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Re: CRL format revision -Reply -Reply
I should have perhaps underscored the problem that would result
from having to revoke a CA's certificate, especially. Just reissuing that
certificate wouldn't be enough -- you would have to reissue all of the
subordinate certificates as well.
I agree that the use of a suspense feature until the user confirms receipt
could be handled in many, perhaps most cases, by a not valid until date,
and if the user hasn't responded by then you revoke it. The suspense
feature might offer a little more finesse, but this application by itself
wouldn't justify implementing it.
In general I agree with the rest of Brian's observations, and am
humbled and flattered by his opening remarks.
I apologize if some of this information has been covered before --
I have only been reading the SPKI postings with one eye, as it
were, as I'm up to my ears in some other efforts.
>One last thing: on non-repudiation, I consider myself even less an
authority than on some of this. However, it seems to me that two
things have to be established: 1) the signature happened at the time
indicated; and 2) the certificate binding the signing key to some
legally-verifiable identity was valid at that time. 1) is accomplished
rather simply using Haber & Stornetta's "Surety" service at the time of
the signing; 2) seems the hard part to me, and it seems that, at
minimum, a similar certification of the CRL existing at the time is
needed. The nice thing is that Surety-style services don't really need
to meet traditional TTP trust requirements since everything they do is
publicly verifiable as a matter of public record. I don't see how
anything in either the structure of either a certificate or a CRL could
The Haber/Stornetta service certainly satisfies the signature
timestamping requirement, although I'm not sure exactly how
that gets appended to the document itself (I may have forgotten some
of the important aspects of their system.)
One of the things that the State of Utah has done recently is to issue
an RFP for both CA tools and digital signature applications, and
in particular a licensed repository. I think it is worth noting that
the concept of a trusted third party repository that is independent of
most CAs, but which would reliably represent the status of their
certificates extends the existing paradigm in new and interesting ways.
Once the contract is awarded, it is going to be well worth observing
how all of this plays out, for I think this represents some important new
thinking in the area of non-repudiation.