Annotation of src/usr.bin/ssh/kexc25519c.c, Revision 1.4
1.4 ! djm 1: /* $OpenBSD: kexc25519c.c,v 1.3 2014/01/09 23:20:00 djm Exp $ */
1.1 markus 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 <sys/types.h>
29:
30: #include <stdio.h>
31: #include <string.h>
32: #include <signal.h>
33:
34: #include "xmalloc.h"
35: #include "buffer.h"
36: #include "key.h"
37: #include "cipher.h"
38: #include "kex.h"
39: #include "log.h"
40: #include "packet.h"
41: #include "ssh2.h"
42:
43: void
44: kexc25519_client(Kex *kex)
45: {
46: Key *server_host_key;
47: u_char client_key[CURVE25519_SIZE];
48: u_char client_pubkey[CURVE25519_SIZE];
49: u_char *server_pubkey = NULL;
50: u_char *server_host_key_blob = NULL, *signature = NULL;
51: u_char *hash;
52: u_int slen, sbloblen, hashlen;
1.4 ! djm 53: Buffer shared_secret;
1.1 markus 54:
55: kexc25519_keygen(client_key, client_pubkey);
56:
57: packet_start(SSH2_MSG_KEX_ECDH_INIT);
58: packet_put_string(client_pubkey, sizeof(client_pubkey));
59: packet_send();
60: debug("sending SSH2_MSG_KEX_ECDH_INIT");
61:
62: #ifdef DEBUG_KEXECDH
63: dump_digest("client private key:", client_key, sizeof(client_key));
64: #endif
65:
66: debug("expecting SSH2_MSG_KEX_ECDH_REPLY");
67: packet_read_expect(SSH2_MSG_KEX_ECDH_REPLY);
68:
69: /* hostkey */
70: server_host_key_blob = packet_get_string(&sbloblen);
71: server_host_key = key_from_blob(server_host_key_blob, sbloblen);
72: if (server_host_key == NULL)
73: fatal("cannot decode server_host_key_blob");
74: if (server_host_key->type != kex->hostkey_type)
75: fatal("type mismatch for decoded server_host_key_blob");
76: if (kex->verify_host_key == NULL)
77: fatal("cannot verify server_host_key");
78: if (kex->verify_host_key(server_host_key) == -1)
79: fatal("server_host_key verification failed");
80:
81: /* Q_S, server public key */
82: server_pubkey = packet_get_string(&slen);
83: if (slen != CURVE25519_SIZE)
84: fatal("Incorrect size for server Curve25519 pubkey: %d", slen);
85:
86: #ifdef DEBUG_KEXECDH
87: dump_digest("server public key:", server_pubkey, CURVE25519_SIZE);
88: #endif
89:
90: /* signed H */
91: signature = packet_get_string(&slen);
92: packet_check_eom();
93:
1.4 ! djm 94: buffer_init(&shared_secret);
! 95: kexc25519_shared_key(client_key, server_pubkey, &shared_secret);
1.1 markus 96:
97: /* calc and verify H */
98: kex_c25519_hash(
1.3 djm 99: kex->hash_alg,
1.1 markus 100: kex->client_version_string,
101: kex->server_version_string,
102: buffer_ptr(&kex->my), buffer_len(&kex->my),
103: buffer_ptr(&kex->peer), buffer_len(&kex->peer),
104: server_host_key_blob, sbloblen,
105: client_pubkey,
106: server_pubkey,
1.4 ! djm 107: buffer_ptr(&shared_secret), buffer_len(&shared_secret),
1.1 markus 108: &hash, &hashlen
109: );
110: free(server_host_key_blob);
111: free(server_pubkey);
112: if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
113: fatal("key_verify failed for server_host_key");
114: key_free(server_host_key);
115: free(signature);
116:
117: /* save session id */
118: if (kex->session_id == NULL) {
119: kex->session_id_len = hashlen;
120: kex->session_id = xmalloc(kex->session_id_len);
121: memcpy(kex->session_id, hash, kex->session_id_len);
122: }
1.4 ! djm 123: kex_derive_keys(kex, hash, hashlen,
! 124: buffer_ptr(&shared_secret), buffer_len(&shared_secret));
! 125: buffer_free(&shared_secret);
1.1 markus 126: kex_finish(kex);
127: }