It seems as though lately a lot of heated conversations revolve around X.509. Whether it’s implementations using IPsec or SSL/TLS certificates, someone always ends up frustrated. Why? Because it really does suck when you think about it.
There are many facets one could rant on and on about, when the topic is X.509: the PKI that could have been but isn’t and never will be. It’s a losing argument and if I’ve already got your blood pressure on the rise (I’m lookin’ at you, registrars!) you know why it sucks but there’s zero motivation to do anything about it. Well, there is some motivation, but that will be quickly squashed with FUD coming out of those corporations telling you how need them. You need the warm fuzzy feeling of having a Certificate Authority that’s WebTrust certified to create certificates to provide security and authenticity. But… didn’t someone break that?
Enter cheesy diagram:
I know, I know – that’s a work of art in and of itself. I can be hired for crappy vector art at the low low hourly rate of $29.95. There’s my pitch – now back to the story.
So I bet at this point you’re telling yourself that I could have made this diagram much more readable had I arranged it differently. In reality I did it on purpose because, like X.509, stuff is there that doesn’t work quite right. That aside, I want to make sure you get two things out of this rant:
- “Joe Schmoe” will never be able to make a decision at this level of complexity. Some people can; others cannot. Expecting everyone on the Internet to figure this stuff out is a recipe for failure and fraud.
- The X.509 chain of trust is a big reason it sucks so much.
Let me explain.
In the diagram “Joe” is visibly upset. Rightly so, because he’s at his local coffee shop and doing a little social network stalking and banking. Aside from all of the other possible attacks when using public WiFi today, he’s been had by a MiTM attack to explicitly steal his credentials even though he’s careful to make sure the little lock icon says that he’s good to go. There’s no way for him to validate this. So is this attack feasible today? That’s probably the wrong question to ask – the question is: is it possible?
Let’s move on to the second item of interest: chain of trust. X.509 is very rigid – if any certificates along the certificate chain are invalidated, you must resign and reissue all the certs below them. Think about that as it applies to thousands of computers using IPsec and X.509 for phase one authentication: if you have a mid-level signing server that either expires or is compromised, you have to distribute and install all new certificates. Now think of that same situation as it applies to the certificate authorities you get your SSL/TLS certificates from (and other kinds, but that’s not the point). The problem is that if in fact that CA certificate is invalidated, then what is the process to revoke on the client side (meaning every browser installed on every computer across the Internet)? That really sucks. Don’t even bring up CRL or OCSP – because neither works and/or was designed to manage at this magnitude (let alone any decent-size environment).
So let’s fix it! Let’s do something with DNSSEC to get around this rigidity – as Robert Hansen, Dan Kaminsky, and others have suggested. I’ve got bad news, my friends: vested interests. If we remove the existing rigid system, in favor of something more flexible and dynamic – say, as the distributed as DNS – we have destroyed the very lucrative choke point that currently creates a major revenue stream. That’s not to say this problem will never get fixed, but I expect major pressure to ensure that any replacement preserves the lucrative ‘sweet spot’ for CAs, rather than something more viable and open which might also be much cheaper. As usual, it is unlikely any real progress will occur happen without a catastrophic event to kick-start the proces, but if you’re even remotely cognizant of how things get fixed around these parts, you already knew that.