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Re: Security team successfully cracks SSL using 200 PS3's and MD5
From: Randy Bush <randy () psg com>
Date: Tue, 06 Jan 2009 06:09:34 +0900

On 09.01.06 05:59, Joe Abley wrote:
perhaps i am a bit slow. but could someone explain to me how trust in
dns data transfers to trust in an http partner and other uses to which
ssl is put?

If I can get secure answers to "www.bank.example IN CERT?" and
"www.bank.example IN A?" then perhaps when I connect to
www.bank.example:443 I can decide to trust the certificate presented by
the server based on the trust anchor I extracted from the DNS, rather
than whatever trust anchors were bundled with my browser.

That presumably would mean that the organisation responsible for
bank.example could run their own CA and publish their own trust anchor,
without having to buy that service from one of the traditional CA
companies.

No doubt there is more to it than that. I don't know anything much about
X.509.

x.509 is not the issue. it is your assumption that dns trust is formally transferrable to ssl/tls cert trust.

to use your example, the contractor who serves dns for www.bank.example could insert a cert and then fake the web site having (a child of) that cert. whereas, if the site had its cert a descendant of the ca for all banks, this attack would fail.

and i am not interested in quibbling about banks and who issues root cas. the point is that there are two different trust models here, and trust is not transitive.

but then again, i have not even had coffee yet this morning.

randy


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