Internet Engineering Task Force (IETF) Y. Pettersen
Request for Comments: 6961 June 2013
Category: Standards Track
ISSN: 2070-1721
The Transport Layer Security (TLS)
Multiple Certificate Status Request Extension
Abstract
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
about not only the server's own certificate but also the status of
intermediate certificates in the chain.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6961.
Pettersen Standards Track [Page 1]RFC 6961 Multiple Certificate Status Extension June 2013Copyright Notice
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1. Introduction
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
server.
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 prevent a
client from offering the server multiple status methods.
Pettersen Standards Track [Page 2]RFC 6961 Multiple Certificate Status Extension June 2013
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 [RFC6960]
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 issuing CA is less
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