Annotation of src/usr.bin/ssh/kexkems.c, Revision 1.4
1.4 ! djm 1: /* $OpenBSD: kexkems.c,v 1.3 2019/01/21 10:28:02 djm Exp $ */
1.1 djm 2: /*
3: * Copyright (c) 2019 Markus Friedl. All rights reserved.
4: *
5: * modification, are permitted provided that the following conditions
6: * are met:
7: * 1. Redistributions of source code must retain the above copyright
8: * notice, this list of conditions and the following disclaimer.
9: * 2. Redistributions in binary form must reproduce the above copyright
10: * notice, this list of conditions and the following disclaimer in the
11: * documentation and/or other materials provided with the distribution.
12: *
13: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
14: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
15: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
16: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
17: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
18: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
22: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: */
24:
25: #include <sys/types.h>
26: #include <stdio.h>
27: #include <string.h>
28: #include <signal.h>
29:
30: #include "sshkey.h"
31: #include "digest.h"
32: #include "kex.h"
33: #include "log.h"
34: #include "packet.h"
35: #include "ssh2.h"
36: #include "sshbuf.h"
37: #include "ssherr.h"
38:
39: static int input_kex_kem_init(int, u_int32_t, struct ssh *);
40:
41: int
42: kex_kem_server(struct ssh *ssh)
43: {
44: debug("expecting SSH2_MSG_KEX_ECDH_INIT");
45: ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_INIT, &input_kex_kem_init);
46: return 0;
47: }
48:
49: static int
50: input_kex_kem_init(int type, u_int32_t seq, struct ssh *ssh)
51: {
52: struct kex *kex = ssh->kex;
53: struct sshkey *server_host_private, *server_host_public;
54: struct sshbuf *shared_secret = NULL;
55: struct sshbuf *server_pubkey = NULL;
56: u_char *server_host_key_blob = NULL, *signature = NULL;
57: u_char *client_pubkey = NULL;
58: u_char hash[SSH_DIGEST_MAX_LENGTH];
59: size_t slen, pklen, sbloblen, hashlen;
60: int r;
61:
62: if ((r = kex_load_hostkey(ssh, &server_host_private,
63: &server_host_public)) != 0)
64: goto out;
65:
66: if ((r = sshpkt_get_string(ssh, &client_pubkey, &pklen)) != 0 ||
67: (r = sshpkt_get_end(ssh)) != 0)
68: goto out;
69:
70: /* compute shared secret */
1.2 djm 71: switch (kex->kex_type) {
1.3 djm 72: case KEX_DH_GRP1_SHA1:
73: case KEX_DH_GRP14_SHA1:
74: case KEX_DH_GRP14_SHA256:
75: case KEX_DH_GRP16_SHA512:
76: case KEX_DH_GRP18_SHA512:
77: r = kex_dh_enc(kex, client_pubkey, pklen, &server_pubkey,
1.4 ! djm 78: &shared_secret);
! 79: break;
! 80: case KEX_ECDH_SHA2:
! 81: r = kex_ecdh_enc(kex, client_pubkey, pklen, &server_pubkey,
1.3 djm 82: &shared_secret);
83: break;
1.2 djm 84: case KEX_C25519_SHA256:
85: r = kex_c25519_enc(kex, client_pubkey, pklen, &server_pubkey,
86: &shared_secret);
87: break;
88: case KEX_KEM_SNTRUP4591761X25519_SHA512:
89: r = kex_kem_sntrup4591761x25519_enc(kex, client_pubkey, pklen,
90: &server_pubkey, &shared_secret);
91: break;
92: default:
93: r = SSH_ERR_INVALID_ARGUMENT;
94: break;
95: }
96: if (r !=0 )
1.1 djm 97: goto out;
98:
99: /* calc H */
100: if ((r = sshkey_to_blob(server_host_public, &server_host_key_blob,
101: &sbloblen)) != 0)
102: goto out;
103: hashlen = sizeof(hash);
104: if ((r = kex_c25519_hash(
105: kex->hash_alg,
106: kex->client_version,
107: kex->server_version,
108: sshbuf_ptr(kex->peer), sshbuf_len(kex->peer),
109: sshbuf_ptr(kex->my), sshbuf_len(kex->my),
110: server_host_key_blob, sbloblen,
111: client_pubkey, pklen,
112: sshbuf_ptr(server_pubkey), sshbuf_len(server_pubkey),
113: sshbuf_ptr(shared_secret), sshbuf_len(shared_secret),
114: hash, &hashlen)) != 0)
115: goto out;
116:
117: /* sign H */
118: if ((r = kex->sign(ssh, server_host_private, server_host_public,
119: &signature, &slen, hash, hashlen, kex->hostkey_alg)) != 0)
120: goto out;
121:
122: /* send server hostkey, ECDH pubkey 'Q_S' and signed H */
123: if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_REPLY)) != 0 ||
124: (r = sshpkt_put_string(ssh, server_host_key_blob, sbloblen)) != 0 ||
125: (r = sshpkt_put_stringb(ssh, server_pubkey)) != 0 ||
126: (r = sshpkt_put_string(ssh, signature, slen)) != 0 ||
127: (r = sshpkt_send(ssh)) != 0)
128: goto out;
129:
130: if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0)
131: r = kex_send_newkeys(ssh);
132: out:
133: explicit_bzero(hash, sizeof(hash));
134: free(server_host_key_blob);
135: free(signature);
136: free(client_pubkey);
137: sshbuf_free(shared_secret);
138: sshbuf_free(server_pubkey);
139: return r;
140: }
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