Subject: Why is dcs-00's scalability deprecated?

From: "Linn, John" <[email-masked]>
Date: Wed, 2 Dec 1998 12:22:24 -0500

In reviewing the dcs-00 draft, I believe that this represents a valuable and
versatile service. There's a paragraph in its introduction which I'm
wondering about:

"It is not recommended that the DCS be used as a substitute for normal
public key certificate revocation checking (e.g., CRLs, OCSP) in large
environments, due to concerns about the scalability of this protocol.  It
should only be used to support non-repudiation or to supplement more
traditional revocation services when more timely information is required." 

Why is the scalability of DCS, if applied for certificate validation
purposes using unsigned cpkc requests, sufficiently different from OCSP's as
to motivate this deprecation?  Is the driving issue that DCSReqInfo's
mandated nonces (vs. requester ID and reqTime, which are optional) prevent
response preproduction, the potential that chain validations could prove
costly to aggregate at a common responder, and/or what other concerns are
being considered here?

Any clarifications and thoughts appreciated.

--jl

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From: Robert Zuccherato <[email-masked]>
Date: Wed, 2 Dec 1998 17:21:17 -0500

John;

We were considering both of the issues you mentioned as reasons for being
concerned about the scalability of DCS.  Primarily though, it was the fact
that each response must be individually constructed, thus preventing
response preproduction and caching, that made us feel that this protocol is
not appropriate for normal cert revocation checking.  

I would note that if responses were not preproduced by an OCSP responder,
then the two protocols would be approximately equivalent with respect to
scalability.

	Robert.

> ----------
> From: 	Linn, John[SMTP:[email-masked]]
> Sent: 	Wednesday, December 02, 1998 12:22 PM
> To: 	[email-masked]'
> Subject: 	Why is dcs-00's scalability deprecated?
>