Stephen Kent wrote: > <snip> > Could you elaborate, perhaps privately, with why you believe a "true > PKI" needs multiple roots? > > <snip> > My view is that too many > folks have tried to get too much out of any single PKI, and that has > caused a lot of our headaches. if we admit to the need for many PKIs, > each serving a well-defined user community, then I think each of > these PKIS would be easier to create, manage, and deal with from a > liability standpoint. Steve: You have answered your own question above. As you say, folks have tried too much out of a single PKI and failed. That is why a true PKI (ie, one that works as an infrastructure) would need to include many PKIs. Each one of these "many PKIs" represents one root, with multiple PKIs creating multiple roots. Now, unless you want each one of these many PKIs to be isolated -- and not create an infrastructure -- there is a need for cross-certification allowing users of one PKI community to talk to users of another PKi community. In DNS parlance, you need to find AND validate routes among multiple roots. > if I look in my wallet, I have a lot of credentials, each issued by a > different organization. Each is useful only in certain contexts. Each > tends to uniquely identify me via a number of some sort and often > that number is meaningful only in the context for which the > credential was developed. We would be in pretty good shape if we had > PKIs that parallel these paper and plastic credentials. Agreed. The fundamental problem is that the PKI architecture cannot directly provide mutiple root functionality. You need to overlay bridge CAs and other artifacts in order to create the paths. Now, imagine a different mathematical structure, one that is not based on a hierarchy and yet works with hierarchical systems (as well as non-hierarchical systems liek a peer-to-peer network). Such structure could allow paths to be found, and validated, from one hierarchy (PKI, DNS) to another (PKI, DNS). Someone may add that the DNS is not really a hierarchy, it is just an ontology. My argument still holds for ontologies and also applies to how names are used in PKI certificates (as I have discussed elsewhere, see google). A certificate is just an authenticated assertion made within the context of a name space. The name space in a PKI forms an ontology and that ontology is defined by name space ownership, just like in the DNS. > The security > would be better and with good software, the convenience would be > better for users. Trying to create a single PKI that issues a cert > that replaces all of these credentials is just not going to work. Agreed again. What we may see, because it is the only thing that will work, are small PKIs using the DNS as a "directory". These PKIs do not need to interoperate and so they will be useful. But one will not see a single PKI that issues certs for all the DNS space. For that we would need a different beast. Cheers, Ed Gerck PS: IMO the PKI market has been grossly exaggerated. There are only 30,000 servers worldwide that can do SSL -- which limits PKI server certs to that number worldwide, with a factor for virtual server usage. PKI client certs have the private key problem, that cannot be solved by PKI, and has not really taken off (except for military apps, with smart cards controlling access to the private key). And I am not the only saying that PKI is at a dead end. Which is good -- because now perhaps some serious consideration will be given to solutions. PKI is not dead, though. It is just at a dead end.