Annotation of src/usr.bin/ssh/kexc25519s.c, Revision 1.2
1.2 ! markus 1: /* $OpenBSD: myproposal.h,v 1.33 2013/11/02 21:59:15 markus 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: * modification, are permitted provided that the following conditions
8: * are met:
9: * 1. Redistributions of source code must retain the above copyright
10: * notice, this list of conditions and the following disclaimer.
11: * 2. Redistributions in binary form must reproduce the above copyright
12: * notice, this list of conditions and the following disclaimer in the
13: * documentation and/or other materials provided with the distribution.
14: *
15: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25: */
26:
27: #include <sys/types.h>
28: #include <string.h>
29: #include <signal.h>
30:
31: #include "xmalloc.h"
32: #include "buffer.h"
33: #include "key.h"
34: #include "cipher.h"
35: #include "kex.h"
36: #include "log.h"
37: #include "packet.h"
38: #include "ssh2.h"
39:
40: void
41: kexc25519_server(Kex *kex)
42: {
43: BIGNUM *shared_secret;
44: Key *server_host_private, *server_host_public;
45: u_char *server_host_key_blob = NULL, *signature = NULL;
46: u_char server_key[CURVE25519_SIZE];
47: u_char *client_pubkey = NULL;
48: u_char server_pubkey[CURVE25519_SIZE];
49: u_char *hash;
50: u_int slen, sbloblen, hashlen;
51:
52: /* generate private key */
53: kexc25519_keygen(server_key, server_pubkey);
54: #ifdef DEBUG_KEXECDH
55: dump_digest("server private key:", server_key, sizeof(server_key));
56: #endif
57:
58: if (kex->load_host_public_key == NULL ||
59: kex->load_host_private_key == NULL)
60: fatal("Cannot load hostkey");
61: server_host_public = kex->load_host_public_key(kex->hostkey_type);
62: if (server_host_public == NULL)
63: fatal("Unsupported hostkey type %d", kex->hostkey_type);
64: server_host_private = kex->load_host_private_key(kex->hostkey_type);
65:
66: debug("expecting SSH2_MSG_KEX_ECDH_INIT");
67: packet_read_expect(SSH2_MSG_KEX_ECDH_INIT);
68: client_pubkey = packet_get_string(&slen);
69: if (slen != CURVE25519_SIZE)
70: fatal("Incorrect size for server Curve25519 pubkey: %d", slen);
71: packet_check_eom();
72:
73: #ifdef DEBUG_KEXECDH
74: dump_digest("client public key:", client_pubkey, CURVE25519_SIZE);
75: #endif
76:
77: shared_secret = kexc25519_shared_key(server_key, client_pubkey);
78:
79: /* calc H */
80: key_to_blob(server_host_public, &server_host_key_blob, &sbloblen);
81: kex_c25519_hash(
82: kex->evp_md,
83: kex->client_version_string,
84: kex->server_version_string,
85: buffer_ptr(&kex->peer), buffer_len(&kex->peer),
86: buffer_ptr(&kex->my), buffer_len(&kex->my),
87: server_host_key_blob, sbloblen,
88: client_pubkey,
89: server_pubkey,
90: shared_secret,
91: &hash, &hashlen
92: );
93:
94: /* save session id := H */
95: if (kex->session_id == NULL) {
96: kex->session_id_len = hashlen;
97: kex->session_id = xmalloc(kex->session_id_len);
98: memcpy(kex->session_id, hash, kex->session_id_len);
99: }
100:
101: /* sign H */
102: kex->sign(server_host_private, server_host_public, &signature, &slen,
103: hash, hashlen);
104:
105: /* destroy_sensitive_data(); */
106:
107: /* send server hostkey, ECDH pubkey 'Q_S' and signed H */
108: packet_start(SSH2_MSG_KEX_ECDH_REPLY);
109: packet_put_string(server_host_key_blob, sbloblen);
110: packet_put_string(server_pubkey, sizeof(server_pubkey));
111: packet_put_string(signature, slen);
112: packet_send();
113:
114: free(signature);
115: free(server_host_key_blob);
116: /* have keys, free server key */
117: free(client_pubkey);
118: kex_derive_keys(kex, hash, hashlen, shared_secret);
119: BN_clear_free(shared_secret);
120: kex_finish(kex);
121: }