Annotation of src/usr.bin/ssh/kexc25519.c, Revision 1.5
1.5 ! tedu 1: /* $OpenBSD: kexc25519.c,v 1.4 2014/01/12 08:13:13 djm Exp $ */
1.1 markus 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 <sys/types.h>
29:
30: #include <signal.h>
31: #include <string.h>
32:
33: #include <openssl/bn.h>
34: #include <openssl/evp.h>
35:
36: #include "buffer.h"
37: #include "ssh2.h"
38: #include "key.h"
39: #include "cipher.h"
40: #include "kex.h"
41: #include "log.h"
1.3 djm 42: #include "digest.h"
1.1 markus 43:
44: extern int crypto_scalarmult_curve25519(u_char a[CURVE25519_SIZE],
45: const u_char b[CURVE25519_SIZE], const u_char c[CURVE25519_SIZE])
46: __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE)))
47: __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE)))
48: __attribute__((__bounded__(__minbytes__, 3, CURVE25519_SIZE)));
49:
50: void
51: kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE])
52: {
53: static const u_char basepoint[CURVE25519_SIZE] = {9};
54:
55: arc4random_buf(key, CURVE25519_SIZE);
56: crypto_scalarmult_curve25519(pub, key, basepoint);
57: }
58:
1.4 djm 59: void
1.1 markus 60: kexc25519_shared_key(const u_char key[CURVE25519_SIZE],
1.4 djm 61: const u_char pub[CURVE25519_SIZE], Buffer *out)
1.1 markus 62: {
63: u_char shared_key[CURVE25519_SIZE];
64:
65: crypto_scalarmult_curve25519(shared_key, key, pub);
66: #ifdef DEBUG_KEXECDH
67: dump_digest("shared secret", shared_key, CURVE25519_SIZE);
68: #endif
1.4 djm 69: buffer_clear(out);
70: buffer_put_bignum2_from_string(out, shared_key, CURVE25519_SIZE);
1.5 ! tedu 71: explicit_bzero(shared_key, CURVE25519_SIZE);
1.1 markus 72: }
73:
74: void
75: kex_c25519_hash(
1.3 djm 76: int hash_alg,
1.1 markus 77: char *client_version_string,
78: char *server_version_string,
79: char *ckexinit, int ckexinitlen,
80: char *skexinit, int skexinitlen,
81: u_char *serverhostkeyblob, int sbloblen,
82: const u_char client_dh_pub[CURVE25519_SIZE],
83: const u_char server_dh_pub[CURVE25519_SIZE],
1.4 djm 84: const u_char *shared_secret, u_int secretlen,
1.1 markus 85: u_char **hash, u_int *hashlen)
86: {
87: Buffer b;
1.3 djm 88: static u_char digest[SSH_DIGEST_MAX_LENGTH];
1.1 markus 89:
90: buffer_init(&b);
91: buffer_put_cstring(&b, client_version_string);
92: buffer_put_cstring(&b, server_version_string);
93:
94: /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
95: buffer_put_int(&b, ckexinitlen+1);
96: buffer_put_char(&b, SSH2_MSG_KEXINIT);
97: buffer_append(&b, ckexinit, ckexinitlen);
98: buffer_put_int(&b, skexinitlen+1);
99: buffer_put_char(&b, SSH2_MSG_KEXINIT);
100: buffer_append(&b, skexinit, skexinitlen);
101:
102: buffer_put_string(&b, serverhostkeyblob, sbloblen);
103: buffer_put_string(&b, client_dh_pub, CURVE25519_SIZE);
104: buffer_put_string(&b, server_dh_pub, CURVE25519_SIZE);
1.4 djm 105: buffer_append(&b, shared_secret, secretlen);
1.1 markus 106:
107: #ifdef DEBUG_KEX
108: buffer_dump(&b);
109: #endif
1.3 djm 110: if (ssh_digest_buffer(hash_alg, &b, digest, sizeof(digest)) != 0)
111: fatal("%s: digest_buffer failed", __func__);
1.1 markus 112:
113: buffer_free(&b);
114:
115: #ifdef DEBUG_KEX
1.3 djm 116: dump_digest("hash", digest, ssh_digest_bytes(hash_alg));
1.1 markus 117: #endif
118: *hash = digest;
1.3 djm 119: *hashlen = ssh_digest_bytes(hash_alg);
1.1 markus 120: }