jcs.org
jcs's openbsd hax
openbsd
1/* $OpenBSD: kexgex.c,v 1.33 2026/02/14 00:18:34 jsg Exp $ */
2/*
3 * Copyright (c) 2000 Niels Provos. All rights reserved.
4 * Copyright (c) 2001 Markus Friedl. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
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
29#include <openssl/evp.h>
30#include <signal.h>
31
32#include "kex.h"
33#include "ssh2.h"
34#include "ssherr.h"
35#include "sshbuf.h"
36#include "digest.h"
37
38int
39kexgex_hash(
40 int hash_alg,
41 const struct sshbuf *client_version,
42 const struct sshbuf *server_version,
43 const struct sshbuf *client_kexinit,
44 const struct sshbuf *server_kexinit,
45 const struct sshbuf *server_host_key_blob,
46 int min, int wantbits, int max,
47 const BIGNUM *prime,
48 const BIGNUM *gen,
49 const BIGNUM *client_dh_pub,
50 const BIGNUM *server_dh_pub,
51 const u_char *shared_secret, size_t secretlen,
52 u_char *hash, size_t *hashlen)
53{
54 struct sshbuf *b;
55 int r;
56
57 if (*hashlen < ssh_digest_bytes(SSH_DIGEST_SHA1))
58 return SSH_ERR_INVALID_ARGUMENT;
59 if ((b = sshbuf_new()) == NULL)
60 return SSH_ERR_ALLOC_FAIL;
61 if ((r = sshbuf_put_stringb(b, client_version)) < 0 ||
62 (r = sshbuf_put_stringb(b, server_version)) < 0 ||
63 /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
64 (r = sshbuf_put_u32(b, sshbuf_len(client_kexinit) + 1)) != 0 ||
65 (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
66 (r = sshbuf_putb(b, client_kexinit)) != 0 ||
67 (r = sshbuf_put_u32(b, sshbuf_len(server_kexinit) + 1)) != 0 ||
68 (r = sshbuf_put_u8(b, SSH2_MSG_KEXINIT)) != 0 ||
69 (r = sshbuf_putb(b, server_kexinit)) != 0 ||
70 (r = sshbuf_put_stringb(b, server_host_key_blob)) != 0 ||
71 (min != -1 && (r = sshbuf_put_u32(b, min)) != 0) ||
72 (r = sshbuf_put_u32(b, wantbits)) != 0 ||
73 (max != -1 && (r = sshbuf_put_u32(b, max)) != 0) ||
74 (r = sshbuf_put_bignum2(b, prime)) != 0 ||
75 (r = sshbuf_put_bignum2(b, gen)) != 0 ||
76 (r = sshbuf_put_bignum2(b, client_dh_pub)) != 0 ||
77 (r = sshbuf_put_bignum2(b, server_dh_pub)) != 0 ||
78 (r = sshbuf_put(b, shared_secret, secretlen)) != 0) {
79 sshbuf_free(b);
80 return r;
81 }
82#ifdef DEBUG_KEXDH
83 sshbuf_dump(b, stderr);
84#endif
85 if (ssh_digest_buffer(hash_alg, b, hash, *hashlen) != 0) {
86 sshbuf_free(b);
87 return SSH_ERR_LIBCRYPTO_ERROR;
88 }
89 sshbuf_free(b);
90 *hashlen = ssh_digest_bytes(hash_alg);
91#ifdef DEBUG_KEXDH
92 dump_digest("hash", hash, *hashlen);
93#endif
94 return 0;
95}