1 /* $OpenBSD: ssh-ed25519.c,v 1.19 2022/10/28 00:44:44 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 #define SSHKEY_INTERNAL
18 #include <sys/types.h>
19 #include <limits.h>
20
21 #include "crypto_api.h"
22
23 #include <string.h>
24 #include <stdarg.h>
25
26 #include "log.h"
27 #include "sshbuf.h"
28 #include "sshkey.h"
29 #include "ssherr.h"
30 #include "ssh.h"
31
32 static void
ssh_ed25519_cleanup(struct sshkey * k)33 ssh_ed25519_cleanup(struct sshkey *k)
34 {
35 freezero(k->ed25519_pk, ED25519_PK_SZ);
36 freezero(k->ed25519_sk, ED25519_SK_SZ);
37 k->ed25519_pk = NULL;
38 k->ed25519_sk = NULL;
39 }
40
41 static int
ssh_ed25519_equal(const struct sshkey * a,const struct sshkey * b)42 ssh_ed25519_equal(const struct sshkey *a, const struct sshkey *b)
43 {
44 if (a->ed25519_pk == NULL || b->ed25519_pk == NULL)
45 return 0;
46 if (memcmp(a->ed25519_pk, b->ed25519_pk, ED25519_PK_SZ) != 0)
47 return 0;
48 return 1;
49 }
50
51 static int
ssh_ed25519_serialize_public(const struct sshkey * key,struct sshbuf * b,enum sshkey_serialize_rep opts)52 ssh_ed25519_serialize_public(const struct sshkey *key, struct sshbuf *b,
53 enum sshkey_serialize_rep opts)
54 {
55 int r;
56
57 if (key->ed25519_pk == NULL)
58 return SSH_ERR_INVALID_ARGUMENT;
59 if ((r = sshbuf_put_string(b, key->ed25519_pk, ED25519_PK_SZ)) != 0)
60 return r;
61
62 return 0;
63 }
64
65 static int
ssh_ed25519_serialize_private(const struct sshkey * key,struct sshbuf * b,enum sshkey_serialize_rep opts)66 ssh_ed25519_serialize_private(const struct sshkey *key, struct sshbuf *b,
67 enum sshkey_serialize_rep opts)
68 {
69 int r;
70
71 if ((r = sshbuf_put_string(b, key->ed25519_pk, ED25519_PK_SZ)) != 0 ||
72 (r = sshbuf_put_string(b, key->ed25519_sk, ED25519_SK_SZ)) != 0)
73 return r;
74
75 return 0;
76 }
77
78 static int
ssh_ed25519_generate(struct sshkey * k,int bits)79 ssh_ed25519_generate(struct sshkey *k, int bits)
80 {
81 if ((k->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL ||
82 (k->ed25519_sk = malloc(ED25519_SK_SZ)) == NULL)
83 return SSH_ERR_ALLOC_FAIL;
84 crypto_sign_ed25519_keypair(k->ed25519_pk, k->ed25519_sk);
85 return 0;
86 }
87
88 static int
ssh_ed25519_copy_public(const struct sshkey * from,struct sshkey * to)89 ssh_ed25519_copy_public(const struct sshkey *from, struct sshkey *to)
90 {
91 if (from->ed25519_pk == NULL)
92 return 0; /* XXX SSH_ERR_INTERNAL_ERROR ? */
93 if ((to->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL)
94 return SSH_ERR_ALLOC_FAIL;
95 memcpy(to->ed25519_pk, from->ed25519_pk, ED25519_PK_SZ);
96 return 0;
97 }
98
99 static int
ssh_ed25519_deserialize_public(const char * ktype,struct sshbuf * b,struct sshkey * key)100 ssh_ed25519_deserialize_public(const char *ktype, struct sshbuf *b,
101 struct sshkey *key)
102 {
103 u_char *pk = NULL;
104 size_t len = 0;
105 int r;
106
107 if ((r = sshbuf_get_string(b, &pk, &len)) != 0)
108 return r;
109 if (len != ED25519_PK_SZ) {
110 freezero(pk, len);
111 return SSH_ERR_INVALID_FORMAT;
112 }
113 key->ed25519_pk = pk;
114 return 0;
115 }
116
117 static int
ssh_ed25519_deserialize_private(const char * ktype,struct sshbuf * b,struct sshkey * key)118 ssh_ed25519_deserialize_private(const char *ktype, struct sshbuf *b,
119 struct sshkey *key)
120 {
121 int r;
122 size_t sklen = 0;
123 u_char *ed25519_sk = NULL;
124
125 if ((r = ssh_ed25519_deserialize_public(NULL, b, key)) != 0)
126 goto out;
127 if ((r = sshbuf_get_string(b, &ed25519_sk, &sklen)) != 0)
128 goto out;
129 if (sklen != ED25519_SK_SZ) {
130 r = SSH_ERR_INVALID_FORMAT;
131 goto out;
132 }
133 key->ed25519_sk = ed25519_sk;
134 ed25519_sk = NULL; /* transferred */
135 /* success */
136 r = 0;
137 out:
138 freezero(ed25519_sk, sklen);
139 return r;
140 }
141
142 static int
ssh_ed25519_sign(struct sshkey * key,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen,const char * alg,const char * sk_provider,const char * sk_pin,u_int compat)143 ssh_ed25519_sign(struct sshkey *key,
144 u_char **sigp, size_t *lenp,
145 const u_char *data, size_t datalen,
146 const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
147 {
148 u_char *sig = NULL;
149 size_t slen = 0, len;
150 unsigned long long smlen;
151 int r, ret;
152 struct sshbuf *b = NULL;
153
154 if (lenp != NULL)
155 *lenp = 0;
156 if (sigp != NULL)
157 *sigp = NULL;
158
159 if (key == NULL ||
160 sshkey_type_plain(key->type) != KEY_ED25519 ||
161 key->ed25519_sk == NULL ||
162 datalen >= INT_MAX - crypto_sign_ed25519_BYTES)
163 return SSH_ERR_INVALID_ARGUMENT;
164 smlen = slen = datalen + crypto_sign_ed25519_BYTES;
165 if ((sig = malloc(slen)) == NULL)
166 return SSH_ERR_ALLOC_FAIL;
167
168 if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen,
169 key->ed25519_sk)) != 0 || smlen <= datalen) {
170 r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */
171 goto out;
172 }
173 /* encode signature */
174 if ((b = sshbuf_new()) == NULL) {
175 r = SSH_ERR_ALLOC_FAIL;
176 goto out;
177 }
178 if ((r = sshbuf_put_cstring(b, "ssh-ed25519")) != 0 ||
179 (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0)
180 goto out;
181 len = sshbuf_len(b);
182 if (sigp != NULL) {
183 if ((*sigp = malloc(len)) == NULL) {
184 r = SSH_ERR_ALLOC_FAIL;
185 goto out;
186 }
187 memcpy(*sigp, sshbuf_ptr(b), len);
188 }
189 if (lenp != NULL)
190 *lenp = len;
191 /* success */
192 r = 0;
193 out:
194 sshbuf_free(b);
195 if (sig != NULL)
196 freezero(sig, slen);
197
198 return r;
199 }
200
201 static int
ssh_ed25519_verify(const struct sshkey * key,const u_char * sig,size_t siglen,const u_char * data,size_t dlen,const char * alg,u_int compat,struct sshkey_sig_details ** detailsp)202 ssh_ed25519_verify(const struct sshkey *key,
203 const u_char *sig, size_t siglen,
204 const u_char *data, size_t dlen, const char *alg, u_int compat,
205 struct sshkey_sig_details **detailsp)
206 {
207 struct sshbuf *b = NULL;
208 char *ktype = NULL;
209 const u_char *sigblob;
210 u_char *sm = NULL, *m = NULL;
211 size_t len;
212 unsigned long long smlen = 0, mlen = 0;
213 int r, ret;
214
215 if (key == NULL ||
216 sshkey_type_plain(key->type) != KEY_ED25519 ||
217 key->ed25519_pk == NULL ||
218 dlen >= INT_MAX - crypto_sign_ed25519_BYTES ||
219 sig == NULL || siglen == 0)
220 return SSH_ERR_INVALID_ARGUMENT;
221
222 if ((b = sshbuf_from(sig, siglen)) == NULL)
223 return SSH_ERR_ALLOC_FAIL;
224 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 ||
225 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0)
226 goto out;
227 if (strcmp("ssh-ed25519", ktype) != 0) {
228 r = SSH_ERR_KEY_TYPE_MISMATCH;
229 goto out;
230 }
231 if (sshbuf_len(b) != 0) {
232 r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
233 goto out;
234 }
235 if (len > crypto_sign_ed25519_BYTES) {
236 r = SSH_ERR_INVALID_FORMAT;
237 goto out;
238 }
239 if (dlen >= SIZE_MAX - len) {
240 r = SSH_ERR_INVALID_ARGUMENT;
241 goto out;
242 }
243 smlen = len + dlen;
244 mlen = smlen;
245 if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) {
246 r = SSH_ERR_ALLOC_FAIL;
247 goto out;
248 }
249 memcpy(sm, sigblob, len);
250 memcpy(sm+len, data, dlen);
251 if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
252 key->ed25519_pk)) != 0) {
253 debug2_f("crypto_sign_ed25519_open failed: %d", ret);
254 }
255 if (ret != 0 || mlen != dlen) {
256 r = SSH_ERR_SIGNATURE_INVALID;
257 goto out;
258 }
259 /* XXX compare 'm' and 'data' ? */
260 /* success */
261 r = 0;
262 out:
263 if (sm != NULL)
264 freezero(sm, smlen);
265 if (m != NULL)
266 freezero(m, smlen); /* NB mlen may be invalid if r != 0 */
267 sshbuf_free(b);
268 free(ktype);
269 return r;
270 }
271
272 /* NB. not static; used by ED25519-SK */
273 const struct sshkey_impl_funcs sshkey_ed25519_funcs = {
274 /* .size = */ NULL,
275 /* .alloc = */ NULL,
276 /* .cleanup = */ ssh_ed25519_cleanup,
277 /* .equal = */ ssh_ed25519_equal,
278 /* .ssh_serialize_public = */ ssh_ed25519_serialize_public,
279 /* .ssh_deserialize_public = */ ssh_ed25519_deserialize_public,
280 /* .ssh_serialize_private = */ ssh_ed25519_serialize_private,
281 /* .ssh_deserialize_private = */ ssh_ed25519_deserialize_private,
282 /* .generate = */ ssh_ed25519_generate,
283 /* .copy_public = */ ssh_ed25519_copy_public,
284 /* .sign = */ ssh_ed25519_sign,
285 /* .verify = */ ssh_ed25519_verify,
286 };
287
288 const struct sshkey_impl sshkey_ed25519_impl = {
289 /* .name = */ "ssh-ed25519",
290 /* .shortname = */ "ED25519",
291 /* .sigalg = */ NULL,
292 /* .type = */ KEY_ED25519,
293 /* .nid = */ 0,
294 /* .cert = */ 0,
295 /* .sigonly = */ 0,
296 /* .keybits = */ 256,
297 /* .funcs = */ &sshkey_ed25519_funcs,
298 };
299
300 const struct sshkey_impl sshkey_ed25519_cert_impl = {
301 /* .name = */ "ssh-ed25519-cert-v01@openssh.com",
302 /* .shortname = */ "ED25519-CERT",
303 /* .sigalg = */ NULL,
304 /* .type = */ KEY_ED25519_CERT,
305 /* .nid = */ 0,
306 /* .cert = */ 1,
307 /* .sigonly = */ 0,
308 /* .keybits = */ 256,
309 /* .funcs = */ &sshkey_ed25519_funcs,
310 };
311