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
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 static void
ssh_ed25519_cleanup(struct sshkey * k)36 ssh_ed25519_cleanup(struct sshkey *k)
37 {
38 freezero(k->ed25519_pk, ED25519_PK_SZ);
39 freezero(k->ed25519_sk, ED25519_SK_SZ);
40 k->ed25519_pk = NULL;
41 k->ed25519_sk = NULL;
42 }
43
44 static int
ssh_ed25519_equal(const struct sshkey * a,const struct sshkey * b)45 ssh_ed25519_equal(const struct sshkey *a, const struct sshkey *b)
46 {
47 if (a->ed25519_pk == NULL || b->ed25519_pk == NULL)
48 return 0;
49 if (memcmp(a->ed25519_pk, b->ed25519_pk, ED25519_PK_SZ) != 0)
50 return 0;
51 return 1;
52 }
53
54 static int
ssh_ed25519_serialize_public(const struct sshkey * key,struct sshbuf * b,enum sshkey_serialize_rep opts)55 ssh_ed25519_serialize_public(const struct sshkey *key, struct sshbuf *b,
56 enum sshkey_serialize_rep opts)
57 {
58 int r;
59
60 if (key->ed25519_pk == NULL)
61 return SSH_ERR_INVALID_ARGUMENT;
62 if ((r = sshbuf_put_string(b, key->ed25519_pk, ED25519_PK_SZ)) != 0)
63 return r;
64
65 return 0;
66 }
67
68 static int
ssh_ed25519_serialize_private(const struct sshkey * key,struct sshbuf * b,enum sshkey_serialize_rep opts)69 ssh_ed25519_serialize_private(const struct sshkey *key, struct sshbuf *b,
70 enum sshkey_serialize_rep opts)
71 {
72 int r;
73
74 if ((r = sshbuf_put_string(b, key->ed25519_pk, ED25519_PK_SZ)) != 0 ||
75 (r = sshbuf_put_string(b, key->ed25519_sk, ED25519_SK_SZ)) != 0)
76 return r;
77
78 return 0;
79 }
80
81 static int
ssh_ed25519_generate(struct sshkey * k,int bits)82 ssh_ed25519_generate(struct sshkey *k, int bits)
83 {
84 if ((k->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL ||
85 (k->ed25519_sk = malloc(ED25519_SK_SZ)) == NULL)
86 return SSH_ERR_ALLOC_FAIL;
87 crypto_sign_ed25519_keypair(k->ed25519_pk, k->ed25519_sk);
88 return 0;
89 }
90
91 static int
ssh_ed25519_copy_public(const struct sshkey * from,struct sshkey * to)92 ssh_ed25519_copy_public(const struct sshkey *from, struct sshkey *to)
93 {
94 if (from->ed25519_pk == NULL)
95 return 0; /* XXX SSH_ERR_INTERNAL_ERROR ? */
96 if ((to->ed25519_pk = malloc(ED25519_PK_SZ)) == NULL)
97 return SSH_ERR_ALLOC_FAIL;
98 memcpy(to->ed25519_pk, from->ed25519_pk, ED25519_PK_SZ);
99 return 0;
100 }
101
102 static int
ssh_ed25519_deserialize_public(const char * ktype,struct sshbuf * b,struct sshkey * key)103 ssh_ed25519_deserialize_public(const char *ktype, struct sshbuf *b,
104 struct sshkey *key)
105 {
106 u_char *pk = NULL;
107 size_t len = 0;
108 int r;
109
110 if ((r = sshbuf_get_string(b, &pk, &len)) != 0)
111 return r;
112 if (len != ED25519_PK_SZ) {
113 freezero(pk, len);
114 return SSH_ERR_INVALID_FORMAT;
115 }
116 key->ed25519_pk = pk;
117 return 0;
118 }
119
120 static int
ssh_ed25519_deserialize_private(const char * ktype,struct sshbuf * b,struct sshkey * key)121 ssh_ed25519_deserialize_private(const char *ktype, struct sshbuf *b,
122 struct sshkey *key)
123 {
124 int r;
125 size_t sklen = 0;
126 u_char *ed25519_sk = NULL;
127
128 if ((r = ssh_ed25519_deserialize_public(NULL, b, key)) != 0)
129 goto out;
130 if ((r = sshbuf_get_string(b, &ed25519_sk, &sklen)) != 0)
131 goto out;
132 if (sklen != ED25519_SK_SZ) {
133 r = SSH_ERR_INVALID_FORMAT;
134 goto out;
135 }
136 key->ed25519_sk = ed25519_sk;
137 ed25519_sk = NULL; /* transferred */
138 /* success */
139 r = 0;
140 out:
141 freezero(ed25519_sk, sklen);
142 return r;
143 }
144
145 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)146 ssh_ed25519_sign(struct sshkey *key,
147 u_char **sigp, size_t *lenp,
148 const u_char *data, size_t datalen,
149 const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
150 {
151 u_char *sig = NULL;
152 size_t slen = 0, len;
153 unsigned long long smlen;
154 int r, ret;
155 struct sshbuf *b = NULL;
156
157 if (lenp != NULL)
158 *lenp = 0;
159 if (sigp != NULL)
160 *sigp = NULL;
161
162 if (key == NULL ||
163 sshkey_type_plain(key->type) != KEY_ED25519 ||
164 key->ed25519_sk == NULL ||
165 datalen >= INT_MAX - crypto_sign_ed25519_BYTES)
166 return SSH_ERR_INVALID_ARGUMENT;
167 smlen = slen = datalen + crypto_sign_ed25519_BYTES;
168 if ((sig = malloc(slen)) == NULL)
169 return SSH_ERR_ALLOC_FAIL;
170
171 if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen,
172 key->ed25519_sk)) != 0 || smlen <= datalen) {
173 r = SSH_ERR_INVALID_ARGUMENT; /* XXX better error? */
174 goto out;
175 }
176 /* encode signature */
177 if ((b = sshbuf_new()) == NULL) {
178 r = SSH_ERR_ALLOC_FAIL;
179 goto out;
180 }
181 if ((r = sshbuf_put_cstring(b, "ssh-ed25519")) != 0 ||
182 (r = sshbuf_put_string(b, sig, smlen - datalen)) != 0)
183 goto out;
184 len = sshbuf_len(b);
185 if (sigp != NULL) {
186 if ((*sigp = malloc(len)) == NULL) {
187 r = SSH_ERR_ALLOC_FAIL;
188 goto out;
189 }
190 memcpy(*sigp, sshbuf_ptr(b), len);
191 }
192 if (lenp != NULL)
193 *lenp = len;
194 /* success */
195 r = 0;
196 out:
197 sshbuf_free(b);
198 if (sig != NULL)
199 freezero(sig, slen);
200
201 return r;
202 }
203
204 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)205 ssh_ed25519_verify(const struct sshkey *key,
206 const u_char *sig, size_t siglen,
207 const u_char *data, size_t dlen, const char *alg, u_int compat,
208 struct sshkey_sig_details **detailsp)
209 {
210 struct sshbuf *b = NULL;
211 char *ktype = NULL;
212 const u_char *sigblob;
213 u_char *sm = NULL, *m = NULL;
214 size_t len;
215 unsigned long long smlen = 0, mlen = 0;
216 int r, ret;
217
218 if (key == NULL ||
219 sshkey_type_plain(key->type) != KEY_ED25519 ||
220 key->ed25519_pk == NULL ||
221 dlen >= INT_MAX - crypto_sign_ed25519_BYTES ||
222 sig == NULL || siglen == 0)
223 return SSH_ERR_INVALID_ARGUMENT;
224
225 if ((b = sshbuf_from(sig, siglen)) == NULL)
226 return SSH_ERR_ALLOC_FAIL;
227 if ((r = sshbuf_get_cstring(b, &ktype, NULL)) != 0 ||
228 (r = sshbuf_get_string_direct(b, &sigblob, &len)) != 0)
229 goto out;
230 if (strcmp("ssh-ed25519", ktype) != 0) {
231 r = SSH_ERR_KEY_TYPE_MISMATCH;
232 goto out;
233 }
234 if (sshbuf_len(b) != 0) {
235 r = SSH_ERR_UNEXPECTED_TRAILING_DATA;
236 goto out;
237 }
238 if (len > crypto_sign_ed25519_BYTES) {
239 r = SSH_ERR_INVALID_FORMAT;
240 goto out;
241 }
242 if (dlen >= SIZE_MAX - len) {
243 r = SSH_ERR_INVALID_ARGUMENT;
244 goto out;
245 }
246 smlen = len + dlen;
247 mlen = smlen;
248 if ((sm = malloc(smlen)) == NULL || (m = malloc(mlen)) == NULL) {
249 r = SSH_ERR_ALLOC_FAIL;
250 goto out;
251 }
252 memcpy(sm, sigblob, len);
253 memcpy(sm+len, data, dlen);
254 if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
255 key->ed25519_pk)) != 0) {
256 debug2_f("crypto_sign_ed25519_open failed: %d", ret);
257 }
258 if (ret != 0 || mlen != dlen) {
259 r = SSH_ERR_SIGNATURE_INVALID;
260 goto out;
261 }
262 /* XXX compare 'm' and 'data' ? */
263 /* success */
264 r = 0;
265 out:
266 if (sm != NULL)
267 freezero(sm, smlen);
268 if (m != NULL)
269 freezero(m, smlen); /* NB mlen may be invalid if r != 0 */
270 sshbuf_free(b);
271 free(ktype);
272 return r;
273 }
274
275 /* NB. not static; used by ED25519-SK */
276 const struct sshkey_impl_funcs sshkey_ed25519_funcs = {
277 /* .size = */ NULL,
278 /* .alloc = */ NULL,
279 /* .cleanup = */ ssh_ed25519_cleanup,
280 /* .equal = */ ssh_ed25519_equal,
281 /* .ssh_serialize_public = */ ssh_ed25519_serialize_public,
282 /* .ssh_deserialize_public = */ ssh_ed25519_deserialize_public,
283 /* .ssh_serialize_private = */ ssh_ed25519_serialize_private,
284 /* .ssh_deserialize_private = */ ssh_ed25519_deserialize_private,
285 /* .generate = */ ssh_ed25519_generate,
286 /* .copy_public = */ ssh_ed25519_copy_public,
287 /* .sign = */ ssh_ed25519_sign,
288 /* .verify = */ ssh_ed25519_verify,
289 };
290
291 const struct sshkey_impl sshkey_ed25519_impl = {
292 /* .name = */ "ssh-ed25519",
293 /* .shortname = */ "ED25519",
294 /* .sigalg = */ NULL,
295 /* .type = */ KEY_ED25519,
296 /* .nid = */ 0,
297 /* .cert = */ 0,
298 /* .sigonly = */ 0,
299 /* .keybits = */ 256,
300 /* .funcs = */ &sshkey_ed25519_funcs,
301 };
302
303 const struct sshkey_impl sshkey_ed25519_cert_impl = {
304 /* .name = */ "ssh-ed25519-cert-v01@openssh.com",
305 /* .shortname = */ "ED25519-CERT",
306 /* .sigalg = */ NULL,
307 /* .type = */ KEY_ED25519_CERT,
308 /* .nid = */ 0,
309 /* .cert = */ 1,
310 /* .sigonly = */ 0,
311 /* .keybits = */ 256,
312 /* .funcs = */ &sshkey_ed25519_funcs,
313 };
314