- pvalchev@cvs.openbsd.org 2007/06/07 19:37:34
[kex.h mac.c mac.h monitor_wrap.c myproposal.h packet.c ssh.1]
[ssh_config.5 sshd.8 sshd_config.5]
Add a new MAC algorithm for data integrity, UMAC-64 (not default yet,
must specify umac-64@openssh.com). Provides about 20% end-to-end speedup
compared to hmac-md5. Represents a different approach to message
authentication to that of HMAC that may be beneficial if HMAC based on
one of its underlying hash algorithms is found to be vulnerable to a
new attack. http://www.ietf.org/rfc/rfc4418.txt
in conjunction with and OK djm@
diff --git a/mac.c b/mac.c
index 6a5fd47..3446465 100644
--- a/mac.c
+++ b/mac.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: mac.c,v 1.13 2007/06/05 06:52:37 djm Exp $ */
+/* $OpenBSD: mac.c,v 1.14 2007/06/07 19:37:34 pvalchev Exp $ */
/*
* Copyright (c) 2001 Markus Friedl. All rights reserved.
*
@@ -42,35 +42,57 @@
#include "mac.h"
#include "misc.h"
+#include "umac.h"
+
+#define SSH_EVP 1 /* OpenSSL EVP-based MAC */
+#define SSH_UMAC 2 /* UMAC (not integrated with OpenSSL) */
+
struct {
char *name;
+ int type;
const EVP_MD * (*mdfunc)(void);
int truncatebits; /* truncate digest if != 0 */
+ int key_len; /* just for UMAC */
+ int len; /* just for UMAC */
} macs[] = {
- { "hmac-sha1", EVP_sha1, 0, },
- { "hmac-sha1-96", EVP_sha1, 96 },
- { "hmac-md5", EVP_md5, 0 },
- { "hmac-md5-96", EVP_md5, 96 },
- { "hmac-ripemd160", EVP_ripemd160, 0 },
- { "hmac-ripemd160@openssh.com", EVP_ripemd160, 0 },
- { NULL, NULL, 0 }
+ { "hmac-sha1", SSH_EVP, EVP_sha1, 0, -1, -1 },
+ { "hmac-sha1-96", SSH_EVP, EVP_sha1, 96, -1, -1 },
+ { "hmac-md5", SSH_EVP, EVP_md5, 0, -1, -1 },
+ { "hmac-md5-96", SSH_EVP, EVP_md5, 96, -1, -1 },
+ { "hmac-ripemd160", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
+ { "hmac-ripemd160@openssh.com", SSH_EVP, EVP_ripemd160, 0, -1, -1 },
+ { "umac-64@openssh.com", SSH_UMAC, NULL, 0, 128, 64 },
+ { NULL, 0, NULL, 0, -1, -1 }
};
+static void
+mac_setup_by_id(Mac *mac, int which)
+{
+ int evp_len;
+ mac->type = macs[which].type;
+ if (mac->type == SSH_EVP) {
+ mac->evp_md = (*macs[which].mdfunc)();
+ if ((evp_len = EVP_MD_size(mac->evp_md)) <= 0)
+ fatal("mac %s len %d", mac->name, evp_len);
+ mac->key_len = mac->mac_len = (u_int)evp_len;
+ } else {
+ mac->mac_len = macs[which].len / 8;
+ mac->key_len = macs[which].key_len / 8;
+ mac->umac_ctx = NULL;
+ }
+ if (macs[which].truncatebits != 0)
+ mac->mac_len = macs[which].truncatebits / 8;
+}
+
int
mac_setup(Mac *mac, char *name)
{
- int i, evp_len;
+ int i;
for (i = 0; macs[i].name; i++) {
if (strcmp(name, macs[i].name) == 0) {
- if (mac != NULL) {
- mac->md = (*macs[i].mdfunc)();
- if ((evp_len = EVP_MD_size(mac->md)) <= 0)
- fatal("mac %s len %d", name, evp_len);
- mac->key_len = mac->mac_len = (u_int)evp_len;
- if (macs[i].truncatebits != 0)
- mac->mac_len = macs[i].truncatebits/8;
- }
+ if (mac != NULL)
+ mac_setup_by_id(mac, i);
debug2("mac_setup: found %s", name);
return (0);
}
@@ -79,34 +101,65 @@
return (-1);
}
-void
+int
mac_init(Mac *mac)
{
if (mac->key == NULL)
fatal("mac_init: no key");
- HMAC_Init(&mac->ctx, mac->key, mac->key_len, mac->md);
+ switch (mac->type) {
+ case SSH_EVP:
+ if (mac->evp_md == NULL)
+ return -1;
+ HMAC_Init(&mac->evp_ctx, mac->key, mac->key_len, mac->evp_md);
+ return 0;
+ case SSH_UMAC:
+ mac->umac_ctx = umac_new(mac->key);
+ return 0;
+ default:
+ return -1;
+ }
}
u_char *
mac_compute(Mac *mac, u_int32_t seqno, u_char *data, int datalen)
{
static u_char m[EVP_MAX_MD_SIZE];
- u_char b[4];
+ u_char b[4], nonce[8];
if (mac->mac_len > sizeof(m))
- fatal("mac_compute: mac too long");
- put_u32(b, seqno);
- HMAC_Init(&mac->ctx, NULL, 0, NULL); /* reset HMAC context */
- HMAC_Update(&mac->ctx, b, sizeof(b));
- HMAC_Update(&mac->ctx, data, datalen);
- HMAC_Final(&mac->ctx, m, NULL);
+ fatal("mac_compute: mac too long %u %lu",
+ mac->mac_len, sizeof(m));
+
+ switch (mac->type) {
+ case SSH_EVP:
+ put_u32(b, seqno);
+ /* reset HMAC context */
+ HMAC_Init(&mac->evp_ctx, NULL, 0, NULL);
+ HMAC_Update(&mac->evp_ctx, b, sizeof(b));
+ HMAC_Update(&mac->evp_ctx, data, datalen);
+ HMAC_Final(&mac->evp_ctx, m, NULL);
+ break;
+ case SSH_UMAC:
+ put_u64(nonce, seqno);
+ umac_update(mac->umac_ctx, data, datalen);
+ umac_final(mac->umac_ctx, m, nonce);
+ break;
+ default:
+ fatal("mac_compute: unknown MAC type");
+ }
return (m);
}
void
mac_clear(Mac *mac)
{
- HMAC_cleanup(&mac->ctx);
+ if (mac->type == SSH_UMAC) {
+ if (mac->umac_ctx != NULL)
+ umac_delete(mac->umac_ctx);
+ } else if (mac->evp_md != NULL)
+ HMAC_cleanup(&mac->evp_ctx);
+ mac->evp_md = NULL;
+ mac->umac_ctx = NULL;
}
/* XXX copied from ciphers_valid */