One document matched: draft-ietf-httpbis-p7-auth-26.xml
<?xml version="1.0" encoding="UTF-8"?>
<!--
This XML document is the output of clean-for-DTD.xslt; a tool that strips
extensions to RFC2629(bis) from documents for processing with xml2rfc.
-->
<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
<?rfc toc="yes" ?>
<?rfc symrefs="yes" ?>
<?rfc sortrefs="yes" ?>
<?rfc compact="yes"?>
<?rfc subcompact="no" ?>
<?rfc linkmailto="no" ?>
<?rfc editing="no" ?>
<?rfc comments="yes"?>
<?rfc inline="yes"?>
<?rfc rfcedstyle="yes"?>
<!DOCTYPE rfc
PUBLIC "" "rfc2629.dtd">
<rfc obsoletes="2616" updates="2617" category="std" ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p7-auth-26">
<front>
<title abbrev="HTTP/1.1 Authentication">Hypertext Transfer Protocol (HTTP/1.1): Authentication</title>
<author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
<organization abbrev="Adobe">Adobe Systems Incorporated</organization>
<address>
<postal>
<street>345 Park Ave</street>
<city>San Jose</city>
<region>CA</region>
<code>95110</code>
<country>USA</country>
</postal>
<email>fielding@gbiv.com</email>
<uri>http://roy.gbiv.com/</uri>
</address>
</author>
<author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
<organization abbrev="greenbytes">greenbytes GmbH</organization>
<address>
<postal>
<street>Hafenweg 16</street>
<city>Muenster</city><region>NW</region><code>48155</code>
<country>Germany</country>
</postal>
<email>julian.reschke@greenbytes.de</email>
<uri>http://greenbytes.de/tech/webdav/</uri>
</address>
</author>
<date month="February" year="2014" day="6"/>
<area>Applications</area>
<workgroup>HTTPbis Working Group</workgroup>
<abstract>
<t>
The Hypertext Transfer Protocol (HTTP) is a stateless application-level
protocol for distributed, collaborative, hypermedia information systems.
This document defines the HTTP Authentication framework.
</t>
</abstract>
<note title="Editorial Note (To be removed by RFC Editor)">
<t>
Discussion of this draft takes place on the HTTPBIS working group
mailing list (ietf-http-wg@w3.org), which is archived at
<eref target="http://lists.w3.org/Archives/Public/ietf-http-wg/"/>.
</t>
<t>
The current issues list is at
<eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/> and related
documents (including fancy diffs) can be found at
<eref target="http://tools.ietf.org/wg/httpbis/"/>.
</t>
<t>
The changes in this draft are summarized in <xref target="changes.since.25"/>.
</t>
</note>
</front>
<middle>
<section title="Introduction" anchor="introduction">
<t>
HTTP provides a general framework for access control and authentication,
via an extensible set of challenge-response authentication schemes, which
can be used by a server to challenge a client request and by a client to
provide authentication information. This document defines HTTP/1.1
authentication in terms of the architecture defined in
<xref target="Part1"/>, including the general framework previously
described in RFC 2617 and
the related fields and status codes previously defined in
RFC 2616.
</t>
<t>
The IANA Authentication Scheme Registry
(<xref target="authentication.scheme.registry"/>) lists registered
authentication schemes and their corresponding specifications, including
the "basic" and "digest" authentication schemes previously defined by
RFC 2617.
</t>
<section title="Conformance and Error Handling" anchor="conformance">
<t>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref target="RFC2119"/>.
</t>
<t>
Conformance criteria and considerations regarding error handling
are defined in Section 2.5 of <xref target="Part1"/>.
</t>
</section>
<section title="Syntax Notation" anchor="notation">
<t>
This specification uses the Augmented Backus-Naur Form (ABNF) notation of
<xref target="RFC5234"/> with a list extension, defined in
Section 7 of <xref target="Part1"/>, that allows for compact definition of
comma-separated lists using a '#' operator (similar to how the '*' operator
indicates repetition).
<xref target="imported.abnf"/> describes rules imported from
other documents.
<xref target="collected.abnf"/> shows the collected grammar with all list
operators expanded to standard ABNF notation.
</t>
</section>
</section>
<section title="Access Authentication Framework" anchor="access.authentication.framework">
<section title="Challenge and Response" anchor="challenge.and.response">
<t>
HTTP provides a simple challenge-response authentication framework
that can be used by a server to challenge a client request and by a
client to provide authentication information. It uses a case-insensitive
token as a means to identify the authentication scheme, followed
by additional information necessary for achieving authentication via that
scheme. The latter can either be a comma-separated list of parameters or a
single sequence of characters capable of holding base64-encoded
information.
</t>
<t>
Authentication parameters are name=value pairs, where the name token is
matched case-insensitively,
and each parameter name MUST only occur once per challenge.
</t>
<figure><iref primary="true" item="Grammar" subitem="auth-scheme"/><iref primary="true" item="Grammar" subitem="auth-param"/><iref primary="true" item="Grammar" subitem="token68"/><artwork type="abnf2616"><![CDATA[
auth-scheme = token
auth-param = token BWS "=" BWS ( token / quoted-string )
token68 = 1*( ALPHA / DIGIT /
"-" / "." / "_" / "~" / "+" / "/" ) *"="
]]></artwork></figure>
<t>
The "token68" syntax allows the 66 unreserved URI characters
(<xref target="RFC3986"/>), plus a few others, so that it can hold a
base64, base64url (URL and filename safe alphabet), base32, or base16 (hex)
encoding, with or without padding, but excluding whitespace
(<xref target="RFC4648"/>).
</t>
<t>
A <xref target="status.401" format="none">401 (Unauthorized)</xref> response message is used by an origin
server to challenge the authorization of a user agent, including a
<xref target="header.www-authenticate" format="none">WWW-Authenticate</xref> header field containing at least one
challenge applicable to the requested resource.
</t>
<t>
A <xref target="status.407" format="none">407 (Proxy Authentication Required)</xref> response message is
used by a proxy to challenge the authorization of a client, including a
<xref target="header.proxy-authenticate" format="none">Proxy-Authenticate</xref> header field containing at least one
challenge applicable to the proxy for the requested resource.
</t>
<figure><iref primary="true" item="Grammar" subitem="challenge"/><artwork type="abnf2616"><![CDATA[
challenge = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
]]></artwork></figure>
<t><list>
<t>
Note: Many clients fail to parse a challenge that contains an unknown
scheme. A workaround for this problem is to list well-supported schemes
(such as "basic") first.<!-- see http://greenbytes.de/tech/tc/httpauth/#multibasicunknown2 -->
</t>
</list></t>
<t>
A user agent that wishes to authenticate itself with an origin server
— usually, but not necessarily, after receiving a
<xref target="status.401" format="none">401 (Unauthorized)</xref> — can do so by including an
<xref target="header.authorization" format="none">Authorization</xref> header field with the request.
</t>
<t>
A client that wishes to authenticate itself with a proxy — usually,
but not necessarily, after receiving a
<xref target="status.407" format="none">407 (Proxy Authentication Required)</xref> — can do so by
including a <xref target="header.proxy-authorization" format="none">Proxy-Authorization</xref> header field with the
request.
</t>
<t>
Both the <xref target="header.authorization" format="none">Authorization</xref> field value and the
<xref target="header.proxy-authorization" format="none">Proxy-Authorization</xref> field value contain the client's
credentials for the realm of the resource being requested, based upon a
challenge received in a response (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 considers to be the most secure auth-scheme that it
understands, 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
<xref target="confidentiality.of.credentials"/>.
</t>
<figure><iref primary="true" item="Grammar" subitem="credentials"/><artwork type="abnf2616"><![CDATA[
credentials = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
]]></artwork></figure>
<t>
Upon receipt of a request for a protected resource that omits credentials,
contains invalid credentials (e.g., a bad password) or partial credentials
(e.g., when the authentication scheme requires more than one round trip),
an origin server SHOULD send a <xref target="status.401" format="none">401 (Unauthorized)</xref> response
that contains a <xref target="header.www-authenticate" format="none">WWW-Authenticate</xref> header field with at least
one (possibly new) challenge applicable to the requested resource.
</t>
<t>
Likewise, upon receipt of a request that omits proxy credentials or
contains invalid or partial proxy credentials, a proxy that requires
authentication SHOULD generate a
<xref target="status.407" format="none">407 (Proxy Authentication Required)</xref> response that contains
a <xref target="header.proxy-authenticate" format="none">Proxy-Authenticate</xref> header field with at least one
(possibly new) challenge applicable to the proxy.
</t>
<t>
A server that receives valid credentials which are not adequate to gain
access ought to respond with the 403 (Forbidden) status
code (Section 6.5.3 of <xref target="Part2"/>).
</t>
<t>
HTTP does not restrict applications to this simple challenge-response
framework for access authentication. Additional mechanisms can be used,
such as authentication at the transport level or via message encapsulation,
and with additional header fields specifying authentication information.
However, such additional mechanisms are not defined by this specification.
</t>
</section>
<section title="Protection Space (Realm)" anchor="protection.space">
<iref item="Protection Space"/>
<iref item="Realm"/>
<iref item="Canonical Root URI"/>
<t>
The "realm" authentication parameter is reserved for use by
authentication schemes that wish to indicate a scope of protection.
</t>
<t>
A protection space is defined by the canonical root URI (the
scheme and authority components of the effective request URI; see
Section 5.5 of <xref target="Part1"/>) of the
server being accessed, in combination with the realm value if present.
These realms allow the protected resources on a server to be
partitioned into a set of protection spaces, each with its own
authentication scheme and/or authorization database. The realm value
is a string, generally assigned by the origin server, which can have
additional semantics specific to the authentication scheme. Note that a
response can have multiple challenges with the same auth-scheme but
different realms.
</t>
<t>
The protection space determines the domain over which credentials can
be automatically applied. If a prior request has been authorized, the
user agent MAY reuse the same credentials for all other requests within
that protection space for a period of time determined by the authentication
scheme, parameters, and/or user preferences (such as a configurable
inactivity timeout). Unless specifically allowed by the authentication
scheme, a single protection space cannot extend outside the scope of its
server.
</t>
<t>
For historical reasons, a sender MUST only generate the quoted-string syntax.
Recipients might have to support both token and quoted-string syntax for
maximum interoperability with existing clients that have been accepting both
notations for a long time.
</t>
</section>
</section>
<section title="Status Code Definitions" anchor="status.code.definitions">
<section title="401 Unauthorized" anchor="status.401">
<iref primary="true" item="401 Unauthorized (status code)"/>
<t>
The 401 (Unauthorized) status code indicates that the
request has not been applied because it lacks valid authentication
credentials for the target resource.
The server generating a 401 response MUST send a
<xref target="header.www-authenticate" format="none">WWW-Authenticate</xref> header field
(<xref target="header.www-authenticate"/>)
containing at least one challenge applicable to the target resource.
</t>
<t>
If the request included authentication credentials, then the 401 response
indicates that authorization has been refused for those credentials.
The user agent MAY repeat the request with a new or replaced
<xref target="header.authorization" format="none">Authorization</xref> header field (<xref target="header.authorization"/>).
If the 401 response contains the same challenge as the prior response, and
the user agent has already attempted authentication at least once, then the
user agent SHOULD present the enclosed representation to the user, since
it usually contains relevant diagnostic information.
</t>
</section>
<section title="407 Proxy Authentication Required" anchor="status.407">
<iref primary="true" item="407 Proxy Authentication Required (status code)"/>
<t>
The 407 (Proxy Authentication Required) status code is
similar to <xref target="status.401" format="none">401 (Unauthorized)</xref>, but indicates that the client
needs to authenticate itself in order to use a proxy.
The proxy MUST send a <xref target="header.proxy-authenticate" format="none">Proxy-Authenticate</xref> header field
(<xref target="header.proxy-authenticate"/>) containing a challenge
applicable to that proxy for the target resource. The client MAY repeat
the request with a new or replaced <xref target="header.proxy-authorization" format="none">Proxy-Authorization</xref>
header field (<xref target="header.proxy-authorization"/>).
</t>
</section>
</section>
<section title="Header Field Definitions" anchor="header.field.definitions">
<t>
This section defines the syntax and semantics of header fields related to
the HTTP authentication framework.
</t>
<section title="WWW-Authenticate" anchor="header.www-authenticate">
<iref primary="true" item="WWW-Authenticate header field"/>
<t>
The "WWW-Authenticate" header field indicates the authentication scheme(s)
and parameters applicable to the target resource.
</t>
<figure><iref primary="true" item="Grammar" subitem="WWW-Authenticate"/><artwork type="abnf2616"><![CDATA[
WWW-Authenticate = 1#challenge
]]></artwork></figure>
<t>
A server generating a <xref target="status.401" format="none">401 (Unauthorized)</xref> 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.
</t>
<t>
A proxy forwarding a response MUST NOT modify any
<xref target="header.www-authenticate" format="none">WWW-Authenticate</xref> fields in that response.
</t>
<t>
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.
</t>
<figure>
<preamble>For instance:</preamble>
<artwork type="example"><![CDATA[
WWW-Authenticate: Newauth realm="apps", type=1,
title="Login to \"apps\"", Basic realm="simple"
]]></artwork>
<postamble>
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".
</postamble></figure>
<t><list>
<t>
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.
</t>
</list></t>
</section>
<section title="Authorization" anchor="header.authorization">
<iref primary="true" item="Authorization header field"/>
<t>
The "Authorization" header field allows a user agent to authenticate itself
with an origin server — usually, but not necessarily, after receiving
a <xref target="status.401" format="none">401 (Unauthorized)</xref> response. Its value consists of
credentials containing the authentication information of the user agent for
the realm of the resource being requested.
</t>
<figure><iref primary="true" item="Grammar" subitem="Authorization"/><artwork type="abnf2616"><![CDATA[
Authorization = credentials
]]></artwork></figure>
<t>
If a request is authenticated and a realm specified, the same credentials
are presumed to be valid for all other requests within this realm (assuming
that the authentication scheme itself does not require otherwise, such as
credentials that vary according to a challenge value or using synchronized
clocks).
</t>
<t>
A proxy forwarding a request MUST NOT modify any
<xref target="header.authorization" format="none">Authorization</xref> fields in that request.
See Section 3.2 of <xref target="Part6"/> for details of and requirements
pertaining to handling of the Authorization field by HTTP caches.
</t>
</section>
<section title="Proxy-Authenticate" anchor="header.proxy-authenticate">
<iref primary="true" item="Proxy-Authenticate header field"/>
<t>
The "Proxy-Authenticate" header field consists of at least one
challenge that indicates the authentication scheme(s) and parameters
applicable to the proxy for this effective request URI
(Section 5.5 of <xref target="Part1"/>).
A proxy MUST send at least one Proxy-Authenticate header field in
each <xref target="status.407" format="none">407 (Proxy Authentication Required)</xref> response that it
generates.
</t>
<figure><iref primary="true" item="Grammar" subitem="Proxy-Authenticate"/><artwork type="abnf2616"><![CDATA[
Proxy-Authenticate = 1#challenge
]]></artwork></figure>
<t>
Unlike <xref target="header.www-authenticate" format="none">WWW-Authenticate</xref>, the Proxy-Authenticate header field
applies only to the next outbound client on the response chain.
This is because only the client that chose a given proxy is likely to have
the credentials necessary for authentication. However, when multiple
proxies are used within the same administrative domain, such as office and
regional caching proxies within a large corporate network, it is common
for credentials to be generated by the user agent and passed through the
hierarchy until consumed. Hence, in such a configuration, it will appear
as if Proxy-Authenticate is being forwarded because each proxy will send
the same challenge set.
</t>
<t>
Note that the parsing considerations for <xref target="header.www-authenticate" format="none">WWW-Authenticate</xref>
apply to this header field as well; see <xref target="header.www-authenticate"/>
for details.
</t>
</section>
<section title="Proxy-Authorization" anchor="header.proxy-authorization">
<iref primary="true" item="Proxy-Authorization header field"/>
<t>
The "Proxy-Authorization" header field allows the client to
identify itself (or its user) to a proxy that requires
authentication. Its value consists of credentials containing the
authentication information of the client for the proxy and/or realm of the
resource being requested.
</t>
<figure><iref primary="true" item="Grammar" subitem="Proxy-Authorization"/><artwork type="abnf2616"><![CDATA[
Proxy-Authorization = credentials
]]></artwork></figure>
<t>
Unlike <xref target="header.authorization" format="none">Authorization</xref>, the Proxy-Authorization header field
applies only to the next inbound proxy that demanded authentication using
the <xref target="header.proxy-authenticate" format="none">Proxy-Authenticate</xref> field. When multiple proxies are used
in a chain, the Proxy-Authorization header field is consumed by the first
inbound proxy that was expecting to receive credentials. A proxy MAY
relay the credentials from the client request to the next proxy if that is
the mechanism by which the proxies cooperatively authenticate a given
request.
</t>
</section>
</section>
<section title="IANA Considerations" anchor="IANA.considerations">
<section title="Authentication Scheme Registry" anchor="authentication.scheme.registry">
<t>
The HTTP Authentication Scheme Registry defines the name space for the
authentication schemes in challenges and credentials. It will be created and
maintained at (the suggested URI) <eref target="http://www.iana.org/assignments/http-authschemes"/>.
</t>
<section title="Procedure" anchor="authentication.scheme.registry.procedure">
<t>
Registrations MUST include the following fields:
<list style="symbols">
<t>Authentication Scheme Name</t>
<t>Pointer to specification text</t>
<t>Notes (optional)</t>
</list>
</t>
<t>
Values to be added to this name space require IETF Review
(see <xref target="RFC5226"/>, Section 4.1).
</t>
</section>
<section title="Considerations for New Authentication Schemes" anchor="considerations.for.new.authentication.schemes">
<t>
There are certain aspects of the HTTP Authentication Framework that put
constraints on how new authentication schemes can work:
</t>
<t>
<list style="symbols">
<t>
HTTP authentication is presumed to be stateless: all of the information
necessary to authenticate a request MUST be provided in the request,
rather than be dependent on the server remembering prior requests.
Authentication based on, or bound to, the underlying connection is
outside the scope of this specification and inherently flawed unless
steps are taken to ensure that the connection cannot be used by any
party other than the authenticated user
(see Section 2.3 of <xref target="Part1"/>).
</t>
<t>
The authentication parameter "realm" is reserved for defining Protection
Spaces as defined in <xref target="protection.space"/>. New schemes
MUST NOT use it in a way incompatible with that definition.
</t>
<t>
The "token68" notation was introduced for compatibility with existing
authentication schemes and can only be used once per challenge or credential.
New schemes thus ought to use the "auth-param" syntax instead, because
otherwise future extensions will be impossible.
</t>
<t>
The parsing of challenges and credentials is defined by this specification,
and cannot be modified by new authentication schemes. When the auth-param
syntax is used, all parameters ought to support both token and
quoted-string syntax, and syntactical constraints ought to be defined on
the field value after parsing (i.e., quoted-string processing). This is
necessary so that recipients can use a generic parser that applies to
all authentication schemes.
<vspace blankLines="1"/>
Note: The fact that the value syntax for the "realm" parameter
is restricted to quoted-string was a bad design choice not to be repeated
for new parameters.
</t>
<t>
Definitions of new schemes ought to define the treatment of unknown
extension parameters. In general, a "must-ignore" rule is preferable
over "must-understand", because otherwise it will be hard to introduce
new parameters in the presence of legacy recipients. Furthermore,
it's good to describe the policy for defining new parameters (such
as "update the specification", or "use this registry").
</t>
<t>
Authentication schemes need to document whether they are usable in
origin-server authentication (i.e., using <xref target="header.www-authenticate" format="none">WWW-Authenticate</xref>),
and/or proxy authentication (i.e., using <xref target="header.proxy-authenticate" format="none">Proxy-Authenticate</xref>).
</t>
<t>
The credentials carried in an <xref target="header.authorization" format="none">Authorization</xref> header field are specific to
the User Agent, and therefore have the same effect on HTTP caches as the
"private" Cache-Control response directive (Section 5.2.2.6 of <xref target="Part6"/>),
within the scope of the request they appear in.
<vspace blankLines="1"/>
Therefore, new authentication schemes that choose not to carry
credentials in the <xref target="header.authorization" format="none">Authorization</xref> header field (e.g., using a newly defined
header field) will need to explicitly disallow caching, by mandating the use of
either Cache-Control request directives (e.g., "no-store",
Section 5.2.1.5 of <xref target="Part6"/>) or response directives (e.g., "private").
</t>
</list>
</t>
</section>
</section>
<section title="Status Code Registration" anchor="status.code.registration">
<t>
The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
shall be updated with the registrations below:
</t>
<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
<ttcol>Value</ttcol>
<ttcol>Description</ttcol>
<ttcol>Reference</ttcol>
<c>401</c>
<c>Unauthorized</c>
<c>
<xref target="status.401"/>
</c>
<c>407</c>
<c>Proxy Authentication Required</c>
<c>
<xref target="status.407"/>
</c>
</texttable>
<!--(END)-->
</section>
<section title="Header Field Registration" anchor="header.field.registration">
<t>
HTTP header fields are registered within the Message Header Field Registry
maintained at
<eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/>.
</t>
<t>
This document defines the following HTTP header fields, so their
associated registry entries shall be updated according to the permanent
registrations below (see <xref target="BCP90"/>):
</t>
<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
<ttcol>Header Field Name</ttcol>
<ttcol>Protocol</ttcol>
<ttcol>Status</ttcol>
<ttcol>Reference</ttcol>
<c>Authorization</c>
<c>http</c>
<c>standard</c>
<c>
<xref target="header.authorization"/>
</c>
<c>Proxy-Authenticate</c>
<c>http</c>
<c>standard</c>
<c>
<xref target="header.proxy-authenticate"/>
</c>
<c>Proxy-Authorization</c>
<c>http</c>
<c>standard</c>
<c>
<xref target="header.proxy-authorization"/>
</c>
<c>WWW-Authenticate</c>
<c>http</c>
<c>standard</c>
<c>
<xref target="header.www-authenticate"/>
</c>
</texttable>
<!--(END)-->
<t>
The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
</t>
</section>
</section>
<section title="Security Considerations" anchor="security.considerations">
<t>
This section is meant to inform developers, information providers, and
users of known security concerns specific to HTTP authentication.
More general security considerations are addressed in HTTP messaging
<xref target="Part1"/> and semantics <xref target="Part2"/>.
</t>
<t>
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., <xref target="OWASP"/>),
including common pitfalls for implementing and using the authentication
schemes found in practice.
</t>
<section title="Confidentiality of Credentials" anchor="confidentiality.of.credentials">
<t>
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.
</t>
<t>
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", <xref target="RFC5246"/>) prior to exchanging
any credentials.
</t>
</section>
<section title="Authentication Credentials and Idle Clients" anchor="auth.credentials.and.idle.clients">
<t>
Existing HTTP clients and user agents typically retain authentication
information indefinitely. HTTP does not provide a mechanism for the
origin server to direct clients to discard these cached credentials, since
the protocol has no awareness of how credentials are obtained or managed
by the user agent. The mechanisms for expiring or revoking credentials can
be specified as part of an authentication scheme definition.
</t>
<t>
Circumstances under which credential caching can interfere with the
application's security model include but are not limited to:
<list style="symbols">
<t>Clients that have been idle for an extended period, following
which the server might wish to cause the client to re-prompt the
user for credentials.</t>
<t>Applications that include a session termination indication
(such as a "logout" or "commit" button on a page) after which
the server side of the application "knows" that there is no
further reason for the client to retain the credentials.</t>
</list>
</t>
<t>
User agents that cache credentials are encouraged to provide a readily
accessible mechanism for discarding cached credentials under user control.
</t>
</section>
<section title="Protection Spaces" anchor="protection.spaces">
<t>
Authentication schemes that solely rely on the "realm" mechanism for
establishing a protection space will expose credentials to all resources on
an origin server. Clients that have successfully made authenticated requests
with a resource can use the same authentication credentials for other
resources on the same origin server. This makes it possible for a different
resource to harvest authentication credentials for other resources.
</t>
<t>
This is of particular concern when an origin server hosts resources for multiple
parties under the same canonical root URI (<xref target="protection.space"/>).
Possible mitigation strategies include restricting direct access to
authentication credentials (i.e., not making the content of the
<xref target="header.authorization" format="none">Authorization</xref> request header field available), and separating protection
spaces by using a different host name (or port number) for each party.
</t>
</section>
</section>
<section title="Acknowledgments" anchor="acks">
<t>
This specification takes over the definition of the HTTP Authentication
Framework, previously defined in RFC 2617.
We thank John Franks, Phillip M. Hallam-Baker, Jeffery L. Hostetler, Scott D. Lawrence,
Paul J. Leach, Ari Luotonen, and Lawrence C. Stewart for their work
on that specification. See Section 6 of <xref target="RFC2617"/>
for further acknowledgements.
</t>
<t>
See Section 10 of <xref target="Part1"/> for the Acknowledgments related to this document revision.
</t>
</section>
</middle>
<back>
<references title="Normative References">
<reference anchor="Part1">
<front>
<title>Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing</title>
<author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
<organization abbrev="Adobe">Adobe Systems Incorporated</organization>
<address><email>fielding@gbiv.com</email></address>
</author>
<author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
<organization abbrev="greenbytes">greenbytes GmbH</organization>
<address><email>julian.reschke@greenbytes.de</email></address>
</author>
<date month="February" year="2014"/>
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-26"/>
</reference>
<reference anchor="Part2">
<front>
<title>Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content</title>
<author fullname="Roy T. Fielding" initials="R." role="editor" surname="Fielding">
<organization abbrev="Adobe">Adobe Systems Incorporated</organization>
<address><email>fielding@gbiv.com</email></address>
</author>
<author fullname="Julian F. Reschke" initials="J. F." role="editor" surname="Reschke">
<organization abbrev="greenbytes">greenbytes GmbH</organization>
<address><email>julian.reschke@greenbytes.de</email></address>
</author>
<date month="February" year="2014"/>
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p2-semantics-26"/>
</reference>
<reference anchor="Part6">
<front>
<title>Hypertext Transfer Protocol (HTTP/1.1): Caching</title>
<author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
<organization abbrev="Adobe">Adobe Systems Incorporated</organization>
<address><email>fielding@gbiv.com</email></address>
</author>
<author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
<organization>Akamai</organization>
<address><email>mnot@mnot.net</email></address>
</author>
<author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
<organization abbrev="greenbytes">greenbytes GmbH</organization>
<address><email>julian.reschke@greenbytes.de</email></address>
</author>
<date month="February" year="2014"/>
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-26"/>
</reference>
<reference anchor="RFC2119">
<front>
<title>Key words for use in RFCs to Indicate Requirement Levels</title>
<author initials="S." surname="Bradner" fullname="Scott Bradner">
<organization>Harvard University</organization>
<address><email>sob@harvard.edu</email></address>
</author>
<date month="March" year="1997"/>
</front>
<seriesInfo name="BCP" value="14"/>
<seriesInfo name="RFC" value="2119"/>
</reference>
<reference anchor="RFC5234">
<front>
<title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
<author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
<organization>Brandenburg InternetWorking</organization>
<address>
<email>dcrocker@bbiw.net</email>
</address>
</author>
<author initials="P." surname="Overell" fullname="Paul Overell">
<organization>THUS plc.</organization>
<address>
<email>paul.overell@thus.net</email>
</address>
</author>
<date month="January" year="2008"/>
</front>
<seriesInfo name="STD" value="68"/>
<seriesInfo name="RFC" value="5234"/>
</reference>
</references>
<references title="Informative References">
<reference anchor="RFC2616">
<front>
<title>Hypertext Transfer Protocol -- HTTP/1.1</title>
<author initials="R." surname="Fielding" fullname="R. Fielding">
<organization>University of California, Irvine</organization>
<address><email>fielding@ics.uci.edu</email></address>
</author>
<author initials="J." surname="Gettys" fullname="J. Gettys">
<organization>W3C</organization>
<address><email>jg@w3.org</email></address>
</author>
<author initials="J." surname="Mogul" fullname="J. Mogul">
<organization>Compaq Computer Corporation</organization>
<address><email>mogul@wrl.dec.com</email></address>
</author>
<author initials="H." surname="Frystyk" fullname="H. Frystyk">
<organization>MIT Laboratory for Computer Science</organization>
<address><email>frystyk@w3.org</email></address>
</author>
<author initials="L." surname="Masinter" fullname="L. Masinter">
<organization>Xerox Corporation</organization>
<address><email>masinter@parc.xerox.com</email></address>
</author>
<author initials="P." surname="Leach" fullname="P. Leach">
<organization>Microsoft Corporation</organization>
<address><email>paulle@microsoft.com</email></address>
</author>
<author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
<organization>W3C</organization>
<address><email>timbl@w3.org</email></address>
</author>
<date month="June" year="1999"/>
</front>
<seriesInfo name="RFC" value="2616"/>
</reference>
<reference anchor="RFC2617">
<front>
<title abbrev="HTTP Authentication">HTTP Authentication: Basic and Digest Access Authentication</title>
<author initials="J." surname="Franks" fullname="John Franks">
<organization>Northwestern University, Department of Mathematics</organization>
<address><email>john@math.nwu.edu</email></address>
</author>
<author initials="P.M." surname="Hallam-Baker" fullname="Phillip M. Hallam-Baker">
<organization>Verisign Inc.</organization>
<address><email>pbaker@verisign.com</email></address>
</author>
<author initials="J.L." surname="Hostetler" fullname="Jeffery L. Hostetler">
<organization>AbiSource, Inc.</organization>
<address><email>jeff@AbiSource.com</email></address>
</author>
<author initials="S.D." surname="Lawrence" fullname="Scott D. Lawrence">
<organization>Agranat Systems, Inc.</organization>
<address><email>lawrence@agranat.com</email></address>
</author>
<author initials="P.J." surname="Leach" fullname="Paul J. Leach">
<organization>Microsoft Corporation</organization>
<address><email>paulle@microsoft.com</email></address>
</author>
<author initials="A." surname="Luotonen" fullname="Ari Luotonen">
<organization>Netscape Communications Corporation</organization>
</author>
<author initials="L." surname="Stewart" fullname="Lawrence C. Stewart">
<organization>Open Market, Inc.</organization>
<address><email>stewart@OpenMarket.com</email></address>
</author>
<date month="June" year="1999"/>
</front>
<seriesInfo name="RFC" value="2617"/>
</reference>
<reference anchor="BCP90">
<front>
<title>Registration Procedures for Message Header Fields</title>
<author initials="G." surname="Klyne" fullname="G. Klyne">
<organization>Nine by Nine</organization>
<address><email>GK-IETF@ninebynine.org</email></address>
</author>
<author initials="M." surname="Nottingham" fullname="M. Nottingham">
<organization>BEA Systems</organization>
<address><email>mnot@pobox.com</email></address>
</author>
<author initials="J." surname="Mogul" fullname="J. Mogul">
<organization>HP Labs</organization>
<address><email>JeffMogul@acm.org</email></address>
</author>
<date year="2004" month="September"/>
</front>
<seriesInfo name="BCP" value="90"/>
<seriesInfo name="RFC" value="3864"/>
</reference>
<reference anchor="RFC3986">
<front>
<title abbrev="URI Generic Syntax">Uniform Resource Identifier (URI): Generic Syntax</title>
<author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
<organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
<address>
<email>timbl@w3.org</email>
<uri>http://www.w3.org/People/Berners-Lee/</uri>
</address>
</author>
<author initials="R." surname="Fielding" fullname="Roy T. Fielding">
<organization abbrev="Day Software">Day Software</organization>
<address>
<email>fielding@gbiv.com</email>
<uri>http://roy.gbiv.com/</uri>
</address>
</author>
<author initials="L." surname="Masinter" fullname="Larry Masinter">
<organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
<address>
<email>LMM@acm.org</email>
<uri>http://larry.masinter.net/</uri>
</address>
</author>
<date month="January" year="2005"/>
</front>
<seriesInfo name="STD" value="66"/>
<seriesInfo name="RFC" value="3986"/>
</reference>
<reference anchor="RFC4648">
<front>
<title>The Base16, Base32, and Base64 Data Encodings</title>
<author fullname="S. Josefsson" initials="S." surname="Josefsson"/>
<date year="2006" month="October"/>
</front>
<seriesInfo value="4648" name="RFC"/>
</reference>
<reference anchor="RFC5226">
<front>
<title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
<author initials="T." surname="Narten" fullname="T. Narten">
<organization>IBM</organization>
<address><email>narten@us.ibm.com</email></address>
</author>
<author initials="H." surname="Alvestrand" fullname="H. Alvestrand">
<organization>Google</organization>
<address><email>Harald@Alvestrand.no</email></address>
</author>
<date year="2008" month="May"/>
</front>
<seriesInfo name="BCP" value="26"/>
<seriesInfo name="RFC" value="5226"/>
</reference>
<reference anchor="OWASP" target="https://www.owasp.org/">
<front>
<title abbrev="OWASP">A Guide to Building Secure Web Applications and Web Services</title>
<author role="editor" initials="A." surname="van der Stock" fullname="Andrew van der Stock"/>
<date month="July" day="27" year="2005"/>
</front>
<seriesInfo name="The Open Web Application Security Project (OWASP)" value="2.0.1"/>
</reference>
<reference anchor="RFC5246">
<front>
<title>The Transport Layer Security (TLS) Protocol Version 1.2</title>
<author initials="T." surname="Dierks" fullname="T. Dierks"/>
<author initials="E." surname="Rescorla" fullname="E. Rescorla">
<organization>RTFM, Inc.</organization>
</author>
<date year="2008" month="August"/>
</front>
<seriesInfo name="RFC" value="5246"/>
</reference>
</references>
<section title="Changes from RFCs 2616 and 2617" anchor="changes.from.rfc.2616">
<t>
The framework for HTTP Authentication is now defined by this document,
rather than RFC 2617.
</t>
<t>
The "realm" parameter is no longer always required on challenges;
consequently, the ABNF allows challenges without any auth parameters.
(<xref target="access.authentication.framework"/>)
</t>
<t>
The "token68" alternative to auth-param lists has been added for consistency
with legacy authentication schemes such as "Basic".
(<xref target="access.authentication.framework"/>)
</t>
<t>
This specification introduces the Authentication Scheme Registry, along with
considerations for new authentication schemes.
(<xref target="authentication.scheme.registry"/>)
</t>
</section>
<section title="Imported ABNF" anchor="imported.abnf">
<t>
The following core rules are included by
reference, as defined in Appendix B.1 of <xref target="RFC5234"/>:
ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
DIGIT (decimal 0-9), DQUOTE (double quote),
HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
OCTET (any 8-bit sequence of data), SP (space), and
VCHAR (any visible US-ASCII character).
</t>
<t>
The rules below are defined in <xref target="Part1"/>:
</t>
<figure><artwork type="abnf2616"><![CDATA[
BWS = <BWS, defined in [Part1], Section 3.2.3>
OWS = <OWS, defined in [Part1], Section 3.2.3>
quoted-string = <quoted-string, defined in [Part1], Section 3.2.6>
token = <token, defined in [Part1], Section 3.2.6>
]]></artwork></figure>
</section>
<section title="Collected ABNF" anchor="collected.abnf">
<t>
In the collected ABNF below, list rules are expanded as per Section 1.2 of <xref target="Part1"/>.
</t><figure>
<artwork type="abnf" name="p7-auth.parsed-abnf"><![CDATA[
Authorization = credentials
BWS = <BWS, defined in [Part1], Section 3.2.3>
OWS = <OWS, defined in [Part1], Section 3.2.3>
Proxy-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS
challenge ] )
Proxy-Authorization = credentials
WWW-Authenticate = *( "," OWS ) challenge *( OWS "," [ OWS challenge
] )
auth-param = token BWS "=" BWS ( token / quoted-string )
auth-scheme = token
challenge = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param ) *(
OWS "," [ OWS auth-param ] ) ] ) ]
credentials = auth-scheme [ 1*SP ( token68 / [ ( "," / auth-param )
*( OWS "," [ OWS auth-param ] ) ] ) ]
quoted-string = <quoted-string, defined in [Part1], Section 3.2.6>
token = <token, defined in [Part1], Section 3.2.6>
token68 = 1*( ALPHA / DIGIT / "-" / "." / "_" / "~" / "+" / "/" )
*"="
]]></artwork>
</figure>
</section>
<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
<t>
Changes up to the IETF Last Call draft are summarized
in <eref target="http://trac.tools.ietf.org/html/draft-ietf-httpbis-p7-auth-24#appendix-D"/>.
</t>
<section title="Since draft-ietf-httpbis-p7-auth-24" anchor="changes.since.24">
<t>
Closed issues:
<list style="symbols">
<t>
<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/510"/>:
"SECDIR review of draft-ietf-httpbis-p7-auth-24"
</t>
<t>
<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/513"/>:
"APPSDIR review of draft-ietf-httpbis-p7-auth-24"
</t>
<t>
<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/516"/>:
"note about WWW-A parsing potentially misleading"
</t>
</list>
</t>
</section>
<section title="Since draft-ietf-httpbis-p7-auth-25" anchor="changes.since.25">
<t>
Closed issues:
<list style="symbols">
<t>
<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/522"/>:
"Gen-art review of draft-ietf-httpbis-p7-auth-25"
</t>
<t>
<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/536"/>:
"IESG ballot on draft-ietf-httpbis-p7-auth-25"
</t>
<t>
<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/538"/>:
"add 'stateless' to Abstract"
</t>
<t>
<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/539"/>:
"mention TLS vs plain text passwords or dict attacks?"
</t>
<t>
<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/542"/>:
"improve introduction of list rule"
</t>
<t>
<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/549"/>:
"augment security considerations with pointers to current research"
</t>
</list>
</t>
</section>
</section>
</back>
</rfc>| PAFTECH AB 2003-2026 | 2026-04-23 13:47:08 |