1 /* $OpenBSD: mac.c,v 1.24 2013/06/03 00:03:18 dtucker Exp $ */
3 * Copyright (c) 2001 Markus Friedl. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #include <sys/types.h>
30 #include <openssl/hmac.h>
47 #include "openbsd-compat/openssl-compat.h"
49 #define SSH_EVP 1 /* OpenSSL EVP-based MAC */
50 #define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
56 const EVP_MD * (*mdfunc)(void);
57 int truncatebits; /* truncate digest if != 0 */
58 int key_len; /* just for UMAC */
59 int len; /* just for UMAC */
60 int etm; /* Encrypt-then-MAC */
63 static const struct macalg macs[] = {
64 /* Encrypt-and-MAC (encrypt-and-authenticate) variants */
65 { "hmac-sha1", SSH_EVP, EVP_sha1, 0, 0, 0, 0 },
66 { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, 0, 0, 0 },
67 #ifdef HAVE_EVP_SHA256
68 { "hmac-sha2-256", SSH_EVP, EVP_sha256, 0, 0, 0, 0 },
69 { "hmac-sha2-512", SSH_EVP, EVP_sha512, 0, 0, 0, 0 },
71 { "hmac-md5", SSH_EVP, EVP_md5, 0, 0, 0, 0 },
72 { "hmac-md5-96", SSH_EVP, EVP_md5, 96, 0, 0, 0 },
73 { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 },
74 { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 0 },
75 { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 0 },
76 { "umac-128@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 0 },
78 /* Encrypt-then-MAC variants */
79 { "hmac-sha1-etm@openssh.com", SSH_EVP, EVP_sha1, 0, 0, 0, 1 },
80 { "hmac-sha1-96-etm@openssh.com", SSH_EVP, EVP_sha1, 96, 0, 0, 1 },
81 #ifdef HAVE_EVP_SHA256
82 { "hmac-sha2-256-etm@openssh.com", SSH_EVP, EVP_sha256, 0, 0, 0, 1 },
83 { "hmac-sha2-512-etm@openssh.com", SSH_EVP, EVP_sha512, 0, 0, 0, 1 },
85 { "hmac-md5-etm@openssh.com", SSH_EVP, EVP_md5, 0, 0, 0, 1 },
86 { "hmac-md5-96-etm@openssh.com", SSH_EVP, EVP_md5, 96, 0, 0, 1 },
87 { "hmac-ripemd160-etm@openssh.com", SSH_EVP, EVP_ripemd160, 0, 0, 0, 1 },
88 { "umac-64-etm@openssh.com", SSH_UMAC, NULL, 0, 128, 64, 1 },
89 { "umac-128-etm@openssh.com", SSH_UMAC128, NULL, 0, 128, 128, 1 },
91 { NULL, 0, NULL, 0, 0, 0, 0 }
94 /* Returns a comma-separated list of supported MACs. */
99 size_t nlen, rlen = 0;
100 const struct macalg *m;
102 for (m = macs; m->name != NULL; m++) {
105 nlen = strlen(m->name);
106 ret = xrealloc(ret, 1, rlen + nlen + 2);
107 memcpy(ret + rlen, m->name, nlen + 1);
114 mac_setup_by_alg(Mac *mac, const struct macalg *macalg)
118 mac->type = macalg->type;
119 if (mac->type == SSH_EVP) {
120 mac->evp_md = macalg->mdfunc();
121 if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
122 fatal("mac %s len %d", mac->name, evp_len);
123 mac->key_len = mac->mac_len = (u_int)evp_len;
125 mac->mac_len = macalg->len / 8;
126 mac->key_len = macalg->key_len / 8;
127 mac->umac_ctx = NULL;
129 if (macalg->truncatebits != 0)
130 mac->mac_len = macalg->truncatebits / 8;
131 mac->etm = macalg->etm;
135 mac_setup(Mac *mac, char *name)
137 const struct macalg *m;
139 for (m = macs; m->name != NULL; m++) {
140 if (strcmp(name, m->name) != 0)
143 mac_setup_by_alg(mac, m);
144 debug2("mac_setup: found %s", name);
147 debug2("mac_setup: unknown %s", name);
154 if (mac->key == NULL)
155 fatal("mac_init: no key");
158 if (mac->evp_md == NULL)
160 HMAC_CTX_init(&mac->evp_ctx);
161 HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
164 mac->umac_ctx = umac_new(mac->key);
167 mac->umac_ctx = umac128_new(mac->key);
175 mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
178 u_char m[EVP_MAX_MD_SIZE];
181 u_char b[4], nonce[8];
183 if (mac->mac_len > sizeof(u))
184 fatal("mac_compute: mac too long %u %lu",
185 mac->mac_len, (u_long)sizeof(u));
190 /* reset HMAC context */
191 HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
192 HMAC_Update(&mac->evp_ctx, b, sizeof(b));
193 HMAC_Update(&mac->evp_ctx, data, datalen);
194 HMAC_Final(&mac->evp_ctx, u.m, NULL);
197 put_u64(nonce, seqno);
198 umac_update(mac->umac_ctx, data, datalen);
199 umac_final(mac->umac_ctx, u.m, nonce);
202 put_u64(nonce, seqno);
203 umac128_update(mac->umac_ctx, data, datalen);
204 umac128_final(mac->umac_ctx, u.m, nonce);
207 fatal("mac_compute: unknown MAC type");
215 if (mac->type == SSH_UMAC) {
216 if (mac->umac_ctx != NULL)
217 umac_delete(mac->umac_ctx);
218 } else if (mac->type == SSH_UMAC128) {
219 if (mac->umac_ctx != NULL)
220 umac128_delete(mac->umac_ctx);
221 } else if (mac->evp_md != NULL)
222 HMAC_cleanup(&mac->evp_ctx);
224 mac->umac_ctx = NULL;
227 /* XXX copied from ciphers_valid */
230 mac_valid(const char *names)
232 char *maclist, *cp, *p;
234 if (names == NULL || strcmp(names, "") == 0)
236 maclist = cp = xstrdup(names);
237 for ((p = strsep(&cp, MAC_SEP)); p && *p != '\0';
238 (p = strsep(&cp, MAC_SEP))) {
239 if (mac_setup(NULL, p) < 0) {
240 debug("bad mac %s [%s]", p, names);
244 debug3("mac ok: %s [%s]", p, names);
247 debug3("macs ok: [%s]", names);