--- /dev/null
+/*
+ * Copyright (C) 2008 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * 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.
+ *
+ * $Id$
+ */
+
+#include <openssl/ec.h>
+#include <openssl/objects.h>
+
+#include "openssl_ec_diffie_hellman.h"
+
+#include <debug.h>
+
+#define COORD_LEN(group) ((EC_GROUP_get_degree(group) + 7) / 8)
+
+typedef struct private_openssl_ec_diffie_hellman_t private_openssl_ec_diffie_hellman_t;
+
+/**
+ * Private data of an openssl_ec_diffie_hellman_t object.
+ */
+struct private_openssl_ec_diffie_hellman_t {
+ /**
+ * Public openssl_ec_diffie_hellman_t interface.
+ */
+ openssl_ec_diffie_hellman_t public;
+
+ /**
+ * Diffie Hellman group number.
+ */
+ u_int16_t group;
+
+ /**
+ * EC private (public) key
+ */
+ EC_KEY *key;
+
+ /**
+ * EC group
+ */
+ const EC_GROUP *ec_group;
+
+ /**
+ * Other public key
+ */
+ EC_POINT *pub_key;
+
+ /**
+ * Shared secret
+ */
+ chunk_t shared_secret;
+
+ /**
+ * True if shared secret is computed
+ */
+ bool computed;
+};
+
+/**
+ * Convert a chunk to an EC_POINT (which must already exist). The x and y
+ * coordinates of the point have to be concatenated in the chunk.
+ */
+static bool chunk2ecp(const EC_GROUP *group, chunk_t chunk, EC_POINT *point)
+{
+ BN_CTX *ctx;
+ BIGNUM *x, *y;
+ int coord_len;
+ bool ret = FALSE;
+
+ ctx = BN_CTX_new();
+ if (!ctx)
+ {
+ return FALSE;
+ }
+
+ BN_CTX_start(ctx);
+ x = BN_CTX_get(ctx);
+ y = BN_CTX_get(ctx);
+ if (!x || !y)
+ {
+ goto error;
+ }
+
+ coord_len = COORD_LEN(group);
+ if (chunk.len != coord_len * 2)
+ {
+ goto error;
+ }
+
+ if (!BN_bin2bn(chunk.ptr, coord_len, x) ||
+ !BN_bin2bn(chunk.ptr + coord_len, coord_len, y))
+ {
+ goto error;
+ }
+
+ if (!EC_POINT_set_affine_coordinates_GFp(group, point, x, y, ctx))
+ {
+ goto error;
+ }
+
+ ret = TRUE;
+error:
+ BN_CTX_end(ctx);
+ BN_CTX_free(ctx);
+ return ret;
+}
+
+/**
+ * Convert an EC_POINT to a chunk by concatenating the x and y coordinates of
+ * the point. This function allocates memory for the chunk.
+ */
+static bool ecp2chunk(const EC_GROUP *group, const EC_POINT *point, chunk_t *chunk)
+{
+ BN_CTX *ctx;
+ BIGNUM *x, *y;
+ int coord_len, offset;
+ bool ret = FALSE;
+
+ ctx = BN_CTX_new();
+ if (!ctx)
+ {
+ return FALSE;
+ }
+
+ BN_CTX_start(ctx);
+ x = BN_CTX_get(ctx);
+ y = BN_CTX_get(ctx);
+ if (!x || !y)
+ {
+ goto error;
+ }
+
+ if (!EC_POINT_get_affine_coordinates_GFp(group, point, x, y, ctx))
+ {
+ goto error;
+ }
+
+ coord_len = COORD_LEN(group);
+ chunk->len = coord_len * 2;
+ chunk->ptr = malloc(chunk->len);
+ memset(chunk->ptr, 0, chunk->len);
+
+ offset = coord_len - BN_num_bytes(x);
+ if (!BN_bn2bin(x, chunk->ptr + offset))
+ {
+ chunk_free(chunk);
+ goto error;
+ }
+
+ offset = coord_len - BN_num_bytes(y);
+ if (!BN_bn2bin(y, chunk->ptr + coord_len + offset))
+ {
+ chunk_free(chunk);
+ goto error;
+ }
+
+ ret = TRUE;
+error:
+ BN_CTX_end(ctx);
+ BN_CTX_free(ctx);
+ return ret;
+}
+
+/**
+ * Compute the shared secret.
+ *
+ * We cannot use the function ECDH_compute_key() because that returns only the
+ * x coordinate of the shared secret point (which is defined, for instance, in
+ * 'NIST SP 800-56A').
+ * However, we need both coordinates as RFC 4753 says: "The Diffie-Hellman
+ * public value is obtained by concatenating the x and y values. The format
+ * of the Diffie-Hellman shared secret value is the same as that of the
+ * Diffie-Hellman public value."
+ */
+static bool compute_shared_key(private_openssl_ec_diffie_hellman_t *this, chunk_t *shared_secret)
+{
+ const BIGNUM *priv_key;
+ EC_POINT *secret;
+ bool ret = FALSE;
+
+ priv_key = EC_KEY_get0_private_key(this->key);
+ if (!priv_key)
+ {
+ goto error;
+ }
+
+ secret = EC_POINT_new(this->ec_group);
+ if (!secret)
+ {
+ goto error;
+ }
+
+ if (!EC_POINT_mul(this->ec_group, secret, NULL, this->pub_key, priv_key, NULL))
+ {
+ goto error;
+ }
+
+ if (!ecp2chunk(this->ec_group, secret, shared_secret))
+ {
+ goto error;
+ }
+
+ ret = TRUE;
+error:
+ if (secret)
+ {
+ EC_POINT_clear_free(secret);
+ }
+ return ret;
+}
+
+/**
+ * Implementation of openssl_ec_diffie_hellman_t.set_other_public_value.
+ */
+static void set_other_public_value(private_openssl_ec_diffie_hellman_t *this, chunk_t value)
+{
+ if (!chunk2ecp(this->ec_group, value, this->pub_key))
+ {
+ DBG1("ECDH public value is malformed");
+ return;
+ }
+
+ chunk_free(&this->shared_secret);
+
+ if (!compute_shared_key(this, &this->shared_secret)) {
+ DBG1("ECDH shared secret computation failed");
+ return;
+ }
+
+ this->computed = TRUE;
+}
+
+/**
+ * Implementation of openssl_ec_diffie_hellman_t.get_other_public_value.
+ */
+static status_t get_other_public_value(private_openssl_ec_diffie_hellman_t *this,
+ chunk_t *value)
+{
+ if (!this->computed)
+ {
+ return FAILED;
+ }
+
+ if (!ecp2chunk(this->ec_group, this->pub_key, value))
+ {
+ return FAILED;
+ }
+ return SUCCESS;
+}
+
+/**
+ * Implementation of openssl_ec_diffie_hellman_t.get_my_public_value.
+ */
+static void get_my_public_value(private_openssl_ec_diffie_hellman_t *this,chunk_t *value)
+{
+ ecp2chunk(this->ec_group, EC_KEY_get0_public_key(this->key), value);
+}
+
+/**
+ * Implementation of openssl_ec_diffie_hellman_t.get_shared_secret.
+ */
+static status_t get_shared_secret(private_openssl_ec_diffie_hellman_t *this, chunk_t *secret)
+{
+ if (!this->computed)
+ {
+ return FAILED;
+ }
+ *secret = chunk_clone(this->shared_secret);
+ return SUCCESS;
+}
+
+/**
+ * Implementation of openssl_ec_diffie_hellman_t.get_dh_group.
+ */
+static diffie_hellman_group_t get_dh_group(private_openssl_ec_diffie_hellman_t *this)
+{
+ return this->group;
+}
+
+/**
+ * Implementation of openssl_ec_diffie_hellman_t.destroy.
+ */
+static void destroy(private_openssl_ec_diffie_hellman_t *this)
+{
+ EC_POINT_clear_free(this->pub_key);
+ EC_KEY_free(this->key);
+ chunk_free(&this->shared_secret);
+ free(this);
+}
+
+/*
+ * Described in header.
+ */
+openssl_ec_diffie_hellman_t *openssl_ec_diffie_hellman_create(diffie_hellman_group_t group)
+{
+ private_openssl_ec_diffie_hellman_t *this = malloc_thing(private_openssl_ec_diffie_hellman_t);
+
+ this->public.dh.get_shared_secret = (status_t (*)(diffie_hellman_t *, chunk_t *)) get_shared_secret;
+ this->public.dh.set_other_public_value = (void (*)(diffie_hellman_t *, chunk_t )) set_other_public_value;
+ this->public.dh.get_other_public_value = (status_t (*)(diffie_hellman_t *, chunk_t *)) get_other_public_value;
+ this->public.dh.get_my_public_value = (void (*)(diffie_hellman_t *, chunk_t *)) get_my_public_value;
+ this->public.dh.get_dh_group = (diffie_hellman_group_t (*)(diffie_hellman_t *)) get_dh_group;
+ this->public.dh.destroy = (void (*)(diffie_hellman_t *)) destroy;
+
+ switch (group)
+ {
+ case ECP_256_BIT:
+ this->key = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
+ break;
+ case ECP_384_BIT:
+ this->key = EC_KEY_new_by_curve_name(NID_secp384r1);
+ break;
+ case ECP_521_BIT:
+ this->key = EC_KEY_new_by_curve_name(NID_secp521r1);
+ break;
+ default:
+ this->key = NULL;
+ break;
+ }
+
+ if (!this->key)
+ {
+ free(this);
+ return NULL;
+ }
+
+ /* caching the EC group */
+ this->ec_group = EC_KEY_get0_group(this->key);
+
+ this->pub_key = EC_POINT_new(this->ec_group);
+ if (!this->pub_key)
+ {
+ free(this);
+ return NULL;
+ }
+
+ /* generate an EC private (public) key */
+ if (!EC_KEY_generate_key(this->key))
+ {
+ free(this);
+ return NULL;
+ }
+
+ this->group = group;
+ this->computed = FALSE;
+
+ this->shared_secret = chunk_empty;
+
+ return &this->public;
+}
--- /dev/null
+/*
+ * Copyright (C) 2008 Tobias Brunner
+ * Hochschule fuer Technik Rapperswil
+ *
+ * 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.
+ */
+
+/**
+ * @defgroup openssl_ec_diffie_hellman openssl_ec_diffie_hellman
+ * @{ @ingroup openssl_p
+ */
+
+#ifndef OPENSSL_EC_DIFFIE_HELLMAN_H_
+#define OPENSSL_EC_DIFFIE_HELLMAN_H_
+
+typedef struct openssl_ec_diffie_hellman_t openssl_ec_diffie_hellman_t;
+
+#include <library.h>
+
+/**
+ * Implementation of the EC Diffie-Hellman algorithm using OpenSSL.
+ */
+struct openssl_ec_diffie_hellman_t {
+
+ /**
+ * Implements diffie_hellman_t interface.
+ */
+ diffie_hellman_t dh;
+};
+
+/**
+ * Creates a new openssl_ec_diffie_hellman_t object.
+ *
+ * @param group EC Diffie Hellman group number to use
+ * @return openssl_ec_diffie_hellman_t object, NULL if not supported
+ */
+openssl_ec_diffie_hellman_t *openssl_ec_diffie_hellman_create(diffie_hellman_group_t group);
+
+#endif /*OPENSSL_EC_DIFFIE_HELLMAN_H_ @}*/
+
#include "openssl_crypter.h"
#include "openssl_hasher.h"
#include "openssl_diffie_hellman.h"
+#include "openssl_ec_diffie_hellman.h"
#include "openssl_rsa_private_key.h"
#include "openssl_rsa_public_key.h"
(hasher_constructor_t)openssl_hasher_create);
lib->crypto->remove_dh(lib->crypto,
(dh_constructor_t)openssl_diffie_hellman_create);
+ lib->crypto->remove_dh(lib->crypto,
+ (dh_constructor_t)openssl_ec_diffie_hellman_create);
lib->creds->remove_builder(lib->creds,
(builder_constructor_t)openssl_rsa_private_key_builder);
lib->creds->remove_builder(lib->creds,
lib->crypto->add_dh(lib->crypto, MODP_8192_BIT,
(dh_constructor_t)openssl_diffie_hellman_create);
+ /* ec diffie hellman */
+ lib->crypto->add_dh(lib->crypto, ECP_256_BIT,
+ (dh_constructor_t)openssl_ec_diffie_hellman_create);
+ lib->crypto->add_dh(lib->crypto, ECP_384_BIT,
+ (dh_constructor_t)openssl_ec_diffie_hellman_create);
+ lib->crypto->add_dh(lib->crypto, ECP_521_BIT,
+ (dh_constructor_t)openssl_ec_diffie_hellman_create);
+
/* rsa */
lib->creds->add_builder(lib->creds, CRED_PRIVATE_KEY, KEY_RSA,
(builder_constructor_t)openssl_rsa_private_key_builder);
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