draft-ietf-httpbis-p7-auth-25.txt   draft-ietf-httpbis-p7-auth-26.txt 
HTTPbis Working Group R. Fielding, Ed. HTTPbis Working Group R. Fielding, Ed.
Internet-Draft Adobe Internet-Draft Adobe
Obsoletes: 2616 (if approved) J. Reschke, Ed. Obsoletes: 2616 (if approved) J. Reschke, Ed.
Updates: 2617 (if approved) greenbytes Updates: 2617 (if approved) greenbytes
Intended status: Standards Track November 17, 2013 Intended status: Standards Track February 6, 2014
Expires: May 21, 2014 Expires: August 10, 2014
Hypertext Transfer Protocol (HTTP/1.1): Authentication Hypertext Transfer Protocol (HTTP/1.1): Authentication
draft-ietf-httpbis-p7-auth-25 draft-ietf-httpbis-p7-auth-26
Abstract Abstract
The Hypertext Transfer Protocol (HTTP) is an application-level The Hypertext Transfer Protocol (HTTP) is a stateless application-
protocol for distributed, collaborative, hypermedia information level protocol for distributed, collaborative, hypermedia information
systems. This document defines the HTTP Authentication framework. systems. This document defines the HTTP Authentication framework.
Editorial Note (To be removed by RFC Editor) Editorial Note (To be removed by RFC Editor)
Discussion of this draft takes place on the HTTPBIS working group Discussion of this draft takes place on the HTTPBIS working group
mailing list (ietf-http-wg@w3.org), which is archived at mailing list (ietf-http-wg@w3.org), which is archived at
<http://lists.w3.org/Archives/Public/ietf-http-wg/>. <http://lists.w3.org/Archives/Public/ietf-http-wg/>.
The current issues list is at The current issues list is at
<http://tools.ietf.org/wg/httpbis/trac/report/3> and related <http://tools.ietf.org/wg/httpbis/trac/report/3> and related
documents (including fancy diffs) can be found at documents (including fancy diffs) can be found at
<http://tools.ietf.org/wg/httpbis/>. <http://tools.ietf.org/wg/httpbis/>.
The changes in this draft are summarized in Appendix D.1. The changes in this draft are summarized in Appendix D.2.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 21, 2014. This Internet-Draft will expire on August 10, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 3, line 17 skipping to change at page 3, line 17
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Conformance and Error Handling . . . . . . . . . . . . . . 4 1.1. Conformance and Error Handling . . . . . . . . . . . . . . 4
1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 4 1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 4
2. Access Authentication Framework . . . . . . . . . . . . . . . 4 2. Access Authentication Framework . . . . . . . . . . . . . . . 4
2.1. Challenge and Response . . . . . . . . . . . . . . . . . . 4 2.1. Challenge and Response . . . . . . . . . . . . . . . . . . 4
2.2. Protection Space (Realm) . . . . . . . . . . . . . . . . . 6 2.2. Protection Space (Realm) . . . . . . . . . . . . . . . . . 6
3. Status Code Definitions . . . . . . . . . . . . . . . . . . . 7 3. Status Code Definitions . . . . . . . . . . . . . . . . . . . 7
3.1. 401 Unauthorized . . . . . . . . . . . . . . . . . . . . . 7 3.1. 401 Unauthorized . . . . . . . . . . . . . . . . . . . . . 7
3.2. 407 Proxy Authentication Required . . . . . . . . . . . . 7 3.2. 407 Proxy Authentication Required . . . . . . . . . . . . 7
4. Header Field Definitions . . . . . . . . . . . . . . . . . . . 7 4. Header Field Definitions . . . . . . . . . . . . . . . . . . . 7
4.1. Authorization . . . . . . . . . . . . . . . . . . . . . . 7 4.1. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 8
4.2. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . . 8 4.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 8
4.3. Proxy-Authorization . . . . . . . . . . . . . . . . . . . 8 4.3. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . . 9
4.4. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 9 4.4. Proxy-Authorization . . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
5.1. Authentication Scheme Registry . . . . . . . . . . . . . . 10 5.1. Authentication Scheme Registry . . . . . . . . . . . . . . 10
5.1.1. Procedure . . . . . . . . . . . . . . . . . . . . . . 10 5.1.1. Procedure . . . . . . . . . . . . . . . . . . . . . . 10
5.1.2. Considerations for New Authentication Schemes . . . . 10 5.1.2. Considerations for New Authentication Schemes . . . . 10
5.2. Status Code Registration . . . . . . . . . . . . . . . . . 11 5.2. Status Code Registration . . . . . . . . . . . . . . . . . 12
5.3. Header Field Registration . . . . . . . . . . . . . . . . 12 5.3. Header Field Registration . . . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12 6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6.1. Authentication Credentials and Idle Clients . . . . . . . 12 6.1. Confidentiality of Credentials . . . . . . . . . . . . . . 13
6.2. Protection Spaces . . . . . . . . . . . . . . . . . . . . 13 6.2. Authentication Credentials and Idle Clients . . . . . . . 13
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 6.3. Protection Spaces . . . . . . . . . . . . . . . . . . . . 14
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8.1. Normative References . . . . . . . . . . . . . . . . . . . 14 8.1. Normative References . . . . . . . . . . . . . . . . . . . 14
8.2. Informative References . . . . . . . . . . . . . . . . . . 14 8.2. Informative References . . . . . . . . . . . . . . . . . . 15
Appendix A. Changes from RFCs 2616 and 2617 . . . . . . . . . . . 15 Appendix A. Changes from RFCs 2616 and 2617 . . . . . . . . . . . 16
Appendix B. Imported ABNF . . . . . . . . . . . . . . . . . . . . 15 Appendix B. Imported ABNF . . . . . . . . . . . . . . . . . . . . 16
Appendix C. Collected ABNF . . . . . . . . . . . . . . . . . . . 15 Appendix C. Collected ABNF . . . . . . . . . . . . . . . . . . . 16
Appendix D. Change Log (to be removed by RFC Editor before Appendix D. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 16 publication) . . . . . . . . . . . . . . . . . . . . 17
D.1. Since draft-ietf-httpbis-p7-auth-24 . . . . . . . . . . . 16 D.1. Since draft-ietf-httpbis-p7-auth-24 . . . . . . . . . . . 17
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 D.2. Since draft-ietf-httpbis-p7-auth-25 . . . . . . . . . . . 18
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
This document defines HTTP/1.1 access control and authentication. It HTTP provides a general framework for access control and
includes the relevant parts of RFC 2616 with only minor changes authentication, via an extensible set of challenge-response
([RFC2616]), plus the general framework for HTTP authentication, as authentication schemes, which can be used by a server to challenge a
previously defined in "HTTP Authentication: Basic and Digest Access client request and by a client to provide authentication information.
Authentication" ([RFC2617]). This document defines HTTP/1.1 authentication in terms of the
architecture defined in [Part1], including the general framework
previously described in RFC 2617 and the related fields and status
codes previously defined in RFC 2616.
HTTP provides several OPTIONAL challenge-response authentication The IANA Authentication Scheme Registry (Section 5.1) lists
schemes that can be used by a server to challenge a client request registered authentication schemes and their corresponding
and by a client to provide authentication information. The "basic" specifications, including the "basic" and "digest" authentication
and "digest" authentication schemes continue to be specified in RFC schemes previously defined by RFC 2617.
2617.
1.1. Conformance and Error Handling 1.1. Conformance and Error Handling
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
Conformance criteria and considerations regarding error handling are Conformance criteria and considerations regarding error handling are
defined in Section 2.5 of [Part1]. defined in Section 2.5 of [Part1].
1.2. Syntax Notation 1.2. Syntax Notation
This specification uses the Augmented Backus-Naur Form (ABNF) This specification uses the Augmented Backus-Naur Form (ABNF)
notation of [RFC5234] with the list rule extension defined in Section notation of [RFC5234] with a list extension, defined in Section 7 of
7 of [Part1]. Appendix B describes rules imported from other [Part1], that allows for compact definition of comma-separated lists
documents. Appendix C shows the collected ABNF with the list rule using a '#' operator (similar to how the '*' operator indicates
expanded. repetition). Appendix B describes rules imported from other
documents. Appendix C shows the collected grammar with all list
operators expanded to standard ABNF notation.
2. Access Authentication Framework 2. Access Authentication Framework
2.1. Challenge and Response 2.1. Challenge and Response
HTTP provides a simple challenge-response authentication framework HTTP provides a simple challenge-response authentication framework
that can be used by a server to challenge a client request and by a that can be used by a server to challenge a client request and by a
client to provide authentication information. It uses a case- client to provide authentication information. It uses a case-
insensitive token as a means to identify the authentication scheme, insensitive token as a means to identify the authentication scheme,
followed by additional information necessary for achieving followed by additional information necessary for achieving
authentication via that scheme. The latter can either be a comma- authentication via that scheme. The latter can either be a comma-
separated list of parameters or a single sequence of characters separated list of parameters or a single sequence of characters
capable of holding base64-encoded information. capable of holding base64-encoded information.
Parameters are name-value pairs where the name is matched case- Authentication parameters are name=value pairs, where the name token
insensitively, and each parameter name MUST only occur once per is matched case-insensitively, and each parameter name MUST only
challenge. occur once per challenge.
auth-scheme = token auth-scheme = token
auth-param = token BWS "=" BWS ( token / quoted-string ) auth-param = token BWS "=" BWS ( token / quoted-string )
token68 = 1*( ALPHA / DIGIT / token68 = 1*( ALPHA / DIGIT /
"-" / "." / "_" / "~" / "+" / "/" ) *"=" "-" / "." / "_" / "~" / "+" / "/" ) *"="
The "token68" syntax allows the 66 unreserved URI characters The "token68" syntax allows the 66 unreserved URI characters
([RFC3986]), plus a few others, so that it can hold a base64, ([RFC3986]), plus a few others, so that it can hold a base64,
base64url (URL and filename safe alphabet), base32, or base16 (hex) base64url (URL and filename safe alphabet), base32, or base16 (hex)
encoding, with or without padding, but excluding whitespace encoding, with or without padding, but excluding whitespace
([RFC4648]). ([RFC4648]).
The 401 (Unauthorized) response message is used by an origin server A 401 (Unauthorized) response message is used by an origin server to
to challenge the authorization of a user agent. This response MUST challenge the authorization of a user agent, including a WWW-
include a WWW-Authenticate header field containing at least one Authenticate header field containing at least one challenge
challenge applicable to the requested resource. applicable to the requested resource.
The 407 (Proxy Authentication Required) response message is used by a A 407 (Proxy Authentication Required) response message is used by a
proxy to challenge the authorization of a client and MUST include a proxy to challenge the authorization of a client, including a Proxy-
Proxy-Authenticate header field containing at least one challenge Authenticate header field containing at least one challenge
applicable to the proxy for the requested resource. applicable to the proxy for the requested resource.
challenge = auth-scheme [ 1*SP ( token68 / #auth-param ) ] challenge = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
Note: Many clients fail to parse challenges containing unknown Note: Many clients fail to parse a challenge that contains an
schemes. A workaround for this problem is to list well-supported unknown scheme. A workaround for this problem is to list well-
schemes (such as "basic") first. supported schemes (such as "basic") first.
A user agent that wishes to authenticate itself with an origin server A user agent that wishes to authenticate itself with an origin server
-- usually, but not necessarily, after receiving a 401 (Unauthorized) -- usually, but not necessarily, after receiving a 401 (Unauthorized)
-- can do so by including an Authorization header field with the -- can do so by including an Authorization header field with the
request. request.
A client that wishes to authenticate itself with a proxy -- usually, A client that wishes to authenticate itself with a proxy -- usually,
but not necessarily, after receiving a 407 (Proxy Authentication but not necessarily, after receiving a 407 (Proxy Authentication
Required) -- can do so by including a Proxy-Authorization header Required) -- can do so by including a Proxy-Authorization header
field with the request. field with the request.
Both the Authorization field value and the Proxy-Authorization field Both the Authorization field value and the Proxy-Authorization field
value contain the client's credentials for the realm of the resource value contain the client's credentials for the realm of the resource
being requested, based upon a challenge received in a response being requested, based upon a challenge received in a response
(possibly at some point in the past). When creating their values, (possibly at some point in the past). When creating their values,
the user agent ought to do so by selecting the challenge with what it the user agent ought to do so by selecting the challenge with what it
considers to be the most secure auth-scheme that it understands, considers to be the most secure auth-scheme that it understands,
obtaining credentials from the user as appropriate. obtaining credentials from the user as appropriate. Transmission of
credentials within header field values implies significant security
considerations regarding the confidentiality of the underlying
connection, as described in Section 6.1.
credentials = auth-scheme [ 1*SP ( token68 / #auth-param ) ] credentials = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
Upon receipt of a request for a protected resource that omits Upon receipt of a request for a protected resource that omits
credentials, contains invalid credentials (e.g., a bad password) or credentials, contains invalid credentials (e.g., a bad password) or
partial credentials (e.g., when the authentication scheme requires partial credentials (e.g., when the authentication scheme requires
more than one round trip), an origin server SHOULD send a 401 more than one round trip), an origin server SHOULD send a 401
(Unauthorized) response that contains a WWW-Authenticate header field (Unauthorized) response that contains a WWW-Authenticate header field
with at least one (possibly new) challenge applicable to the with at least one (possibly new) challenge applicable to the
requested resource. requested resource.
Likewise, upon receipt of a request that requires authentication by Likewise, upon receipt of a request that omits proxy credentials or
proxies that omit credentials or contain invalid or partial contains invalid or partial proxy credentials, a proxy that requires
credentials, a proxy SHOULD send a 407 (Proxy Authentication authentication SHOULD generate a 407 (Proxy Authentication Required)
Required) response that contains a Proxy-Authenticate header field response that contains a Proxy-Authenticate header field with at
with a (possibly new) challenge applicable to the proxy. least one (possibly new) challenge applicable to the proxy.
A server receiving credentials that are valid, but not adequate to A server that receives valid credentials which are not adequate to
gain access, ought to respond with the 403 (Forbidden) status code gain access ought to respond with the 403 (Forbidden) status code
(Section 6.5.3 of [Part2]). (Section 6.5.3 of [Part2]).
HTTP does not restrict applications to this simple challenge-response HTTP does not restrict applications to this simple challenge-response
framework for access authentication. Additional mechanisms can be framework for access authentication. Additional mechanisms can be
used, such as authentication at the transport level or via message used, such as authentication at the transport level or via message
encapsulation, and with additional header fields specifying encapsulation, and with additional header fields specifying
authentication information. However, such additional mechanisms are authentication information. However, such additional mechanisms are
not defined by this specification. not defined by this specification.
A proxy MUST forward the WWW-Authenticate and Authorization header
fields unmodified and follow the rules found in Section 4.1.
2.2. Protection Space (Realm) 2.2. Protection Space (Realm)
The authentication parameter realm is reserved for use by The "realm" authentication parameter is reserved for use by
authentication schemes that wish to indicate the scope of protection. authentication schemes that wish to indicate a scope of protection.
A protection space is defined by the canonical root URI (the scheme A protection space is defined by the canonical root URI (the scheme
and authority components of the effective request URI; see Section and authority components of the effective request URI; see Section
5.5 of [Part1]) of the server being accessed, in combination with the 5.5 of [Part1]) of the server being accessed, in combination with the
realm value if present. These realms allow the protected resources realm value if present. These realms allow the protected resources
on a server to be partitioned into a set of protection spaces, each on a server to be partitioned into a set of protection spaces, each
with its own authentication scheme and/or authorization database. with its own authentication scheme and/or authorization database.
The realm value is a string, generally assigned by the origin server, The realm value is a string, generally assigned by the origin server,
which can have additional semantics specific to the authentication which can have additional semantics specific to the authentication
scheme. Note that a response can have multiple challenges with the scheme. Note that a response can have multiple challenges with the
skipping to change at page 7, line 20 skipping to change at page 7, line 25
syntax. Recipients might have to support both token and quoted- syntax. Recipients might have to support both token and quoted-
string syntax for maximum interoperability with existing clients that string syntax for maximum interoperability with existing clients that
have been accepting both notations for a long time. have been accepting both notations for a long time.
3. Status Code Definitions 3. Status Code Definitions
3.1. 401 Unauthorized 3.1. 401 Unauthorized
The 401 (Unauthorized) status code indicates that the request has not The 401 (Unauthorized) status code indicates that the request has not
been applied because it lacks valid authentication credentials for been applied because it lacks valid authentication credentials for
the target resource. The origin server MUST send a WWW-Authenticate the target resource. The server generating a 401 response MUST send
header field (Section 4.4) containing at least one challenge a WWW-Authenticate header field (Section 4.1) containing at least one
applicable to the target resource. If the request included challenge applicable to the target resource.
authentication credentials, then the 401 response indicates that
authorization has been refused for those credentials. The user agent If the request included authentication credentials, then the 401
MAY repeat the request with a new or replaced Authorization header response indicates that authorization has been refused for those
field (Section 4.1). If the 401 response contains the same challenge credentials. The user agent MAY repeat the request with a new or
as the prior response, and the user agent has already attempted replaced Authorization header field (Section 4.2). If the 401
authentication at least once, then the user agent SHOULD present the response contains the same challenge as the prior response, and the
enclosed representation to the user, since it usually contains user agent has already attempted authentication at least once, then
relevant diagnostic information. the user agent SHOULD present the enclosed representation to the
user, since it usually contains relevant diagnostic information.
3.2. 407 Proxy Authentication Required 3.2. 407 Proxy Authentication Required
The 407 (Proxy Authentication Required) status code is similar to 401 The 407 (Proxy Authentication Required) status code is similar to 401
(Unauthorized), but indicates that the client needs to authenticate (Unauthorized), but indicates that the client needs to authenticate
itself in order to use a proxy. The proxy MUST send a Proxy- itself in order to use a proxy. The proxy MUST send a Proxy-
Authenticate header field (Section 4.2) containing a challenge Authenticate header field (Section 4.3) containing a challenge
applicable to that proxy for the target resource. The client MAY applicable to that proxy for the target resource. The client MAY
repeat the request with a new or replaced Proxy-Authorization header repeat the request with a new or replaced Proxy-Authorization header
field (Section 4.3). field (Section 4.4).
4. Header Field Definitions 4. Header Field Definitions
This section defines the syntax and semantics of HTTP/1.1 header This section defines the syntax and semantics of header fields
fields related to authentication. related to the HTTP authentication framework.
4.1. Authorization 4.1. WWW-Authenticate
The "WWW-Authenticate" header field indicates the authentication
scheme(s) and parameters applicable to the target resource.
WWW-Authenticate = 1#challenge
A server generating a 401 (Unauthorized) response MUST send a WWW-
Authenticate header field containing at least one challenge. A
server MAY generate a WWW-Authenticate header field in other response
messages to indicate that supplying credentials (or different
credentials) might affect the response.
A proxy forwarding a response MUST NOT modify any WWW-Authenticate
fields in that response.
User agents are advised to take special care in parsing the field
value, as it might contain more than one challenge, and each
challenge can contain a comma-separated list of authentication
parameters. Furthermore, the header field itself can occur multiple
times.
For instance:
WWW-Authenticate: Newauth realm="apps", type=1,
title="Login to \"apps\"", Basic realm="simple"
This header field contains two challenges; one for the "Newauth"
scheme with a realm value of "apps", and two additional parameters
"type" and "title", and another one for the "Basic" scheme with a
realm value of "simple".
Note: The challenge grammar production uses the list syntax as
well. Therefore, a sequence of comma, whitespace, and comma can
be considered either as applying to the preceding challenge, or to
be an empty entry in the list of challenges. In practice, this
ambiguity does not affect the semantics of the header field value
and thus is harmless.
4.2. Authorization
The "Authorization" header field allows a user agent to authenticate The "Authorization" header field allows a user agent to authenticate
itself with an origin server -- usually, but not necessarily, after itself with an origin server -- usually, but not necessarily, after
receiving a 401 (Unauthorized) response. Its value consists of receiving a 401 (Unauthorized) response. Its value consists of
credentials containing the authentication information of the user credentials containing the authentication information of the user
agent for the realm of the resource being requested. agent for the realm of the resource being requested.
Authorization = credentials Authorization = credentials
If a request is authenticated and a realm specified, the same If a request is authenticated and a realm specified, the same
credentials are presumed to be valid for all other requests within credentials are presumed to be valid for all other requests within
this realm (assuming that the authentication scheme itself does not this realm (assuming that the authentication scheme itself does not
require otherwise, such as credentials that vary according to a require otherwise, such as credentials that vary according to a
challenge value or using synchronized clocks). challenge value or using synchronized clocks).
See Section 3.2 of [Part6] for details of and requirements pertaining A proxy forwarding a request MUST NOT modify any Authorization fields
to handling of the Authorization field by HTTP caches. in that request. See Section 3.2 of [Part6] for details of and
requirements pertaining to handling of the Authorization field by
HTTP caches.
4.2. Proxy-Authenticate 4.3. Proxy-Authenticate
The "Proxy-Authenticate" header field consists of at least one The "Proxy-Authenticate" header field consists of at least one
challenge that indicates the authentication scheme(s) and parameters challenge that indicates the authentication scheme(s) and parameters
applicable to the proxy for this effective request URI (Section 5.5 applicable to the proxy for this effective request URI (Section 5.5
of [Part1]). It MUST be included as part of a 407 (Proxy of [Part1]). A proxy MUST send at least one Proxy-Authenticate
Authentication Required) response. header field in each 407 (Proxy Authentication Required) response
that it generates.
Proxy-Authenticate = 1#challenge Proxy-Authenticate = 1#challenge
Unlike WWW-Authenticate, the Proxy-Authenticate header field applies Unlike WWW-Authenticate, the Proxy-Authenticate header field applies
only to the next outbound client on the response chain that chose to only to the next outbound client on the response chain. This is
direct its request to the responding proxy. If that recipient is because only the client that chose a given proxy is likely to have
also a proxy, it will generally consume the Proxy-Authenticate header the credentials necessary for authentication. However, when multiple
field (and generate an appropriate Proxy-Authorization in a proxies are used within the same administrative domain, such as
subsequent request) rather than forward the header field to its own office and regional caching proxies within a large corporate network,
outbound clients. However, if a recipient proxy needs to obtain its it is common for credentials to be generated by the user agent and
own credentials by requesting them from a further outbound client, it passed through the hierarchy until consumed. Hence, in such a
will generate its own 407 response, which might have the appearance configuration, it will appear as if Proxy-Authenticate is being
of forwarding the Proxy-Authenticate header field if both proxies use forwarded because each proxy will send the same challenge set.
the same challenge set.
Note that the parsing considerations for WWW-Authenticate apply to Note that the parsing considerations for WWW-Authenticate apply to
this header field as well; see Section 4.4 for details. this header field as well; see Section 4.1 for details.
4.3. Proxy-Authorization 4.4. Proxy-Authorization
The "Proxy-Authorization" header field allows the client to identify The "Proxy-Authorization" header field allows the client to identify
itself (or its user) to a proxy that requires authentication. Its itself (or its user) to a proxy that requires authentication. Its
value consists of credentials containing the authentication value consists of credentials containing the authentication
information of the client for the proxy and/or realm of the resource information of the client for the proxy and/or realm of the resource
being requested. being requested.
Proxy-Authorization = credentials Proxy-Authorization = credentials
Unlike Authorization, the Proxy-Authorization header field applies Unlike Authorization, the Proxy-Authorization header field applies
only to the next inbound proxy that demanded authentication using the only to the next inbound proxy that demanded authentication using the
Proxy-Authenticate field. When multiple proxies are used in a chain, Proxy-Authenticate field. When multiple proxies are used in a chain,
the Proxy-Authorization header field is consumed by the first inbound the Proxy-Authorization header field is consumed by the first inbound
proxy that was expecting to receive credentials. A proxy MAY relay 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 credentials from the client request to the next proxy if that is
the mechanism by which the proxies cooperatively authenticate a given the mechanism by which the proxies cooperatively authenticate a given
request. request.
4.4. WWW-Authenticate
The "WWW-Authenticate" header field consists of at least one
challenge that indicates the authentication scheme(s) and parameters
applicable to the effective request URI (Section 5.5 of [Part1]).
It MUST be included in 401 (Unauthorized) response messages and MAY
be included in other response messages to indicate that supplying
credentials (or different credentials) might affect the response.
WWW-Authenticate = 1#challenge
User agents are advised to take special care in parsing the field
value, as it might contain more than one challenge, and each
challenge can contain a comma-separated list of authentication
parameters. Furthermore, the header field itself can occur multiple
times.
For instance:
WWW-Authenticate: Newauth realm="apps", type=1,
title="Login to \"apps\"", Basic realm="simple"
This header field contains two challenges; one for the "Newauth"
scheme with a realm value of "apps", and two additional parameters
"type" and "title", and another one for the "Basic" scheme with a
realm value of "simple".
Note: The challenge grammar production uses the list syntax as
well. Therefore, a sequence of comma, whitespace, and comma can
be considered either as applying to the preceding challenge, or to
be an empty entry in the list of challenges. In practice, this
ambiguity does not affect the semantics of the header field value
and thus is harmless.
5. IANA Considerations 5. IANA Considerations
5.1. Authentication Scheme Registry 5.1. Authentication Scheme Registry
The HTTP Authentication Scheme Registry defines the name space for The HTTP Authentication Scheme Registry defines the name space for
the authentication schemes in challenges and credentials. It will be the authentication schemes in challenges and credentials. It will be
created and maintained at (the suggested URI) created and maintained at (the suggested URI)
<http://www.iana.org/assignments/http-authschemes>. <http://www.iana.org/assignments/http-authschemes>.
5.1.1. Procedure 5.1.1. Procedure
skipping to change at page 12, line 25 skipping to change at page 12, line 31
Registry maintained at <http://www.iana.org/assignments/ Registry maintained at <http://www.iana.org/assignments/
message-headers/message-header-index.html>. message-headers/message-header-index.html>.
This document defines the following HTTP header fields, so their This document defines the following HTTP header fields, so their
associated registry entries shall be updated according to the associated registry entries shall be updated according to the
permanent registrations below (see [BCP90]): permanent registrations below (see [BCP90]):
+---------------------+----------+----------+-------------+ +---------------------+----------+----------+-------------+
| Header Field Name | Protocol | Status | Reference | | Header Field Name | Protocol | Status | Reference |
+---------------------+----------+----------+-------------+ +---------------------+----------+----------+-------------+
| Authorization | http | standard | Section 4.1 | | Authorization | http | standard | Section 4.2 |
| Proxy-Authenticate | http | standard | Section 4.2 | | Proxy-Authenticate | http | standard | Section 4.3 |
| Proxy-Authorization | http | standard | Section 4.3 | | Proxy-Authorization | http | standard | Section 4.4 |
| WWW-Authenticate | http | standard | Section 4.4 | | WWW-Authenticate | http | standard | Section 4.1 |
+---------------------+----------+----------+-------------+ +---------------------+----------+----------+-------------+
The change controller is: "IETF (iesg@ietf.org) - Internet The change controller is: "IETF (iesg@ietf.org) - Internet
Engineering Task Force". Engineering Task Force".
6. Security Considerations 6. Security Considerations
This section is meant to inform developers, information providers, This section is meant to inform developers, information providers,
and users of known security concerns specific to HTTP/1.1 and users of known security concerns specific to HTTP authentication.
authentication. More general security considerations are addressed More general security considerations are addressed in HTTP messaging
in HTTP messaging [Part1] and semantics [Part2]. [Part1] and semantics [Part2].
6.1. Authentication Credentials and Idle Clients Everything about the topic of HTTP authentication is a security
consideration, so the list of considerations below is not exhaustive.
Furthermore, it is limited to security considerations regarding the
authentication framework, in general, rather than discussing all of
the potential considerations for specific authentication schemes
(which ought to be documented in the specifications that define those
schemes). Various organizations maintain topical information and
links to current research on Web application security (e.g.,
[OWASP]), including common pitfalls for implementing and using the
authentication schemes found in practice.
6.1. Confidentiality of Credentials
The HTTP authentication framework does not define a single mechanism
for maintaining the confidentiality of credentials; instead, each
authentication scheme defines how the credentials are encoded prior
to transmission. While this provides flexibility for the development
of future authentication schemes, it is inadequate for the protection
of existing schemes that provide no confidentiality on their own, or
that do not sufficiently protect against replay attacks.
Furthermore, if the server expects credentials that are specific to
each individual user, the exchange of those credentials will have the
effect of identifying that user even if the content within
credentials remains confidential.
HTTP depends on the security properties of the underlying transport
or session-level connection to provide confidential transmission of
header fields. In other words, if a server limits access to
authenticated users using this framework, the server needs to ensure
that the connection is properly secured in accordance with the nature
of the authentication scheme used. For example, services that depend
on individual user authentication often require a connection to be
secured with TLS ("Transport Layer Security", [RFC5246]) prior to
exchanging any credentials.
6.2. Authentication Credentials and Idle Clients
Existing HTTP clients and user agents typically retain authentication Existing HTTP clients and user agents typically retain authentication
information indefinitely. HTTP does not provide a mechanism for the information indefinitely. HTTP does not provide a mechanism for the
origin server to direct clients to discard these cached credentials, origin server to direct clients to discard these cached credentials,
since the protocol has no awareness of how credentials are obtained since the protocol has no awareness of how credentials are obtained
or managed by the user agent. The mechanisms for expiring or or managed by the user agent. The mechanisms for expiring or
revoking credentials can be specified as part of an authentication revoking credentials can be specified as part of an authentication
scheme definition. scheme definition.
Circumstances under which credential caching can interfere with the Circumstances under which credential caching can interfere with the
skipping to change at page 13, line 18 skipping to change at page 14, line 11
o Applications that include a session termination indication (such o Applications that include a session termination indication (such
as a "logout" or "commit" button on a page) after which the server as a "logout" or "commit" button on a page) after which the server
side of the application "knows" that there is no further reason side of the application "knows" that there is no further reason
for the client to retain the credentials. for the client to retain the credentials.
User agents that cache credentials are encouraged to provide a User agents that cache credentials are encouraged to provide a
readily accessible mechanism for discarding cached credentials under readily accessible mechanism for discarding cached credentials under
user control. user control.
6.2. Protection Spaces 6.3. Protection Spaces
Authentication schemes that solely rely on the "realm" mechanism for Authentication schemes that solely rely on the "realm" mechanism for
establishing a protection space will expose credentials to all establishing a protection space will expose credentials to all
resources on an origin server. Clients that have successfully made resources on an origin server. Clients that have successfully made
authenticated requests with a resource can use the same authenticated requests with a resource can use the same
authentication credentials for other resources on the same origin authentication credentials for other resources on the same origin
server. This makes it possible for a different resource to harvest server. This makes it possible for a different resource to harvest
authentication credentials for other resources. authentication credentials for other resources.
This is of particular concern when an origin server hosts resources This is of particular concern when an origin server hosts resources
skipping to change at page 14, line 4 skipping to change at page 14, line 42
Authentication Framework, previously defined in RFC 2617. We thank Authentication Framework, previously defined in RFC 2617. We thank
John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D. John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D.
Lawrence, Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for Lawrence, Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for
their work on that specification. See Section 6 of [RFC2617] for their work on that specification. See Section 6 of [RFC2617] for
further acknowledgements. further acknowledgements.
See Section 10 of [Part1] for the Acknowledgments related to this See Section 10 of [Part1] for the Acknowledgments related to this
document revision. document revision.
8. References 8. References
8.1. Normative References 8.1. Normative References
[Part1] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [Part1] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing", Protocol (HTTP/1.1): Message Syntax and Routing",
draft-ietf-httpbis-p1-messaging-25 (work in progress), draft-ietf-httpbis-p1-messaging-26 (work in progress),
November 2013. February 2014.
[Part2] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [Part2] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", Protocol (HTTP/1.1): Semantics and Content",
draft-ietf-httpbis-p2-semantics-25 (work in progress), draft-ietf-httpbis-p2-semantics-26 (work in progress),
November 2013. February 2014.
[Part6] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, [Part6] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching", Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
draft-ietf-httpbis-p6-cache-25 (work in progress), draft-ietf-httpbis-p6-cache-26 (work in progress),
November 2013. February 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
8.2. Informative References 8.2. Informative References
[BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration [BCP90] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864, Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004. September 2004.
[OWASP] van der Stock, A., Ed., "A Guide to Building Secure Web
Applications and Web Services", The Open Web Application
Security Project (OWASP) 2.0.1, July 2005,
<https://www.owasp.org/>.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
Leach, P., Luotonen, A., and L. Stewart, "HTTP Leach, P., Luotonen, A., and L. Stewart, "HTTP
Authentication: Basic and Digest Access Authentication", Authentication: Basic and Digest Access Authentication",
RFC 2617, June 1999. RFC 2617, June 1999.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005. RFC 3986, January 2005.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006. Encodings", RFC 4648, October 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
Appendix A. Changes from RFCs 2616 and 2617 Appendix A. Changes from RFCs 2616 and 2617
The framework for HTTP Authentication is now defined by this The framework for HTTP Authentication is now defined by this
document, rather than RFC 2617. document, rather than RFC 2617.
The "realm" parameter is no longer always required on challenges; The "realm" parameter is no longer always required on challenges;
consequently, the ABNF allows challenges without any auth parameters. consequently, the ABNF allows challenges without any auth parameters.
(Section 2) (Section 2)
The "token68" alternative to auth-param lists has been added for The "token68" alternative to auth-param lists has been added for
skipping to change at page 17, line 5 skipping to change at page 18, line 5
o <http://tools.ietf.org/wg/httpbis/trac/ticket/510>: "SECDIR review o <http://tools.ietf.org/wg/httpbis/trac/ticket/510>: "SECDIR review
of draft-ietf-httpbis-p7-auth-24" of draft-ietf-httpbis-p7-auth-24"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/513>: "APPSDIR o <http://tools.ietf.org/wg/httpbis/trac/ticket/513>: "APPSDIR
review of draft-ietf-httpbis-p7-auth-24" review of draft-ietf-httpbis-p7-auth-24"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/516>: "note about o <http://tools.ietf.org/wg/httpbis/trac/ticket/516>: "note about
WWW-A parsing potentially misleading" WWW-A parsing potentially misleading"
D.2. Since draft-ietf-httpbis-p7-auth-25
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/522>: "Gen-art
review of draft-ietf-httpbis-p7-auth-25"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/536>: "IESG ballot
on draft-ietf-httpbis-p7-auth-25"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/538>: "add
'stateless' to Abstract"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/539>: "mention TLS
vs plain text passwords or dict attacks?"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/542>: "improve
introduction of list rule"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/549>: "augment
security considerations with pointers to current research"
Index Index
4 4
401 Unauthorized (status code) 7 401 Unauthorized (status code) 7
407 Proxy Authentication Required (status code) 7 407 Proxy Authentication Required (status code) 7
A A
Authorization header field 7 Authorization header field 8
C C
Canonical Root URI 6 Canonical Root URI 6
G G
Grammar Grammar
auth-param 5 auth-param 5
auth-scheme 5 auth-scheme 5
Authorization 8 Authorization 8
challenge 5 challenge 5
credentials 5 credentials 6
Proxy-Authenticate 8 Proxy-Authenticate 9
Proxy-Authorization 8 Proxy-Authorization 9
token68 5 token68 5
WWW-Authenticate 9 WWW-Authenticate 8
P P
Protection Space 6 Protection Space 6
Proxy-Authenticate header field 8 Proxy-Authenticate header field 9
Proxy-Authorization header field 8 Proxy-Authorization header field 9
R R
Realm 6 Realm 6
W W
WWW-Authenticate header field 9 WWW-Authenticate header field 8
Authors' Addresses Authors' Addresses
Roy T. Fielding (editor) Roy T. Fielding (editor)
Adobe Systems Incorporated Adobe Systems Incorporated
345 Park Ave 345 Park Ave
San Jose, CA 95110 San Jose, CA 95110
USA USA
EMail: fielding@gbiv.com EMail: fielding@gbiv.com
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