Why are we still using the CA model? (Re: Microsoft deems all DigiNotar certificates untrustworthy, releases updates)

Mike Jones mike at mikejones.in
Sun Sep 11 13:44:20 CDT 2011


On 11 September 2011 16:55, Bjørn Mork <bjorn at mork.no> wrote:
> You can rewrite that: Trust is the CA business.  Trust has a price.  If
> the CA is not trusted, the price increases.
>
> Yes, they may end up out of business because of that price jump, but you
> should not neglect the fact that trust is for sale here.
>

The CA model is fundamentally flawed in the fact that you have CAs
whose sole "trustworthiness" is the fact that they paid for an audit
(for Microsoft, lower requirements for others), they then issue
intermediate certificates to other companies (many web hosts and other
minor companies have them) whose sole "trustworthiness" is the fact
that they paid for an intermediate certificate, all of those
companies/organisations/people are then considered trustworthy enough
to confirm the identity of my web server despite the fact that none of
them have any connection at all to me or my website.

There is already a chain of trust down the DNS tree, if that is
compromised then my SSL is already compromised (if they control my
domain, they can "verify" they are me and get a certificate), what
happened to RFC4398 and other such proposals? EV certificates have a
different status and probably still need the CA model, however with
"standard" SSL certificates the only validation done these days is
checking someone has control over the domain. DNSSEC deployment is
advanced enough now to do that automatically at the client. We just
need browsers to start checking for certificates in DNS when making a
HTTPS connection (and if one is found do client side DNSSEC validation
- I don't trust my ISPs DNS servers to validate something like that,
considering they are the ones likely to be intercepting my connections
in the first place!).

It will take a while to get updated browsers rolled out to enough
users for it do be practical to start using DNS based self-signed
certificated instead of CA-Signed certificates, so why don't any
browsers have support yet? are any of them working on it?

- Mike



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