Cleanup of default ciphersuite list

* don't offer DHE ciphersuites like Chrome
* don't offer AES-CBC-SHA2 like Firefox and Chrome
* don't offer AES-GCM for plain RSA like Firefox
* don't offer ECDSA with AES-CBC like Chrome
* don't offer weak DES-CBC3-SHA
* prefer AES256 over AES128 like Mozilla Modern, Safari and Edge

components/net/connector.rs

@@ -201,18 +201,11 @@ where
         .build(connector)
 }
 
-// The basic logic here is to prefer ciphers with ECDSA certificates, Forward
-// Secrecy, AES GCM ciphers, AES ciphers, and finally 3DES ciphers.
+// Prefer Forward Secrecy over plain RSA, AES-GCM over AES-CBC, ECDSA over RSA.
 // A complete discussion of the issues involved in TLS configuration can be found here:
 // https://wiki.mozilla.org/Security/Server_Side_TLS
 const DEFAULT_CIPHERS: &'static str = concat!(
-    "ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:",
     "ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:",
-    "DHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-SHA256:",
-    "ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:",
-    "ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA:",
-    "ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:",
-    "DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-RSA-DES-CBC3-SHA:",
-    "ECDHE-ECDSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:",
-    "AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA"
+    "ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:",
+    "ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:AES256-SHA:AES128-SHA"
 );