From ee8a214318fd6dbe6bc5d6b510896f30d92d46c6 Mon Sep 17 00:00:00 2001 From: Guus Sliepen Date: Mon, 27 Jun 2011 21:52:23 +0200 Subject: [PATCH] Preliminary implementation of Elliptic Curve Diffie-Hellman Ephemeral key exchange. --- src/Makefile.am | 4 +-- src/openssl/ecdh.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++ src/openssl/ecdh.h | 32 +++++++++++++++++ 3 files changed, 121 insertions(+), 2 deletions(-) create mode 100644 src/openssl/ecdh.c create mode 100644 src/openssl/ecdh.h diff --git a/src/Makefile.am b/src/Makefile.am index 23bbfbcd..f7876907 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -11,7 +11,7 @@ tincd_SOURCES = \ protocol_key.c protocol_subnet.c route.c subnet.c tincd.c nodist_tincd_SOURCES = \ - device.c cipher.c crypto.c digest.c rsa.c + device.c cipher.c crypto.c ecdh.c digest.c rsa.c tincctl_SOURCES = \ utils.c getopt.c getopt1.c dropin.c \ @@ -32,7 +32,7 @@ INCLUDES = @INCLUDES@ -I$(top_builddir) noinst_HEADERS = \ xalloc.h utils.h getopt.h list.h splay_tree.h dropin.h fake-getaddrinfo.h fake-getnameinfo.h fake-gai-errnos.h ipv6.h ipv4.h ethernet.h \ - buffer.h cipher.h conf.h connection.h control.h control_common.h crypto.h device.h digest.h edge.h graph.h logger.h meta.h net.h netutl.h node.h process.h \ + buffer.h cipher.h conf.h connection.h control.h control_common.h crypto.h device.h ecdh.h digest.h edge.h graph.h logger.h meta.h net.h netutl.h node.h process.h \ protocol.h route.h rsa.h rsagen.h subnet.h tincctl.h top.h bsd/tunemu.h LIBS = @LIBS@ @LIBGCRYPT_LIBS@ diff --git a/src/openssl/ecdh.c b/src/openssl/ecdh.c new file mode 100644 index 00000000..642b3c30 --- /dev/null +++ b/src/openssl/ecdh.c @@ -0,0 +1,87 @@ +/* + ecdh.c -- Diffie-Hellman key exchange handling + Copyright (C) 2011 Guus Sliepen + + 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. + + 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. + + You should have received a copy of the GNU General Public License along + with this program; if not, write to the Free Software Foundation, Inc., + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. +*/ + +#include "system.h" +#include "utils.h" +#include "xalloc.h" + +#include +#include +#include + +#include "ecdh.h" +#include "logger.h" + +EC_GROUP *secp256k1 = NULL; +EC_GROUP *secp384r1 = NULL; +EC_GROUP *secp521r1 = NULL; + +// TODO: proper KDF +static void *kdf(const void *in, size_t inlen, void *out, size_t *outlen) { + memcpy(out, in, inlen); + *outlen = inlen; + return out; +} + +bool ecdh_generate_public(ecdh_t *ecdh, void *pubkey) { + if(!secp521r1) + secp521r1 = EC_GROUP_new_by_curve_name(NID_secp521r1); + + *ecdh = EC_KEY_new_by_curve_name(NID_secp521r1); + if(!EC_KEY_generate_key(*ecdh)) { + logger(LOG_ERR, "Generating EC key failed: %s", ERR_error_string(ERR_get_error(), NULL)); + abort(); + } + + const EC_POINT *point = EC_KEY_get0_public_key(*ecdh); + if(!point) { + logger(LOG_ERR, "Getting public key failed: %s", ERR_error_string(ERR_get_error(), NULL)); + abort(); + } + + size_t result = EC_POINT_point2oct(secp521r1, point, POINT_CONVERSION_COMPRESSED, pubkey, ECDH_SIZE, NULL); + if(!result) { + logger(LOG_ERR, "Converting EC_POINT to binary failed: %s", ERR_error_string(ERR_get_error(), NULL)); + abort(); + } + + return true; +} + +bool ecdh_compute_shared(ecdh_t *ecdh, const void *pubkey, void *shared) { + EC_POINT *point = EC_POINT_new(secp521r1); + + int result = EC_POINT_oct2point(secp521r1, point, pubkey, ECDH_SIZE, NULL); + if(!point) { + logger(LOG_ERR, "Converting binary to EC_POINT failed: %s", ERR_error_string(ERR_get_error(), NULL)); + abort(); + } + + result = ECDH_compute_key(shared, ECDH_SIZE, point, *ecdh, kdf); + EC_POINT_free(point); + EC_KEY_free(*ecdh); + *ecdh = NULL; + + if(!result) { + logger(LOG_ERR, "Computing Elliptic Curve Diffie-Hellman shared key failed: %s", ERR_error_string(ERR_get_error(), NULL)); + return false; + } + + return true; +} diff --git a/src/openssl/ecdh.h b/src/openssl/ecdh.h new file mode 100644 index 00000000..c5b43d88 --- /dev/null +++ b/src/openssl/ecdh.h @@ -0,0 +1,32 @@ +/* + ecdh.h -- header file for ecdh.c + Copyright (C) 2011 Guus Sliepen + + 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. + + 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. + + You should have received a copy of the GNU General Public License along + with this program; if not, write to the Free Software Foundation, Inc., + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. +*/ + +#ifndef __TINC_ECDH_H__ +#define __TINC_ECDH_H__ + +#include + +#define ECDH_SIZE 67 + +typedef EC_KEY *ecdh_t; + +extern bool ecdh_generate_public(ecdh_t *ecdh, void *pubkey); +extern bool ecdh_compute_shared(ecdh_t *ecdh, const void *pubkey, void *shared); + +#endif -- 2.20.1