David Gubler

Java handshake simulation is a bit... too simple

Discussion created by David Gubler on Apr 9, 2015
Latest reply on Apr 19, 2015 by Adm Selec

Hi all,

 

First, thanks for your great SSL test! However... as I have noticed today, your Java 8 handshake simulation is a bit too simple.

 

First, Java 8 (currently) does not support Forward Secrecy with Diffie-Hellman key sizes above 2048 bits. Now, if a server uses e.g. 4096 bits, your test says that Java 8 can connect just fine, when in reality it can't (throws Exception). There's a bug report here: https://bugzilla.redhat.com/show_bug.cgi?id=1163501

 

Second, there is a subtle issue with SNI. If Java requests a certain host name using SNI and the server responds "I don't know that host name" (because it's missing from its host alias configuration or a similar issue), normal browsers can connect just fine, but Java can't (Exception). This could be reported, too.

 

Admittedly, both could be considered bugs in Java and at least the first one is definitely not a misconfiguration of the server, but either way your report that Java 8 can connect is wrong for such servers.

 

In general, it would be nice if the SSL test would report the DH key size (I had to resort to the gnutls-cli command to find it out, because openssl s_client won't show it either).

 

Thanks!

 

David

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