openssl: Add support for X25519 and X448
While X25519 was already added with 1.1.0a, its use would be a lot more complicated, as the helpers like EVP_PKEY_new_raw_public_key() were only added in 1.1.1, which also added X448.
This commit is contained in:
Tobias Brunner
@@ -29,7 +29,8 @@ libstrongswan_openssl_la_SOURCES = \
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openssl_pkcs12.c openssl_pkcs12.h \
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openssl_rng.c openssl_rng.h \
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openssl_hmac.c openssl_hmac.h \
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openssl_gcm.c openssl_gcm.h
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openssl_gcm.c openssl_gcm.h \
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openssl_x_diffie_hellman.c openssl_x_diffie_hellman.h
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libstrongswan_openssl_la_LDFLAGS = -module -avoid-version
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libstrongswan_openssl_la_LIBADD = $(OPENSSL_LIB)
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@@ -47,6 +47,7 @@
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#include "openssl_rng.h"
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#include "openssl_hmac.h"
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#include "openssl_gcm.h"
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#include "openssl_x_diffie_hellman.h"
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#ifndef FIPS_MODE
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#define FIPS_MODE 0
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@@ -594,7 +595,14 @@ METHOD(plugin_t, get_features, int,
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PLUGIN_PROVIDE(DH, ECP_384_BP),
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PLUGIN_PROVIDE(DH, ECP_512_BP),
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PLUGIN_PROVIDE(DH, ECP_224_BP),
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#endif
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#if OPENSSL_VERSION_NUMBER >= 0x1010100fL
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PLUGIN_REGISTER(DH, openssl_x_diffie_hellman_create),
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/* available since 1.1.0a, but we require 1.1.1 features */
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PLUGIN_PROVIDE(DH, CURVE_25519),
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/* available since 1.1.1 */
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PLUGIN_PROVIDE(DH, CURVE_448),
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#endif /* OPENSSL_VERSION_NUMBER */
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#endif /* OPENSSL_NO_ECDH */
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#ifndef OPENSSL_NO_DH
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/* MODP DH groups */
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PLUGIN_REGISTER(DH, openssl_diffie_hellman_create),
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@@ -0,0 +1,256 @@
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/*
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* Copyright (C) 2018 Tobias Brunner
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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 <openssl/evp.h>
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/* basic support for X25519 was added with 1.1.0a, but we require features (e.g.
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* to load the keys) that were only added with 1.1.1 */
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#if OPENSSL_VERSION_NUMBER >= 0x1010100fL && !defined(OPENSSL_NO_ECDH)
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#include "openssl_x_diffie_hellman.h"
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#include <utils/debug.h>
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typedef struct private_diffie_hellman_t private_diffie_hellman_t;
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/**
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* Private data
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*/
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struct private_diffie_hellman_t {
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/**
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* Public interface.
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*/
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diffie_hellman_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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* Private (public) key
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*/
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EVP_PKEY *key;
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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 shared secret is computed
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*/
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bool computed;
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};
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/**
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* Map a DH group to a key type
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*/
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static int map_key_type(diffie_hellman_group_t group)
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{
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switch (group)
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{
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case CURVE_25519:
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return EVP_PKEY_X25519;
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case CURVE_448:
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return EVP_PKEY_X448;
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default:
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return 0;
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}
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}
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/**
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* Compute the shared secret
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*/
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static bool compute_shared_key(private_diffie_hellman_t *this, EVP_PKEY *pub,
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chunk_t *shared_secret)
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{
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EVP_PKEY_CTX *ctx;
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bool success = FALSE;
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ctx = EVP_PKEY_CTX_new(this->key, NULL);
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if (!ctx)
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{
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return FALSE;
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}
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if (EVP_PKEY_derive_init(ctx) <= 0)
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{
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goto error;
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}
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if (EVP_PKEY_derive_set_peer(ctx, pub) <= 0)
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{
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goto error;
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}
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if (EVP_PKEY_derive(ctx, NULL, &shared_secret->len) <= 0)
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{
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goto error;
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}
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*shared_secret = chunk_alloc(shared_secret->len);
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if (EVP_PKEY_derive(ctx, shared_secret->ptr, &shared_secret->len) <= 0)
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{
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goto error;
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}
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success = TRUE;
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error:
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EVP_PKEY_CTX_free(ctx);
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return success;
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}
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METHOD(diffie_hellman_t, set_other_public_value, bool,
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private_diffie_hellman_t *this, chunk_t value)
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{
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EVP_PKEY *pub;
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if (!diffie_hellman_verify_value(this->group, value))
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{
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return FALSE;
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}
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pub = EVP_PKEY_new_raw_public_key(map_key_type(this->group), NULL,
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value.ptr, value.len);
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if (!pub)
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{
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DBG1(DBG_LIB, "%N public value is malformed",
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diffie_hellman_group_names, this->group);
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return FALSE;
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}
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chunk_clear(&this->shared_secret);
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if (!compute_shared_key(this, pub, &this->shared_secret))
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{
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DBG1(DBG_LIB, "%N shared secret computation failed",
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diffie_hellman_group_names, this->group);
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EVP_PKEY_free(pub);
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return FALSE;
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}
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this->computed = TRUE;
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EVP_PKEY_free(pub);
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return TRUE;
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}
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METHOD(diffie_hellman_t, get_my_public_value, bool,
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private_diffie_hellman_t *this, chunk_t *value)
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{
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size_t len;
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if (!EVP_PKEY_get_raw_public_key(this->key, NULL, &len))
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{
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return FALSE;
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}
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*value = chunk_alloc(len);
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if (!EVP_PKEY_get_raw_public_key(this->key, value->ptr, &value->len))
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{
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chunk_free(value);
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return FALSE;
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}
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return TRUE;
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}
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METHOD(diffie_hellman_t, set_private_value, bool,
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private_diffie_hellman_t *this, chunk_t value)
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{
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EVP_PKEY_free(this->key);
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this->key = EVP_PKEY_new_raw_private_key(map_key_type(this->group), NULL,
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value.ptr, value.len);
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if (!this->key)
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{
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return FALSE;
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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_diffie_hellman_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(this->shared_secret);
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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_diffie_hellman_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_diffie_hellman_t *this)
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{
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EVP_PKEY_free(this->key);
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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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diffie_hellman_t *openssl_x_diffie_hellman_create(diffie_hellman_group_t group)
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{
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private_diffie_hellman_t *this;
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EVP_PKEY_CTX *ctx = NULL;
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EVP_PKEY *key = NULL;
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switch (group)
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{
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case CURVE_25519:
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ctx = EVP_PKEY_CTX_new_id(NID_X25519, NULL);
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break;
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case CURVE_448:
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ctx = EVP_PKEY_CTX_new_id(NID_X448, NULL);
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break;
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default:
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break;
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}
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if (!ctx ||
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EVP_PKEY_keygen_init(ctx) <= 0 ||
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EVP_PKEY_keygen(ctx, &key) <= 0)
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{
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DBG1(DBG_LIB, "generating key for %N failed",
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diffie_hellman_group_names, group);
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EVP_PKEY_CTX_free(ctx);
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return NULL;
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}
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EVP_PKEY_CTX_free(ctx);
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INIT(this,
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.public = {
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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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.group = group,
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.key = key,
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);
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return &this->public;
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}
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#endif /* OPENSSL_NO_ECDH */
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@@ -0,0 +1,37 @@
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/*
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* Copyright (C) 2018 Tobias Brunner
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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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/**
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* Implementation of the X25519/X448 Diffie-Hellman algorithm using OpenSSL.
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*
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* @defgroup openssl_x_diffie_hellman openssl_x_diffie_hellman
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* @{ @ingroup openssl_p
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*/
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#ifndef OPENSSL_X_DIFFIE_HELLMAN_H_
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#define OPENSSL_X_DIFFIE_HELLMAN_H_
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#include <library.h>
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/**
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* Creates a new diffie_hellman_t object.
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*
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* @param group Diffie Hellman group number to use
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* @return object, NULL if not supported
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*/
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diffie_hellman_t *openssl_x_diffie_hellman_create(diffie_hellman_group_t group);
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#endif /** OPENSSL_X_DIFFIE_HELLMAN_H_ @}*/
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