Branch data Line data Source code
1 : : /* $OpenBSD: kexc25519.c,v 1.5 2014/01/31 16:39:19 tedu Exp $ */
2 : : /*
3 : : * Copyright (c) 2001, 2013 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 <signal.h>
33 : : #include <string.h>
34 : :
35 : : #include <openssl/bn.h>
36 : : #include <openssl/evp.h>
37 : :
38 : : #include "buffer.h"
39 : : #include "ssh2.h"
40 : : #include "key.h"
41 : : #include "cipher.h"
42 : : #include "kex.h"
43 : : #include "log.h"
44 : : #include "digest.h"
45 : :
46 : : extern int crypto_scalarmult_curve25519(u_char a[CURVE25519_SIZE],
47 : : const u_char b[CURVE25519_SIZE], const u_char c[CURVE25519_SIZE])
48 : : __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
49 : : __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)))
50 : : __attribute__((__bounded__(__minbytes__, 3, CURVE25519_SIZE)));
51 : :
52 : : void
53 : 1612 : kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE])
54 : : {
55 : : static const u_char basepoint[CURVE25519_SIZE] = {9};
56 : :
57 : 1612 : arc4random_buf(key, CURVE25519_SIZE);
58 : 1612 : crypto_scalarmult_curve25519(pub, key, basepoint);
59 : 1612 : }
60 : :
61 : : void
62 : 1609 : kexc25519_shared_key(const u_char key[CURVE25519_SIZE],
63 : : const u_char pub[CURVE25519_SIZE], Buffer *out)
64 : : {
65 : : u_char shared_key[CURVE25519_SIZE];
66 : :
67 : 1609 : crypto_scalarmult_curve25519(shared_key, key, pub);
68 : : #ifdef DEBUG_KEXECDH
69 : : dump_digest("shared secret", shared_key, CURVE25519_SIZE);
70 : : #endif
71 : 1609 : buffer_clear(out);
72 : 1609 : buffer_put_bignum2_from_string(out, shared_key, CURVE25519_SIZE);
73 : 1609 : explicit_bzero(shared_key, CURVE25519_SIZE);
74 : 1609 : }
75 : :
76 : : void
77 : 1609 : kex_c25519_hash(
78 : : int hash_alg,
79 : : char *client_version_string,
80 : : char *server_version_string,
81 : : char *ckexinit, int ckexinitlen,
82 : : char *skexinit, int skexinitlen,
83 : : u_char *serverhostkeyblob, int sbloblen,
84 : : const u_char client_dh_pub[CURVE25519_SIZE],
85 : : const u_char server_dh_pub[CURVE25519_SIZE],
86 : : const u_char *shared_secret, u_int secretlen,
87 : : u_char **hash, u_int *hashlen)
88 : : {
89 : : Buffer b;
90 : : static u_char digest[SSH_DIGEST_MAX_LENGTH];
91 : :
92 : 1609 : buffer_init(&b);
93 : 1609 : buffer_put_cstring(&b, client_version_string);
94 : 1609 : buffer_put_cstring(&b, server_version_string);
95 : :
96 : : /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
97 : 1609 : buffer_put_int(&b, ckexinitlen+1);
98 : 1609 : buffer_put_char(&b, SSH2_MSG_KEXINIT);
99 : 1609 : buffer_append(&b, ckexinit, ckexinitlen);
100 : 1609 : buffer_put_int(&b, skexinitlen+1);
101 : 1609 : buffer_put_char(&b, SSH2_MSG_KEXINIT);
102 : 1609 : buffer_append(&b, skexinit, skexinitlen);
103 : :
104 : 1609 : buffer_put_string(&b, serverhostkeyblob, sbloblen);
105 : 1609 : buffer_put_string(&b, client_dh_pub, CURVE25519_SIZE);
106 : 1609 : buffer_put_string(&b, server_dh_pub, CURVE25519_SIZE);
107 : 1609 : buffer_append(&b, shared_secret, secretlen);
108 : :
109 : : #ifdef DEBUG_KEX
110 : : buffer_dump(&b);
111 : : #endif
112 [ - + ]: 1609 : if (ssh_digest_buffer(hash_alg, &b, digest, sizeof(digest)) != 0)
113 : 0 : fatal("%s: digest_buffer failed", __func__);
114 : :
115 : 1609 : buffer_free(&b);
116 : :
117 : : #ifdef DEBUG_KEX
118 : : dump_digest("hash", digest, ssh_digest_bytes(hash_alg));
119 : : #endif
120 : 1609 : *hash = digest;
121 : 1609 : *hashlen = ssh_digest_bytes(hash_alg);
122 : 1609 : }
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