1 /* $OpenBSD: ssh-xmss.c,v 1.2 2020/02/26 13:40:09 jsg Exp $*/
2 /*
3 * Copyright (c) 2017 Stefan-Lukas Gazdag.
4 * Copyright (c) 2017 Markus Friedl.
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18 #include "includes.h"
19 #ifdef WITH_XMSS
20
21 #define SSHKEY_INTERNAL
22 #include <sys/types.h>
23 #include <limits.h>
24
25 #include <string.h>
26 #include <stdarg.h>
27 #include <unistd.h>
28
29 #include "log.h"
30 #include "sshbuf.h"
31 #include "sshkey.h"
32 #include "sshkey-xmss.h"
33 #include "ssherr.h"
34 #include "ssh.h"
35
36 #include "xmss_fast.h"
37
38 int
ssh_xmss_sign(const struct sshkey * key,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen,u_int compat)39 ssh_xmss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
40 const u_char *data, size_t datalen, u_int compat)
41 {
42 u_char *sig = NULL;
43 size_t slen = 0, len = 0, required_siglen;
44 unsigned long long smlen;
45 int r, ret;
46 struct sshbuf *b = NULL;
47
48 if (lenp != NULL)
49 *lenp = 0;
50 if (sigp != NULL)
51 *sigp = NULL;
52
53 if (key == NULL ||
54 sshkey_type_plain(key->type) != KEY_XMSS ||
55 key->xmss_sk == NULL ||
56 sshkey_xmss_params(key) == NULL)
57 return SSH_ERR_INVALID_ARGUMENT;
58 if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0)
59 return r;
60 if (datalen >= INT_MAX - required_siglen)
61 return SSH_ERR_INVALID_ARGUMENT;
62 smlen = slen = datalen + required_siglen;
63 if ((sig = malloc(slen)) == NULL)
64 return SSH_ERR_ALLOC_FAIL;
65 if ((r = sshkey_xmss_get_state(key, error)) != 0)
66 goto out;
67 if ((ret = xmss_sign(key->xmss_sk, sshkey_xmss_bds_state(key), sig, &smlen,
68 data, datalen, sshkey_xmss_params(key))) != 0 || smlen <= datalen) {
69 r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */
70 goto out;
71 }
72 /* encode signature */
73 if ((b = sshbuf_new()) == NULL) {
74 r = SSH_ERR_ALLOC_FAIL;
75 goto out;
76 }
77 if ((r = sshbuf_put_cstring(b, "ssh-xmss@openssh.com")) != 0 ||
78 (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0)
79 goto out;
80 len = sshbuf_len(b);
81 if (sigp != NULL) {
82 if ((*sigp = malloc(len)) == NULL) {
83 r = SSH_ERR_ALLOC_FAIL;
84 goto out;
85 }
86 memcpy(*sigp, sshbuf_ptr(b), len);
87 }
88 if (lenp != NULL)
89 *lenp = len;
90 /* success */
91 r = 0;
92 out:
93 if ((ret = sshkey_xmss_update_state(key, error)) != 0) {
94 /* discard signature since we cannot update the state */
95 if (r == 0 && sigp != NULL && *sigp != NULL) {
96 explicit_bzero(*sigp, len);
97 free(*sigp);
98 }
99 if (sigp != NULL)
100 *sigp = NULL;
101 if (lenp != NULL)
102 *lenp = 0;
103 r = ret;
104 }
105 sshbuf_free(b);
106 if (sig != NULL)
107 freezero(sig, slen);
108
109 return r;
110 }
111
112 int
ssh_xmss_verify(const struct sshkey * key,const u_char * signature,size_t signaturelen,const u_char * data,size_t datalen,u_int compat)113 ssh_xmss_verify(const struct sshkey *key,
114 const u_char *signature, size_t signaturelen,
115 const u_char *data, size_t datalen, u_int compat)
116 {
117 struct sshbuf *b = NULL;
118 char *ktype = NULL;
119 const u_char *sigblob;
120 u_char *sm = NULL, *m = NULL;
121 size_t len, required_siglen;
122 unsigned long long smlen = 0, mlen = 0;
123 int r, ret;
124
125 if (key == NULL ||
126 sshkey_type_plain(key->type) != KEY_XMSS ||
127 key->xmss_pk == NULL ||
128 sshkey_xmss_params(key) == NULL ||
129 signature == NULL || signaturelen == 0)
130 return SSH_ERR_INVALID_ARGUMENT;
131 if ((r = sshkey_xmss_siglen(key, &required_siglen)) != 0)
132 return r;
133 if (datalen >= INT_MAX - required_siglen)
134 return SSH_ERR_INVALID_ARGUMENT;
135
136 if ((b = sshbuf_from(signature, signaturelen)) == NULL)
137 return SSH_ERR_ALLOC_FAIL;
138 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 ||
139 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0)
140 goto out;
141 if (strcmp("ssh-xmss@openssh.com", ktype) != 0) {
142 r = SSH_ERR_KEY_TYPE_MISMATCH;
143 goto out;
144 }
145 if (sshbuf_len(b) != 0) {
146 r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
147 goto out;
148 }
149 if (len != required_siglen) {
150 r = SSH_ERR_INVALID_FORMAT;
151 goto out;
152 }
153 if (datalen >= SIZE_MAX - len) {
154 r = SSH_ERR_INVALID_ARGUMENT;
155 goto out;
156 }
157 smlen = len + datalen;
158 mlen = smlen;
159 if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) {
160 r = SSH_ERR_ALLOC_FAIL;
161 goto out;
162 }
163 memcpy(sm, sigblob, len);
164 memcpy(sm+len, data, datalen);
165 if ((ret = xmss_sign_open(m, &mlen, sm, smlen,
166 key->xmss_pk, sshkey_xmss_params(key))) != 0) {
167 debug2("%s: crypto_sign_xmss_open failed: %d",
168 __func__, ret);
169 }
170 if (ret != 0 || mlen != datalen) {
171 r = SSH_ERR_SIGNATURE_INVALID;
172 goto out;
173 }
174 /* XXX compare 'm' and 'data' ? */
175 /* success */
176 r = 0;
177 out:
178 if (sm != NULL)
179 freezero(sm, smlen);
180 if (m != NULL)
181 freezero(m, smlen);
182 sshbuf_free(b);
183 free(ktype);
184 return r;
185 }
186 #endif /* WITH_XMSS */
187