diff options
Diffstat (limited to 'kexkemc.c')
-rw-r--r-- | kexkemc.c | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/kexkemc.c b/kexkemc.c new file mode 100644 index 000000000..47f15c30c --- /dev/null +++ b/kexkemc.c | |||
@@ -0,0 +1,128 @@ | |||
1 | /* $OpenBSD: kexkemc.c,v 1.1 2019/01/21 10:20:12 djm Exp $ */ | ||
2 | /* | ||
3 | * Copyright (c) 2019 Markus Friedl. All rights reserved. | ||
4 | * | ||
5 | * Redistribution and use in source and binary forms, with or without | ||
6 | * modification, are permitted provided that the following conditions | ||
7 | * are met: | ||
8 | * 1. Redistributions of source code must retain the above copyright | ||
9 | * notice, this list of conditions and the following disclaimer. | ||
10 | * 2. Redistributions in binary form must reproduce the above copyright | ||
11 | * notice, this list of conditions and the following disclaimer in the | ||
12 | * documentation and/or other materials provided with the distribution. | ||
13 | * | ||
14 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | ||
15 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | ||
16 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | ||
17 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | ||
18 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | ||
19 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | ||
20 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | ||
21 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | ||
22 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | ||
23 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | ||
24 | */ | ||
25 | |||
26 | #include <sys/types.h> | ||
27 | |||
28 | #include <stdio.h> | ||
29 | #include <string.h> | ||
30 | #include <signal.h> | ||
31 | |||
32 | #include "sshkey.h" | ||
33 | #include "kex.h" | ||
34 | #include "log.h" | ||
35 | #include "packet.h" | ||
36 | #include "ssh2.h" | ||
37 | #include "sshbuf.h" | ||
38 | #include "digest.h" | ||
39 | #include "ssherr.h" | ||
40 | |||
41 | static int | ||
42 | input_kex_kem_reply(int type, u_int32_t seq, struct ssh *ssh); | ||
43 | |||
44 | int | ||
45 | kex_kem_client(struct ssh *ssh) | ||
46 | { | ||
47 | struct kex *kex = ssh->kex; | ||
48 | int r; | ||
49 | |||
50 | if ((r = kex_kem_sntrup4591761x25519_keypair(kex)) != 0) | ||
51 | return r; | ||
52 | if ((r = sshpkt_start(ssh, SSH2_MSG_KEX_ECDH_INIT)) != 0 || | ||
53 | (r = sshpkt_put_stringb(ssh, kex->kem_client_pub)) != 0 || | ||
54 | (r = sshpkt_send(ssh)) != 0) | ||
55 | return r; | ||
56 | debug("expecting SSH2_MSG_KEX_ECDH_REPLY"); | ||
57 | ssh_dispatch_set(ssh, SSH2_MSG_KEX_ECDH_REPLY, &input_kex_kem_reply); | ||
58 | return 0; | ||
59 | } | ||
60 | |||
61 | static int | ||
62 | input_kex_kem_reply(int type, u_int32_t seq, struct ssh *ssh) | ||
63 | { | ||
64 | struct kex *kex = ssh->kex; | ||
65 | struct sshkey *server_host_key = NULL; | ||
66 | struct sshbuf *shared_secret = NULL; | ||
67 | u_char *server_pubkey = NULL; | ||
68 | u_char *server_host_key_blob = NULL, *signature = NULL; | ||
69 | u_char hash[SSH_DIGEST_MAX_LENGTH]; | ||
70 | size_t slen, pklen, sbloblen, hashlen; | ||
71 | int r; | ||
72 | |||
73 | /* hostkey */ | ||
74 | if ((r = sshpkt_get_string(ssh, &server_host_key_blob, | ||
75 | &sbloblen)) != 0 || | ||
76 | (r = sshkey_from_blob(server_host_key_blob, sbloblen, | ||
77 | &server_host_key)) != 0) | ||
78 | goto out; | ||
79 | if ((r = kex_verify_host_key(ssh, server_host_key)) != 0) | ||
80 | goto out; | ||
81 | |||
82 | /* Q_S, server public key */ | ||
83 | /* signed H */ | ||
84 | if ((r = sshpkt_get_string(ssh, &server_pubkey, &pklen)) != 0 || | ||
85 | (r = sshpkt_get_string(ssh, &signature, &slen)) != 0 || | ||
86 | (r = sshpkt_get_end(ssh)) != 0) | ||
87 | goto out; | ||
88 | |||
89 | /* compute shared secret */ | ||
90 | if ((r = kex_kem_sntrup4591761x25519_dec(kex, server_pubkey, pklen, | ||
91 | &shared_secret)) != 0) | ||
92 | goto out; | ||
93 | |||
94 | /* calc and verify H */ | ||
95 | hashlen = sizeof(hash); | ||
96 | if ((r = kex_c25519_hash( | ||
97 | kex->hash_alg, | ||
98 | kex->client_version, | ||
99 | kex->server_version, | ||
100 | sshbuf_ptr(kex->my), sshbuf_len(kex->my), | ||
101 | sshbuf_ptr(kex->peer), sshbuf_len(kex->peer), | ||
102 | server_host_key_blob, sbloblen, | ||
103 | sshbuf_ptr(kex->kem_client_pub), sshbuf_len(kex->kem_client_pub), | ||
104 | server_pubkey, pklen, | ||
105 | sshbuf_ptr(shared_secret), sshbuf_len(shared_secret), | ||
106 | hash, &hashlen)) != 0) | ||
107 | goto out; | ||
108 | |||
109 | if ((r = sshkey_verify(server_host_key, signature, slen, hash, hashlen, | ||
110 | kex->hostkey_alg, ssh->compat)) != 0) | ||
111 | goto out; | ||
112 | |||
113 | if ((r = kex_derive_keys(ssh, hash, hashlen, shared_secret)) == 0) | ||
114 | r = kex_send_newkeys(ssh); | ||
115 | out: | ||
116 | explicit_bzero(hash, sizeof(hash)); | ||
117 | explicit_bzero(kex->c25519_client_key, sizeof(kex->c25519_client_key)); | ||
118 | explicit_bzero(kex->sntrup4591761_client_key, | ||
119 | sizeof(kex->sntrup4591761_client_key)); | ||
120 | free(server_host_key_blob); | ||
121 | free(server_pubkey); | ||
122 | free(signature); | ||
123 | sshkey_free(server_host_key); | ||
124 | sshbuf_free(shared_secret); | ||
125 | sshbuf_free(kex->kem_client_pub); | ||
126 | kex->kem_client_pub = NULL; | ||
127 | return r; | ||
128 | } | ||