Internet DRAFT - draft-thomson-httpbis-catch
draft-thomson-httpbis-catch
HTTPBIS M. Thomson
Internet-Draft Mozilla
Intended status: Standards Track March 9, 2014
Expires: September 10, 2014
Client Authentication over TLS Connection Header
draft-thomson-httpbis-catch-00
Abstract
This document defines an HTTP header field that can be added to a
response to indicate to a client that a response will only be
provided over a TLS connection, and only if the client has provided a
certificate on that connection.
Status of This Memo
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This Internet-Draft will expire on September 10, 2014.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions and Terminology . . . . . . . . . . . . . . . 2
2. Client Certificate Challenge . . . . . . . . . . . . . . . . 2
3. Security Considerations . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . 4
6.2. Informational References . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
Client authentication in HTTP sometimes relies on certificate-based
authentication of clients in TLS. Some uses of client authentication
rely on Transport Layer Security (TLS) [RFC5246] renegotiation,
triggering renegotiation in response to a request for a particular
resource.
HTTP/2 [I-D.ietf-httpbis-http2] forbids the use of renegotiation,
except for at the very beginning of a connection. This makes
addressing some client authentication use cases difficult.
This document defines a new type of authentication scheme,
"ClientCertificate" for use in HTTP authentication challenges
[I-D.ietf-httpbis-p7-auth]. In combination with the 401
(Unauthorized) status code, this indicates that the resource requires
client authentication at the TLS layer in order to access it.
1.1. Conventions and Terminology
At times, this document falls back on shorthands for establishing
interoperability requirements on implementations: the capitalized
words "MUST", "SHOULD" and "MAY". These terms are defined in
[RFC2119].
2. Client Certificate Challenge
A new kind of authentication scheme (auth-scheme
[I-D.ietf-httpbis-p7-auth]) for the "WWW-Authenticate" and "Proxy-
Authenticate" header fields is defined with the name
"ClientCertificate".
A challenge with this auth-scheme does not define the use of any
parameters other than "realm". Other parameters MAY be used to
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provide a client with information it can use to select an appropriate
certificate. Unknown parameters MUST be ignored.
This challenge cannot be satisfied by constructing an Authorization
header field [I-D.ietf-httpbis-p7-auth], it can only be satisfied by
making the request on a TLS connection where an appropriate
certificate has been provided by the client.
A client can use this information as a trigger to open a new
connection and to use client authentication on that connection. The
client can use the mechanism in [I-D.thomson-tls-care] to prompt the
server to request a client certificate, to avoid the problem where
the server doesn't know to make this request.
3. Security Considerations
Clients that support this authentication scheme will create a new
connection each time that they see a challenge. This could be
exploited in order to generate additional load in terms of
connections on both server and client.
Using new connections for client authentication has additional
processing costs to the client in proving access to the private keys
associated with the client certificate; and to the server in proving
access to the private keys associated with their certificate twice in
the case that the client opts for confidentiality protection on the
client certificate.
HTTP/2 [I-D.ietf-httpbis-http2] allows clients to use the same
connection for multiple origins [RFC6454]. Certificate-based client
authentication as defined by this specification is bound to a single
origin. This could create issues whereby the security properties of
a connection could become confused. Clients MUST ensure that a
client-authenticated connection is only used for the origin for which
it was created.
4. IANA Considerations
IANA will [has] create[d] an entry in the HTTP Authentication Scheme
Registry with the following information:
ClientCertificate
RFCXXXX (this document)
This scheme does not rely on the Authorization header field.
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5. Acknowledgements
Eric Rescorla helped identify the problem and formulate this
mechanism. Julian Reschke hasn't provided any contribution yet, but
he will.
6. References
6.1. Normative References
[I-D.ietf-httpbis-p7-auth]
Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Authentication", draft-ietf-httpbis-p7-auth-26
(work in progress), February 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication",
RFC 2617, June 1999.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, December
2011.
6.2. Informational References
[I-D.ietf-httpbis-http2]
Belshe, M., Peon, R., and M. Thomson, "Hypertext Transfer
Protocol version 2", draft-ietf-httpbis-http2-10 (work in
progress), February 2014.
[I-D.thomson-tls-care]
Thomson, M., draft-thomson-tls-care-00 (work in progress),
March 2014.
Author's Address
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Martin Thomson
Mozilla
Suite 300
650 Castro Street
Mountain View, CA 94041
US
Email: martin.thomson@gmail.com
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