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91b580e4be
[bufaux.c buffer.h kex.c kex.h kexc25519.c kexc25519c.c kexc25519s.c]
[kexdhc.c kexdhs.c kexecdhc.c kexecdhs.c kexgexc.c kexgexs.c]
avoid use of OpenSSL BIGNUM type and functions for KEX with
Curve25519 by adding a buffer_put_bignum2_from_string() that stores
a string using the bignum encoding rules. Will make it easier to
build a reduced-feature OpenSSH without OpenSSL in the future;
ok markus@
130 lines
4.2 KiB
C
130 lines
4.2 KiB
C
/* $OpenBSD: kexc25519c.c,v 1.4 2014/01/12 08:13:13 djm Exp $ */
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/*
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* Copyright (c) 2001 Markus Friedl. All rights reserved.
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* Copyright (c) 2010 Damien Miller. All rights reserved.
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* Copyright (c) 2013 Aris Adamantiadis. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <stdio.h>
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#include <string.h>
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#include <signal.h>
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#include "xmalloc.h"
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#include "buffer.h"
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#include "key.h"
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#include "cipher.h"
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#include "kex.h"
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#include "log.h"
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#include "packet.h"
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#include "ssh2.h"
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void
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kexc25519_client(Kex *kex)
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{
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Key *server_host_key;
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u_char client_key[CURVE25519_SIZE];
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u_char client_pubkey[CURVE25519_SIZE];
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u_char *server_pubkey = NULL;
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u_char *server_host_key_blob = NULL, *signature = NULL;
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u_char *hash;
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u_int slen, sbloblen, hashlen;
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Buffer shared_secret;
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kexc25519_keygen(client_key, client_pubkey);
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packet_start(SSH2_MSG_KEX_ECDH_INIT);
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packet_put_string(client_pubkey, sizeof(client_pubkey));
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packet_send();
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debug("sending SSH2_MSG_KEX_ECDH_INIT");
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#ifdef DEBUG_KEXECDH
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dump_digest("client private key:", client_key, sizeof(client_key));
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#endif
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debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
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packet_read_expect(SSH2_MSG_KEX_ECDH_REPLY);
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/* hostkey */
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server_host_key_blob = packet_get_string(&sbloblen);
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server_host_key = key_from_blob(server_host_key_blob, sbloblen);
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if (server_host_key == NULL)
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fatal("cannot decode server_host_key_blob");
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if (server_host_key->type != kex->hostkey_type)
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fatal("type mismatch for decoded server_host_key_blob");
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if (kex->verify_host_key == NULL)
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fatal("cannot verify server_host_key");
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if (kex->verify_host_key(server_host_key) == -1)
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fatal("server_host_key verification failed");
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/* Q_S, server public key */
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server_pubkey = packet_get_string(&slen);
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if (slen != CURVE25519_SIZE)
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fatal("Incorrect size for server Curve25519 pubkey: %d", slen);
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#ifdef DEBUG_KEXECDH
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dump_digest("server public key:", server_pubkey, CURVE25519_SIZE);
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#endif
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/* signed H */
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signature = packet_get_string(&slen);
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packet_check_eom();
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buffer_init(&shared_secret);
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kexc25519_shared_key(client_key, server_pubkey, &shared_secret);
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/* calc and verify H */
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kex_c25519_hash(
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kex->hash_alg,
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kex->client_version_string,
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kex->server_version_string,
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buffer_ptr(&kex->my), buffer_len(&kex->my),
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buffer_ptr(&kex->peer), buffer_len(&kex->peer),
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server_host_key_blob, sbloblen,
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client_pubkey,
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server_pubkey,
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buffer_ptr(&shared_secret), buffer_len(&shared_secret),
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&hash, &hashlen
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);
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free(server_host_key_blob);
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free(server_pubkey);
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if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
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fatal("key_verify failed for server_host_key");
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key_free(server_host_key);
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free(signature);
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/* save session id */
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if (kex->session_id == NULL) {
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kex->session_id_len = hashlen;
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kex->session_id = xmalloc(kex->session_id_len);
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memcpy(kex->session_id, hash, kex->session_id_len);
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}
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kex_derive_keys(kex, hash, hashlen,
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buffer_ptr(&shared_secret), buffer_len(&shared_secret));
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buffer_free(&shared_secret);
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kex_finish(kex);
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}
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