Add support for automatic ECDH temporary key parameter selection. When

enabled instead of requiring an application to hard code a (possibly
inappropriate) parameter set and delve into EC internals we just
automatically use the preferred curve.

diff --git a/CHANGES b/CHANGES
index 5421f3dbb04fd1515e08ad10978ffd6c6f623b5c..c596c35e452c320559d896a619ad3e7538053f11 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -4,6 +4,13 @@
 
  Changes between 1.0.1 and 1.1.0  [xx XXX xxxx]
 
+  *) Support for automatic EC temporary key parameter selection. If enabled
+     the most preferred EC parameters are automatically used instead of
+     hardcoded fixed parameters. Now a server just has to call:
+     SSL_CTX_set_ecdh_auto(ctx, 1) and the server will automatically
+     support ECDH and use the most appropriate parameters.
+     [Steve Henson]
+
   *) Enhance and tidy EC curve and point format TLS extension code. Use
      static structures instead of allocation if default values are used.
      New ctrls to set curves we wish to support and to retrieve shared curves.

diff --git a/apps/s_cb.c b/apps/s_cb.c
index 141c222895206400b9880e6d1d75513094e59685..4395f194aa838d587c4048140f83e362ed2a20e7 100644 (file)
--- a/apps/s_cb.c
+++ b/apps/s_cb.c
@@ -355,6 +355,8 @@ int ssl_print_curves(BIO *out, SSL *s)
                        cname = OBJ_nid2sn(nid);
                BIO_printf(out, "%s", cname);
                }
+       if (ncurves == 0)
+               BIO_puts(out, "NONE");
        BIO_puts(out, "\n");
        return 1;
        }

diff --git a/apps/s_server.c b/apps/s_server.c
index 5f1bcffb91c098f412f479b57a63f34baa6b3eb9..063a9f6c41026a573753a4b3a2beb9e73d7cf60a 100644 (file)
--- a/apps/s_server.c
+++ b/apps/s_server.c
@@ -1713,10 +1713,11 @@ bad:
                {
                EC_KEY *ecdh=NULL;
 
-               if (named_curve)
+               if (named_curve && strcmp(named_curve, "auto"))
                        {
-                       int nid = OBJ_sn2nid(named_curve);
-
+                       int nid = EC_curve_nist2nid(named_curve);
+                       if (nid == NID_undef)
+                               nid = OBJ_sn2nid(named_curve);
                        if (nid == 0)
                                {
                                BIO_printf(bio_err, "unknown curve name (%s)\n", 
@@ -1736,6 +1737,8 @@ bad:
                        {
                        BIO_printf(bio_s_out,"Setting temp ECDH parameters\n");
                        }
+               else if (named_curve)
+                       SSL_CTX_set_ecdh_auto(ctx, 1);
                else
                        {
                        BIO_printf(bio_s_out,"Using default temp ECDH parameters\n");

diff --git a/ssl/s3_lib.c b/ssl/s3_lib.c
index 1ff5e9db55cde6348830733b4797c58328f9afd5..bd373e326b9ce44c98bed510461e1e3b416052ec 100644 (file)
--- a/ssl/s3_lib.c
+++ b/ssl/s3_lib.c
@@ -3398,7 +3398,10 @@ long ssl3_ctrl(SSL *s, int cmd, long larg, void *parg)
 
        case SSL_CTRL_GET_SHARED_CURVE:
                return tls1_shared_curve(s, larg);
- 
+
+       case SSL_CTRL_SET_ECDH_AUTO:
+               s->cert->ecdh_tmp_auto = larg;
+               break;
 
        default:
                break;
@@ -3678,6 +3681,9 @@ long ssl3_ctx_ctrl(SSL_CTX *ctx, int cmd, long larg, void *parg)
                return tls1_set_curves_list(&ctx->tlsext_ellipticcurvelist,
                                        &ctx->tlsext_ellipticcurvelist_length,
                                                                parg);
+       case SSL_CTRL_SET_ECDH_AUTO:
+               ctx->cert->ecdh_tmp_auto = larg;
+               break;
 #endif /* !OPENSSL_NO_TLSEXT */
 
        /* A Thawte special :-) */

diff --git a/ssl/s3_srvr.c b/ssl/s3_srvr.c
index 4b483c9bafc91d91354c8284b4ecf5f6d268852d..296e27f924eedfa8396b63021935be7a0de236bb 100644 (file)
--- a/ssl/s3_srvr.c
+++ b/ssl/s3_srvr.c
@@ -1683,7 +1683,14 @@ int ssl3_send_server_key_exchange(SSL *s)
                        const EC_GROUP *group;
 
                        ecdhp=cert->ecdh_tmp;
-                       if ((ecdhp == NULL) && (s->cert->ecdh_tmp_cb != NULL))
+                       if (s->cert->ecdh_tmp_auto)
+                               {
+                               /* Get NID of first shared curve */
+                               int nid = tls1_shared_curve(s, 0);
+                               if (nid != NID_undef)
+                                       ecdhp = EC_KEY_new_by_curve_name(nid);
+                               }
+                       else if ((ecdhp == NULL) && s->cert->ecdh_tmp_cb)
                                {
                                ecdhp=s->cert->ecdh_tmp_cb(s,
                                      SSL_C_IS_EXPORT(s->s3->tmp.new_cipher),
@@ -1708,7 +1715,9 @@ int ssl3_send_server_key_exchange(SSL *s)
                                SSLerr(SSL_F_SSL3_SEND_SERVER_KEY_EXCHANGE,ERR_R_ECDH_LIB);
                                goto err;
                                }
-                       if ((ecdh = EC_KEY_dup(ecdhp)) == NULL)
+                       if (s->cert->ecdh_tmp_auto)
+                               ecdh = ecdhp;
+                       else if ((ecdh = EC_KEY_dup(ecdhp)) == NULL)
                                {
                                SSLerr(SSL_F_SSL3_SEND_SERVER_KEY_EXCHANGE,ERR_R_ECDH_LIB);
                                goto err;

diff --git a/ssl/ssl.h b/ssl/ssl.h
index 6f5c305f72dfa79e9038437d0027438964e730f1..c433364a8fb08734686d50d2acb6dd9209afe478 100644 (file)
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -1629,6 +1629,7 @@ DECLARE_PEM_rw(SSL_SESSION, SSL_SESSION)
 #define SSL_CTRL_SET_CURVES                    91
 #define SSL_CTRL_SET_CURVES_LIST               92
 #define SSL_CTRL_GET_SHARED_CURVE              93
+#define SSL_CTRL_SET_ECDH_AUTO                 94
 
 #define DTLSv1_get_timeout(ssl, arg) \
        SSL_ctrl(ssl,DTLS_CTRL_GET_TIMEOUT,0, (void *)arg)
@@ -1700,6 +1701,10 @@ DECLARE_PEM_rw(SSL_SESSION, SSL_SESSION)
        SSL_ctrl(ctx,SSL_CTRL_SET_CURVES_LIST,0,(char *)s)
 #define SSL_get_shared_curve(s, n) \
        SSL_ctrl(s,SSL_CTRL_GET_SHARED_CURVE,n,NULL)
+#define SSL_CTX_set_ecdh_auto(ctx, onoff) \
+       SSL_CTX_ctrl(ctx,SSL_CTRL_SET_ECDH_AUTO,onoff,NULL)
+#define SSL_set_ecdh_auto(s, onoff) \
+       SSL_ctrl(s,SSL_CTRL_SET_ECDH_AUTO,onoff,NULL)
 
 #ifndef OPENSSL_NO_BIO
 BIO_METHOD *BIO_f_ssl(void);

diff --git a/ssl/ssl_cert.c b/ssl/ssl_cert.c
index 6a1c484fc3c5def0f053311b417edb8e67077e16..a2682daaedd951321a57ccc8e0e1bf8b387ca6dc 100644 (file)
--- a/ssl/ssl_cert.c
+++ b/ssl/ssl_cert.c
@@ -270,6 +270,7 @@ CERT *ssl_cert_dup(CERT *cert)
                        }
                }
        ret->ecdh_tmp_cb = cert->ecdh_tmp_cb;
+       ret->ecdh_tmp_auto = cert->ecdh_tmp_auto;
 #endif
 
        for (i = 0; i < SSL_PKEY_NUM; i++)

diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index af25d3e4d3148140800fe9e9fbd482c7477ebbec..679894cb3db15328c03b0d89a2cae9bbc652b32a 100644 (file)
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -2072,7 +2072,7 @@ void ssl_set_cert_masks(CERT *c, const SSL_CIPHER *cipher)
 #endif
 
 #ifndef OPENSSL_NO_ECDH
-       have_ecdh_tmp=(c->ecdh_tmp != NULL || c->ecdh_tmp_cb != NULL);
+       have_ecdh_tmp=(c->ecdh_tmp || c->ecdh_tmp_cb || c->ecdh_tmp_auto);
 #endif
        cpk= &(c->pkeys[SSL_PKEY_RSA_ENC]);
        rsa_enc= (cpk->x509 != NULL && cpk->privatekey != NULL);

diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h
index 1b646515a0a92cd680011f90e9bc4ca171185168..32f1a6108a3b4c6f341d903006670a52bce126fe 100644 (file)
--- a/ssl/ssl_locl.h
+++ b/ssl/ssl_locl.h
@@ -502,6 +502,8 @@ typedef struct cert_st
        EC_KEY *ecdh_tmp;
        /* Callback for generating ephemeral ECDH keys */
        EC_KEY *(*ecdh_tmp_cb)(SSL *ssl,int is_export,int keysize);
+       /* Select ECDH parameters automatically */
+       int ecdh_tmp_auto;
 #endif
 
        CERT_PKEY pkeys[SSL_PKEY_NUM];

diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c
index ffc78c9bae925580abf17c34f7c0fb2b1a0762c6..73924392f962577024b0ea3d000086651927a70b 100644 (file)
--- a/ssl/t1_lib.c
+++ b/ssl/t1_lib.c
@@ -332,33 +332,24 @@ static void tls1_get_curvelist(SSL *s, int sess,
                }
        }
 
-/* Return any common values from two lists. One list is used as a 
- * preference list where we return the most preferred match.
+/* Return nth shared curve. If nmatch == -1 return number of
+ * matches.
  */
-int tls1_shared_list(SSL *s,
-                       const unsigned char *l1, size_t l1len,
-                       const unsigned char *l2, size_t l2len,
-                       int nmatch)
+
+int tls1_shared_curve(SSL *s, int nmatch)
        {
        const unsigned char *pref, *supp;
        size_t preflen, supplen, i, j;
        int k;
-       l1len /= 2;
-       l2len /= 2;
-       if (s->options & SSL_OP_CIPHER_SERVER_PREFERENCE)
-               {
-               pref = l1;
-               preflen = l1len;
-               supp = l2;
-               supplen = l2len;
-               }
-       else
-               {
-               supp = l1;
-               supplen = l1len;
-               pref = l2;
-               preflen = l2len;
-               }
+       /* Can't do anything on client side */
+       if (s->server == 0)
+               return -1;
+       tls1_get_curvelist(s, !!(s->options & SSL_OP_CIPHER_SERVER_PREFERENCE),
+                               &supp, &supplen);
+       tls1_get_curvelist(s, !(s->options & SSL_OP_CIPHER_SERVER_PREFERENCE),
+                               &pref, &preflen);
+       preflen /= 2;
+       supplen /= 2;
        k = 0;
        for (i = 0; i < preflen; i++, pref+=2)
                {
@@ -368,32 +359,17 @@ int tls1_shared_list(SSL *s,
                        if (pref[0] == tsupp[0] && pref[1] == tsupp[1])
                                {
                                if (nmatch == k)
-                                       return (pref[0] << 8) | pref[1];
+                                       {
+                                       int id = (pref[0] << 8) | pref[1];
+                                       return tls1_ec_curve_id2nid(id);
+                                       }
                                k++;
                                }
                        }
                }
-       if (nmatch == -1 && k > 0)
-               return k;
-       return -1;
-       }
-
-int tls1_shared_curve(SSL *s, int nmatch)
-       {
-       const unsigned char *l1, *l2;
-       size_t l1len, l2len;
-       int id;
-       /* Can't do anything on client side */
-       if (s->server == 0)
-               return -1;
-       /* Get supported curves */
-       tls1_get_curvelist(s, 0, &l1, &l1len);
-       tls1_get_curvelist(s, 1, &l2, &l2len);
-
-       id = tls1_shared_list(s, l1, l1len, l2, l2len, nmatch);
        if (nmatch == -1)
-               return id;
-       return tls1_ec_curve_id2nid(id);
+               return k;
+       return 0;
        }
 
 int tls1_set_curves(unsigned char **pext, size_t *pextlen,
@@ -531,6 +507,7 @@ static int tls1_check_ec_key(SSL *s,
        {
        const unsigned char *p;
        size_t plen, i;
+       int j;
        /* If point formats extension present check it, otherwise everything
         * is supported (see RFC4492).
         */
@@ -546,19 +523,17 @@ static int tls1_check_ec_key(SSL *s,
                if (i == plen)
                        return 0;
                }
-       /* If curve list present check it, otherwise everything is
-        * supported.
-        */
-       if (s->session->tlsext_ellipticcurvelist)
+       /* Check curve is consistent with client and server preferences */
+       for (j = 0; j <= 1; j++)
                {
-               p = s->session->tlsext_ellipticcurvelist;
-               plen = s->session->tlsext_ellipticcurvelist_length;
+               tls1_get_curvelist(s, j, &p, &plen);
                for (i = 0; i < plen; i+=2, p+=2)
                        {
                        if (p[0] == curve_id[0] && p[1] == curve_id[1])
-                               return 1;
+                               break;
                        }
-               return 0;
+               if (i == plen)
+                       return 0;
                }
        return 1;
        }
@@ -585,6 +560,13 @@ int tls1_check_ec_tmp_key(SSL *s)
        {
        unsigned char curve_id[2];
        EC_KEY *ec = s->cert->ecdh_tmp;
+       if (s->cert->ecdh_tmp_auto)
+               {
+               /* Need a shared curve */
+               if (tls1_shared_curve(s, 0))
+                       return 1;
+               else return 0;
+               }
        if (!ec)
                {
                if (s->cert->ecdh_tmp_cb)