wdiff rfc7615.original rfc7615.txt

HTTP Working Group
Internet Engineering Task Force (IETF) J. Reschke
Internet-Draft
Request for Comments: 7615 greenbytes
Updates:
Obsoletes: 2617 (if approved) April 7, September 2015
Intended status:
Category: Standards Track
Expires: October 9, 2015

The Hypertext Transfer Protocol (HTTP)
ISSN: 2070-1721

HTTP Authentication-Info and Proxy-
Authentication-Info Proxy-Authentication-Info
Response Header Fields
draft-ietf-httpbis-auth-info-05

Abstract

This specification defines the "Authentication-Info" and "Proxy-
Authentication-Info" response header fields for use in HTTP Hypertext
Transfer Protocol (HTTP) authentication schemes which that need to return
information once the client's authentication credentials have been
accepted.

Editorial Note (To be removed by RFC Editor)

Discussion of this draft takes place on the HTTPBIS working group
mailing list (ietf-http-wg@w3.org), which is archived at
<https://lists.w3.org/Archives/Public/ietf-http-wg/>.

Working Group information can be found at
<https://tools.ietf.org/wg/httpbis/> and <http://httpwg.github.io/>;
source code and issues list for this draft can be found at
<https://github.com/httpwg/http-extensions>.

The changes in this draft are summarized in Appendix A.6.

Status of This Memo

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents an Internet Standards Track document.

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This Internet-Draft will expire on October 9, 2015.
http://www.rfc-editor.org/info/rfc7615.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. The Authentication-Info Response Header Field . . . . . . . . . 3
3.1. Parameter Value Format . . . . . . . . . . . . . . . . . . 4
4. The Proxy-Authentication-Info Response Header Field . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . . 5
Appendix A. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . .
Acknowledgements . . . . . . . . . . . . 6
A.1. draft-reschke-httpauth-auth-info-00 . . . . . . . . . . . . 6
A.2. Since draft-ietf-httpbis-auth-info-00 . . . . . . . . .
Author's Address . . 6
A.3. Since draft-ietf-httpbis-auth-info-01 . . . . . . . . . . . 6
A.4. Since draft-ietf-httpbis-auth-info-02 . . . . . . . . . . . 6
A.5. Since draft-ietf-httpbis-auth-info-03 . . . . . . . . . . . 7
A.6. Since draft-ietf-httpbis-auth-info-04 . . . . . . . . . . . 7
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . . 7

1. Introduction

This specification defines the "Authentication-Info" and "Proxy-
Authentication-Info" response header fields for use in HTTP
authentication schemes ([RFC7235]) which that need to return information
once the client's authentication credentials have been accepted.

Both were previously defined in Section 3 of [RFC2617], defining the
HTTP "Digest" authentication scheme. This document generalizes the
description for use not only in "Digest" ([DIGEST]), ([RFC7616]), but also in
other future schemes that might have the same requirements for
carrying additional information during authentication.

2. Notational Conventions

This specification uses the Augmented Backus-Naur Form (ABNF)
notation of [RFC5234] with a list extension, defined in Section 7 of
[RFC7230], that allows for compact definition of comma-separated
lists using a '#' operator (similar to how the '*' operator indicates
repetition). The ABNF production for "auth-param" is defined in
Section 2.1 of [RFC7235].

3. The Authentication-Info Response Header Field

HTTP authentication schemes can use the Authentication-Info response
header field to communicate information after the client's
authentication credentials have been accepted. This information can
include a finalization message from the server (e.g., it can contain
the server authentication).

The field value is a list of parameters (name/value pairs), using the
"auth-param" syntax defined in Section 2.1 of [RFC7235]. This
specification only describes the generic format; authentication
schemes using "Authentication-Info" Authentication-Info will define the individual
parameters. The "Digest" Authentication Scheme, for instance,
defines multiple parameters in Section 3.5 of [DIGEST]. [RFC7616].

Authentication-Info = #auth-param

The Authentication-Info header field can be used in any HTTP
response, independently of request method and status code. Its
semantics are defined by the authentication scheme indicated by the
Authorization header field ([RFC7235], Section 4.2) of the
corresponding request.

A proxy forwarding a response is not allowed to modify the field
value in any way.

Authentication-Info can be used inside trailers ([RFC7230],
Section 4.1.2) when the authentication scheme explicitly allows this.

3.1. Parameter Value Format

Parameter values can be expressed either as "token" or as "quoted-
string" (Section 3.2.6 of [RFC7230]).

Authentication scheme definitions need to allow both notations, both
for senders and recipients. This allows recipients to use generic
parsing components, independent of the authentication scheme in use.

For backwards compatibility, authentication scheme definitions can
restrict the format for senders to one of the two variants. This can
be important when it is known that deployed implementations will fail
when encountering one of the two formats.

4. The Proxy-Authentication-Info Response Header Field

The Proxy-Authentication-Info response header field is equivalent to
Authentication-Info, except that it applies to proxy authentication
([RFC7235], Section 2) and its semantics are defined by the
authentication scheme indicated by the Proxy-Authorization header
field ([RFC7235], Section 4.4) of the corresponding request, and
applies to proxy authentication ([RFC7235], Section 2): request:

Proxy-Authentication-Info = #auth-param

However, unlike Authentication-Info, the Proxy-Authentication-Info
header field applies only to the next outbound client on the response
chain. This is because only the client that chose a given proxy is
likely to have the credentials necessary for authentication.
However, when multiple proxies are used within the same
administrative domain, such as office and regional caching proxies
within a large corporate network, it is common for credentials to be
generated by the user agent and passed through the hierarchy until
consumed. Hence, in such a configuration, it will appear as if
Proxy-Authentication-Info is being forwarded because each proxy will
send the same field value.

5. Security Considerations

Adding information to HTTP responses that are sent over an
unencrypted channel can affect security and privacy. The presence of
the header fields alone indicates that HTTP authentication is in use.
Additional information could be exposed by the contents of the
authentication-scheme specific parameters; this will have to be
considered in the definitions of these schemes.

6. IANA Considerations

HTTP header fields are registered within the "Message Headers"
registry located at
<http://www.iana.org/assignments/message-headers>, <http://www.iana.org/assignments/
message-headers>, as defined by [BCP90].

This document updates the definitions of the "Authentication-Info"
and "Proxy-Authentication-Info" header fields, so the "Permanent
Message Header Field Names" registry shall be has been updated accordingly:

7. References

7.1. Normative References

[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>.

[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>.

[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<http://www.rfc-editor.org/info/rfc7235>.

7.2. Informative References

[BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004, <http://www.rfc-editor.org/info/rfc3864>.

[DIGEST] Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP
Digest Access Authentication",
draft-ietf-httpauth-digest-15 (work in progress),
March 2015. <http://www.rfc-editor.org/info/bcp90>.

[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, DOI 10.17487/RFC2617, June 1999,
<http://www.rfc-editor.org/info/rfc2617>.

Appendix A. Change Log (to be removed by RFC Editor before publication)

A.1. draft-reschke-httpauth-auth-info-00

Changed boilerplate to make this an HTTPbis WG draft. Added
Acknowledgements.

In the Security Considerations, remind people that those apply to
unencryped channels.

Make it clearer that these are really just response header fields.

A.2. Since draft-ietf-httpbis-auth-info-00

Rephrase introduction of header field to be closer to what RFC 2617
said ("successful authentication").

Update DIGEST reference.

A.3. Since draft-ietf-httpbis-auth-info-01

State that scheme definitions need to define whether the header field
can be used in trailers.

Add "updates: 2617" to boilerplate.

A.4. Since draft-ietf-httpbis-auth-info-02

Updated DIGEST reference.

Clarify purpose of header consistently
(<https://github.com/httpwg/http-extensions/issues/49>).

The do-not-modify rule does not include proxies that consume
Authentication-Info
(<https://github.com/httpwg/http-extensions/issues/50>).

Borrow more proxy auth related considerations from RFC 7235 for the
description of Proxy-Authentication-Info
(<https://github.com/httpwg/http-extensions/issues/51>).

A.5. Since draft-ietf-httpbis-auth-info-03

Updated DIGEST reference.

Clarify how the applicable auth scheme is determined (it is present
in the request's (Proxy-)Authorization header field).

Adjust the IPR boilerplate because we are using some text from

[RFC7616] Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP
Digest Access Authentication", RFC
2617.

A.6. Since draft-ietf-httpbis-auth-info-04

Add another clarification about how the applicable scheme for Proxy-
Authentication-Info is determined.

Appendix B. 7616,
DOI 10.17487/RFC7616, September 2015,
<http://www.rfc-editor.org/info/rfc7616>.

Acknowledgements

This document is based on the header field definitions in RFCs 2069
and 2617, whose authors are: John Franks, Phillip M. Hallam-Baker,
Jeffery L. Hostetler, Scott D. Lawrence, Paul J. Leach, Ari Luotonen,
Eric W. Sink, and Lawrence C. Stewart.

Additional thanks go to the members of the HTTPAuth HTTPAUTH and HTTPbis HTTPBIS
Working Groups, namely namely, Amos Jeffries, Benjamin Kaduk, Alexey
Melnikov, Mark Nottingham, Yutaka Oiwa, Rifaat Shekh-Yusef, and
Martin Thomson.

Author's Address

Julian F. Reschke
greenbytes GmbH
Hafenweg 16
Muenster, NW 48155
Germany

EMail:

Email: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/