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24 25 26 RFC 7235
HTTPbis Working Group R. Fielding, Ed.
Internet-Draft Day Software
Obsoletes: 2616 (if approved) J. Gettys
Updates: 2617 (if approved) One Laptop per Child
Intended status: Standards Track J. Mogul
Expires: September 10, 2009 HP
H. Frystyk
Microsoft
L. Masinter
Adobe Systems
P. Leach
Microsoft
T. Berners-Lee
W3C/MIT
Y. Lafon, Ed.
W3C
J. Reschke, Ed.
greenbytes
March 9, 2009
HTTP/1.1, part 7: Authentication
draft-ietf-httpbis-p7-auth-06
Status of this Memo
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Abstract
The Hypertext Transfer Protocol (HTTP) is an application-level
protocol for distributed, collaborative, hypermedia information
systems. HTTP has been in use by the World Wide Web global
information initiative since 1990. This document is Part 7 of the
seven-part specification that defines the protocol referred to as
"HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 7 defines
HTTP Authentication.
Editorial Note (To be removed by RFC Editor)
Discussion of this draft should take place on the HTTPBIS working
group mailing list (ietf-http-wg@w3.org). The current issues list is
at <http://tools.ietf.org/wg/httpbis/trac/report/11> and related
documents (including fancy diffs) can be found at
<http://tools.ietf.org/wg/httpbis/>.
The changes in this draft are summarized in Appendix C.7.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 4
1.2.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 5
1.2.2. ABNF Rules defined in other Parts of the
Specification . . . . . . . . . . . . . . . . . . . . 5
2. Status Code Definitions . . . . . . . . . . . . . . . . . . . 5
2.1. 401 Unauthorized . . . . . . . . . . . . . . . . . . . . . 5
2.2. 407 Proxy Authentication Required . . . . . . . . . . . . 5
3. Header Field Definitions . . . . . . . . . . . . . . . . . . . 5
3.1. Authorization . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . . 7
3.3. Proxy-Authorization . . . . . . . . . . . . . . . . . . . 7
3.4. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
4.1. Message Header Registration . . . . . . . . . . . . . . . 8
5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
5.1. Authentication Credentials and Idle Clients . . . . . . . 8
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative References . . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . . 10
Appendix A. Compatibility with Previous Versions . . . . . . . . 10
A.1. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 10
Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 10
Appendix C. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 11
C.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 11
C.2. Since draft-ietf-httpbis-p7-auth-00 . . . . . . . . . . . 11
C.3. Since draft-ietf-httpbis-p7-auth-01 . . . . . . . . . . . 11
C.4. Since draft-ietf-httpbis-p7-auth-02 . . . . . . . . . . . 11
C.5. Since draft-ietf-httpbis-p7-auth-03 . . . . . . . . . . . 11
C.6. Since draft-ietf-httpbis-p7-auth-04 . . . . . . . . . . . 11
C.7. Since draft-ietf-httpbis-p7-auth-05 . . . . . . . . . . . 12
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13
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1. Introduction
This document defines HTTP/1.1 access control and authentication.
Right now it includes the extracted relevant sections of RFC 2616
with only minor changes. The intention is to move the general
framework for HTTP authentication here, as currently specified in
[RFC2617], and allow the individual authentication mechanisms to be
defined elsewhere. This introduction will be rewritten when that
occurs.
HTTP provides several OPTIONAL challenge-response authentication
mechanisms which can be used by a server to challenge a client
request and by a client to provide authentication information. The
general framework for access authentication, and the specification of
"basic" and "digest" authentication, are specified in "HTTP
Authentication: Basic and Digest Access Authentication" [RFC2617].
This specification adopts the definitions of "challenge" and
"credentials" from that specification.
1.1. Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
An implementation is not compliant if it fails to satisfy one or more
of the MUST or REQUIRED level requirements for the protocols it
implements. An implementation that satisfies all the MUST or
REQUIRED level and all the SHOULD level requirements for its
protocols is said to be "unconditionally compliant"; one that
satisfies all the MUST level requirements but not all the SHOULD
level requirements for its protocols is said to be "conditionally
compliant."
1.2. Syntax Notation
This specification uses the ABNF syntax defined in Section 1.2 of
[Part1] (which extends the syntax defined in [RFC5234] with a list
rule). Appendix B shows the collected ABNF, with the list rule
expanded.
The following core rules are included by reference, as defined in
[RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF
(CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote),
HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit
sequence of data), SP (space), VCHAR (any visible USASCII character),
and WSP (whitespace).
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1.2.1. Core Rules
The core rules below are defined in Section 1.2.2 of [Part1]:
OWS = <OWS, defined in [Part1], Section 1.2.2>
1.2.2. ABNF Rules defined in other Parts of the Specification
The ABNF rules below are defined in other specifications:
challenge = <challenge, defined in [RFC2617], Section 1.2>
credentials = <credentials, defined in [RFC2617], Section 1.2>
2. Status Code Definitions
2.1. 401 Unauthorized
The request requires user authentication. The response MUST include
a WWW-Authenticate header field (Section 3.4) containing a challenge
applicable to the requested resource. The client MAY repeat the
request with a suitable Authorization header field (Section 3.1). If
the request already included Authorization credentials, then the 401
response indicates that authorization has been refused for those
credentials. If the 401 response contains the same challenge as the
prior response, and the user agent has already attempted
authentication at least once, then the user SHOULD be presented the
entity that was given in the response, since that entity might
include relevant diagnostic information. HTTP access authentication
is explained in "HTTP Authentication: Basic and Digest Access
Authentication" [RFC2617].
2.2. 407 Proxy Authentication Required
This code is similar to 401 (Unauthorized), but indicates that the
client must first authenticate itself with the proxy. The proxy MUST
return a Proxy-Authenticate header field (Section 3.2) containing a
challenge applicable to the proxy for the requested resource. The
client MAY repeat the request with a suitable Proxy-Authorization
header field (Section 3.3). HTTP access authentication is explained
in "HTTP Authentication: Basic and Digest Access Authentication"
[RFC2617].
3. Header Field Definitions
This section defines the syntax and semantics of HTTP/1.1 header
fields related to authentication.
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3.1. Authorization
A user agent that wishes to authenticate itself with a server--
usually, but not necessarily, after receiving a 401 response--does so
by including an Authorization request-header field with the request.
The field "Authorization" consists of credentials containing the
authentication information of the user agent for the realm of the
resource being requested.
Authorization = "Authorization" ":" OWS Authorization-v
Authorization-v = credentials
HTTP access authentication is described in "HTTP Authentication:
Basic and Digest Access Authentication" [RFC2617]. If a request is
authenticated and a realm specified, the same credentials SHOULD be
valid for all other requests within this realm (assuming that the
authentication scheme itself does not require otherwise, such as
credentials that vary according to a challenge value or using
synchronized clocks).
When a shared cache (see Section 1.2 of [Part6]) receives a request
containing an Authorization field, it MUST NOT return the
corresponding response as a reply to any other request, unless one of
the following specific exceptions holds:
1. If the response includes the "s-maxage" cache-control directive,
the cache MAY use that response in replying to a subsequent
request. But (if the specified maximum age has passed) a proxy
cache MUST first revalidate it with the origin server, using the
request-headers from the new request to allow the origin server
to authenticate the new request. (This is the defined behavior
for s-maxage.) If the response includes "s-maxage=0", the proxy
MUST always revalidate it before re-using it.
2. If the response includes the "must-revalidate" cache-control
directive, the cache MAY use that response in replying to a
subsequent request. But if the response is stale, all caches
MUST first revalidate it with the origin server, using the
request-headers from the new request to allow the origin server
to authenticate the new request.
3. If the response includes the "public" cache-control directive, it
MAY be returned in reply to any subsequent request.
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3.2. Proxy-Authenticate
The response-header field "Proxy-Authenticate" MUST be included as
part of a 407 (Proxy Authentication Required) response. The field
value consists of a challenge that indicates the authentication
scheme and parameters applicable to the proxy for this request-
target.
Proxy-Authenticate = "Proxy-Authenticate" ":" OWS
Proxy-Authenticate-v
Proxy-Authenticate-v = 1#challenge
The HTTP access authentication process is described in "HTTP
Authentication: Basic and Digest Access Authentication" [RFC2617].
Unlike WWW-Authenticate, the Proxy-Authenticate header field applies
only to the current connection and SHOULD NOT be passed on to
downstream clients. However, an intermediate proxy might need to
obtain its own credentials by requesting them from the downstream
client, which in some circumstances will appear as if the proxy is
forwarding the Proxy-Authenticate header field.
3.3. Proxy-Authorization
The request-header field "Proxy-Authorization" allows the client to
identify itself (or its user) to a proxy which requires
authentication. The Proxy-Authorization field value consists of
credentials containing the authentication information of the user
agent for the proxy and/or realm of the resource being requested.
Proxy-Authorization = "Proxy-Authorization" ":" OWS
Proxy-Authorization-v
Proxy-Authorization-v = credentials
The HTTP access authentication process is described in "HTTP
Authentication: Basic and Digest Access Authentication" [RFC2617].
Unlike Authorization, the Proxy-Authorization header field applies
only to the next outbound proxy that demanded authentication using
the Proxy-Authenticate field. When multiple proxies are used in a
chain, the Proxy-Authorization header field is consumed by the first
outbound proxy that was expecting to receive credentials. A proxy
MAY relay the credentials from the client request to the next proxy
if that is the mechanism by which the proxies cooperatively
authenticate a given request.
3.4. WWW-Authenticate
The WWW-Authenticate response-header field MUST be included in 401
(Unauthorized) response messages. The field value consists of at
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least one challenge that indicates the authentication scheme(s) and
parameters applicable to the request-target.
WWW-Authenticate = "WWW-Authenticate" ":" OWS WWW-Authenticate-v
WWW-Authenticate-v = 1#challenge
The HTTP access authentication process is described in "HTTP
Authentication: Basic and Digest Access Authentication" [RFC2617].
User agents are advised to take special care in parsing the WWW-
Authenticate field value as it might contain more than one challenge,
or if more than one WWW-Authenticate header field is provided, the
contents of a challenge itself can contain a comma-separated list of
authentication parameters.
4. IANA Considerations
4.1. Message Header Registration
The Message Header Registry located at <http://www.iana.org/
assignments/message-headers/message-header-index.html> should be
updated with the permanent registrations below (see [RFC3864]):
+---------------------+----------+----------+-------------+
| Header Field Name | Protocol | Status | Reference |
+---------------------+----------+----------+-------------+
| Authorization | http | standard | Section 3.1 |
| Proxy-Authenticate | http | standard | Section 3.2 |
| Proxy-Authorization | http | standard | Section 3.3 |
| WWW-Authenticate | http | standard | Section 3.4 |
+---------------------+----------+----------+-------------+
The change controller is: "IETF (iesg@ietf.org) - Internet
Engineering Task Force".
5. Security Considerations
This section is meant to inform application developers, information
providers, and users of the security limitations in HTTP/1.1 as
described by this document. The discussion does not include
definitive solutions to the problems revealed, though it does make
some suggestions for reducing security risks.
5.1. Authentication Credentials and Idle Clients
Existing HTTP clients and user agents typically retain authentication
information indefinitely. HTTP/1.1 does not provide a method for a
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server to direct clients to discard these cached credentials. This
is a significant defect that requires further extensions to HTTP.
Circumstances under which credential caching can interfere with the
application's security model include but are not limited to:
o Clients which have been idle for an extended period following
which the server might wish to cause the client to reprompt the
user for credentials.
o Applications which include a session termination indication (such
as a `logout' or `commit' button on a page) after which the server
side of the application `knows' that there is no further reason
for the client to retain the credentials.
This is currently under separate study. There are a number of work-
arounds to parts of this problem, and we encourage the use of
password protection in screen savers, idle time-outs, and other
methods which mitigate the security problems inherent in this
problem. In particular, user agents which cache credentials are
encouraged to provide a readily accessible mechanism for discarding
cached credentials under user control.
6. Acknowledgments
[[anchor2: TBD.]]
7. References
7.1. Normative References
[Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections,
and Message Parsing", draft-ietf-httpbis-p1-messaging-06
(work in progress), March 2009.
[Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
and J. Reschke, Ed., "HTTP/1.1, part 6: Caching",
draft-ietf-httpbis-p6-cache-06 (work in progress),
March 2009.
[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.,
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Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication",
RFC 2617, June 1999.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
7.2. Informative References
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004.
Appendix A. Compatibility with Previous Versions
A.1. Changes from RFC 2616
Appendix B. Collected ABNF
Authorization = "Authorization:" OWS Authorization-v
Authorization-v = credentials
OWS = <OWS, defined in [Part1], Section 1.2.2>
Proxy-Authenticate = "Proxy-Authenticate:" OWS Proxy-Authenticate-v
Proxy-Authenticate-v = *( "," OWS ) challenge *( OWS "," [ OWS
challenge ] )
Proxy-Authorization = "Proxy-Authorization:" OWS
Proxy-Authorization-v
Proxy-Authorization-v = credentials
WWW-Authenticate = "WWW-Authenticate:" OWS WWW-Authenticate-v
WWW-Authenticate-v = *( "," OWS ) challenge *( OWS "," [ OWS
challenge ] )
challenge = <challenge, defined in [RFC2617], Section 1.2>
credentials = <credentials, defined in [RFC2617], Section 1.2>
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ABNF diagnostics:
; Authorization defined but not used
; Proxy-Authenticate defined but not used
; Proxy-Authorization defined but not used
; WWW-Authenticate defined but not used
Appendix C. Change Log (to be removed by RFC Editor before publication)
C.1. Since RFC2616
Extracted relevant partitions from [RFC2616].
C.2. Since draft-ietf-httpbis-p7-auth-00
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/35>: "Normative and
Informative references"
C.3. Since draft-ietf-httpbis-p7-auth-01
Ongoing work on ABNF conversion
(<http://tools.ietf.org/wg/httpbis/trac/ticket/36>):
o Explicitly import BNF rules for "challenge" and "credentials" from
RFC2617.
o Add explicit references to BNF syntax and rules imported from
other parts of the specification.
C.4. Since draft-ietf-httpbis-p7-auth-02
Ongoing work on IANA Message Header Registration
(<http://tools.ietf.org/wg/httpbis/trac/ticket/40>):
o Reference RFC 3984, and update header registrations for headers
defined in this document.
C.5. Since draft-ietf-httpbis-p7-auth-03
C.6. Since draft-ietf-httpbis-p7-auth-04
Ongoing work on ABNF conversion
(<http://tools.ietf.org/wg/httpbis/trac/ticket/36>):
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o Use "/" instead of "|" for alternatives.
o Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
whitespace ("OWS") and required whitespace ("RWS").
o Rewrite ABNFs to spell out whitespace rules, factor out header
value format definitions.
C.7. Since draft-ietf-httpbis-p7-auth-05
Final work on ABNF conversion
(<http://tools.ietf.org/wg/httpbis/trac/ticket/36>):
o Add appendix containing collected and expanded ABNF, reorganize
ABNF introduction.
Index
4
401 Unauthorized (status code) 5
407 Proxy Authentication Required (status code) 5
A
Authorization header 6
G
Grammar
Authorization 6
Authorization-v 6
challenge 5
credentials 5
Proxy-Authenticate 7
Proxy-Authenticate-v 7
Proxy-Authorization 7
Proxy-Authorization-v 7
WWW-Authenticate 8
WWW-Authenticate-v 8
H
Headers
Authorization 6
Proxy-Authenticate 7
Proxy-Authorization 7
WWW-Authenticate 7
P
Proxy-Authenticate header 7
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Proxy-Authorization header 7
S
Status Codes
401 Unauthorized 5
407 Proxy Authentication Required 5
W
WWW-Authenticate header 7
Authors' Addresses
Roy T. Fielding (editor)
Day Software
23 Corporate Plaza DR, Suite 280
Newport Beach, CA 92660
USA
Phone: +1-949-706-5300
Fax: +1-949-706-5305
Email: fielding@gbiv.com
URI: http://roy.gbiv.com/
Jim Gettys
One Laptop per Child
21 Oak Knoll Road
Carlisle, MA 01741
USA
Email: jg@laptop.org
URI: http://www.laptop.org/
Jeffrey C. Mogul
Hewlett-Packard Company
HP Labs, Large Scale Systems Group
1501 Page Mill Road, MS 1177
Palo Alto, CA 94304
USA
Email: JeffMogul@acm.org
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Henrik Frystyk Nielsen
Microsoft Corporation
1 Microsoft Way
Redmond, WA 98052
USA
Email: henrikn@microsoft.com
Larry Masinter
Adobe Systems, Incorporated
345 Park Ave
San Jose, CA 95110
USA
Email: LMM@acm.org
URI: http://larry.masinter.net/
Paul J. Leach
Microsoft Corporation
1 Microsoft Way
Redmond, WA 98052
Email: paulle@microsoft.com
Tim Berners-Lee
World Wide Web Consortium
MIT Computer Science and Artificial Intelligence Laboratory
The Stata Center, Building 32
32 Vassar Street
Cambridge, MA 02139
USA
Email: timbl@w3.org
URI: http://www.w3.org/People/Berners-Lee/
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Yves Lafon (editor)
World Wide Web Consortium
W3C / ERCIM
2004, rte des Lucioles
Sophia-Antipolis, AM 06902
France
Email: ylafon@w3.org
URI: http://www.raubacapeu.net/people/yves/
Julian F. Reschke (editor)
greenbytes GmbH
Hafenweg 16
Muenster, NW 48155
Germany
Phone: +49 251 2807760
Fax: +49 251 2807761
Email: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/
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