1 /* $OpenBSD: ssh-ed25519.c,v 1.7 2016/04/21 06:08:02 djm 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 signature == NULL || signaturelen == 0)
112 return SSH_ERR_INVALID_ARGUMENT;
113
114 if ((b = sshbuf_from(signature, signaturelen)) == NULL)
115 return SSH_ERR_ALLOC_FAIL;
116 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 ||
117 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0)
118 goto out;
119 if (strcmp("ssh-ed25519", ktype) != 0) {
120 r = SSH_ERR_KEY_TYPE_MISMATCH;
121 goto out;
122 }
123 if (sshbuf_len(b) != 0) {
124 r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
125 goto out;
126 }
127 if (len > crypto_sign_ed25519_BYTES) {
128 r = SSH_ERR_INVALID_FORMAT;
129 goto out;
130 }
131 if (datalen >= SIZE_MAX - len) {
132 r = SSH_ERR_INVALID_ARGUMENT;
133 goto out;
134 }
135 smlen = len + datalen;
136 mlen = smlen;
137 if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) {
138 r = SSH_ERR_ALLOC_FAIL;
139 goto out;
140 }
141 memcpy(sm, sigblob, len);
142 memcpy(sm+len, data, datalen);
143 if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
144 key->ed25519_pk)) != 0) {
145 debug2("%s: crypto_sign_ed25519_open failed: %d",
146 __func__, ret);
147 }
148 if (ret != 0 || mlen != datalen) {
149 r = SSH_ERR_SIGNATURE_INVALID;
150 goto out;
151 }
152 /* XXX compare 'm' and 'data' ? */
153 /* success */
154 r = 0;
155 out:
156 if (sm != NULL) {
157 explicit_bzero(sm, smlen);
158 free(sm);
159 }
160 if (m != NULL) {
161 explicit_bzero(m, smlen); /* NB mlen may be invalid if r != 0 */
162 free(m);
163 }
164 sshbuf_free(b);
165 free(ktype);
166 return r;
167 }
168