[cap-talk] A petname toolbar for Firefox

[Ian G]

Tyler Close wrote:

>> There's one thing i
>>don't understand, though.  Why do you store the petname keyed by
>>the root CA's fingerprint instead of the site's fingerprint?
>>(I see that you still use the domain name so that different
>>domains signed by the same CA are distinct, but i don't see why
>>the CA's certificate needs to be involved at all.)
>>    
>>
>
>Under HTTPS, the end entity certificate typically has a lifetime of only
>1 year. The only persistent identifier for the site is the ( domain
>name, CA public key ) pair.
>

Isn't the same key used on renewal?  And only
the cert changes?


>Binding the petname to a non-persistent site identifier would suck, as
>the binding would regularly become invalid, producing a situation much
>like a spoofing attack. This interaction model would desensitize the
>user to broken petnames, undermining the protection model.
>  
>

This would indeed be a problem of quite
serious proportions.  OTOH, by binding
the domain+CA, it is now open to a CA
substitution attack.  I suppose that's just
a nicety that we didn't get rather than
something that was lost, though.

Good work.  (I can't see it as I also have a
Firefox sans plugins.)

iang

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