1 /* $OpenBSD: ssh-ed25519.c,v 1.6 2015/01/15 21:38:50 markus Exp $ */
2 /*
3 * Copyright (c) 2013 Markus Friedl <markus@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 #include "includes.h"
19
20 #include <sys/types.h>
21 #include <limits.h>
22
23 #include "crypto_api.h"
24
25 #include <string.h>
26 #include <stdarg.h>
27
28 #include "log.h"
29 #include "sshbuf.h"
30 #define SSHKEY_INTERNAL
31 #include "sshkey.h"
32 #include "ssherr.h"
33 #include "ssh.h"
34
35 int
ssh_ed25519_sign(const struct sshkey * key,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen,u_int compat)36 ssh_ed25519_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
37 const u_char *data, size_t datalen, u_int compat)
38 {
39 u_char *sig = NULL;
40 size_t slen = 0, len;
41 unsigned long long smlen;
42 int r, ret;
43 struct sshbuf *b = NULL;
44
45 if (lenp != NULL)
46 *lenp = 0;
47 if (sigp != NULL)
48 *sigp = NULL;
49
50 if (key == NULL ||
51 sshkey_type_plain(key->type) != KEY_ED25519 ||
52 key->ed25519_sk == NULL ||
53 datalen >= INT_MAX - crypto_sign_ed25519_BYTES)
54 return SSH_ERR_INVALID_ARGUMENT;
55 smlen = slen = datalen + crypto_sign_ed25519_BYTES;
56 if ((sig = malloc(slen)) == NULL)
57 return SSH_ERR_ALLOC_FAIL;
58
59 if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen,
60 key->ed25519_sk)) != 0 || smlen <= datalen) {
61 r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */
62 goto out;
63 }
64 /* encode signature */
65 if ((b = sshbuf_new()) == NULL) {
66 r = SSH_ERR_ALLOC_FAIL;
67 goto out;
68 }
69 if ((r = sshbuf_put_cstring(b, "ssh-ed25519")) != 0 ||
70 (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0)
71 goto out;
72 len = sshbuf_len(b);
73 if (sigp != NULL) {
74 if ((*sigp = malloc(len)) == NULL) {
75 r = SSH_ERR_ALLOC_FAIL;
76 goto out;
77 }
78 memcpy(*sigp, sshbuf_ptr(b), len);
79 }
80 if (lenp != NULL)
81 *lenp = len;
82 /* success */
83 r = 0;
84 out:
85 sshbuf_free(b);
86 if (sig != NULL) {
87 explicit_bzero(sig, slen);
88 free(sig);
89 }
90
91 return r;
92 }
93
94 int
ssh_ed25519_verify(const struct sshkey * key,const u_char * signature,size_t signaturelen,const u_char * data,size_t datalen,u_int compat)95 ssh_ed25519_verify(const struct sshkey *key,
96 const u_char *signature, size_t signaturelen,
97 const u_char *data, size_t datalen, u_int compat)
98 {
99 struct sshbuf *b = NULL;
100 char *ktype = NULL;
101 const u_char *sigblob;
102 u_char *sm = NULL, *m = NULL;
103 size_t len;
104 unsigned long long smlen = 0, mlen = 0;
105 int r, ret;
106
107 if (key == NULL ||
108 sshkey_type_plain(key->type) != KEY_ED25519 ||
109 key->ed25519_pk == NULL ||
110 datalen >= INT_MAX - crypto_sign_ed25519_BYTES)
111 return SSH_ERR_INVALID_ARGUMENT;
112
113 if ((b = sshbuf_from(signature, signaturelen)) == NULL)
114 return SSH_ERR_ALLOC_FAIL;
115 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 ||
116 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0)
117 goto out;
118 if (strcmp("ssh-ed25519", ktype) != 0) {
119 r = SSH_ERR_KEY_TYPE_MISMATCH;
120 goto out;
121 }
122 if (sshbuf_len(b) != 0) {
123 r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
124 goto out;
125 }
126 if (len > crypto_sign_ed25519_BYTES) {
127 r = SSH_ERR_INVALID_FORMAT;
128 goto out;
129 }
130 if (datalen >= SIZE_MAX - len) {
131 r = SSH_ERR_INVALID_ARGUMENT;
132 goto out;
133 }
134 smlen = len + datalen;
135 mlen = smlen;
136 if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) {
137 r = SSH_ERR_ALLOC_FAIL;
138 goto out;
139 }
140 memcpy(sm, sigblob, len);
141 memcpy(sm+len, data, datalen);
142 if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
143 key->ed25519_pk)) != 0) {
144 debug2("%s: crypto_sign_ed25519_open failed: %d",
145 __func__, ret);
146 }
147 if (ret != 0 || mlen != datalen) {
148 r = SSH_ERR_SIGNATURE_INVALID;
149 goto out;
150 }
151 /* XXX compare 'm' and 'data' ? */
152 /* success */
153 r = 0;
154 out:
155 if (sm != NULL) {
156 explicit_bzero(sm, smlen);
157 free(sm);
158 }
159 if (m != NULL) {
160 explicit_bzero(m, smlen); /* NB mlen may be invalid if r != 0 */
161 free(m);
162 }
163 sshbuf_free(b);
164 free(ktype);
165 return r;
166 }
167