Damien Miller | 91b580e | 2014-01-12 19:21:22 +1100 | [diff] [blame] | 1 | /* $OpenBSD: kexc25519c.c,v 1.4 2014/01/12 08:13:13 djm Exp $ */ |
Damien Miller | 094003f | 2013-11-04 22:59:27 +1100 | [diff] [blame] | 2 | /* |
| 3 | * Copyright (c) 2001 Markus Friedl. All rights reserved. |
| 4 | * Copyright (c) 2010 Damien Miller. All rights reserved. |
| 5 | * Copyright (c) 2013 Aris Adamantiadis. All rights reserved. |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * 1. Redistributions of source code must retain the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer. |
| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in the |
| 14 | * documentation and/or other materials provided with the distribution. |
| 15 | * |
| 16 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 17 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 18 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 19 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 20 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 21 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 22 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 23 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 24 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 25 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 26 | */ |
| 27 | |
| 28 | #include "includes.h" |
| 29 | |
| 30 | #include <sys/types.h> |
| 31 | |
| 32 | #include <stdio.h> |
| 33 | #include <string.h> |
| 34 | #include <signal.h> |
| 35 | |
| 36 | #include "xmalloc.h" |
| 37 | #include "buffer.h" |
| 38 | #include "key.h" |
| 39 | #include "cipher.h" |
| 40 | #include "kex.h" |
| 41 | #include "log.h" |
| 42 | #include "packet.h" |
| 43 | #include "ssh2.h" |
| 44 | |
| 45 | void |
| 46 | kexc25519_client(Kex *kex) |
| 47 | { |
Damien Miller | 094003f | 2013-11-04 22:59:27 +1100 | [diff] [blame] | 48 | Key *server_host_key; |
| 49 | u_char client_key[CURVE25519_SIZE]; |
| 50 | u_char client_pubkey[CURVE25519_SIZE]; |
| 51 | u_char *server_pubkey = NULL; |
| 52 | u_char *server_host_key_blob = NULL, *signature = NULL; |
| 53 | u_char *hash; |
| 54 | u_int slen, sbloblen, hashlen; |
Damien Miller | 91b580e | 2014-01-12 19:21:22 +1100 | [diff] [blame] | 55 | Buffer shared_secret; |
Damien Miller | 094003f | 2013-11-04 22:59:27 +1100 | [diff] [blame] | 56 | |
| 57 | kexc25519_keygen(client_key, client_pubkey); |
| 58 | |
| 59 | packet_start(SSH2_MSG_KEX_ECDH_INIT); |
| 60 | packet_put_string(client_pubkey, sizeof(client_pubkey)); |
| 61 | packet_send(); |
| 62 | debug("sending SSH2_MSG_KEX_ECDH_INIT"); |
| 63 | |
| 64 | #ifdef DEBUG_KEXECDH |
| 65 | dump_digest("client private key:", client_key, sizeof(client_key)); |
| 66 | #endif |
| 67 | |
| 68 | debug("expecting SSH2_MSG_KEX_ECDH_REPLY"); |
| 69 | packet_read_expect(SSH2_MSG_KEX_ECDH_REPLY); |
| 70 | |
| 71 | /* hostkey */ |
| 72 | server_host_key_blob = packet_get_string(&sbloblen); |
| 73 | server_host_key = key_from_blob(server_host_key_blob, sbloblen); |
| 74 | if (server_host_key == NULL) |
| 75 | fatal("cannot decode server_host_key_blob"); |
| 76 | if (server_host_key->type != kex->hostkey_type) |
| 77 | fatal("type mismatch for decoded server_host_key_blob"); |
| 78 | if (kex->verify_host_key == NULL) |
| 79 | fatal("cannot verify server_host_key"); |
| 80 | if (kex->verify_host_key(server_host_key) == -1) |
| 81 | fatal("server_host_key verification failed"); |
| 82 | |
| 83 | /* Q_S, server public key */ |
| 84 | server_pubkey = packet_get_string(&slen); |
| 85 | if (slen != CURVE25519_SIZE) |
| 86 | fatal("Incorrect size for server Curve25519 pubkey: %d", slen); |
| 87 | |
| 88 | #ifdef DEBUG_KEXECDH |
| 89 | dump_digest("server public key:", server_pubkey, CURVE25519_SIZE); |
| 90 | #endif |
| 91 | |
| 92 | /* signed H */ |
| 93 | signature = packet_get_string(&slen); |
| 94 | packet_check_eom(); |
| 95 | |
Damien Miller | 91b580e | 2014-01-12 19:21:22 +1100 | [diff] [blame] | 96 | buffer_init(&shared_secret); |
| 97 | kexc25519_shared_key(client_key, server_pubkey, &shared_secret); |
Damien Miller | 094003f | 2013-11-04 22:59:27 +1100 | [diff] [blame] | 98 | |
| 99 | /* calc and verify H */ |
| 100 | kex_c25519_hash( |
Damien Miller | b3051d0 | 2014-01-10 10:58:53 +1100 | [diff] [blame] | 101 | kex->hash_alg, |
Damien Miller | 094003f | 2013-11-04 22:59:27 +1100 | [diff] [blame] | 102 | kex->client_version_string, |
| 103 | kex->server_version_string, |
| 104 | buffer_ptr(&kex->my), buffer_len(&kex->my), |
| 105 | buffer_ptr(&kex->peer), buffer_len(&kex->peer), |
| 106 | server_host_key_blob, sbloblen, |
| 107 | client_pubkey, |
| 108 | server_pubkey, |
Damien Miller | 91b580e | 2014-01-12 19:21:22 +1100 | [diff] [blame] | 109 | buffer_ptr(&shared_secret), buffer_len(&shared_secret), |
Damien Miller | 094003f | 2013-11-04 22:59:27 +1100 | [diff] [blame] | 110 | &hash, &hashlen |
| 111 | ); |
| 112 | free(server_host_key_blob); |
| 113 | free(server_pubkey); |
| 114 | if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1) |
| 115 | fatal("key_verify failed for server_host_key"); |
| 116 | key_free(server_host_key); |
| 117 | free(signature); |
| 118 | |
| 119 | /* save session id */ |
| 120 | if (kex->session_id == NULL) { |
| 121 | kex->session_id_len = hashlen; |
| 122 | kex->session_id = xmalloc(kex->session_id_len); |
| 123 | memcpy(kex->session_id, hash, kex->session_id_len); |
| 124 | } |
Damien Miller | 91b580e | 2014-01-12 19:21:22 +1100 | [diff] [blame] | 125 | kex_derive_keys(kex, hash, hashlen, |
| 126 | buffer_ptr(&shared_secret), buffer_len(&shared_secret)); |
| 127 | buffer_free(&shared_secret); |
Damien Miller | 094003f | 2013-11-04 22:59:27 +1100 | [diff] [blame] | 128 | kex_finish(kex); |
| 129 | } |