- (djm) [kex.c] Slightly more clean deactivation of dhgex-sha256 on old

[openssh.git] / kex.c

diff --git a/kex.c b/kex.c
index 5dce335fe5f11d1fe3533425544a5760263011ef..23d8d292359278db7ef6c72db8c418c3721d7066 100644 (file)
--- a/kex.c
+++ b/kex.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: kex.c,v 1.64 2005/07/25 11:59:39 markus Exp $");
+RCSID("$OpenBSD: kex.c,v 1.66 2006/03/07 09:07:40 djm Exp $");
 
 #include <openssl/crypto.h>
 
@@ -44,6 +44,14 @@ RCSID("$OpenBSD: kex.c,v 1.64 2005/07/25 11:59:39 markus Exp $");
 
 #define KEX_COOKIE_LEN 16
 
+#if OPENSSL_VERSION_NUMBER >= 0x00907000L
+# if defined(HAVE_EVP_SHA256)
+# define evp_ssh_sha256 EVP_sha256
+# else
+extern const EVP_MD *evp_ssh_sha256(void);
+# endif
+#endif
+
 /* prototype */
 static void kex_kexinit_finish(Kex *);
 static void kex_choose_conf(Kex *);
@@ -294,13 +302,22 @@ choose_kex(Kex *k, char *client, char *server)
                fatal("no kex alg");
        if (strcmp(k->name, KEX_DH1) == 0) {
                k->kex_type = KEX_DH_GRP1_SHA1;
+               k->evp_md = EVP_sha1();
        } else if (strcmp(k->name, KEX_DH14) == 0) {
                k->kex_type = KEX_DH_GRP14_SHA1;
-       } else if (strcmp(k->name, KEX_DHGEX) == 0) {
+               k->evp_md = EVP_sha1();
+       } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) {
                k->kex_type = KEX_DH_GEX_SHA1;
+               k->evp_md = EVP_sha1();
+#if OPENSSL_VERSION_NUMBER >= 0x00907000L
+       } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) {
+               k->kex_type = KEX_DH_GEX_SHA256;
+               k->evp_md = evp_ssh_sha256();
+#endif
        } else
                fatal("bad kex alg %s", k->name);
 }
+
 static void
 choose_hostkeyalg(Kex *k, char *client, char *server)
 {
@@ -404,28 +421,28 @@ kex_choose_conf(Kex *kex)
 }
 
 static u_char *
-derive_key(Kex *kex, int id, u_int need, u_char *hash, BIGNUM *shared_secret)
+derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
+    BIGNUM *shared_secret)
 {
        Buffer b;
-       const EVP_MD *evp_md = EVP_sha1();
        EVP_MD_CTX md;
        char c = id;
        u_int have;
-       int mdsz = EVP_MD_size(evp_md);
+       int mdsz;
        u_char *digest;
 
-       if (mdsz < 0)
-               fatal("derive_key: mdsz < 0");
-       digest = xmalloc(roundup(need, mdsz));
+       if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0)
+               fatal("bad kex md size %d", mdsz);
+       digest = xmalloc(roundup(need, mdsz));
 
        buffer_init(&b);
        buffer_put_bignum2(&b, shared_secret);
 
        /* K1 = HASH(K || H || "A" || session_id) */
-       EVP_DigestInit(&md, evp_md);
+       EVP_DigestInit(&md, kex->evp_md);
        if (!(datafellows & SSH_BUG_DERIVEKEY))
                EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
-       EVP_DigestUpdate(&md, hash, mdsz);
+       EVP_DigestUpdate(&md, hash, hashlen);
        EVP_DigestUpdate(&md, &c, 1);
        EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
        EVP_DigestFinal(&md, digest, NULL);
@@ -436,10 +453,10 @@ derive_key(Kex *kex, int id, u_int need, u_char *hash, BIGNUM *shared_secret)
         * Key = K1 || K2 || ... || Kn
         */
        for (have = mdsz; need > have; have += mdsz) {
-               EVP_DigestInit(&md, evp_md);
+               EVP_DigestInit(&md, kex->evp_md);
                if (!(datafellows & SSH_BUG_DERIVEKEY))
                        EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
-               EVP_DigestUpdate(&md, hash, mdsz);
+               EVP_DigestUpdate(&md, hash, hashlen);
                EVP_DigestUpdate(&md, digest, have);
                EVP_DigestFinal(&md, digest + have, NULL);
        }
@@ -455,13 +472,15 @@ Newkeys *current_keys[MODE_MAX];
 
 #define NKEYS  6
 void
-kex_derive_keys(Kex *kex, u_char *hash, BIGNUM *shared_secret)
+kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret)
 {
        u_char *keys[NKEYS];
        u_int i, mode, ctos;
 
-       for (i = 0; i < NKEYS; i++)
-               keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, shared_secret);
+       for (i = 0; i < NKEYS; i++) {
+               keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
+                   shared_secret);
+       }
 
        debug2("kex_derive_keys");
        for (mode = 0; mode < MODE_MAX; mode++) {