[86925] in North American Network Operators' Group
Re: BGP Security and PKI Hierarchies (was: Re: Wifi Security)
daemon@ATHENA.MIT.EDU (Steven M. Bellovin)
Tue Nov 22 15:54:50 2005
From: "Steven M. Bellovin" <smb@cs.columbia.edu>
To: Randy Bush <randy@psg.com>
Cc: nanog@nanog.org
In-Reply-To: Your message of "Tue, 22 Nov 2005 10:45:23 -1000."
<17283.33635.774719.679@roam.psg.com>
Date: Tue, 22 Nov 2005 15:54:20 -0500
Errors-To: owner-nanog@merit.edu
In message <17283.33635.774719.679@roam.psg.com>, 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
