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Re: BGP Security and PKI Hierarchies (was: Re: Wifi Security)
- From: Steven M. Bellovin
- Date: Tue Nov 22 15:55:32 2005
In message <firstname.lastname@example.org>, Randy Bush writes:
>>>> I believe a web of trust can be operationally feasible only if the web
>>>> is more like a forest - if there are several well known examples of
>>>> "tops" to the web. Otherwise, you have to be storing a plethora of
>>>> different signers' certificates to be able to validate all the
>>>> institution's certificates that come in.
>>> you need those certs to verify the live data anyway
>> Right. The real issue is the trust determination -- how do you know
>> that the certificate corresponds to something resembling reality
>> (whatever that is)?
>for how many years have i been asking you and your evil-minded cert
>designing friends for a pgp-like web of trust cert that could be
>used for just this application?
Actually, I don't do certs; it's my evil-minded friends...
That said, I think the problem is that we need an algebra of trust that
will let a program, not a human, decide whether or not to trust a
certficate. You don't want to accept something if it's a twisty loop
of subsidiaries or allied evil ASs vouching for each other. OTOH,
there are some situations where we know that absolute trust is
indicated -- say, 701 signing 702's certificate, or an upstream signing
the address certificate for a customer. And it's not just honesty,
it's competence you're assessing -- we've all seen problems when major
ISPs didn't get their filters straight.
Furthermore, given that a trust algebra may yield a trust value, rather
than a simple 0/1, is it reasonable to use that assessment as a BGP
preference selector? That would tie the security very deeply -- too
deeply? -- into BGP's guts.
--Steven M. Bellovin, http://www.cs.columbia.edu/~smb