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Diffstat (limited to 'kexc25519.c')
-rw-r--r-- | kexc25519.c | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/kexc25519.c b/kexc25519.c new file mode 100644 index 000000000..348a7d50d --- /dev/null +++ b/kexc25519.c | |||
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1 | /* $OpenBSD: kexc25519.c,v 1.2 2013/11/02 22:02:14 markus 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 | |||
45 | extern int crypto_scalarmult_curve25519(u_char a[CURVE25519_SIZE], | ||
46 | const u_char b[CURVE25519_SIZE], const u_char c[CURVE25519_SIZE]) | ||
47 | __attribute__((__bounded__(__minbytes__, 1, CURVE25519_SIZE))) | ||
48 | __attribute__((__bounded__(__minbytes__, 2, CURVE25519_SIZE))) | ||
49 | __attribute__((__bounded__(__minbytes__, 3, CURVE25519_SIZE))); | ||
50 | |||
51 | void | ||
52 | kexc25519_keygen(u_char key[CURVE25519_SIZE], u_char pub[CURVE25519_SIZE]) | ||
53 | { | ||
54 | static const u_char basepoint[CURVE25519_SIZE] = {9}; | ||
55 | |||
56 | arc4random_buf(key, CURVE25519_SIZE); | ||
57 | crypto_scalarmult_curve25519(pub, key, basepoint); | ||
58 | } | ||
59 | |||
60 | BIGNUM * | ||
61 | kexc25519_shared_key(const u_char key[CURVE25519_SIZE], | ||
62 | const u_char pub[CURVE25519_SIZE]) | ||
63 | { | ||
64 | u_char shared_key[CURVE25519_SIZE]; | ||
65 | BIGNUM *shared_secret; | ||
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 | if ((shared_secret = BN_new()) == NULL) | ||
72 | fatal("%s: BN_new failed", __func__); | ||
73 | if (BN_bin2bn(shared_key, sizeof(shared_key), shared_secret) == NULL) | ||
74 | fatal("%s: BN_bin2bn failed", __func__); | ||
75 | memset(shared_key, 0, CURVE25519_SIZE); /* XXX explicit_bzero() */ | ||
76 | return (shared_secret); | ||
77 | } | ||
78 | |||
79 | void | ||
80 | kex_c25519_hash( | ||
81 | const EVP_MD *evp_md, | ||
82 | char *client_version_string, | ||
83 | char *server_version_string, | ||
84 | char *ckexinit, int ckexinitlen, | ||
85 | char *skexinit, int skexinitlen, | ||
86 | u_char *serverhostkeyblob, int sbloblen, | ||
87 | const u_char client_dh_pub[CURVE25519_SIZE], | ||
88 | const u_char server_dh_pub[CURVE25519_SIZE], | ||
89 | const BIGNUM *shared_secret, | ||
90 | u_char **hash, u_int *hashlen) | ||
91 | { | ||
92 | Buffer b; | ||
93 | EVP_MD_CTX md; | ||
94 | static u_char digest[EVP_MAX_MD_SIZE]; | ||
95 | |||
96 | buffer_init(&b); | ||
97 | buffer_put_cstring(&b, client_version_string); | ||
98 | buffer_put_cstring(&b, server_version_string); | ||
99 | |||
100 | /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */ | ||
101 | buffer_put_int(&b, ckexinitlen+1); | ||
102 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | ||
103 | buffer_append(&b, ckexinit, ckexinitlen); | ||
104 | buffer_put_int(&b, skexinitlen+1); | ||
105 | buffer_put_char(&b, SSH2_MSG_KEXINIT); | ||
106 | buffer_append(&b, skexinit, skexinitlen); | ||
107 | |||
108 | buffer_put_string(&b, serverhostkeyblob, sbloblen); | ||
109 | buffer_put_string(&b, client_dh_pub, CURVE25519_SIZE); | ||
110 | buffer_put_string(&b, server_dh_pub, CURVE25519_SIZE); | ||
111 | buffer_put_bignum2(&b, shared_secret); | ||
112 | |||
113 | #ifdef DEBUG_KEX | ||
114 | buffer_dump(&b); | ||
115 | #endif | ||
116 | EVP_DigestInit(&md, evp_md); | ||
117 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | ||
118 | EVP_DigestFinal(&md, digest, NULL); | ||
119 | |||
120 | buffer_free(&b); | ||
121 | |||
122 | #ifdef DEBUG_KEX | ||
123 | dump_digest("hash", digest, EVP_MD_size(evp_md)); | ||
124 | #endif | ||
125 | *hash = digest; | ||
126 | *hashlen = EVP_MD_size(evp_md); | ||
127 | } | ||