
 	chunk_t pub_key, cipher_text, i_shared_secret, r_shared_secret;
 	diffie_hellman_t *i_ntru, *r_ntru;
 	char buf[10];
-	int len;
+	int n, len;
 	status_t status;
 	
 	len = snprintf(buf, sizeof(buf), "%N", diffie_hellman_group_names,
@@ -41,37 +48,63 @@ START_TEST(test_ke)
 	ck_assert(len == 8);
 	ck_assert(streq(buf, params[_i].group_name));
 
-	i_ntru = lib->crypto->create_dh(lib->crypto, params[_i].group);
+	for (n = 0; n < countof(param_set_selection); n++)
-	ck_assert(i_ntru != NULL);
+	{
-	ck_assert(i_ntru->get_dh_group(i_ntru) == params[_i].group);
+		lib->settings->set_str(lib->settings,
+							  "libcharon.plugins.ntru.param_set_selection",
+							   param_set_selection[n]);
 
-	i_ntru->get_my_public_value(i_ntru, &pub_key);
+		i_ntru = lib->crypto->create_dh(lib->crypto, params[_i].group);
-	ck_assert(pub_key.len > 0);
+		ck_assert(i_ntru != NULL);
+		ck_assert(i_ntru->get_dh_group(i_ntru) == params[_i].group);
 
-	r_ntru = lib->crypto->create_dh(lib->crypto, params[_i].group);
+		i_ntru->get_my_public_value(i_ntru, &pub_key);
-	ck_assert(r_ntru != NULL);
+		ck_assert(pub_key.len > 0);
 
-	r_ntru->set_other_public_value(r_ntru, pub_key);
+		r_ntru = lib->crypto->create_dh(lib->crypto, params[_i].group);
+		ck_assert(r_ntru != NULL);
+
+		r_ntru->set_other_public_value(r_ntru, pub_key);
+		r_ntru->get_my_public_value(r_ntru, &cipher_text);
+		ck_assert(cipher_text.len > 0);
+
+		status = r_ntru->get_shared_secret(r_ntru, &r_shared_secret);
+		ck_assert(status == SUCCESS);
+		ck_assert(r_shared_secret.len > 0);
+
+		i_ntru->set_other_public_value(i_ntru, cipher_text);
+		status = i_ntru->get_shared_secret(i_ntru, &i_shared_secret);
+
+		if (status == SUCCESS)
+		{
+			ck_assert(chunk_equals(i_shared_secret, r_shared_secret));
+		}
+		else
+		{
+			ck_assert(i_shared_secret.len == 0);
+		}
+
+		chunk_clear(&i_shared_secret);
+		chunk_clear(&r_shared_secret);
+		chunk_free(&pub_key);
+		chunk_free(&cipher_text);
+		i_ntru->destroy(i_ntru);
+		r_ntru->destroy(r_ntru);
+	}
+}
+END_TEST
+
+START_TEST(test_ntru_pubkey)
+{
+	diffie_hellman_t *r_ntru;
+	chunk_t cipher_text;
+
+	r_ntru = lib->crypto->create_dh(lib->crypto, NTRU_128_BIT);
+	r_ntru->set_other_public_value(r_ntru, chunk_empty);
 	r_ntru->get_my_public_value(r_ntru, &cipher_text);
-	ck_assert(cipher_text.len > 0);
+	ck_assert(cipher_text.len == 0);
-
-	i_ntru->set_other_public_value(i_ntru, cipher_text);
-	status = i_ntru->get_shared_secret(i_ntru, &i_shared_secret);
-	ck_assert(status == SUCCESS);
-	ck_assert(i_shared_secret.len > 0);
-
-	status = r_ntru->get_shared_secret(r_ntru, &r_shared_secret);
-	ck_assert(status == SUCCESS);
-	ck_assert(r_shared_secret.len > 0);
-
-	ck_assert(chunk_equals(i_shared_secret, r_shared_secret));
-
-	chunk_clear(&i_shared_secret);
-	chunk_clear(&r_shared_secret);
-	chunk_free(&pub_key);
-	chunk_free(&cipher_text);
-	i_ntru->destroy(i_ntru);
 	r_ntru->destroy(r_ntru);
+
 }
 END_TEST
 
@@ -83,7 +116,11 @@ Suite *ntru_suite_create()
 	s = suite_create("ntru");
 
 	tc = tcase_create("ke");
-	tcase_add_loop_test(tc, test_ke, 0, countof(params));
+	tcase_add_loop_test(tc, test_ntru_ke, 0, countof(params));
+	suite_add_tcase(s, tc);
+
+	tc = tcase_create("pubkey");
+	tcase_add_test(tc, test_ntru_pubkey);
 	suite_add_tcase(s, tc);
 
 	return s;