:
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, Steven M. Bellovin