Internet DRAFT - draft-reschke-httpauth-auth-info
draft-reschke-httpauth-auth-info
Network Working Group J. Reschke
Internet-Draft greenbytes
Intended status: Standards Track January 24, 2015
Expires: July 28, 2015
The Hypertext Transfer Protocol (HTTP) Authentication-Info Header Field
draft-reschke-httpauth-auth-info-00
Abstract
This specification defines the "Authentication-Info" and "Proxy-
Authentication-Info" header fields for use in HTTP authentication
schemes which need to return additional information during or after
authentication.
Editorial Note (To be removed by RFC Editor before publication)
Distribution of this document is unlimited. Although this is not a
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Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. The Authentication-Info Header Field . . . . . . . . . . . . . 3
3.1. Parameter Value Format . . . . . . . . . . . . . . . . . . 3
4. The Proxy-Authentication-Info Header Field . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . . 5
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1. Introduction
This specification defines the "Authentication-Info" and "Proxy-
Authentication-Info" header fields for use in HTTP authentication
schemes ([RFC7235]) which need to return additional information
during or after authentication.
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]), but also 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 Header Field
HTTP authentication schemes can use the Authentication-Info response
header field to return additional information applicable to the
authentication currently in use.
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" will define the individual
parameters. The "Digest" Authentication Scheme, for instance,
defines multiple parameters in Section 3.5.1 of [DIGEST].
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 applicable authentication scheme.
Intermediaries are not allowed to modify the field value in any way.
Authentication-Info can be used inside trailers ([RFC7230], Section
4.1.2).
3.1. Parameter Value Format
Parameter values can be expressed either as "token" or as "quoted-
string" (Section 3.2.6 of [RFC7230]).
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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 Header Field
The Proxy-Authentication-Info header field is equivalent to
Authentication-Info, except that it applies to proxy authentication
([RFC7235]):
Proxy-Authentication-Info = #auth-param
5. Security Considerations
Adding information to HTTP responses 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>, 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 updated accordingly:
+---------------------------+----------+----------+-----------------+
| Header Field Name | Protocol | Status | Reference |
+---------------------------+----------+----------+-----------------+
| Authentication-Info | http | standard | Section 3 of |
| | | | this document |
| Proxy-Authentication-Info | http | standard | Section 4 of |
| | | | this document |
+---------------------------+----------+----------+-----------------+
7. References
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7.1. Normative References
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, June 2014.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235, June 2014.
7.2. Informative References
[BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004.
[DIGEST] Shekh-Yusef, R., Ed., Ahrens, D., and S. Bremer, "HTTP
Digest Access Authentication",
draft-ietf-httpauth-digest-12 (work in progress),
January 2015.
[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.
Author's Address
Julian F. Reschke
greenbytes GmbH
Hafenweg 16
Muenster, NW 48155
Germany
EMail: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/
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