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Diffstat (limited to 'kexc25519.c')
-rw-r--r-- | kexc25519.c | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/kexc25519.c b/kexc25519.c new file mode 100644 index 000000000..48ca4aaa2 --- /dev/null +++ b/kexc25519.c | |||
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1 | /* $OpenBSD: kexc25519.c,v 1.4 2014/01/12 08:13:13 djm 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 | kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) | ||
54 | { | ||
55 | static const u_char basepoint[CURVE25519_SIZE] = {9}; | ||
56 | |||
57 | arc4random_buf(key, CURVE25519_SIZE); | ||
58 | crypto_scalarmult_curve25519(pub, key, basepoint); | ||
59 | } | ||
60 | |||
61 | void | ||
62 | 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 | crypto_scalarmult_curve25519(shared_key, key, pub); | ||
68 | #ifdef DEBUG_KEXECDH | ||
69 | dump_digest("shared secret", shared_key, CURVE25519_SIZE); | ||
70 | #endif | ||
71 | buffer_clear(out); | ||
72 | buffer_put_bignum2_from_string(out, shared_key, CURVE25519_SIZE); | ||
73 | memset(shared_key, 0, CURVE25519_SIZE); /* XXX explicit_bzero() */ | ||
74 | } | ||
75 | |||
76 | void | ||
77 | 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 | buffer_init(&b); | ||
93 | buffer_put_cstring(&b, client_version_string); | ||
94 | buffer_put_cstring(&b, server_version_string); | ||
95 | |||
96 | /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ | ||
97 | buffer_put_int(&b, ckexinitlen+1); | ||
98 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | ||
99 | buffer_append(&b, ckexinit, ckexinitlen); | ||
100 | buffer_put_int(&b, skexinitlen+1); | ||
101 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | ||
102 | buffer_append(&b, skexinit, skexinitlen); | ||
103 | |||
104 | buffer_put_string(&b, serverhostkeyblob, sbloblen); | ||
105 | buffer_put_string(&b, client_dh_pub, CURVE25519_SIZE); | ||
106 | buffer_put_string(&b, server_dh_pub, CURVE25519_SIZE); | ||
107 | buffer_append(&b, shared_secret, secretlen); | ||
108 | |||
109 | #ifdef DEBUG_KEX | ||
110 | buffer_dump(&b); | ||
111 | #endif | ||
112 | if (ssh_digest_buffer(hash_alg, &b, digest, sizeof(digest)) != 0) | ||
113 | fatal("%s: digest_buffer failed", __func__); | ||
114 | |||
115 | buffer_free(&b); | ||
116 | |||
117 | #ifdef DEBUG_KEX | ||
118 | dump_digest("hash", digest, ssh_digest_bytes(hash_alg)); | ||
119 | #endif | ||
120 | *hash = digest; | ||
121 | *hashlen = ssh_digest_bytes(hash_alg); | ||
122 | } | ||