draft-ietf-httpbis-p7-auth-26.txt   draft-ietf-httpbis-p7-auth-latest.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 February 6, 2014 Intended status: Standards Track June 2014
Expires: August 10, 2014 Expires: December 3, 2014
Hypertext Transfer Protocol (HTTP/1.1): Authentication Hypertext Transfer Protocol (HTTP/1.1): Authentication
draft-ietf-httpbis-p7-auth-26 draft-ietf-httpbis-p7-auth-latest
Abstract Abstract
The Hypertext Transfer Protocol (HTTP) is a stateless application- The Hypertext Transfer Protocol (HTTP) is a stateless application-
level 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.2. _This is a temporary document for the purpose of tracking the
editorial changes made during the AUTH48 (RFC publication) phase._
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 August 10, 2014. This Internet-Draft will expire on December 3, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2014 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
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
skipping to change at page 3, line 16 skipping to change at page 3, line 16
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 . . . . . . . . . . . . . . . . . . . 8
4.1. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 8 4.1. WWW-Authenticate . . . . . . . . . . . . . . . . . . . . . 8
4.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 8 4.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 9
4.3. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . . 9 4.3. Proxy-Authenticate . . . . . . . . . . . . . . . . . . . . 9
4.4. Proxy-Authorization . . . . . . . . . . . . . . . . . . . 9 4.4. Proxy-Authorization . . . . . . . . . . . . . . . . . . . 10
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 . . . . . . . . . . . . . . . . . 12 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. Confidentiality of Credentials . . . . . . . . . . . . . . 13 6.1. Confidentiality of Credentials . . . . . . . . . . . . . . 13
6.2. Authentication Credentials and Idle Clients . . . . . . . 13 6.2. Authentication Credentials and Idle Clients . . . . . . . 13
6.3. Protection Spaces . . . . . . . . . . . . . . . . . . . . 14 6.3. Protection Spaces . . . . . . . . . . . . . . . . . . . . 14
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1. Normative References . . . . . . . . . . . . . . . . . . . 14 8.1. Normative References . . . . . . . . . . . . . . . . . . . 15
8.2. Informative References . . . . . . . . . . . . . . . . . . 15 8.2. Informative References . . . . . . . . . . . . . . . . . . 15
Appendix A. Changes from RFCs 2616 and 2617 . . . . . . . . . . . 16 Appendix A. Changes from RFCs 2616 and 2617 . . . . . . . . . . . 16
Appendix B. Imported ABNF . . . . . . . . . . . . . . . . . . . . 16 Appendix B. Imported ABNF . . . . . . . . . . . . . . . . . . . . 16
Appendix C. Collected ABNF . . . . . . . . . . . . . . . . . . . 16 Appendix C. Collected ABNF . . . . . . . . . . . . . . . . . . . 16
Appendix D. Change Log (to be removed by RFC Editor before Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
publication) . . . . . . . . . . . . . . . . . . . . 17
D.1. Since draft-ietf-httpbis-p7-auth-24 . . . . . . . . . . . 17
D.2. Since draft-ietf-httpbis-p7-auth-25 . . . . . . . . . . . 18
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
HTTP provides a general framework for access control and HTTP provides a general framework for access control and
authentication, via an extensible set of challenge-response authentication, via an extensible set of challenge-response
authentication schemes, which can be used by a server to challenge a authentication schemes, which can be used by a server to challenge a
client request and by a client to provide authentication information. client request and by a client to provide authentication information.
This document defines HTTP/1.1 authentication in terms of the This document defines HTTP/1.1 authentication in terms of the
architecture defined in [Part1], including the general framework architecture defined in "Hypertext Transfer Protocol (HTTP/1.1):
previously described in RFC 2617 and the related fields and status Message Syntax and Routing" [RFC7230], including the general
codes previously defined in RFC 2616. framework previously described in "HTTP Authentication: Basic and
Digest Access Authentication" [RFC2617] and the related fields and
status codes previously defined in "Hypertext Transfer Protocol --
HTTP/1.1" [RFC2616].
The IANA Authentication Scheme Registry (Section 5.1) lists The IANA Authentication Scheme Registry (Section 5.1) lists
registered authentication schemes and their corresponding registered authentication schemes and their corresponding
specifications, including the "basic" and "digest" authentication specifications, including the "basic" and "digest" authentication
schemes previously defined by RFC 2617. schemes previously defined by RFC 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 [RFC7230].
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 a list extension, defined in Section 7 of notation of [RFC5234] with a list extension, defined in Section 7 of
[Part1], that allows for compact definition of comma-separated lists [RFC7230], that allows for compact definition of comma-separated
using a '#' operator (similar to how the '*' operator indicates lists using a '#' operator (similar to how the '*' operator indicates
repetition). Appendix B describes rules imported from other repetition). Appendix B describes rules imported from other
documents. Appendix C shows the collected grammar with all list documents. Appendix C shows the collected grammar with all list
operators expanded to standard ABNF notation. 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 be either 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.
Authentication parameters are name=value pairs, where the name token Authentication parameters are name=value pairs, where the name token
is matched case-insensitively, and each parameter name MUST only is matched case-insensitively, and each parameter name MUST only
occur once per 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]).
A 401 (Unauthorized) response message is used by an origin server to A 401 (Unauthorized) response message is used by an origin server to
challenge the authorization of a user agent, including a WWW- challenge the authorization of a user agent, including a WWW-
Authenticate header field containing at least one challenge Authenticate header field containing at least one challenge
applicable to the requested resource. applicable to the requested resource.
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(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 omits proxy credentials or Likewise, upon receipt of a request that omits proxy credentials or
contains invalid or partial proxy credentials, a proxy that requires contains invalid or partial proxy credentials, a proxy that requires
authentication SHOULD generate a 407 (Proxy Authentication Required) authentication SHOULD generate a 407 (Proxy Authentication Required)
response that contains a Proxy-Authenticate header field with at response that contains a Proxy-Authenticate header field with at
least one (possibly new) challenge applicable to the proxy. least one (possibly new) challenge applicable to the proxy.
A server that receives valid credentials which are not adequate to A server that receives valid credentials that 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 [RFC7231]).
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.
2.2. Protection Space (Realm) 2.2. Protection Space (Realm)
The "realm" authentication parameter is reserved for use by The "realm" authentication parameter is reserved for use by
authentication schemes that wish to indicate a 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 [RFC7230]) of the server being accessed, in combination with
realm value if present. These realms allow the protected resources the realm value if present. These realms allow the protected
on a server to be partitioned into a set of protection spaces, each resources on a server to be partitioned into a set of protection
with its own authentication scheme and/or authorization database. spaces, each with its own authentication scheme and/or authorization
The realm value is a string, generally assigned by the origin server, database. The realm value is a string, generally assigned by the
which can have additional semantics specific to the authentication origin server, that can have additional semantics specific to the
scheme. Note that a response can have multiple challenges with the authentication scheme. Note that a response can have multiple
same auth-scheme but different realms. challenges with the same auth-scheme but with different realms.
The protection space determines the domain over which credentials can The protection space determines the domain over which credentials can
be automatically applied. If a prior request has been authorized, be automatically applied. If a prior request has been authorized,
the user agent MAY reuse the same credentials for all other requests the user agent MAY reuse the same credentials for all other requests
within that protection space for a period of time determined by the within that protection space for a period of time determined by the
authentication scheme, parameters, and/or user preferences (such as a authentication scheme, parameters, and/or user preferences (such as a
configurable inactivity timeout). Unless specifically allowed by the configurable inactivity timeout). Unless specifically allowed by the
authentication scheme, a single protection space cannot extend authentication scheme, a single protection space cannot extend
outside the scope of its server. outside the scope of its server.
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credentials. The user agent MAY repeat the request with a new or credentials. The user agent MAY repeat the request with a new or
replaced Authorization header field (Section 4.2). If the 401 replaced Authorization header field (Section 4.2). If the 401
response contains the same challenge as the prior response, and the response contains the same challenge as the prior response, and the
user agent has already attempted authentication at least once, then user agent has already attempted authentication at least once, then
the user agent SHOULD present the enclosed representation to the the user agent SHOULD present the enclosed representation to the
user, since it usually contains relevant diagnostic information. 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 it indicates that the client needs to
itself in order to use a proxy. The proxy MUST send a Proxy- authenticate itself in order to use a proxy. The proxy MUST send a
Authenticate header field (Section 4.3) containing a challenge Proxy-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 4.4). field (Section 4.4).
4. Header Field Definitions 4. Header Field Definitions
This section defines the syntax and semantics of header fields This section defines the syntax and semantics of header fields
related to the HTTP authentication framework. related to the HTTP authentication framework.
4.1. WWW-Authenticate 4.1. WWW-Authenticate
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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).
A proxy forwarding a request MUST NOT modify any Authorization fields A proxy forwarding a request MUST NOT modify any Authorization fields
in that request. See Section 3.2 of [Part6] for details of and in that request. See Section 3.2 of [RFC7234] for details of and
requirements pertaining to handling of the Authorization field by requirements pertaining to handling of the Authorization field by
HTTP caches. HTTP caches.
4.3. 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]). A proxy MUST send at least one Proxy-Authenticate of [RFC7230]). A proxy MUST send at least one Proxy-Authenticate
header field in each 407 (Proxy Authentication Required) response header field in each 407 (Proxy Authentication Required) response
that it generates. 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. This is 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 because only the client that chose a given proxy is likely to have
the credentials necessary for authentication. However, when multiple the credentials necessary for authentication. However, when multiple
proxies are used within the same administrative domain, such as proxies are used within the same administrative domain, such as
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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.
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 "Hypertext Transfer Protocol (HTTP) Authentication Scheme
the authentication schemes in challenges and credentials. It will be Registry" defines the namespace for the authentication schemes in
created and maintained at (the suggested URI) challenges and credentials. It has been created and is now
<http://www.iana.org/assignments/http-authschemes>. maintained at <http://www.iana.org/assignments/http-authschemes>.
5.1.1. Procedure 5.1.1. Procedure
Registrations MUST include the following fields: Registrations MUST include the following fields:
o Authentication Scheme Name o Authentication Scheme Name
o Pointer to specification text o Pointer to specification text
o Notes (optional) o Notes (optional)
Values to be added to this name space require IETF Review (see Values to be added to this namespace require IETF Review (see
[RFC5226], Section 4.1). [RFC5226], Section 4.1).
5.1.2. Considerations for New Authentication Schemes 5.1.2. Considerations for New Authentication Schemes
There are certain aspects of the HTTP Authentication Framework that There are certain aspects of the HTTP Authentication Framework that
put constraints on how new authentication schemes can work: put constraints on how new authentication schemes can work:
o HTTP authentication is presumed to be stateless: all of the o HTTP authentication is presumed to be stateless: all of the
information necessary to authenticate a request MUST be provided information necessary to authenticate a request MUST be provided
in the request, rather than be dependent on the server remembering in the request, rather than be dependent on the server remembering
prior requests. Authentication based on, or bound to, the prior requests. Authentication based on, or bound to, the
underlying connection is outside the scope of this specification underlying connection is outside the scope of this specification
and inherently flawed unless steps are taken to ensure that the and inherently flawed unless steps are taken to ensure that the
connection cannot be used by any party other than the connection cannot be used by any party other than the
authenticated user (see Section 2.3 of [Part1]). authenticated user (see Section 2.3 of [RFC7230]).
o The authentication parameter "realm" is reserved for defining o The authentication parameter "realm" is reserved for defining
Protection Spaces as defined in Section 2.2. New schemes MUST NOT protection spaces as described in Section 2.2. New schemes MUST
use it in a way incompatible with that definition. NOT use it in a way incompatible with that definition.
o The "token68" notation was introduced for compatibility with o The "token68" notation was introduced for compatibility with
existing authentication schemes and can only be used once per existing authentication schemes and can only be used once per
challenge or credential. New schemes thus ought to use the "auth- challenge or credential. Thus, new schemes ought to use the auth-
param" syntax instead, because otherwise future extensions will be param syntax instead, because otherwise future extensions will be
impossible. impossible.
o The parsing of challenges and credentials is defined by this o The parsing of challenges and credentials is defined by this
specification, and cannot be modified by new authentication specification and cannot be modified by new authentication
schemes. When the auth-param syntax is used, all parameters ought schemes. When the auth-param syntax is used, all parameters ought
to support both token and quoted-string syntax, and syntactical to support both token and quoted-string syntax, and syntactical
constraints ought to be defined on the field value after parsing constraints ought to be defined on the field value after parsing
(i.e., quoted-string processing). This is necessary so that (i.e., quoted-string processing). This is necessary so that
recipients can use a generic parser that applies to all recipients can use a generic parser that applies to all
authentication schemes. authentication schemes.
Note: The fact that the value syntax for the "realm" parameter is Note: The fact that the value syntax for the "realm" parameter is
restricted to quoted-string was a bad design choice not to be restricted to quoted-string was a bad design choice not to be
repeated for new parameters. repeated for new parameters.
o Definitions of new schemes ought to define the treatment of o Definitions of new schemes ought to define the treatment of
unknown extension parameters. In general, a "must-ignore" rule is unknown extension parameters. In general, a "must-ignore" rule is
preferable over "must-understand", because otherwise it will be preferable to a "must-understand" rule, because otherwise it will
hard to introduce new parameters in the presence of legacy be hard to introduce new parameters in the presence of legacy
recipients. Furthermore, it's good to describe the policy for recipients. Furthermore, it's good to describe the policy for
defining new parameters (such as "update the specification", or defining new parameters (such as "update the specification" or
"use this registry"). "use this registry").
o Authentication schemes need to document whether they are usable in o Authentication schemes need to document whether they are usable in
origin-server authentication (i.e., using WWW-Authenticate), origin-server authentication (i.e., using WWW-Authenticate),
and/or proxy authentication (i.e., using Proxy-Authenticate). and/or proxy authentication (i.e., using Proxy-Authenticate).
o The credentials carried in an Authorization header field are o The credentials carried in an Authorization header field are
specific to the User Agent, and therefore have the same effect on specific to the user agent and, therefore, have the same effect on
HTTP caches as the "private" Cache-Control response directive HTTP caches as the "private" Cache-Control response directive
(Section 5.2.2.6 of [Part6]), within the scope of the request they (Section 5.2.2.6 of [RFC7234]), within the scope of the request in
appear in. which they appear.
Therefore, new authentication schemes that choose not to carry Therefore, new authentication schemes that choose not to carry
credentials in the Authorization header field (e.g., using a newly credentials in the Authorization header field (e.g., using a newly
defined header field) will need to explicitly disallow caching, by defined header field) will need to explicitly disallow caching, by
mandating the use of either Cache-Control request directives mandating the use of either Cache-Control request directives
(e.g., "no-store", Section 5.2.1.5 of [Part6]) or response (e.g., "no-store", Section 5.2.1.5 of [RFC7234]) or response
directives (e.g., "private"). directives (e.g., "private").
5.2. Status Code Registration 5.2. Status Code Registration
The HTTP Status Code Registry located at The "Hypertext Transfer Protocol (HTTP) Status Code Registry" located
<http://www.iana.org/assignments/http-status-codes> shall be updated at <http://www.iana.org/assignments/http-status-codes> has been
with the registrations below: updated with the registrations below:
+-------+-------------------------------+-------------+ +-------+-------------------------------+-------------+
| Value | Description | Reference | | Value | Description | Reference |
+-------+-------------------------------+-------------+ +-------+-------------------------------+-------------+
| 401 | Unauthorized | Section 3.1 | | 401 | Unauthorized | Section 3.1 |
| 407 | Proxy Authentication Required | Section 3.2 | | 407 | Proxy Authentication Required | Section 3.2 |
+-------+-------------------------------+-------------+ +-------+-------------------------------+-------------+
5.3. Header Field Registration 5.3. Header Field Registration
HTTP header fields are registered within the Message Header Field HTTP header fields are registered within the "Message Headers"
Registry maintained at <http://www.iana.org/assignments/ registry maintained at
message-headers/message-header-index.html>. <http://www.iana.org/assignments/message-headers/>.
This document defines the following HTTP header fields, so their This document defines the following HTTP header fields, so the
associated registry entries shall be updated according to the "Permanent Message Header Field Names" registry has been updated
permanent registrations below (see [BCP90]): accordingly (see [BCP90]).
+---------------------+----------+----------+-------------+ +---------------------+----------+----------+-------------+
| Header Field Name | Protocol | Status | Reference | | Header Field Name | Protocol | Status | Reference |
+---------------------+----------+----------+-------------+ +---------------------+----------+----------+-------------+
| Authorization | http | standard | Section 4.2 | | Authorization | http | standard | Section 4.2 |
| Proxy-Authenticate | http | standard | Section 4.3 | | Proxy-Authenticate | http | standard | Section 4.3 |
| Proxy-Authorization | http | standard | Section 4.4 | | Proxy-Authorization | http | standard | Section 4.4 |
| WWW-Authenticate | http | standard | Section 4.1 | | WWW-Authenticate | http | standard | Section 4.1 |
+---------------------+----------+----------+-------------+ +---------------------+----------+----------+-------------+
skipping to change at page 12, line 44 skipping to change at page 13, line 4
| WWW-Authenticate | http | standard | Section 4.1 | | 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 authentication. and users of known security concerns specific to HTTP authentication.
More general security considerations are addressed in HTTP messaging More general security considerations are addressed in HTTP messaging
[Part1] and semantics [Part2]. [RFC7230] and semantics [RFC7231].
Everything about the topic of HTTP authentication is a security Everything about the topic of HTTP authentication is a security
consideration, so the list of considerations below is not exhaustive. consideration, so the list of considerations below is not exhaustive.
Furthermore, it is limited to security considerations regarding the Furthermore, it is limited to security considerations regarding the
authentication framework, in general, rather than discussing all of authentication framework, in general, rather than discussing all of
the potential considerations for specific authentication schemes the potential considerations for specific authentication schemes
(which ought to be documented in the specifications that define those (which ought to be documented in the specifications that define those
schemes). Various organizations maintain topical information and schemes). Various organizations maintain topical information and
links to current research on Web application security (e.g., links to current research on Web application security (e.g.,
[OWASP]), including common pitfalls for implementing and using the [OWASP]), including common pitfalls for implementing and using the
skipping to change at page 13, line 23 skipping to change at page 13, line 33
authentication scheme defines how the credentials are encoded prior authentication scheme defines how the credentials are encoded prior
to transmission. While this provides flexibility for the development to transmission. While this provides flexibility for the development
of future authentication schemes, it is inadequate for the protection of future authentication schemes, it is inadequate for the protection
of existing schemes that provide no confidentiality on their own, or of existing schemes that provide no confidentiality on their own, or
that do not sufficiently protect against replay attacks. that do not sufficiently protect against replay attacks.
Furthermore, if the server expects credentials that are specific to Furthermore, if the server expects credentials that are specific to
each individual user, the exchange of those credentials will have the each individual user, the exchange of those credentials will have the
effect of identifying that user even if the content within effect of identifying that user even if the content within
credentials remains confidential. credentials remains confidential.
HTTP depends on the security properties of the underlying transport HTTP depends on the security properties of the underlying transport-
or session-level connection to provide confidential transmission of or session-level connection to provide confidential transmission of
header fields. In other words, if a server limits access to header fields. In other words, if a server limits access to
authenticated users using this framework, the server needs to ensure authenticated users using this framework, the server needs to ensure
that the connection is properly secured in accordance with the nature that the connection is properly secured in accordance with the nature
of the authentication scheme used. For example, services that depend of the authentication scheme used. For example, services that depend
on individual user authentication often require a connection to be on individual user authentication often require a connection to be
secured with TLS ("Transport Layer Security", [RFC5246]) prior to secured with TLS ("Transport Layer Security", [RFC5246]) prior to
exchanging any credentials. exchanging any credentials.
6.2. Authentication Credentials and Idle Clients 6.2. Authentication Credentials and Idle Clients
skipping to change at page 14, line 38 skipping to change at page 14, line 48
7. Acknowledgments 7. Acknowledgments
This specification takes over the definition of the HTTP This specification takes over the definition of the HTTP
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 [RFC7230] 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
Protocol (HTTP/1.1): Message Syntax and Routing",
draft-ietf-httpbis-p1-messaging-26 (work in progress),
February 2014.
[Part2] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content",
draft-ietf-httpbis-p2-semantics-26 (work in progress),
February 2014.
[Part6] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
draft-ietf-httpbis-p6-cache-26 (work in progress),
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.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
draft-ietf-httpbis-p1-messaging-latest (work in progress),
June 2014.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content",
draft-ietf-httpbis-p2-semantics-latest (work in progress),
June 2014.
[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "Hypertext Transfer Protocol (HTTP/1.1): Caching",
draft-ietf-httpbis-p6-cache-latest (work in progress),
June 2014.
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 [OWASP] van der Stock, A., Ed., "A Guide to Building Secure Web
Applications and Web Services", The Open Web Application Applications and Web Services", The Open Web Application
Security Project (OWASP) 2.0.1, July 2005, Security Project (OWASP) 2.0.1, July 2005,
<https://www.owasp.org/>. <https://www.owasp.org/>.
skipping to change at page 16, line 31 skipping to change at page 16, line 39
Appendix B. Imported ABNF Appendix B. Imported ABNF
The following core rules are included by reference, as defined in The following core rules are included by reference, as defined in
Appendix B.1 of [RFC5234]: ALPHA (letters), CR (carriage return), Appendix B.1 of [RFC5234]: ALPHA (letters), CR (carriage return),
CRLF (CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double 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 quote), HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any
8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII 8-bit sequence of data), SP (space), and VCHAR (any visible US-ASCII
character). character).
The rules below are defined in [Part1]: The rules below are defined in [RFC7230]:
BWS = <BWS, defined in [Part1], Section 3.2.3> BWS = <BWS, see [RFC7230], Section 3.2.3>
OWS = <OWS, defined in [Part1], Section 3.2.3> OWS = <OWS, see [RFC7230], Section 3.2.3>
quoted-string = <quoted-string, defined in [Part1], Section 3.2.6> quoted-string = <quoted-string, see [RFC7230], Section 3.2.6>
token = <token, defined in [Part1], Section 3.2.6> token = <token, see [RFC7230], Section 3.2.6>
Appendix C. Collected ABNF Appendix C. Collected ABNF
In the collected ABNF below, list rules are expanded as per Section In the collected ABNF below, list rules are expanded as per Section
1.2 of [Part1]. 1.2 of [RFC7230].
Authorization = credentials Authorization = credentials
BWS = <BWS, defined in [Part1], Section 3.2.3> BWS = <BWS, see [RFC7230], Section 3.2.3>
OWS = <OWS, defined in [Part1], Section 3.2.3> OWS = <OWS, see [RFC7230], Section 3.2.3>
Proxy-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS Proxy-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS
challenge ] ) challenge ] )
Proxy-Authorization = credentials Proxy-Authorization = credentials
WWW-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS challenge WWW-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS challenge
] ) ] )
auth-param = token BWS "=" BWS ( token / quoted-string ) auth-param = token BWS "=" BWS ( token / quoted-string )
auth-scheme = token auth-scheme = token
challenge = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param ) *( challenge = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param ) *(
OWS "," [ OWS auth-param ] ) ] ) ] OWS "," [ OWS auth-param ] ) ] ) ]
credentials = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param ) credentials = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param )
*( OWS "," [ OWS auth-param ] ) ] ) ] *( OWS "," [ OWS auth-param ] ) ] ) ]
quoted-string = <quoted-string, defined in [Part1], Section 3.2.6> quoted-string = <quoted-string, see [RFC7230], Section 3.2.6>
token = <token, defined in [Part1], Section 3.2.6> token = <token, see [RFC7230], Section 3.2.6>
token68 = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" ) token68 = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" )
*"=" *"="
Appendix D. Change Log (to be removed by RFC Editor before publication)
Changes up to the IETF Last Call draft are summarized in <http://
trac.tools.ietf.org/html/draft-ietf-httpbis-p7-auth-24#appendix-D>.
D.1. Since draft-ietf-httpbis-p7-auth-24
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/510>: "SECDIR review
of draft-ietf-httpbis-p7-auth-24"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/513>: "APPSDIR
review of draft-ietf-httpbis-p7-auth-24"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/516>: "note about
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 8 Authorization header field 9
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 9
challenge 5 challenge 5
credentials 6 credentials 6
Proxy-Authenticate 9 Proxy-Authenticate 9
Proxy-Authorization 9 Proxy-Authorization 10
token68 5 token68 5
WWW-Authenticate 8 WWW-Authenticate 8
P P
Protection Space 6 Protection Space 6
Proxy-Authenticate header field 9 Proxy-Authenticate header field 9
Proxy-Authorization header field 9 Proxy-Authorization header field 10
R R
Realm 6 Realm 6
W W
WWW-Authenticate header field 8 WWW-Authenticate header field 8
Authors' Addresses Authors' Addresses
Roy T. Fielding (editor) Roy T. Fielding (editor)
 End of changes. 54 change blocks. 
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