[TLS] CRL Stapling? (was Re: I-D Action: draft-ietf-tls-multiple-cert-status-extension-00.txt)

Yngve,

IIRC, when Opera does an online revocation check, it currently checks 
CRLs for intermediate CA certificates and OCSP for end-entity 
certificates.  This makes sense because:
   - CRLs covering intermediate CA certificates tend to be roughly the 
same size (sometimes smaller!) as the equivalent OCSP Responses (since 
it's quite rare for intermediate CA certificates to be revoked).
   - Possessing a current CRL means you won't have to do an online 
revocation check if you encounter another certificate issued by the same 
issuer.

How would you feel about updating the multi-stapling I-D so that it 
permits CRLs to be stapled (with a note to implementers that they should 
only staple CRLs that are deemed to be "small enough")?

Simply adding something like "case crl_multi: CRLList;" to your 
definition of CertificateStatus.response would be problematic, because 
it would require the server to staple a (potentially huge!) CRL for the 
end-entity certificate too.  So...

How about changing the scope of the multi-stapling I-D so that it *only* 
covers the intermediate CA certificate(s) in the chain?

With this approach, an end-entity OCSP Response could be stapled using 
the RFC6066 TLS extension, and the intermediate CRL(s) could be stapled 
using the new multi-stapling TLS extension.

(End-entity certificate stapling is already defined in RFC6066 and this 
existing TLS extension is already supported by many clients and servers. 
  So why not make the multi-stapling TLS extension complement it, rather 
than replace it?)

On 09/05/12 16:35, internet-drafts@ietf.org wrote:
>
> A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Transport Layer Security Working Group of the IETF.
>
> 	Title           : The TLS Multiple Certificate Status Request Extension
> 	Author(s)       : Yngve N. Pettersen
> 	Filename        : draft-ietf-tls-multiple-cert-status-extension-00.txt
> 	Pages           : 9
> 	Date            : 2012-05-09
>
>     This document defines the Transport Layer Security (TLS) Certificate
>     Status Version 2 Extension to allow clients to specify and support
>     multiple certificate status methods.  Also defined is a new method
>     based on the Online Certificate Status Protocol (OCSP) that servers
>     can use to provide status information not just about the server's own
>     certificate, but also the status of intermediate certificates in the
>     chain.
>
>
>
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-ietf-tls-multiple-cert-status-extension-00.txt
>
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>
> This Internet-Draft can be retrieved at:
> ftp://ftp.ietf.org/internet-drafts/draft-ietf-tls-multiple-cert-status-extension-00.txt
>
> The IETF datatracker page for this Internet-Draft is:
> https://datatracker.ietf.org/doc/draft-ietf-tls-multiple-cert-status-extension/
>
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>

-- 
Rob Stradling
Senior Research & Development Scientist
COMODO - Creating Trust Online