One document matched: draft-ietf-oauth-v2-bearer-22.xml
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE rfc SYSTEM 'rfc2629.dtd'>
<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>
<rfc category='std' ipr='trust200902' docName='draft-ietf-oauth-v2-bearer-22'>
<?rfc strict='yes' ?>
<?rfc toc='yes' ?>
<?rfc tocdepth='3' ?>
<?rfc symrefs='yes' ?>
<?rfc sortrefs='yes' ?>
<?rfc compact='yes' ?>
<?rfc subcompact='no' ?>
<front>
<title abbrev='OAuth 2.0 Bearer Token Usage'>The OAuth 2.0 Authorization Framework: Bearer Token Usage</title>
<author fullname="Michael B. Jones" surname="Jones" initials="M.B."> <!-- role="editor" -->
<organization>Microsoft</organization>
<address>
<email>mbj@microsoft.com</email>
<uri>http://self-issued.info/</uri>
</address>
</author>
<author fullname='Dick Hardt' surname='Hardt' initials='D'>
<organization>independent</organization>
<address>
<email>dick.hardt@gmail.com</email>
<uri>http://dickhardt.org/</uri>
</address>
</author>
<author fullname='David Recordon' surname='Recordon' initials='D'>
<organization>Facebook</organization>
<address>
<email>dr@fb.com</email>
<uri>http://www.davidrecordon.com/</uri>
</address>
</author>
<date year="2012" month="July" day="12" />
<area>Security</area>
<workgroup>OAuth Working Group</workgroup>
<abstract>
<t>
This specification describes how to use bearer tokens in HTTP
requests to access OAuth 2.0 protected resources. Any party
in possession of a bearer token (a "bearer") can use it to get
access to the associated resources (without demonstrating possession
of a cryptographic key). To prevent misuse, bearer tokens
need to be protected from disclosure in storage and in transport.
</t>
</abstract>
</front>
<middle>
<section title='Introduction'>
<t>
OAuth enables clients to access protected resources by
obtaining an access token, which is defined in
OAuth 2.0 Authorization <xref target="I-D.ietf-oauth-v2"/>
as "a string representing an access
authorization issued to the client", rather than using the
resource owner's credentials directly.
</t>
<t>
Tokens are issued to clients by an authorization server with the approval of
the resource owner. The client uses the access token to access the protected resources
hosted by the resource server. This specification describes how to make protected resource
requests when the OAuth access token is a bearer token.
</t>
<t>
This specification defines the use of bearer tokens over
HTTP/1.1 <xref target='RFC2616'/>
using
TLS <xref target='RFC5246' /> to access protected resources.
TLS is mandatory to implement
and use with this specification; other specifications may
extend this specification for use with other protocols.
While designed for use with access tokens resulting from
OAuth 2.0 Authorization <xref target="I-D.ietf-oauth-v2" />
flows to access OAuth protected resources, this
specification actually defines a general HTTP authorization
method that can be used with bearer tokens from any source
to access any resources protected by those bearer tokens.
The Bearer authentication scheme is intended primarily for
server authentication using the WWW-Authenticate and
Authorization HTTP headers, but does not preclude its use for
proxy authentication.
</t>
<section title='Notational Conventions'>
<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
Key words for use in RFCs to Indicate Requirement Levels <xref target='RFC2119' />.
</t>
<t>
This document uses the Augmented Backus-Naur Form (ABNF)
notation of <xref target='RFC5234' />.
Additionally, the following rules are included from
HTTP/1.1 <xref target='RFC2617'/>:
auth-param and auth-scheme; and from
Uniform Resource Identifier (URI) <xref target='RFC3986' />:
URI-Reference.
</t>
<t>
Unless otherwise noted, all the protocol parameter names and values are case sensitive.
</t>
</section>
<section title='Terminology'>
<t>
<list style='hanging'>
<t hangText="Bearer Token">
<vspace />
A security token with the property that any party in
possession of the token (a "bearer") can use the token
in any way that any other party in possession of it can.
Using a bearer token does not require a bearer to prove
possession of cryptographic key material
(proof-of-possession).
</t>
</list>
</t>
<t>
All other terms are as defined in
OAuth 2.0 Authorization <xref target="I-D.ietf-oauth-v2" />.
</t>
</section>
<section title='Overview'>
<t>
OAuth provides a method for clients to access a protected resource on behalf of a
resource owner. In the general case,
before a client can access a protected resource, it must first obtain
an authorization grant from the resource owner and then exchange the authorization grant for
an access token.
The access token represents the grant's scope, duration, and
other attributes granted by the authorization grant. The
client accesses the protected resource by presenting the
access token to the resource server.
In some cases, a client can directly present its own
credentials to an authorization server to obtain an access
token without having to first obtain an authorization grant from a
resource owner.
</t>
<t>
The access token provides an abstraction, replacing different authorization
constructs (e.g., username and password, assertion) for a single token understood by the
resource server. This abstraction enables issuing access tokens valid for a short time
period, as well as removing the resource server's need to understand a wide range of
authentication schemes.
</t>
<figure title='Abstract Protocol Flow' anchor='Figure-1'>
<artwork><![CDATA[
+--------+ +---------------+
| |--(A)- Authorization Request ->| Resource |
| | | Owner |
| |<-(B)-- Authorization Grant ---| |
| | +---------------+
| |
| | +---------------+
| |--(C)-- Authorization Grant -->| Authorization |
| Client | | Server |
| |<-(D)----- Access Token -------| |
| | +---------------+
| |
| | +---------------+
| |--(E)----- Access Token ------>| Resource |
| | | Server |
| |<-(F)--- Protected Resource ---| |
+--------+ +---------------+
]]></artwork>
</figure>
<t>
The abstract OAuth 2.0 flow illustrated in <xref target='Figure-1' /> describes the interaction
between the four roles. The following steps are specified within this
document:
<list>
<t>
E) The client requests the protected resource from the resource server and authenticates by presenting
the access token.
</t>
<t>
F) The resource server validates the access token, and if valid, serves the request.
</t>
</list>
</t>
<t>
This document also imposes semantic requirements upon the
access token returned in Step D.
</t>
</section>
</section>
<section title='Authenticated Requests'>
<t>
This section defines three
methods of sending bearer access tokens in resource requests
to resource servers. Clients MUST NOT use more than one
method to transmit the token in each request.
</t>
<section title='Authorization Request Header Field' anchor='authz-header'>
<t>
When sending the access token in the <spanx
style='verb'>Authorization</spanx> request header field
defined by
HTTP/1.1 <xref target='RFC2617'/>,
the
client uses the <spanx style='verb'>Bearer</spanx>
authentication scheme to transmit the access token.
</t>
<figure>
<preamble>
For example:
</preamble>
<artwork><![CDATA[
GET /resource HTTP/1.1
Host: server.example.com
Authorization: Bearer mF_9.B5f-4.1JqM
]]></artwork>
</figure>
<t>
The <spanx style='verb'>Authorization</spanx> header field uses the framework defined by
HTTP/1.1 <xref target='RFC2617'/>
as follows:
</t>
<figure>
<artwork><![CDATA[
b64token = 1*( ALPHA / DIGIT /
"-" / "." / "_" / "~" / "+" / "/" ) *"="
credentials = "Bearer" 1*SP b64token
]]></artwork>
</figure>
<t>
Clients SHOULD make authenticated requests with a bearer
token using the <spanx style='verb'>Authorization</spanx>
request header field with the <spanx
style='verb'>Bearer</spanx> HTTP authorization scheme.
Resource servers MUST support this method.
</t>
</section>
<section title='Form-Encoded Body Parameter' anchor='body-param'>
<t>
When sending the access token in the HTTP request
entity-body, the client adds the access token to the request
body using the <spanx style='verb'>access_token</spanx>
parameter. The client MUST NOT use this method unless
all of the following conditions are met:
<list style='symbols'>
<t>
The HTTP request entity-header includes the <spanx style='verb'>Content-Type</spanx>
header field set to <spanx style='verb'>application/x-www-form-urlencoded</spanx>.
</t>
<t>
The entity-body follows the encoding requirements of the
<spanx style='verb'>application/x-www-form-urlencoded</spanx> content-type as
defined by
HTML 4.01 <xref target='W3C.REC-html401-19991224' />.
</t>
<t>
The HTTP request entity-body is single-part.
</t>
<t>
The content to be encoded in the entity-body MUST
consist entirely of ASCII <xref target="USASCII" /> characters.
</t>
<t>
The HTTP request method is one for which the request
body has defined semantics. In particular,
this means that the <spanx style='verb'>GET</spanx>
method MUST NOT be used.
</t>
</list>
</t>
<t>
The entity-body MAY include other request-specific
parameters, in which case, the <spanx
style='verb'>access_token</spanx> parameter MUST be properly
separated from the request-specific parameters using <spanx
style='verb'>&</spanx> character(s) (ASCII code 38).
</t>
<figure>
<preamble>
For example, the client makes the following HTTP request using transport-layer
security:
</preamble>
<artwork><![CDATA[
POST /resource HTTP/1.1
Host: server.example.com
Content-Type: application/x-www-form-urlencoded
access_token=mF_9.B5f-4.1JqM
]]></artwork>
</figure>
<t>
The <spanx style='verb'>application/x-www-form-urlencoded</spanx>
method SHOULD NOT be used except in application contexts
where participating browsers do not have access to the
<spanx style='verb'>Authorization</spanx> request header
field.
Resource servers MAY support this method.
</t>
</section>
<section title='URI Query Parameter' anchor='query-param'>
<t>
When sending the access token in the HTTP request URI, the client adds the access
token to the request URI query component as defined by
Uniform Resource Identifier (URI) <xref target='RFC3986' />
using
the <spanx style='verb'>access_token</spanx> parameter.
</t>
<figure>
<preamble>
For example, the client makes the following HTTP request using transport-layer
security:
</preamble>
<artwork><![CDATA[
GET /resource?access_token=mF_9.B5f-4.1JqM HTTP/1.1
Host: server.example.com
]]></artwork>
</figure>
<t>
The HTTP request URI query can include other
request-specific parameters, in which case, the <spanx
style='verb'>access_token</spanx> parameter MUST be properly
separated from the request-specific parameters using <spanx
style='verb'>&</spanx> character(s) (ASCII code 38).
</t>
<figure>
<preamble>
For example:
</preamble>
<artwork><![CDATA[
https://server.example.com/resource?access_token=mF_9.B5f-4.1JqM&p=q
]]></artwork>
</figure>
<t>
Clients using the URI Query Parameter method SHOULD also send a
Cache-Control header containing the "no-store" option. Server success
(2XX status) responses to these requests SHOULD contain a Cache-Control
header with the "private" option.
</t>
<t>
Because of the security weaknesses associated with the URI
method (see <xref target="sec-con" />), including the high
likelihood that the URL containing the access token will be
logged, it SHOULD NOT be used unless it is impossible to
transport the access token in the <spanx
style='verb'>Authorization</spanx> request header field or
the HTTP request entity-body.
Resource servers MAY support this method.
</t>
<t>
This method is included to document current use; its use is
not recommended, both due to its security deficiencies (see
<xref target="sec-con" />) and because it uses a
reserved query parameter name, which is counter to
URI namespace best practices, per the
Architecture of the World Wide Web <xref target='W3C.REC-webarch-20041215' />.
</t>
</section>
</section>
<section title='The WWW-Authenticate Response Header Field' anchor='authn-header'>
<t>
If the protected resource request does not include
authentication credentials or does not contain an access
token that enables access to the protected resource,
the resource server MUST include the HTTP <spanx
style='verb'>WWW-Authenticate</spanx> response header field;
it MAY include it in response to other conditions as well.
The <spanx style='verb'>WWW-Authenticate</spanx> header
field uses the framework defined by
HTTP/1.1 <xref target='RFC2617'/>.
</t>
<t>
All challenges defined by this specification MUST use the
auth-scheme value <spanx style='verb'>Bearer</spanx>. This
scheme MUST be followed by one or more auth-param values. The
auth-param attributes used or defined by this specification
are as follows. Other auth-param attributes MAY be used as
well.
</t>
<t>
A <spanx style='verb'>realm</spanx> attribute MAY be included
to indicate the scope of protection in the manner described in
HTTP/1.1 <xref target='RFC2617'/>.
The <spanx style='verb'>realm</spanx> attribute MUST NOT appear more than once.
</t>
<t>
The <spanx style='verb'>scope</spanx> attribute is defined in
Section 3.3 of OAuth 2.0 Authorization <xref target="I-D.ietf-oauth-v2"/>.
The <spanx style='verb'>scope</spanx> attribute is a space-delimited list
of case sensitive scope values
indicating the required scope of the access token for accessing the requested resource.
<spanx style='verb'>scope</spanx> values are implementation defined;
there is no centralized registry for them;
allowed values are defined by the authorization server.
The order of <spanx style='verb'>scope</spanx> values is not significant.
In some cases, the <spanx style='verb'>scope</spanx> value
will be used when requesting a new access token with
sufficient scope of access to utilize the protected resource.
Use of the <spanx style='verb'>scope</spanx> attribute is OPTIONAL.
The <spanx style='verb'>scope</spanx> attribute MUST NOT appear more than once.
The <spanx style='verb'>scope</spanx> value is intended for
programmatic use and is not meant to be displayed to
end users.
</t>
<figure>
<preamble>
Two example scope values follow; these are taken from the
OpenID Connect <xref target="OpenID.Messages" /> and OATC
Online Multimedia Authorization Protocol <xref target="OMAP"
/> OAuth 2.0 use cases, respectively:
</preamble>
<artwork><![CDATA[
scope="openid profile email"
scope="urn:example:channel=HBO&urn:example:rating=G,PG-13"
]]></artwork>
</figure>
<t>
If the protected resource request included an access token and failed authentication, the
resource server SHOULD include the <spanx style='verb'>error</spanx> attribute to provide
the client with the reason why the access request was declined. The parameter value is
described in <xref target='resource-error-codes' />.
In addition, the resource server MAY include the <spanx
style='verb'>error_description</spanx> attribute to provide
developers a human-readable explanation that is not meant
to be displayed to end users.
It also MAY include
the <spanx style='verb'>error_uri</spanx> attribute with
an absolute URI identifying a human-readable web page explaining the error.
The <spanx style='verb'>error</spanx>, <spanx style='verb'>error_description</spanx>, and
<spanx style='verb'>error_uri</spanx> attributes MUST NOT appear more than once.
</t>
<t>
Values for the <spanx style='verb'>scope</spanx> attribute MUST NOT include
characters outside the set %x21 / %x23-5B / %x5D-7E
specified in Section A.4 of
OAuth 2.0 Authorization <xref target="I-D.ietf-oauth-v2"/>
for representing scope values and %x20 for delimiters between scope values.
Values for the <spanx style='verb'>error</spanx> and <spanx
style='verb'>error_description</spanx> attributes MUST NOT include
characters outside the set %x20-21 / %x23-5B / %x5D-7E
specified in Sections A.7 and A.8 of OAuth 2.0 Authorization.
Values for the <spanx style='verb'>error_uri</spanx> attribute
MUST conform to the URI-Reference syntax, and thus MUST NOT include
characters outside the set %x21 / %x23-5B / %x5D-7E
specified in Section A.9 of OAuth 2.0 Authorization.
</t>
<figure>
<preamble>
For example, in response to a protected resource request without authentication:
</preamble>
<artwork><![CDATA[
HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="example"
]]></artwork>
</figure>
<figure>
<preamble>
And in response to a protected resource request with an authentication attempt using an
expired access token:
</preamble>
<artwork><![CDATA[
HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="example",
error="invalid_token",
error_description="The access token expired"
]]></artwork>
</figure>
<section title='Error Codes' anchor='resource-error-codes'>
<t>
When a request fails, the resource server responds using the appropriate HTTP status
code (typically, 400, 401, 403, or 405),
and includes one of the following error codes in
the response:
<list style='hanging' hangIndent='6'>
<t hangText='invalid_request'>
<vspace />
The request is missing a required parameter, includes an unsupported parameter or
parameter value, repeats the same parameter, uses more than one method for
including an access token, or is otherwise malformed. The resource server SHOULD
respond with the HTTP 400 (Bad Request) status code.
</t>
<t hangText='invalid_token'>
<vspace />
The access token provided is expired, revoked, malformed, or invalid for other
reasons. The resource SHOULD respond with the HTTP 401 (Unauthorized) status
code. The client MAY request a new access token and retry the protected resource
request.
</t>
<t hangText='insufficient_scope'>
<vspace />
The request requires higher privileges than provided by the access token. The
resource server SHOULD respond with the HTTP 403 (Forbidden) status code and MAY
include the <spanx style='verb'>scope</spanx> attribute with the scope necessary to
access the protected resource.
</t>
</list>
</t>
<t>
If the request lacks any authentication information (e.g., the client was unaware
authentication is necessary or attempted using an unsupported authentication method),
the resource server SHOULD NOT include an error code or other error information.
</t>
<figure>
<preamble>
For example:
</preamble>
<artwork><![CDATA[
HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="example"
]]></artwork>
</figure>
</section>
</section>
<section title="Example Access Token Response" anchor="ExAccTokResp">
<t>
Typically a bearer token is returned to the client as part of
an OAuth 2.0 <xref target="I-D.ietf-oauth-v2" /> access token
response. An example of such a response is:
</t>
<figure><artwork><![CDATA[
HTTP/1.1 200 OK
Content-Type: application/json;charset=UTF-8
Cache-Control: no-store
Pragma: no-cache
{
"access_token":"mF_9.B5f-4.1JqM",
"token_type":"Bearer",
"expires_in":3600,
"refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA"
}
]]></artwork></figure>
</section>
<section title='Security Considerations' anchor="sec-con">
<t>
This section describes the relevant security threats regarding
token handling when using bearer tokens and describes how to
mitigate these threats.
</t>
<section title="Security Threats" anchor="threats">
<t>
The following list presents several common threats against
protocols utilizing some form of tokens. This list of
threats is based on
NIST Special Publication 800-63 <xref target="NIST800-63"/>.
Since this document builds on the
OAuth 2.0 Authorization specification, we exclude a discussion of threats
that are described there or in related documents.
</t>
<t>
<list style="hanging">
<t hangText="Token manufacture/modification:">
An attacker may generate a bogus token or modify the
token contents (such as the authentication or attribute
statements) of an existing token, causing the resource
server to grant inappropriate access to the client.
For example, an attacker may modify the token to extend
the validity period; a malicious client may modify the
assertion to gain access to information that they
should not be able to view.
</t>
<t hangText="Token disclosure:">
Tokens may contain authentication and attribute
statements that include sensitive information.
</t>
<t hangText="Token redirect:">
An attacker uses a token generated for consumption by
one resource server to gain access to a different
resource server that mistakenly believes the token to be
for it.
</t>
<t hangText="Token replay:">
An attacker attempts to use a token that has already
been used with that resource server in the past.
</t>
</list>
</t>
</section>
<section title="Threat Mitigation" anchor="mitigation">
<t>
A large range of threats can be mitigated by protecting the
contents of the token by using a digital signature or a
Message Authentication Code (MAC).
Alternatively, a bearer token can contain a reference to
authorization information, rather than encoding the
information directly. Such references MUST be infeasible for
an attacker to guess; using a reference may require an extra
interaction between a server and the token issuer to resolve
the reference to the authorization information.
The mechanics of such an interaction are not defined by this
specification.
</t>
<t>
This document does not specify the encoding or the contents
of the token; hence detailed recommendations about the means
of guaranteeing token integrity protection are outside the
scope of this document. The token integrity protection MUST
be sufficient to prevent the token from being modified.
</t>
<t>
To deal with token redirect, it is important for the
authorization server to include the identity of the intended
recipients (the audience), typically a single resource
server (or a list of resource servers), in the token.
Restricting the use of the token to a specific scope is also
RECOMMENDED.
</t>
<t>
The authorization server MUST implement TLS.
Which version(s) ought to be implemented will vary over
time, and depend on the widespread deployment and known
security vulnerabilities at the time of implementation.
At the time of this writing,
TLS version 1.2 <xref target='RFC5246' />
is the most recent version, but has very limited actual
deployment, and might not be readily available in
implementation toolkits.
TLS version 1.0 <xref target='RFC2246' />
is the most widely deployed version, and will give the
broadest interoperability.
</t>
<t>
To protect against token disclosure, confidentiality
protection MUST be applied using
TLS <xref target='RFC5246' />
with a ciphersuite that provides confidentiality and
integrity protection. This
requires that the communication interaction between the
client and the authorization server, as well as the
interaction between the client and the resource server,
utilize confidentiality and integrity protection.
Since TLS is mandatory to
implement and to use with this specification, it is the
preferred approach for preventing token disclosure via the
communication channel. For those cases where the client
is prevented from observing the contents of the token, token
encryption MUST be applied in addition to the usage of TLS
protection.
As a further defense against token disclosure, the client
MUST validate the TLS certificate chain when making requests
to protected resources, including checking the
Certificate Revocation List (CRL) <xref target='RFC5280' />.
</t>
<t>
Cookies are typically transmitted in the clear. Thus, any
information contained in them is at risk of disclosure.
Therefore, bearer tokens MUST NOT be stored in cookies that
can be sent in the clear.
See HTTP State Management Mechanism <xref target='RFC6265' />
for security considerations about cookies.
</t>
<t>
In some deployments, including those utilizing load
balancers, the TLS connection to the resource server
terminates prior to the actual server that provides the
resource. This could leave the token unprotected between
the front end server where the TLS connection terminates and
the back end server that provides the resource. In such
deployments, sufficient measures MUST be employed to ensure
confidentiality of the token between the front end and
back end servers; encryption of the token is one possible
such measure.
</t>
<t>
To deal with token capture and replay,
the following recommendations are
made: First, the lifetime of the token MUST be limited;
one means of achieving this is by
putting a validity time field inside the protected part of
the token. Note that using short-lived (one hour or less)
tokens reduces the impact of them being
leaked. Second, confidentiality protection of the exchanges
between the client and the authorization server and between
the client and the resource server MUST be applied.
As a
consequence, no eavesdropper along the communication path is
able to observe the token exchange. Consequently, such an
on-path adversary cannot replay the token.
Furthermore, when
presenting the token to a resource server, the client MUST
verify the identity of that resource server, as per
Section 3.1 of HTTP Over TLS <xref target='RFC2818' />.
Note that the
client MUST validate the TLS certificate chain when making
these requests to protected resources. Presenting the token
to an unauthenticated and unauthorized resource server or
failing to validate the certificate chain will allow
adversaries to steal the token and gain unauthorized access
to protected resources.
</t>
</section>
<section title="Summary of Recommendations">
<t>
<list style="hanging">
<t hangText="Safeguard bearer tokens:">
Client implementations MUST ensure that bearer tokens
are not leaked to unintended parties, as they will be
able to use them to gain access to protected resources.
This is the primary security consideration when using
bearer tokens and underlies all the more
specific recommendations that follow.
</t>
<t hangText="Validate TLS certificate chains:">
The client MUST validate the TLS certificate chain when
making requests to protected resources. Failing to do
so may enable DNS hijacking attacks to steal the token
and gain unintended access.
</t>
<t hangText="Always use TLS (https):">
Clients MUST always use
TLS <xref target='RFC5246' />
(https) or equivalent transport security when making requests
with bearer tokens. Failing to do so exposes the token
to numerous attacks that could give attackers unintended
access.
</t>
<t hangText="Don't store bearer tokens in cookies:">
Implementations MUST NOT store bearer tokens within
cookies that can be sent in the clear (which is the
default transmission mode for cookies).
Implementations that do store bearer tokens in cookies
MUST take precautions against cross site request forgery.
</t>
<t hangText="Issue short-lived bearer tokens:">
Token servers SHOULD issue short-lived (one hour or
less) bearer tokens, particularly when issuing tokens to
clients that run within a web browser or other
environments where information leakage may occur. Using
short-lived bearer tokens can reduce the impact of them
being leaked.
</t>
<t hangText="Issue scoped bearer tokens:">
Token servers SHOULD issue bearer tokens that contain an audience
restriction, scoping their use to the intended relying
party or set of relying parties.
</t>
<t hangText="Don't pass bearer tokens in page URLs:">
Bearer tokens SHOULD NOT be passed in page URLs (for
example as query string parameters). Instead, bearer
tokens SHOULD be passed in HTTP message headers or
message bodies for which confidentiality measures are
taken. Browsers, web servers, and other software may not
adequately secure URLs in the browser history, web
server logs, and other data structures. If bearer tokens
are passed in page URLs, attackers might be able to
steal them from the history data, logs, or other
unsecured locations.
</t>
</list>
</t>
</section>
</section>
<section title='IANA Considerations'>
<section title='OAuth Access Token Type Registration'>
<t>
This specification registers the following access token type in the
OAuth Access Token Type Registry defined in
OAuth 2.0 Authorization <xref target="I-D.ietf-oauth-v2"/>.
</t>
<section title='The "Bearer" OAuth Access Token Type'>
<t>
<list style='hanging'>
<t hangText='Type name:'>
<vspace />
Bearer
</t>
<t hangText='Additional Token Endpoint Response Parameters:'>
<vspace />
(none)
</t>
<t hangText='HTTP Authentication Scheme(s):'>
<vspace />
Bearer
</t>
<t hangText='Change controller:'>
<vspace />
IETF
</t>
<t hangText='Specification document(s):'>
<vspace />
[[ this document ]]
</t>
</list>
</t>
</section>
</section>
<section title='OAuth Extensions Error Registration'>
<t>
This specification registers the following error values in the
OAuth Extensions Error Registry defined in
OAuth 2.0 Authorization <xref target="I-D.ietf-oauth-v2"/>.
</t>
<section title='The "invalid_request" Error Value'>
<t>
<list style='hanging'>
<t hangText='Error name:'>
<vspace />
invalid_request
</t>
<t hangText='Error usage location:'>
<vspace />
Resource access error response
</t>
<t hangText='Related protocol extension:'>
<vspace />
Bearer access token type
</t>
<t hangText='Change controller:'>
<vspace />
IETF
</t>
<t hangText='Specification document(s):'>
<vspace />
[[ this document ]]
</t>
</list>
</t>
</section>
<section title='The "invalid_token" Error Value'>
<t>
<list style='hanging'>
<t hangText='Error name:'>
<vspace />
invalid_token
</t>
<t hangText='Error usage location:'>
<vspace />
Resource access error response
</t>
<t hangText='Related protocol extension:'>
<vspace />
Bearer access token type
</t>
<t hangText='Change controller:'>
<vspace />
IETF
</t>
<t hangText='Specification document(s):'>
<vspace />
[[ this document ]]
</t>
</list>
</t>
</section>
<section title='The "insufficient_scope" Error Value'>
<t>
<list style='hanging'>
<t hangText='Error name:'>
<vspace />
insufficient_scope
</t>
<t hangText='Error usage location:'>
<vspace />
Resource access error response
</t>
<t hangText='Related protocol extension:'>
<vspace />
Bearer access token type
</t>
<t hangText='Change controller:'>
<vspace />
IETF
</t>
<t hangText='Specification document(s):'>
<vspace />
[[ this document ]]
</t>
</list>
</t>
</section>
</section>
</section>
</middle>
<back>
<references title='Normative References'>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2246.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2616.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2617.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2818.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.3986.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5234.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5246.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5280.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.6265.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml4/reference.W3C.REC-html401-19991224.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml4/reference.W3C.REC-webarch-20041215.xml' ?>
<reference anchor='I-D.ietf-oauth-v2'>
<front>
<title>The OAuth 2.0 Authorization Framework</title>
<author initials='D' surname='Hardt' fullname='Dick Hardt'>
<organization />
</author>
<author initials='D' surname='Recordon' fullname='David Recordon'>
<organization />
</author>
<date year="2012" month="July" day="12" />
<abstract><t>The OAuth 2.0 authorization framework enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner by orchestrating an approval interaction between the resource owner and the HTTP service, or by allowing the third-party application to obtain access on its own behalf. This specification replaces and obsoletes the OAuth 1.0 protocol described in RFC 5849.</t></abstract>
</front>
<seriesInfo name='Internet-Draft' value='draft-ietf-oauth-v2-29' />
<format type='TXT'
target='http://www.ietf.org/internet-drafts/draft-ietf-oauth-v2-29.txt' />
<format type='PDF'
target='http://www.ietf.org/internet-drafts/draft-ietf-oauth-v2-29.pdf' />
</reference>
<reference anchor="USASCII">
<front>
<title>Coded Character Set -- 7-bit American Standard Code for Information Interchange</title>
<author>
<organization>American National Standards Institute</organization>
</author>
<date year="1986"/>
</front>
<seriesInfo name="ANSI" value="X3.4"/>
</reference>
</references>
<references title="Informative References">
<reference anchor="NIST800-63">
<front>
<title>NIST Special Publication 800-63-1, INFORMATION SECURITY</title>
<author fullname="William E. Burr" initials="W." surname="Burr">
<organization>NIST</organization>
</author>
<author fullname="Donna F. Dodson" initials="D." surname="Dodson">
<organization>NIST</organization>
</author>
<author fullname="Ray A. Perlner" initials="R." surname="Perlner">
<organization>NIST</organization>
</author>
<author fullname="W. Timothy Polk" initials="T." surname="Polk">
<organization>NIST</organization>
</author>
<author fullname="Sarbari Gupta" initials="S." surname="Gupta">
<organization>NIST</organization>
</author>
<author fullname="Emad A. Nabbus" initials="E." surname="Nabbus">
<organization>NIST</organization>
</author>
<date month="December" year="2008"/>
</front>
<format target="http://csrc.nist.gov/publications/PubsDrafts.html#SP-800-63-Rev.%201" type="HTML"/>
</reference>
<reference anchor="OpenID.Messages">
<front>
<title>OpenID Connect Messages 1.0</title>
<author fullname="Nat Sakimura" initials="N." surname="Sakimura">
<organization abbrev="NRI">Nomura Research Institute, Ltd.</organization>
</author>
<author fullname="John Bradley" initials="J." surname="Bradley">
<organization abbrev="Ping Identity">Ping Identity</organization>
</author>
<author fullname="Michael B. Jones" initials="M.B." surname="Jones">
<organization abbrev="Microsoft">Microsoft</organization>
</author>
<author fullname="Breno de Medeiros" initials="B." surname="de Medeiros">
<organization abbrev="Google">Google</organization>
</author>
<author fullname="Chuck Mortimore" initials="C." surname="Mortimore">
<organization abbrev="Salesforce">Salesforce</organization>
</author>
<author fullname="Edmund Jay" initials="E." surname="Jay">
<organization abbrev="Illumila">Illumila</organization>
</author>
<date day="23" month="June" year="2012" />
</front>
<format target="http://openid.net/specs/openid-connect-messages-1_0.html"
type="HTML" />
</reference>
<reference anchor="OMAP">
<front>
<title>Online Multimedia Authorization Protocol:
An Industry Standard for Authorized Access to Internet Multimedia Resources</title>
<author fullname="Joel Huff" initials="J." surname="Huff">
<organization>Adobe Systems</organization>
</author>
<author fullname="David Schlacht" initials="D." surname="Schlacht">
<organization>DirecTV</organization>
</author>
<author fullname="Anthony Nadalin" initials="A." surname="Nadalin">
<organization>Microsoft</organization>
</author>
<author fullname="John Simmons" initials="J." surname="Simmons">
<organization>Microsoft</organization>
</author>
<author fullname="Peter Rosenberg" initials="P." surname="Rosenberg">
<organization>NBC Universal</organization>
</author>
<author fullname="Paul Madsen" initials="P." surname="Madsen">
<organization>Ping Identity</organization>
</author>
<author fullname="Tim Ace" initials="T." surname="Ace">
<organization>Synacor</organization>
</author>
<author fullname="Cyril Rickelton-Abdi" initials="C." surname="Rickelton-Abdi">
<organization>Turner</organization>
</author>
<author fullname="Bill Boyer" initials="B." surname="Boyer">
<organization>Viacom</organization>
</author>
<date day="2" month="April" year="2012" />
</front>
<format target="http://www.oatc.us/Standards/Download.aspx" type="HTML" />
</reference>
</references>
<section title='Acknowledgements'>
<t>
The following people contributed to preliminary versions of this document:
Blaine Cook (BT), Brian Eaton (Google), Yaron Y. Goland (Microsoft), Brent Goldman (Facebook),
Raffi Krikorian (Twitter), Luke Shepard (Facebook), and Allen Tom (Yahoo!). The content and
concepts within are a product of the OAuth community, the WRAP community, and the OAuth Working
Group.
</t>
<t>
The OAuth Working Group has dozens of very active contributors who proposed ideas and
wording for this document, including:
Michael Adams, Amanda Anganes, Andrew Arnott, Derek Atkins, Dirk Balfanz,
John Bradley, Brian Campbell, Francisco Corella, Leah Culver, Bill de hOra, Breno de Medeiros,
Brian Ellin, Stephen Farrell, Igor Faynberg, George Fletcher,
Tim Freeman, Evan Gilbert, Yaron Y. Goland, Thomas Hardjono,
Justin Hart, Phil Hunt, John Kemp, Eran Hammer,
Chasen Le Hara, Dick Hardt, Barry Leiba, Amos Jeffries, Michael B. Jones,
Torsten Lodderstedt, Paul Madsen, Eve Maler, James Manger, Laurence Miao,
William J. Mills, Chuck Mortimore, Anthony Nadalin, Axel Nennker, Mark Nottingham,
David Recordon, Julian Reschke, Rob Richards, Justin Richer, Peter Saint-Andre, Nat Sakimura,
Rob Sayre, Marius Scurtescu, Naitik Shah, Justin Smith,
Jeremy Suriel, Christian Stuebner, Doug Tangren, Paul Tarjan,
Hannes Tschofenig, Franklin Tse, Sean Turner, Paul Walker, Shane Weeden,
Skylar Woodward, and Zachary Zeltsan.
</t>
</section>
<section title='Document History'>
<t>
[[ to be removed by the RFC editor before publication as an RFC ]]
</t>
<t>
-22
<list style='symbols'>
<t>
Removed uses of HTTPbis in favor of RFC 2616 and RFC 2617,
since HTTPbis is not an approved standard.
</t>
<t>
Match formatting of artwork elements with OAuth core specification.
</t>
</list>
</t>
<t>
-21
<list style='symbols'>
<t>
Changed "NOT RECOMMENDED" to "not recommended" in caveat
about the URI Query Parameter method.
</t>
<t>
Changed "other specifications may extend this
specification for use with other transport protocols"
to "other specifications may extend this
specification for use with other protocols".
</t>
<t>
Changed Acknowledgements to use only ASCII characters, per
the RFC style guide.
</t>
</list>
</t>
<t>
-20
<list style='symbols'>
<t>
Added caveat about using a reserved query parameter name
being counter to URI namespace best practices.
</t>
<t>
Specified use of Cache-Control options when using the
URI Query Parameter method.
</t>
<t>
Changed title to
"The OAuth 2.0 Authorization Framework: Bearer Token Usage".
</t>
<t>
Referenced syntax definitions for the
<spanx style='verb'>scope</spanx>,
<spanx style='verb'>error</spanx>,
<spanx style='verb'>error_description</spanx>, and
<spanx style='verb'>error_uri</spanx>
parameters in the OAuth 2.0 core spec.
</t>
<t>
Registered the
<spanx style='verb'>invalid_request</spanx>,
<spanx style='verb'>invalid_token</spanx>, and
<spanx style='verb'>insufficient_scope</spanx>
error values in the OAuth Extensions Error Registry.
</t>
<t>
Acknowledged additional individuals.
</t>
</list>
</t>
<t>
-19
<list style='symbols'>
<t>
Addressed DISCUSS issues and comments raised for which
resolutions have been agreed to. No normative changes were
made. Changes made were:
</t>
<t>
Use ABNF from RFC 5234.
</t>
<t>
Added sentence "The Bearer authentication scheme is intended primarily for
server authentication using the WWW-Authenticate and
Authorization HTTP headers, but does not preclude its use for
proxy authentication" to the introduction.
</t>
<t>
In the introduction, state that this document also imposes
semantic requirements upon the access token.
</t>
<t>
Reference the <spanx style='verb'>scope</spanx> definition
in the OAuth core spec.
</t>
<t>
Added <spanx style='verb'>scope</spanx> examples.
</t>
<t>
Reference RFC 6265 for security considerations about cookies.
</t>
</list>
</t>
<t>
-18
<list style='symbols'>
<t>
Changed example bearer token value from vF9dft4qmT to
mF_9.B5f-4.1JqM.
</t>
<t>
Added example access token response returning a Bearer
token.
</t>
</list>
</t>
<t>
-17
<list style='symbols'>
<t>
Restore RFC 2818 reference for server identity
verification and add RFC 5280 reference for certificate
revocation lists, per Gen-ART review comments.
</t>
</list>
</t>
<t>
-16
<list style='symbols'>
<t>
Use the HTTPbis auth-param syntax for Bearer challenge
attributes.
</t>
<t>
Dropped the sentence "The <spanx
style='verb'>realm</spanx> value is intended for
programmatic use and is not meant to be displayed to end
users".
</t>
<t>
Reordered form-encoded body parameter description bullets
for better readability.
</t>
<t>
Added <xref target="USASCII" /> reference.
</t>
</list>
</t>
<t>
-15
<list style='symbols'>
<t>
Clarified that form-encoded content must consist entirely
of ASCII characters.
</t>
<t>
Added TLS version requirements.
</t>
<t>
Applied editorial improvements suggested by Mark
Nottingham during the APPS area review.
</t>
</list>
</t>
<t>
-14
<list style='symbols'>
<t>
Changes made in response to review comments by Security
Area Director Stephen Farrell. Specifically:
</t>
<t>
Strengthened warnings about passing an access token as a
query parameter and more precisely described the
limitations placed upon the use of this method.
</t>
<t>
Clarified that the <spanx style='verb'>realm</spanx>
attribute MAY included to indicate the scope of protection
in the manner described in
HTTP/1.1, Part 7 [I-D.ietf-httpbis-p7-auth].
</t>
<t>
Normatively stated that "the token integrity protection
MUST be sufficient to prevent the token from being
modified".
</t>
<t>
Added statement that "TLS is mandatory to implement and
use with this specification" to the introduction.
</t>
<t>
Stated that TLS MUST be used with "a ciphersuite that
provides confidentiality and integrity protection".
</t>
<t>
Added "As a further defense against token disclosure, the
client MUST validate the TLS certificate chain when making
requests to protected resources" to the Threat Mitigation
section.
</t>
<t>
Clarified that putting a validity time field inside the
protected part of the token is one means, but not the only
means, of limiting the lifetime of the token.
</t>
<t>
Dropped the confusing phrase "for instance, through the
use of TLS" from the sentence about confidentiality
protection of the exchanges.
</t>
<t>
Reference RFC 6125 for identity verification, rather than
RFC 2818.
</t>
<t>
Stated that the token MUST be protected between front end
and back end servers when the TLS connection terminates at
a front end server that is distinct from the actual server
that provides the resource.
</t>
<t>
Stated that bearer tokens MUST NOT be stored in cookies
that can be sent in the clear in the Threat Mitigation
section.
</t>
<t>
Replaced sole remaining reference to <xref target='RFC2616' /> with
HTTPbis [I-D.ietf-httpbis-p1-messaging]
reference.
</t>
<t>
Replaced all references where the reference is used as if
it were part of the sentence (such as "defined by
[I-D.whatever]") with ones where the specification name is
used, followed by the reference (such as "defined by
Whatever [I-D.whatever]").
</t>
<t>
Other on-normative editorial improvements.
</t>
</list>
</t>
<t>
-13
<list style='symbols'>
<t>
At the request of Hannes Tschofenig, made ABNF changes to
make it clear that no special WWW-Authenticate response
header field parsers are needed. The <spanx
style='verb'>scope</spanx>, <spanx
style='verb'>error-description</spanx>, and <spanx
style='verb'>error-uri</spanx> parameters are all now
defined as quoted-string in the ABNF (as <spanx
style='verb'>error</spanx> already was). Restrictions on
these values that were formerly described in the ABNFs are
now described in normative text instead.
</t>
</list>
</t>
<t>
-12
<list style='symbols'>
<t>
Made non-normative editorial changes that Hannes
Tschofenig requested be applied prior to forwarding the
specification to the IESG.
</t>
<t>
Added rationale for the choice of the b64token syntax.
</t>
<t>
Added rationale stating that receivers are free to parse
the <spanx style='verb'>scope</spanx> attribute using a
standard quoted-string parser, since it will correctly
process all legal <spanx style='verb'>scope</spanx>
values.
</t>
<t>
Added additional active working group contributors to the
Acknowledgements section.
</t>
</list>
</t>
<t>
-11
<list style='symbols'>
<t>
Replaced uses of <"> with DQUOTE to pass ABNF syntax check.
</t>
</list>
</t>
<t>
-10
<list style='symbols'>
<t>
Removed the #auth-param option from Authorization header
syntax (leaving only the b64token syntax).
</t>
<t>
Restricted the <spanx style='verb'>scope</spanx> value
character set to %x21 / %x23-5B / %x5D-7E (printable ASCII
characters excluding double-quote and backslash).
Indicated that scope is intended for programmatic use and
is not meant to be displayed to end users.
</t>
<t>
Restricted the character set for <spanx
style='verb'>error_description</spanx> strings to SP /
VCHAR and indicated that they are not meant to be
displayed to end users.
</t>
<t>
Included more description in the Abstract, since Hannes
Tschofenig indicated that the RFC editor would require
this.
</t>
<t>
Changed "Access Grant" to "Authorization Grant", as was
done in the core spec.
</t>
<t>
Simplified the introduction to the Authenticated Requests
section.
</t>
</list>
</t>
<t>
-09
<list style='symbols'>
<t>
Incorporated working group last call comments. Specific changes were:
</t>
<t>
Use definitions from [I-D.ietf-httpbis-p7-auth] rather than <xref
target='RFC2617' />.
</t>
<t>
Update credentials definition to conform to [I-D.ietf-httpbis-p7-auth].
</t>
<t>
Further clarified that query parameters may occur in any order.
</t>
<t>
Specify that error_description is UTF-8 encoded
(matching the core specification).
</t>
<t>
Registered "Bearer" Authentication Scheme in
Authentication Scheme Registry defined by
[I-D.ietf-httpbis-p7-auth].
</t>
<t>
Updated references to oauth-v2, httpbis-p1-messaging, and
httpbis-p7-auth drafts.
</t>
<t>
Other wording improvements not introducing normative changes.
</t>
</list>
</t>
<t>
-08
<list style='symbols'>
<t>
Updated references to oauth-v2 and HTTPbis drafts.
</t>
</list>
</t>
<t>
-07
<list style='symbols'>
<t>
Added missing comma in error response example.
</t>
</list>
</t>
<t>
-06
<list style='symbols'>
<t>
Changed parameter name <spanx
style="verb">bearer_token</spanx> to <spanx
style="verb">access_token</spanx>, per working group
consensus.
</t>
<t>
Changed HTTP status code for <spanx
style="verb">invalid_request</spanx> error code from HTTP
401 (Unauthorized) back to HTTP 400 (Bad Request), per
input from HTTP working group experts.
</t>
</list>
</t>
<t>
-05
<list style='symbols'>
<t>
Removed OAuth Errors Registry, per design team input.
</t>
<t>
Changed HTTP status code for <spanx
style="verb">invalid_request</spanx> error code from HTTP
400 (Bad Request) to HTTP 401 (Unauthorized) to match HTTP
usage [[ change pending working group consensus ]].
</t>
<t>
Added missing quotation marks in error-uri definition.
</t>
<t>
Added note to add language and encoding information to
error_description if the core specification does.
</t>
<t>
Explicitly reference the Augmented Backus-Naur Form (ABNF)
defined in <xref target='RFC5234' />.
</t>
<t>
Use auth-param instead of repeating its definition, which
is ( token "=" ( token / quoted-string ) ).
</t>
<t>
Clarify security considerations about including an
audience restriction in the token and include a
recommendation to issue scoped bearer tokens in the
summary of recommendations.
</t>
</list>
</t>
<t>
-04
<list style='symbols'>
<t>
Edits responding to working group last call feedback on
-03. Specific edits enumerated below.
</t>
<t>
Added Bearer Token definition in Terminology section.
</t>
<t>
Changed parameter name <spanx
style="verb">oauth_token</spanx> to <spanx
style="verb">bearer_token</spanx>.
</t>
<t>
Added realm parameter to <spanx
style='verb'>WWW-Authenticate</spanx> response to comply
with <xref target='RFC2617' />.
</t>
<t>
Removed "[ RWS 1#auth-param ]" from <spanx
style="verb">credentials</spanx> definition since it did
not comply with the ABNF in [I-D.ietf-httpbis-p7-auth].
</t>
<t>
Removed restriction that the <spanx
style="verb">bearer_token</spanx> (formerly <spanx
style="verb">oauth_token</spanx>) parameter be the last
parameter in the entity-body and the HTTP request URI
query.
</t>
<t>
Do not require WWW-Authenticate Response in a reply to a
malformed request, as an HTTP 400 Bad Request response
without a WWW-Authenticate header is likely the right
response in some cases of malformed requests.
</t>
<t>
Removed OAuth Parameters registry extension.
</t>
<t>
Numerous editorial improvements suggested by working group
members.
</t>
</list>
</t>
<t>
-03
<list style='symbols'>
<t>
Restored the WWW-Authenticate response header
functionality deleted from the framework specification in
draft 12 based upon the specification text from draft 11.
</t>
<t>
Augmented the OAuth Parameters registry by adding two
additional parameter usage locations: "resource request"
and "resource response".
</t>
<t>
Registered the "oauth_token" OAuth parameter with usage
location "resource request".
</t>
<t>
Registered the "error" OAuth parameter.
</t>
<t>
Created the OAuth Error registry and registered errors.
</t>
<t>
Changed the "OAuth2" OAuth access token type name to
"Bearer".
</t>
</list>
</t>
<t>
-02
<list style='symbols'>
<t>
Incorporated feedback received on draft 01. Most changes
were to the security considerations section. No normative
changes were made. Specific changes included:
</t>
<t>
Changed terminology from "token reuse" to "token capture
and replay".
</t>
<t>
Removed sentence "Encrypting the token contents is another
alternative" from the security considerations since it was
redundant and potentially confusing.
</t>
<t>
Corrected some references to "resource server" to be
"authorization server" in the security considerations.
</t>
<t>
Generalized security considerations language about
obtaining consent of the resource owner.
</t>
<t>
Broadened scope of security considerations description for
recommendation "Don't pass bearer tokens in page URLs".
</t>
<t>
Removed unused reference to OAuth 1.0.
</t>
<t>
Updated reference to framework specification and updated
David Recordon's e-mail address.
</t>
<t>
Removed security considerations text on authenticating
clients.
</t>
<t>
Registered the "OAuth2" OAuth access token type and
"oauth_token" parameter.
</t>
</list>
</t>
<t>
-01
<list style='symbols'>
<t>
First public draft, which incorporates feedback received
on -00 including enhanced Security Considerations content.
This version is intended to accompany OAuth 2.0 draft 11.
</t>
</list>
</t>
<t>
-00
<list style='symbols'>
<t>
Initial draft based on preliminary version of OAuth 2.0 draft 11.
</t>
</list>
</t>
</section>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-22 22:23:49 |