- 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@

1 files changed, 80 insertions, 27 deletions

diff --git a/mac.c b/mac.c
index 6a5fd4766..34464659a 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 @@ mac_setup(Mac *mac, char *name)
         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 */