1 /* $OpenBSD: ssh-ed25519.c,v 1.8 2020/02/26 13:40:09 jsg 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 freezero(sig, slen);
88
89 return r;
90 }
91
92 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)93 ssh_ed25519_verify(const struct sshkey *key,
94 const u_char *signature, size_t signaturelen,
95 const u_char *data, size_t datalen, u_int compat)
96 {
97 struct sshbuf *b = NULL;
98 char *ktype = NULL;
99 const u_char *sigblob;
100 u_char *sm = NULL, *m = NULL;
101 size_t len;
102 unsigned long long smlen = 0, mlen = 0;
103 int r, ret;
104
105 if (key == NULL ||
106 sshkey_type_plain(key->type) != KEY_ED25519 ||
107 key->ed25519_pk == NULL ||
108 datalen >= INT_MAX - crypto_sign_ed25519_BYTES ||
109 signature == NULL || signaturelen == 0)
110 return SSH_ERR_INVALID_ARGUMENT;
111
112 if ((b = sshbuf_from(signature, signaturelen)) == NULL)
113 return SSH_ERR_ALLOC_FAIL;
114 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 ||
115 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0)
116 goto out;
117 if (strcmp("ssh-ed25519", ktype) != 0) {
118 r = SSH_ERR_KEY_TYPE_MISMATCH;
119 goto out;
120 }
121 if (sshbuf_len(b) != 0) {
122 r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
123 goto out;
124 }
125 if (len > crypto_sign_ed25519_BYTES) {
126 r = SSH_ERR_INVALID_FORMAT;
127 goto out;
128 }
129 if (datalen >= SIZE_MAX - len) {
130 r = SSH_ERR_INVALID_ARGUMENT;
131 goto out;
132 }
133 smlen = len + datalen;
134 mlen = smlen;
135 if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) {
136 r = SSH_ERR_ALLOC_FAIL;
137 goto out;
138 }
139 memcpy(sm, sigblob, len);
140 memcpy(sm+len, data, datalen);
141 if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
142 key->ed25519_pk)) != 0) {
143 debug2("%s: crypto_sign_ed25519_open failed: %d",
144 __func__, ret);
145 }
146 if (ret != 0 || mlen != datalen) {
147 r = SSH_ERR_SIGNATURE_INVALID;
148 goto out;
149 }
150 /* XXX compare 'm' and 'data' ? */
151 /* success */
152 r = 0;
153 out:
154 if (sm != NULL)
155 freezero(sm, smlen);
156 if (m != NULL)
157 freezero(m, smlen); /* NB mlen may be invalid if r != 0 */
158 sshbuf_free(b);
159 free(ktype);
160 return r;
161 }
162