One document matched: draft-ietf-kitten-sasl-oauth-02.xml
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<rfc ipr="trust200902" docName="draft-ietf-kitten-sasl-oauth-02" category="std">
<front>
<title abbrev="A SASL/GSS-API Mechanism for OAuth">A SASL and GSS-API Mechanism for OAuth</title>
<author fullname="William Mills" initials="W." surname="Mills">
<organization>Yahoo! Inc.</organization>
<address>
<postal>
<street/>
<city/>
<code/>
<region/>
<country/>
</postal>
<phone/>
<email>wmills@yahoo-inc.com </email>
</address>
</author>
<author fullname="Tim Showalter" initials="T." surname="Showalter">
<organization></organization>
<address>
<postal>
<street/>
<city/>
<code/>
<region/>
<country/>
</postal>
<phone/>
<email>tjs@psaux.com</email>
</address>
</author>
<author initials="H." surname="Tschofenig" fullname="Hannes Tschofenig">
<organization>Nokia Siemens Networks</organization>
<address>
<postal>
<street>Linnoitustie 6</street>
<city>Espoo</city>
<code>02600</code>
<country>Finland</country>
</postal>
<phone>+358 (50) 4871445</phone>
<email>Hannes.Tschofenig@gmx.net</email>
<uri>http://www.tschofenig.priv.at</uri>
</address>
</author>
<date year="2012"/>
<workgroup>KITTEN</workgroup>
<abstract>
<t>
OAuth enables a third-party
application to obtain limited access to a protected resource, either on
behalf of a resource owner by orchestrating an approval interaction, or by allowing the
third-party application to obtain access on its own behalf.
</t>
<t>This document defines how an application client uses OAuth
over the Simple Authentication and Security Layer (SASL) or the
Generic Security Service Application Program Interface (GSS-API)
to access a protected resource at a resource serve. Thereby, it enables
schemes defined within the OAuth framework for non-HTTP-based application protocols.
</t>
<t>Clients typically store the user's long term credential. This does, however, lead to
significant security vulnerabilities, for example, when such a
credential leaks. A significant benefit of OAuth for usage in
those clients is that the password is replaced by a
token. Tokens typically provided limited access rights and can
be managed and revoked separately from the user's long-term credential (password).
</t>
</abstract>
</front>
<middle>
<!-- ******************************************************************** -->
<section title="Introduction">
<t>OAuth <xref target="I-D.ietf-oauth-v2"/> enables a third-party
application to obtain limited access to a protected resource, either on
behalf of a resource owner by orchestrating an approval interaction, or by allowing the
third-party application to obtain access on its own behalf. The core OAuth
specification <xref target="I-D.ietf-oauth-v2"/> does not define the interaction between the
client and the resource server with the access to a protected resource using an Access Token.
This functionality is described in two separate specifications, namely <xref
target="I-D.ietf-oauth-v2-bearer"/>, and <xref
target="I-D.ietf-oauth-v2-http-mac"/>, whereby the focus is on an HTTP-based environment only.
</t>
<t><xref target="oauth-exchange"/> shows the abstract message flow as shown in Figure 1 of <xref target="I-D.ietf-oauth-v2"/>.</t>
<t>
<figure anchor="oauth-exchange" title="Abstract OAuth 2.0 Protocol Flow">
<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>
<t>This document takes
advantage of the OAuth protocol and its deployment base to provide a way to use
SASL <xref target="RFC4422"/> as well as the GSS-API <xref target="RFC2743"/> to gain access to resources when using non-HTTP-based protocols,
such as the Internet Message Access Protocol (IMAP) <xref target="RFC3501"/>, which is what this memo uses in the examples.</t>
<t>The Simple Authentication and Security Layer (SASL) is a framework
for providing authentication and data security services in
connection-oriented protocols via replaceable mechanisms. It
provides a structured interface between protocols and mechanisms.
The resulting framework allows new protocols to reuse existing
mechanisms and allows old protocols to make use of new mechanisms.
The framework also provides a protocol for securing subsequent
protocol exchanges within a data security layer.</t>
<t>
The Generic Security Service Application Program Interface (GSS-API)
<xref target="RFC2743"/> provides a framework for applications to support multiple
authentication mechanisms through a unified interface. </t>
<t>
This document
defines a SASL mechanism for OAuth, but it conforms to the new
bridge between SASL and the GSS-API called GS2 <xref target="RFC5801"/>. This means
that this document defines both a SASL mechanism and a GSS-API
mechanism. Implementers may be interested in
either the SASL, the GSS-API, or even both mechanisms. To
faciliate these two variants, the description has been split into two
parts, one part that provides normative references for those interested in
the SASL OAuth mechanism (see <xref target="SASL-OAUTH"/>), and a second part
for those implementers that wish to implement the GSS-API portion (see
<xref target="GSSAPI-OAUTH"/>).
</t>
<t>When OAuth is integrated into SASL and the GSS-API the high-level steps are as follows:
<list style="empty">
<t> (A) The client requests authorization from the resource owner. The
authorization request can be made directly to the resource owner
(as shown), or preferably indirectly via the authorization
server as an intermediary.</t>
<t> (B) The client receives an authorization grant which is a credential
representing the resource owner's authorization, expressed using
one of four grant types defined in this specification or using
an extension grant type. The authorization grant type depends
on the method used by the client to request authorization and
the types supported by the authorization server.</t>
<t> (C) The client requests an access token by authenticating with the
authorization server and presenting the authorization grant.</t>
<t> (D) The authorization server authenticates the client and validates
the authorization grant, and if valid issues an access token.</t>
<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>Steps (E) and (F) are not defined in <xref target="I-D.ietf-oauth-v2"/> and are the
main functionality specified within this document.
Consequently, the message exchange shown in <xref target="overview"/> is the result of this specification.
The client will genrally need to determine the authentication endpoints (and
perhaps the service endpoints) before the OAuth 2.0 protocol
exchange messages in steps (A)-(D) are executed. The discovery of the resource owner
and authorization server endpoints is
outside the scope of this specification. The client must discover those
endpoints using a discovery mechanisms such as Webfinger using host-meta <xref
target="I-D.jones-appsawg-webfinger"/>. In band discovery is not tenable if
clients support the OAuth 2.0 password grant. Once credentials are obtained the
client proceeds to steps (E) and (F) defined in this specification.
</t>
<t>
<figure anchor="overview" title="OAuth SASL Architecture">
<artwork><![CDATA[
----+
+--------+ +---------------+ |
| |--(A)-- Authorization Request --->| Resource | |
| | | Owner | |Plain
| |<-(B)------ Access Grant ---------| | |OAuth
| | +---------------+ |2.0
| | |
| | Client Credentials & +---------------+ |
| |--(C)------ Access Grant -------->| Authorization | |
| Client | | Server | |
| |<-(D)------ Access Token ---------| | |
| | (w/ Optional Refresh Token) +---------------+ |
| | ----+
| | ----+
| | +---------------+ |
| | | | |OAuth
| |--(E)------ Access Token -------->| Resource | |over
| | | Server | |SASL/
| |<-(F)---- Protected Resource -----| | |GSS-
| | | | |API
+--------+ +---------------+ |
----+
]]></artwork>
</figure>
</t>
<t>It is worthwhile to note that this specification is also compatible with OAuth 1.0a <xref
target="RFC5849"/>.</t>
</section>
<!-- ******************************************************************** -->
<section anchor="terminology" title="Terminology">
<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>The reader is assumed to be familiar with the terms used in the OAuth 2.0 specification <xref
target="I-D.ietf-oauth-v2"/>.</t>
<t>In examples, "C:" and "S:" indicate lines sent by the client and server respectively. Line
breaks have been inserted for readability.</t>
<t>Note that the IMAP SASL specification requires base64 encoding message, not this memo.</t>
</section>
<!-- ******************************************************************** -->
<section anchor="SASL-OAUTH" title="OAuth SASL Mechanism Specification">
<t>SASL is used as a generalized authentication method in a variety of application layer protocols. This
document defines two SASL mechanisms for usage with OAuth: "OAUTH" and "OAUTH-PLUS". The "OAUTH" SASL
mechanism enables OAuth authorizattion schemes for SASL, "OAUTH-PLUS" adds channel
binding <xref target="RFC5056"/> capability for additional security guarantees.</t>
<section title="Initial Client Response">
<t>Client responses are a key/value pair sequence. These key/value pairs carry
the equivalent values from an HTTP context in order to be able to complete an
OAuth style HTTP authorization. The ABNF <xref target="RFC5234"/> syntax is
</t>
<t>
<figure>
<artwork>
<![CDATA[
kvsep = %x01
key = 1*ALPHA
value = *(VCHAR | SP | HTAB | CR | LF )
kvpair = key "=" value kvsep
client_resp = 1*kvpair kvsep
]]></artwork>
</figure>
</t>
<t>The following key/value pairs are defined in the client response:
</t>
<t><list><t>
<list style="hanging">
<t hangText="auth (REQUIRED):">The payload of the HTTP Authorization header
for an equivalent HTTP OAuth authroization.</t>
<t hangText="user (REQUIRED):">Contains the user name being authenticated. The server
MAY use this as a routing or database lookup hint. The
server MUST NOT use this as authoritative, the user name
MUST be asserted by the OAuth credential.</t>
<t hangText="host:">Contains the host name to which the client connected.</t>
<t hangText="port:">Contains the port number represented as a
decimal positive integer string without leading zeros
to which the client connected.</t>
</list>
</t></list>
</t>
<t>In authorization schemes that use signatures, the client MUST send host and
port number key/values, and the server MUST fail an authorization request requiring
signatures that does not have host and port values.
</t>
<section title="Reserved Key/Values in OAUTH">
<t> In the OAUTH mechanism values for path, query string and post body are
assigned default values. OAuth authorization schemes MAY define usage of
these in the SASL context and extend this specification. For OAuth
schemes that use request signatures the default values MUST be used unless
explict values are provided in the client response. The following key
values are reserved for future use:
<list><t>
<list style="hanging">
<t hangText="path (RESERVED):">HTTP path data, the default value is "/".
</t>
<t hangText="qs (RESERVED):">HTTP query string, the default value is "".
</t>
<t hangText="post (RESERVED):">HTTP post data, the default value is "".
</t>
</list>
</t></list>
</t>
</section>
</section>
<section title="Server's Response">
<t>The server validates the response per the specification for the authorization
scheme used. If the authorization scheme used includes signing of the request
parameters the client must provide a client response that satisfies
the data requirements for the scheme in use.
</t>
<t>In the OAUTH-PLUS mechanism the server examines the channel binding data,
extracts the channel binding unique prefix, and extracts the raw channel biding
data based on the channel binding type used. It then computes it's own copy of
the channel binding payload and compares that to the payload sent by the client in
the cbdata key/value. Those two must be equal for channel binding to succeed.
</t>
<t> The server responds to a successfully verified client message by completing the SASL
negotiation. The authentication scheme MUST carry the user ID to be used as the
authorization identity (identity to act as). The server
MUST use the ID obtained from the credential as the user being authorized. </t>
<section title="Mapping to SASL Identities">
<t> Some OAuth mechanisms can provide both an authorization identity and an
authentication identity. An example of this is OAuth 1.0a <xref target="RFC5849"/> where
the consumer key (oauth_consumer_key) identifies the entity using the token which equates to the
SASL authentication identity, and is authenticated using the shared secret. The
authorization identity in the OAuth 1.0a case is carried in the token (per the requirement
above), which SHOULD be validated independently. The server MAY use a consumer key, a value
derived from it, or other comparable identity in the OAuth authorization scheme
as the SASL authentication identity.
If an appropriate authentication identity is not available the server MUST use the
authorization identity as the authentication identity.</t>
</section>
<section title="Server response to failed authentication.">
<t>For a failed authentication the server returns a JSON <xref target="RFC4627"/>
formatted error result, and fails the authentication. The error result consists
of the following values:
<list><t>
<list style="hanging">
<t hangText="status (REQUIRED):">The authorization error code. Valid error codes are
defined in the IANA [[need registry name]] registry
specified in the OAuth 2 core specification.
</t>
<t hangText="schemes (REQUIRED):">A space separated list of the OAuth authroization
schemes supported by the server, i.e. "bearer" or "bearer mac".
</t>
<t hangText="scope (OPTIONAL):">The OAuth scope required to access the service.
</t>
</list>
</t></list>
If the resource server provides a scope the client SHOULD always request scoped
tokens from the token endpoint. The client MAY use a scope other than the one
provided by the resource server. Scopes other than those advertised by the
resource server are be defined by the resource owner and provided in service
documentation or discovery information (which is beyond the scope of this memo). If not present then the
client SHOULD presume an empty scope (unscoped token) is needed.
</t>
<t>If channel binding is in use and the channel
binding fails the server responds with a status code set to 412 to indicate that the channel
binding precondition failed. If the authentication scheme in use does not include
signing the server SHOULD revoke the presented credential and the client SHOULD
discard that credential.
</t>
</section>
</section>
<section title="Use of Signature Type Authorization">
<t>This mechanism supports authorization using signatures, which requires that both client and
server construct the string to be signed. OAuth 2 is designed for
authentication/authorization to access specific URIs. SASL is designed for user authentication,
and has no facility for being more specific. In this mechanism we require or
define default values for the data elements from an HTTP request which allow the
signature base string to be constructed properly.
The default HTTP path is "/" and the default post body is empty. These atoms are
defined as extension points so
that no changes are needed if there is a revision of SASL which supports more
specific resource authorization, e.g. IMAP access to a specific folder or FTP access
limited to a specific directory. </t>
<t> Using the example in the MAC specification <xref target="I-D.ietf-oauth-v2-http-mac"/>
as a starting point, on an IMAP server running on port 143 and given
the MAC style authorization request (with %x01 shown as ^A and long lines wrapped for readability) below:
</t>
<t><figure>
<artwork><![CDATA[
host=server.example.com^A
port=143^A
auth=MAC token="h480djs93hd8",timestamp="137131200",nonce="dj83hs9s",
signature="YTVjyNSujYs1WsDurFnvFi4JK6o="^A^A
]]></artwork>
</figure>
</t>
<t>The normalized request string would be constructed per the MAC specification <xref
target="I-D.ietf-oauth-v2-http-mac" />. In this example the normalized
request string with the new line separator character is represented by
"\n" for display purposes only would be:
</t>
<t><figure>
<artwork><![CDATA[
h480djs93hi8\n
137131200\n
dj83hs9s\n
\n
GET\n
server.example.com\n
143\n
/\n
\n
]]></artwork>
</figure>
</t>
</section>
<section title="Channel Binding">
<t>If the specification for the underlying
authorization scheme requires a security layer, such as TLS <xref target="RFC5246"/>, the server
SHOULD only offer a mechanism where channel binding can be enabled.</t>
<t>The channel binding data is computed by the client based on it's choice of
preferred channel binding type. As specified in <xref target="RFC5056"/>, the
channel binding information MUST start with the channel binding unique prefix, followed
by a colon (ASCII 0x3A), followed by a base64 encoded channel binding
payload. The channel binding payload is the raw data from the channel binding
type if the raw channel binding data is less than 500 bytes. If the raw channel
binding data is 500 bytes or larger then a SHA-1 <xref target="RFC3174"/> hash of
the raw channel binding data is computed.</t>
<t>If the client is using tls-unique for a channel binding then the raw channel
binding data equals the first TLS finished message. This is under the 500 byte
limit, so the channel binding payload sent to the server would be the base64
encoded first TLS finished message.</t>
<t>In the case where the client has chosen tls-endpoint, the raw channel binding
data is the certificate of the server the client connected to, which will
frequently be 500 bytes or more. If it is then the channel binding payload
is the base64 encoded SHA-1 hash of the server certificate.</t>
</section>
</section>
<!-- ******************************************************************** -->
<section anchor="GSSAPI-OAUTH" title="GSS-API OAuth Mechanism Specification">
<t>Note: The normative references in this section are informational for SASL
implementers, but they are normative for GSS-API implementers.</t>
<t>The SASL OAuth mechanism is also a GSS-API mechanism and the messages
described in <xref target="SASL-OAUTH"/> are the same, but
<list style="numbers">
<t>the GS2 header on the client's
first message is excluded when OAUTH is used as a GSS-API
mechanism, and</t>
<t>initial context token
header is prefixed to the client's first authentication message
(context token), as described in Section 3.1 of RFC 2743,
</t>
</list>
</t>
<t>The GSS-API mechanism OID for OAuth is [[TBD: IANA]].</t>
<t>OAuth security contexts always have the mutual_state flag
(GSS_C_MUTUAL_FLAG) set to TRUE. OAuth supports credential
delegation, therefore security contexts may have the
deleg_state flag (GSS_C_DELEG_FLAG) set to either TRUE or FALSE.
</t>
<t>The mutual authentication property of this mechanism relies on
successfully comparing the TLS server identity with the negotiated
target name. Since the TLS channel is managed by the application
outside of the GSS-API mechanism, the mechanism itself is unable to
confirm the name while the application is able to perform this
comparison for the mechanism. For this reason, applications MUST
match the TLS server identity with the target name, as discussed in
<xref target="RFC6125"/>.</t>
<t>The OAuth mechanism does not support per-message tokens or
GSS_Pseudo_random.</t>
<t>OAuth supports a standard generic name syntax for acceptors, such as
GSS_C_NT_HOSTBASED_SERVICE (see <xref target="RFC2743"/>, Section 4.1).
These
service names MUST be associated with the "entityID" claimed by
the RP.
OAuth supports only a single name type for initiators:
GSS_C_NT_USER_NAME. GSS_C_NT_USER_NAME is the default name type.
The query, display, and exported name syntaxes for OAuth principal
names are all the same. There is no OAuth-specific name syntax;
applications SHOULD use generic GSS-API name types, such as
GSS_C_NT_USER_NAME and GSS_C_NT_HOSTBASED_SERVICE (see <xref target="RFC2743"/>,
Section 4). The exported name token does, of course, conform to
<xref target="RFC2743"/>, Section 3.2, but the "NAME" part of the token should be
treated as a potential input string to the OAuth name normalization
rules.
</t>
</section>
<!-- ******************************************************************** -->
<section title="Examples">
<t>These example illustrate exchanges between an IMAP client and an IMAP server.</t>
<section title="Successful Bearer Token Exchange">
<t>This example shows a successful OAuth 2.0 bearer token exchange with an initial client
response. Note that line breaks are inserted for readability.</t>
<t>
<figure>
<artwork><![CDATA[
S: * IMAP4rev1 Server Ready
C: t0 CAPABILITY
S: * CAPABILITY IMAP4rev1 AUTH=OAUTH
S: t0 OK Completed
C: t1 AUTHENTICATE OAUTH aG9zdD1zZXJ2ZXIuZXhhbXBsZS5jb20BcG9ydD0xNDMB
YXV0aD1CRUFSRVIgdkY5ZGZ0NHFtVGMyTnZiM1JsY2tCaGJIUmhkbWx6ZEdFdVk
yOXRDZz09AQE=
S: +
S: t1 OK SASL authentication succeeded
]]></artwork>
</figure>
</t>
<t>As required by IMAP <xref target="RFC3501"/>, the payloads are base64-encoded. The
decoded initial client response (with %x01 represented as ^A and long lines
wrapped for readability) is:
</t>
<t><figure>
<artwork><![CDATA[
host=server.example.com^Aport=143^A
auth=BEARER "vF9dft4qmTc2Nvb3RlckBhbHRhdmlzdGEuY29tCg=="^A^A
]]></artwork>
</figure>
</t>
<t>The line containing just a "+" and a space is an empty response from the
server. This response contains error information, and in the success case the
error response is empty. Like other messages, and in accordance with the IMAP
SASL binding, the empty response is base64-encoded. </t>
</section>
<!-- ******************************************************************** -->
<section title="MAC Authentication with Channel Binding">
<t>This example shows a channel binding failure. The example sends the same
request as above, but in the context of an OAUTH-PLUS exchange the channel binding
information is missing. Note that line breaks are inserted for
readability.</t>
<t>
<figure>
<artwork><![CDATA[
S: * CAPABILITY IMAP4rev1 AUTH=OAUTH SASL-IR IMAP4rev1 Server Ready
S: t0 OK Completed
C: t1 AUTHENTICATE MAC aG9zdD1zZXJ2ZXIuZXhhbXBsZS5jb20BcG9ydD0xNDMBYXV0a
D1NQUMgdG9rZW49Img0ODBkanM5M2hkOCIsdGltZXN0YW1wPSIxMzcxMzEyMDAiLG5vbm
NlPSJkajgzaHM5cyIsc2lnbmF0dXJlPSJZVFZqeU5TdWpZczFXc0R1ckZudkZpNEpLNm8
9IgFjYmRhdGE9U0c5M0lHSnBaeUJwY3lCaElGUk1VeUJtYVc1aGJDQnRaWE56WVdkbFB3
bz0BAQ==
S: +
S: t1 OK SASL authentication succeeded
]]></artwork>
</figure>
</t>
<t>As required by IMAP <xref target="RFC3501"/>, the payloads are
base64-encoded. The
decoded initial client response (with %x01 represented as ^A and long lines
wrapped for readability) is: </t>
<t>
<figure>
<artwork><![CDATA[
-
host=server.example.com^A
port=143^A
auth=MAC token="h480djs93hd8",timestamp="137131200",nonce="dj83hs9s",
signature="YTVjyNSujYs1WsDurFnvFi4JK6o="^A
cbdata=SG93IGJpZyBpcyBhIFRMUyBmaW5hbCBtZXNzYWdlPwo=^A^A
]]></artwork>
</figure>
</t>
<t>The line containing just a "+" and a space is an empty response from the server. This response contains
discovery information, and in the success case no discovery information is necessary so the
response is empty. Like other messages, and in accordance with the IMAP SASL binding, the
empty response is base64-encoded.
</t>
</section>
<!-- ******************************************************************** -->
<section title="Failed Exchange">
<t>This example shows a failed exchange because of the empty Authorization header, which is
how a client can query for the needed scope. Note that line breaks are inserted for
readability.</t>
<t>
<figure>
<artwork><![CDATA[
S: * CAPABILITY IMAP4rev1 AUTH=OAUTH SASL-IR IMAP4rev1 Server Ready
S: t0 OK Completed
C: t1 AUTHENTICATE OAUTH aG9zdD1zZXJ2ZXIuZXhhbXBsZS5jb20BcG9ydD0xND
MBYXV0aD0BAQ==
S: + ewoic3RhdHVzIjoiNDAxIiwKInNjb3BlIjoiZXhhbXBsZV9zY29wZSIKfQo=
S: t1 NO SASL authentication failed
]]></artwork>
</figure>
</t>
<t> The decoded initial client response is: </t>
<t>
<figure>
<artwork><![CDATA[
host=server.example.com^Aport=143^Aauth=^A^A
]]></artwork>
</figure>
</t>
<t> The decoded server error response is: </t>
<t>
<figure>
<artwork><![CDATA[
{
"status":"401",
"scope":"example_scope"
}
]]></artwork>
</figure>
</t>
</section>
<!-- ******************************************************************** -->
<section title="Failed Channel Binding">
<t>This example shows a channel binding failure in an empty request.
The channel binding information is empty. Note that line breaks are inserted for
readability.</t>
<t>
<figure>
<artwork><![CDATA[
S: * CAPABILITY IMAP4rev1 AUTH=OAUTH SASL-IR IMAP4rev1 Server Ready
S: t0 OK Completed
C: t1 AUTHENTICATE OAUTH aG9zdD1zZXJ2ZXIuZXhhbXBsZS5jb20BcG9ydD0xND
MBYXV0aD0BY2JkYXRhPQEB
S: + ewoic3RhdHVzIjoiNDEyIiwKInNjb3BlIjoiZXhhbXBsZV9zY29wZSIKfQ==
S: t1 NO SASL authentication failed
]]></artwork>
</figure>
</t>
<t> The decoded initial client response is: </t>
<t>
<figure>
<artwork><![CDATA[
host=server.example.com^Aport=143^Aauth=^Acbdata=^A^A
]]></artwork>
</figure>
</t>
<t> The decoded server response is: </t>
<t>
<figure>
<artwork><![CDATA[
{
"status":"412",
"scope":"example_scope"
}
]]></artwork>
</figure>
</t>
</section>
<!-- ******************************************************************** -->
</section>
<!-- ******************************************************************** -->
<section title="Security Considerations">
<t> This mechanism does not provide a security layer, but does provide a provision for
channel binding. The OAuth 2 specification <xref
target="I-D.ietf-oauth-v2"/> allows for a variety of usages, and the security properties
of these profiles vary. The usage of bearer tokens, for example, provide security features
similar to cookies. Applications using this mechanism SHOULD exercise the same level of care
using this mechanism as they would in using the SASL PLAIN mechanism. In
particular, TLS 1.2 or an equivalent secure channel MUST be implemented and its
usage is RECOMMENDED.
</t>
<t> Channel binding in this mechanism has different properties based on the authentication
scheme used. Channel binding to TLS with a
bearer token provides only a binding to the TLS layer. Authentication schemes like MAC
tokens can implement a signature over the channel binding information. These provide additional
protection against a man in the middle attacks, and the MAC authorization header is bound to the
channel and only valid in that context.
</t>
<t> It is possible that SASL will be authenticating a connection and the life of that
connection may outlast the life of the token used to authenticate
it. This is a common problem in application protocols where connections are long-lived, and
not a problem with this mechanism per se. Servers MAY unilaterally disconnect
clients in accordance with the application protocol.
</t>
<t>An OAuth credential is not equivalent to the password or primary account
credential. There are protocols like XMPP that allow actions like change
password. The server SHOULD ensure that actions taken in the authenticated
channel are appropriate to the strength of the presented credential.
</t>
<t>Tokens have a lifetime associated with them. Reducing the lifetime of a
token provides security benefits in case that tokens leak. In addition a previously obtained
token MAY be revoked or rendered invalid at any time. The client MAY request a new access token for each
connection to a resource server, but it SHOULD cache and re-use access credentials that appear
to be valid.</t>
</section>
<!-- ******************************************************************** -->
<section title="IANA Considerations">
<section title="SASL Registration">
<t> The IANA is requested to register the following SASL profile: <list style="empty">
<t>SASL mechanism profile: OAUTH</t>
<t>Security Considerations: See this document</t>
<t>Published Specification: See this document</t>
<t>For further information: Contact the authors of this document.</t>
<t>Owner/Change controller: the IETF</t>
<t>Note: None</t>
</list>
</t>
<t> The IANA is requested to register the following SASL profile: <list style="empty">
<t>SASL mechanism profile: OAUTH-PLUS</t>
<t>Security Considerations: See this document</t>
<t>Published Specification: See this document</t>
<t>For further information: Contact the authors of this document.</t>
<t>Owner/Change controller: the IETF</t>
<t>Note: None</t>
</list>
</t>
</section>
<section title="GSS-API Registration">
<t>IANA is further requested to assign an OID for this GSS mechanism
in the SMI numbers registry, with the prefix of
iso.org.dod.internet.security.mechanisms (1.3.6.1.5.5) and to
reference this specification in the registry.</t>
</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.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.3174.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.4422.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.4627.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5056.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.5234.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5849.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5929.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5988.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.2743.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.5801.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.6125.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml3/reference.I-D.ietf-oauth-v2.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml3/reference.I-D.ietf-oauth-v2-bearer.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml3/reference.I-D.ietf-oauth-v2-http-mac.xml' ?>
</references>
<references title="Informative References">
<?rfc include='http://xml.resource.org/public/rfc/bibxml/reference.RFC.3501.xml' ?>
<?rfc include='http://xml.resource.org/public/rfc/bibxml3/reference.I-D.jones-appsawg-webfinger.xml' ?>
</references>
<section title='Document History'>
<t>
[[ to be removed by RFC editor before publication as an RFC ]]
</t>
<t>
-02
</t>
<t>
<list style='symbols'>
<t>
Added the user data element back in.
</t>
<t>
Minor editorial changes.
</t>
</list>
</t>
<t>
-01
</t>
<t>
<list style='symbols'>
<t>
Ripping out discovery. Changed to refer to I-D.jones-appsawg-webfinger instead
of WF and SWD older drafts.
</t>
<t>
Replacing HTTP as the message format and adjusted all examples.
</t>
</list>
</t>
<t>
-00
</t>
<t>
<list style='symbols'>
<t>
Renamed draft into proper IETF naming format now that it's adopted.
</t>
<t>
Minor fixes.
</t>
</list>
</t>
<t>
-00
</t>
<t>
<list style='symbols'>
<t>
Initial revision
</t>
</list>
</t>
</section>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-23 11:00:28 |