Re: BGP Security and PKI Hierarchies (was: Re: Wifi Security)

["Steven M. Bellovin" <smb () cs columbia edu>]

In message <20051124113104.0bd275d2 () garlic apnic net>, George Michaelson writes
:
> According to what I understand, there have to be two certificates per
> entity:
>
>       one is the CA-bit enabled certificate, used to sign subsidiary
>       certificates about resources being given to other people to use.
>
>       the other is a self-signed NON-CA certificate, used to sign
>       route assertions you are attesting to yourself: you make this
>       cert using the CA cert you get from your logical parent.
Or your parent could have a CA and issue you two certs, one for signing 
route assertions and one for signing certificates you issue to your 
downstreams.  That in turn has another interesting implication: an ISP 
can *enforce* a contract that prohibits a downstream from reselling 
connectivity, at least if the resold connectivity includes a BGP 
announcement -- the ISP would simply decline to sign a CA certificate 
for its customer, thereby depriving it of the ability to delegate 
portions of its address space.  (N.B.  Certificates include usage 
fields that say what the cert is good for.)

                --Steven M. Bellovin, http://www.cs.columbia.edu/~smb