Yesterday, we had a meeting at CAcert Berlin where I had a little talk about how to almost-perfectly configure your HTTPS server. Motivation for that was the very nice Qualys SSL Server test, which can remote-check your SSL configuration and tell you a bunch of things about it.

While playing with that, I created a test setup which passes with 100 points in the Qualys test. However, you will hardly be able to access that page, which is mainly due to it's exclusive support for TLS 1.2. All major browsers fail. Someone from the audience told me that the iPhone browser was successfully able to access the page. To safe the reputation of free software, someone else found out that the Midori browser is also capable of accessing it. I've described what I did there on the page itself and you may also read it here via http.

Here are my slides "SSL, X.509, HTTPS - How to configure your HTTPS server" as ODP, as PDF and on Slideshare.

And some links mentioned in the slides:
Check SSL and SSH weak keys due to broken random numbers
EFF SSL Observatory
Sovereign Keys proect

Some great talks on the mentioned topics by others:
Facthacks Talk 29c3
MD5 considered harmful today - Creating a rogue CA Certificate
Is the SSLiverse a safe place?

Update: As people seem to find these browser issue interesting: It's been pointed out that the iPad Browser also works. Opera with TLS 1.2 enabled seems to work for some people, but not for me (maybe Windows-only). luakit and epiphany also work, but they don't check certificates at all, so that kind of doesn't count.

In the last weeks, I made a study research project at the EISS at the University of Karlsruhe. The subject was »Session Cookies and SSL«, investigating the problems that arise when trying to secure a web application with HTTPS and using session cookies.

I already wrote about this in the past, presenting vulnerabilities in various web applications.

One of the notable results is probably that ebay has just no measurements against those issues at all, so it's pretty trivial to hijack a session (and use that to do bids and even change the address of the hijacked account).

Download »Session Cookies and SSL« (PDF, 317 KB)

A big problem with web security in the past was that it was impossible to have https-hosts with more than one certificate per IP. This is due to the protocol design of https, which needs to establish an ssl-connection with the certificate before the hostname is transferred.

There is a solution though, called Server Name Indication (SNI) and part of TLS. Strange enough, client compatibility isn't that much of a problem. Firefox, Opera and IE already support it in their current versions, konqueror will with kde4, I've no information when it'll hit safari. Oh, and I haven't testet w3m, lynx, links and wget yet, but if you want, feel free to add your experiences to the comments :-)

The problem was that until some weeks ago, openssl didn't support SNI, apachen mod_ssl didn't, lighttpd didn't. Only GnuTLS, but mod_gnutls is considered unstable by it's authors. With OpenSSL 0.9.8f, TLS Extensions and with them SNI landet in openssl, apache still needs patches.

We've now implemented SNI on schokokeks.org, which you can test:
https://www.schokokeks.org/
https://www.hboeck.de/
https://www.fabian-fingerle.de/

If your browser supports SNI, you should see different certificates, all on the same IP. All certs are cacert-signed, they also have a Wiki page from the VhostTaskForce for SNI and alternative solutions.