ssh-ed25519.c revision 262566 
1/* $OpenBSD: ssh-ed25519.c,v 1.1 2013/12/06 13:39:49 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
22#include "crypto_api.h"
23
24#include <string.h>
25#include <stdarg.h>
26
27#include "xmalloc.h"
28#include "log.h"
29#include "buffer.h"
30#include "key.h"
31#include "ssh.h"
32
33int
34ssh_ed25519_sign(const Key *key, u_char **sigp, u_int *lenp,
35    const u_char *data, u_int datalen)
36{
37	u_char *sig;
38	u_int slen, len;
39	unsigned long long smlen;
40	int ret;
41	Buffer b;
42
43	if (key == NULL || key_type_plain(key->type) != KEY_ED25519 ||
44	    key->ed25519_sk == NULL) {
45		error("%s: no ED25519 key", __func__);
46		return -1;
47	}
48	smlen = slen = datalen + crypto_sign_ed25519_BYTES;
49	sig = xmalloc(slen);
50
51	if ((ret = crypto_sign_ed25519(sig, &smlen, data, datalen,
52	    key->ed25519_sk)) != 0 || smlen <= datalen) {
53		error("%s: crypto_sign_ed25519 failed: %d", __func__, ret);
54		free(sig);
55		return -1;
56	}
57	/* encode signature */
58	buffer_init(&b);
59	buffer_put_cstring(&b, "ssh-ed25519");
60	buffer_put_string(&b, sig, smlen - datalen);
61	len = buffer_len(&b);
62	if (lenp != NULL)
63		*lenp = len;
64	if (sigp != NULL) {
65		*sigp = xmalloc(len);
66		memcpy(*sigp, buffer_ptr(&b), len);
67	}
68	buffer_free(&b);
69	memset(sig, 's', slen);
70	free(sig);
71
72	return 0;
73}
74
75int
76ssh_ed25519_verify(const Key *key, const u_char *signature, u_int signaturelen,
77    const u_char *data, u_int datalen)
78{
79	Buffer b;
80	char *ktype;
81	u_char *sigblob, *sm, *m;
82	u_int len;
83	unsigned long long smlen, mlen;
84	int rlen, ret;
85
86	if (key == NULL || key_type_plain(key->type) != KEY_ED25519 ||
87	    key->ed25519_pk == NULL) {
88		error("%s: no ED25519 key", __func__);
89		return -1;
90	}
91	buffer_init(&b);
92	buffer_append(&b, signature, signaturelen);
93	ktype = buffer_get_cstring(&b, NULL);
94	if (strcmp("ssh-ed25519", ktype) != 0) {
95		error("%s: cannot handle type %s", __func__, ktype);
96		buffer_free(&b);
97		free(ktype);
98		return -1;
99	}
100	free(ktype);
101	sigblob = buffer_get_string(&b, &len);
102	rlen = buffer_len(&b);
103	buffer_free(&b);
104	if (rlen != 0) {
105		error("%s: remaining bytes in signature %d", __func__, rlen);
106		free(sigblob);
107		return -1;
108	}
109	if (len > crypto_sign_ed25519_BYTES) {
110		error("%s: len %u > crypto_sign_ed25519_BYTES %u", __func__,
111		    len, crypto_sign_ed25519_BYTES);
112		free(sigblob);
113		return -1;
114	}
115	smlen = len + datalen;
116	sm = xmalloc(smlen);
117	memcpy(sm, sigblob, len);
118	memcpy(sm+len, data, datalen);
119	mlen = smlen;
120	m = xmalloc(mlen);
121	if ((ret = crypto_sign_ed25519_open(m, &mlen, sm, smlen,
122	    key->ed25519_pk)) != 0) {
123		debug2("%s: crypto_sign_ed25519_open failed: %d",
124		    __func__, ret);
125	}
126	if (ret == 0 && mlen != datalen) {
127		debug2("%s: crypto_sign_ed25519_open "
128		    "mlen != datalen (%llu != %u)", __func__, mlen, datalen);
129		ret = -1;
130	}
131	/* XXX compare 'm' and 'data' ? */
132
133	memset(sigblob, 's', len);
134	memset(sm, 'S', smlen);
135	memset(m, 'm', smlen); /* NB. mlen may be invalid if ret != 0 */
136	free(sigblob);
137	free(sm);
138	free(m);
139	debug("%s: signature %scorrect", __func__, (ret != 0) ? "in" : "");
140
141	/* translate return code carefully */
142	return (ret == 0) ? 1 : -1;
143}
144