Network Working Group Y. Pettersen
Internet-Draft April 12, 2013
Intended status: Standards Track
Expires: October 14, 2013
The TLS Multiple Certificate Status Request Extension
This document defines the Transport Layer Security (TLS) Certificate
Status Version 2 Extension to allow clients to specify and support
several certificate status methods. (The use of the Certificate
Status extension is commonly referred to as "OCSP stapling".) 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.
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Internet-Draft Multiple Certificate Status Extension April 2013
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The Transport Layer Security (TLS) Extension [RFC6066] framework
defines, among other extensions, the Certificate Status Extension
(also referred to as "OCSP stapling") that clients can use to request
the server's copy of the current status of its certificate. The
benefits of this extension include a reduced number of roundtrips and
network delays for the client to verify the status of the server's
certificate and a reduced load on the certificate issuer's status
response servers, thus solving a problem that can become significant
when the issued certificate is presented by a frequently visited
There are two problems with the existing Certificate Status
extension. First, it does not provide functionality to request the
status information about intermediate Certification Authority (CA)
certificates, which means the client has to request status
information through other methods, such as Certificate Revocation
Lists (CRLs), introducing further delays. Second, the current format
of the extension and requirements in the TLS protocol prevents a
client from offering the server multiple status methods.
Many CAs are now issuing intermediate CA certificates that not only
specify the publication point for their CRLs in a CRL Distribution
Point [RFC5280], but also specify a URL for their OCSP
[I-D.ietf-pkix-rfc2560bis] server in Authority Information Access
[RFC5280]. Given that client-cached CRLs are frequently out of date,
clients would benefit from using OCSP to access up-to-date status
information about intermediate CA certificates. The benefit to the