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Moxie Marlinspike's Solution To the SSL CA Problem
Trevelyan writes "In his Blackhat talk on the past and future of SSL (YouTube video) Moxie Marlinspike explains the problems of SSL today, and the history of how it came to be so. He then goes on to not only propose a solution, but he's implemented it as well: Convergence. It will let you turn off all those untrustable CAs in you browser and still safely use HTTPS. It even works with self-signed certificates. You still need to trust someone, but not forever like CAs. The system has 'Notaries,' which you can ask anonymously for their view on a certificate's authenticity. You can pool Notaries for a consensus, and add/remove them at any time."
I always trust what Blackhats tell me.
The dangers of knowledge trigger emotional distress in human beings.
I havent watched the video, but my first question would be:
How do you know the Notaries are who they say they are? How can you prevent a (wo)man in the middle attack?
The Perspectives add-on uses notaries scattered throughout the Internet to see if the certificate changes for different routes through the Internet, or if it has changed over time. This detects some man-in-the-middle attacks, but it doesn't detect what the Perspectives project calls the "Lserver attack": a man in the middle placed in the server's only upstream connection to the Internet. Users who have posted comments to recent Slashdot discussions appear to think that governments will mount an "Lserver attack" inside the country's firewall.
Web Of Trust, really, are you fucking kidding me? This has been implemented for how long already? Thawte personal certificates for e-mail work like that, with "trusted" notaries and shit.
And this is somehow a NEW AND REVOLUTIONARY idea, because it has a Web 2.0 name like "Convergence"?
Sheesh, the shit one has to put up with.
since the paths from notaries to target certificates are multiple
Not necessarily. The server with the target certificate has only one path to the Internet proper, namely through its ISP. Compromising the ISP, which is trivial for a government that maintains a Great Firewall, allows what the whitepaper about Perspectives calls the "Lserver" attack: "A compromise of the server’s local link lets an attacker inject arbitrary keys when either clients or notaries contact the server."
This project is all very well, but we want SSL to solve two problems today: prevent MITM attacks (which Convergence can do) and *also* identification (in other words, EV certificates) to prevent phishing or at least reduce the chances of phishing.
Unfortunately Convergence only does one of them (prevent the MITM attacks). A much bigger problem, certainly in the west, is phishing rather than MITM attacks. I'd suggest for many people Convergence still needs quite a bit of work before we can start using it in place of the current method of CAs (which I agree is broken).
Oolite: Elite-like game. For Mac, Linux and Windows
From the talk, Convergence is based on Perspectives, with some updates:
- Once a client has confirmed a certificate through the notaries, it is cached locally. Future contacts for that site will not need re-notarization until the site's cert is changed. That way your browsing history is not exposed through your notary contacts very often.
- Contact to the notaries can be done through a trusted proxy over SSL, to protect exposure of your browser history.
- The user can choose one or more notaries, and choose to distrust any of them at any time.
- Each notary can use any backend validation method it wants. It could check certs stored in DNSSEC, it could use the existing CA system, the EFF will have one that uses their SSL observatory, etc.
So someone would have to forge a certificate for addons.mozilla.org.
Done!