Apache :: 2.4.7 enables DH-Keys with more than 1024 Bits

jraute · Joined: 13 Sep 2013 Posts: 188 Location: Rheinland, Germany

Did you try it with SSLCertificateFile or with SSLCACertficateFile?

Reading the mod_ssl documentation for 2.4.x it says DH and ECDH parameters are only read from the first SSLCertificateFile directive.

But even this was not working in my tests.

James Blond

You are right! I used the wrong directive Embarassed

Now with SSLCertificateFile I get at least an error. (removed pid and date so the message is not too long for the forum)

glsmith

It also states very easy to miss, to append your certificate with the DH key, it just must be in the first SSLCertificateFile listed.

http://httpd.apache.org/docs/2.4/ssl/ssl_faq.html

James Blond

Gregg your config?

Cause now in short I used

glsmith

Yes I am still awake for a short time.

Standard old SSL config, just I pasted the DH to the bottom of my StartSSL certificate.

conf/ssl/mysslcertificate.crt

James Blond

jraute · Joined: 13 Sep 2013 Posts: 188 Location: Rheinland, Germany

Well

the questions is not always a question of a scoring.

In this special case it was the idea of having self calculated dh-params for a reliable secure initialization of a secure channel. And for that it is a great option to define additional "settings". Maybe you want to have a 4096 bit key with a 8192 bit dh-param file. Therefore you would have to choose a different way than usually.

Besides this, i am not convinced, that copying the dh-param file into the certificate leads to a usage of this dh-params.

Have you checked the initialization phase and the used keys?

James Blond

glsmith

Initialization phase checked and I see nothing. ssl:trace8
I am convinced this is the way to do it however, if you read the docs for the SSLCertificateFile directive it says the same thing in an indirect way, it even says you can optionally include the private key in the file.

This is much like Mongoose in that you only have one file and you paste the private key under the certificate in the file.

As far as ciphers used:

James Blond

Gregg,

why don't you disable camellia with SSLCipherSuite ... :!DHE_RSA_WITH_CAMELLIA_128_CBC_SHA:... ? You still can use DHE_RSA_WITH_CAMELLIA_256_CBC_SHA

jraute · Joined: 13 Sep 2013 Posts: 188 Location: Rheinland, Germany

jraute · Joined: 13 Sep 2013 Posts: 188 Location: Rheinland, Germany

Hahaha, why so complicated. Idea

It's just too late, sorry.

If i get it right (well, it's later than before Very Happy

), the test is very easy.
As long as we don't have any self calculated dh-parameters apache creates keys with the same bit size the certificate has.

If we then would attach a self calculated dh-parameter in a smaller bit size it should be visible which dh-parameter is used.

jraute · Joined: 13 Sep 2013 Posts: 188 Location: Rheinland, Germany

Ok, test is done.
Attaching a 1024 bit dh-parameter to the certificate file while the rsa key is 4096 bit.

Result: It works! You get 1024 bit dh keys while the rest works in 4096.

So i assume that the other way round would work as well.
But the most important thing - we can use our self calculated dh parameter settings.

Great!
Thanks to all who helped with tests etc.

glsmith

jraute · Joined: 13 Sep 2013 Posts: 188 Location: Rheinland, Germany

James Blond

For ssl debuggin I tried openssl s_client -connect example.com:443 -state -nbio

There was no difference between w/out DH-Key.

Here the diff from the two results

http://pastebin.com/3NSkDsLZ

in both cases the init phase was