On Wed, Jul 28, 2010 at 10:42:43AM -0400, Anne & Lynn Wheeler wrote:
> On 07/28/2010 10:05 AM, Perry E. Metzger wrote:
> >I will point out that many security systems, like Kerberos, DNSSEC and
> >SSH, appear to get along with no conventional notion of revocation at all.
> long ago and far away ... one of the tasks we had was to periodically
> go by project athena to "audit" various activities ... including
> Kerberos. The original PK-INIT for kerberos was effectively
> certificateless public key ... 

And PKINIT today also allows for rp-only user certs if you want them.
They must be certificates, but they needn't carry any useful data beyond
the subject public key, and the KDC must know the {principal,
cert|pubkey} associations.

> An issue with Kerberos (as well as RADIUS ... another major
> authentication mechanism) ... is that account-based operation is
> integral to its operation ... unless one is willing to go to a
> strictly certificate-only mode ... where all information about an
> individuals authority and access privileges are also carried in the
> certificate (and eliminate the account records totally).

This is true time you have rp-only certs or certs that carry less
information than the rp will require.  The latter almost always true.
The account can be local to each rp, however, or centralized -- that's
up to the relying parties.

> As long as the account record has to be accessed as part of the
> process ... the certificate remains purely redundant and superfluous
> (in fact, some number of operations running large Kerberos based
> infrastructure have come to realize that they have large redundant
> administrative activity maintaining both the account-based information
> as well as the duplicate PKI certificate-based information).

Agreed.  Certificates should, as much as possible, be rp-only.

> The account-based operations have sense of revocation by updating the
> account-based records. [...]

Exactly.  OCSP can work in that manner.  CRLs cannot.  In terms of
administration updating an account record is much simpler than updating
a CRL (because much less information needs to be available for the
former than for the latter).

> The higher-value operations tend to be able to justify the real-time,
> higher quality, and finer grain information provided by an
> account-based infrastructure ... and as internet and technology has
> reduced the costs and pervasiveness of such operations ... it further
> pushes PKI, certificate-based mode of operation further and further
> into no-value market niches.

Are you arguing for Kerberos for Internet-scale deployment?  Or simply
for PKI with rp-only certs and OCSP?  Or other "federated"
authentication mechanism?  Or all of the above?  :)


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