tls perfect forward secrecy with ecdhe

suggested by djm@ on hackers@, diff ok djm@

2 files changed, 30 insertions, 3 deletions

diff --git a/usr.sbin/smtpd/ssl.c b/usr.sbin/smtpd/ssl.c
index b814f71b4a4..31a9970da8c 100644
--- a/usr.sbin/smtpd/ssl.c
+++ b/usr.sbin/smtpd/ssl.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ssl.c,v 1.53 2013/05/24 17:03:14 eric Exp $	*/
+/*	$OpenBSD: ssl.c,v 1.54 2013/07/19 09:04:06 eric Exp $	*/
 
 /*
  * Copyright (c) 2008 Pierre-Yves Ritschard <pyr@openbsd.org>
@@ -91,6 +91,8 @@ ssl_setup(SSL_CTX **ctxp, struct ssl *ssl)
 	ssl_set_ephemeral_key_exchange(ctx, dh);
 	DH_free(dh);
 
+	ssl_set_ecdh_curve(ctx);
+
 	*ctxp = ctx;
 	return 1;
 
@@ -407,3 +409,26 @@ ssl_set_ephemeral_key_exchange(SSL_CTX *ctx, DH *dh)
 		fatal("ssl_set_ephemeral_key_exchange: cannot set tmp dh");
 	}
 }
+
+void
+ssl_set_ecdh_curve(SSL_CTX *ctx)
+{
+	int	nid;
+	EC_KEY *ecdh;
+
+	if ((nid = OBJ_sn2nid(SSL_ECDH_CURVE)) == 0) {
+		ssl_error("ssl_set_ecdh_curve");
+		fatal("ssl_set_ecdh_curve: unknown curve name "
+		    SSL_ECDH_CURVE);
+	}
+
+	if ((ecdh = EC_KEY_new_by_curve_name(nid)) == NULL) {
+		ssl_error("ssl_set_ecdh_curve");
+		fatal("ssl_set_ecdh_curve: unable to create curve "
+		    SSL_ECDH_CURVE);
+	}
+
+	SSL_CTX_set_tmp_ecdh(ctx, ecdh);
+	SSL_CTX_set_options(ctx, SSL_OP_SINGLE_ECDH_USE);
+	EC_KEY_free(ecdh);
+}
diff --git a/usr.sbin/smtpd/ssl.h b/usr.sbin/smtpd/ssl.h
index 640dc63f491..4cbec59458f 100644
--- a/usr.sbin/smtpd/ssl.h
+++ b/usr.sbin/smtpd/ssl.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ssl.h,v 1.1 2013/01/26 09:37:24 gilles Exp $	*/
+/*	$OpenBSD: ssl.h,v 1.2 2013/07/19 09:04:07 eric Exp $	*/
 /*
  * Copyright (c) 2013 Gilles Chehade <gilles@poolp.org>
  *
@@ -15,7 +15,8 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-#define SSL_CIPHERS		"HIGH"
+#define SSL_CIPHERS		"HIGH:!aNULL:!MD5"
+#define	SSL_ECDH_CURVE		"prime256v1"
 #define	SSL_SESSION_TIMEOUT	300
 
 struct ssl {
@@ -42,6 +43,7 @@ int	        ssl_cmp(struct ssl *, struct ssl *);
 DH	       *get_dh1024(void);
 DH	       *get_dh_from_memory(char *, size_t);
 void		ssl_set_ephemeral_key_exchange(SSL_CTX *, DH *);
+void		ssl_set_ecdh_curve(SSL_CTX *);
 extern int	ssl_ctx_load_verify_memory(SSL_CTX *, char *, off_t);
 char	       *ssl_load_file(const char *, off_t *, mode_t);
 char	       *ssl_load_key(const char *, off_t *, char *);