draft-ietf-kitten-sasl-oauth-08.txt   draft-ietf-kitten-sasl-oauth-09.txt 
KITTEN W. Mills KITTEN W. Mills
Internet-Draft Yahoo! Inc. Internet-Draft Yahoo! Inc.
Intended status: Standards Track T. Showalter Intended status: Standards Track T. Showalter
Expires: March 21, 2013 Expires: June 20, 2013
H. Tschofenig H. Tschofenig
Nokia Siemens Networks Nokia Siemens Networks
September 17, 2012 December 17, 2012
A set of SASL and GSS-API Mechanisms for OAuth A set of SASL and GSS-API Mechanisms for OAuth
draft-ietf-kitten-sasl-oauth-08 draft-ietf-kitten-sasl-oauth-09
Abstract Abstract
OAuth enables a third-party application to obtain limited access to a OAuth enables a third-party application to obtain limited access to a
protected resource, either on behalf of a resource owner by protected resource, either on behalf of a resource owner by
orchestrating an approval interaction, or by allowing the third-party orchestrating an approval interaction, or by allowing the third-party
application to obtain access on its own behalf. application to obtain access on its own behalf.
This document defines how an application client uses credentials This document defines how an application client uses credentials
obtained via OAuth over the Simple Authentication and Security Layer obtained via OAuth over the Simple Authentication and Security Layer
(SASL) or the Generic Security Service Application Program Interface (SASL) or the Generic Security Service Application Program Interface
(GSS-API) to access a protected resource at a resource serve. (GSS-API) to access a protected resource at a resource serve.
Thereby, it enables schemes defined within the OAuth framework for Thereby, it enables schemes defined within the OAuth framework for
non-HTTP-based application protocols. non-HTTP-based application protocols.
Clients typically store the user's long term credential. This does, Clients typically store the user's long-term credential. This does,
however, lead to significant security vulnerabilities, for example, however, lead to significant security vulnerabilities, for example,
when such a credential leaks. A significant benefit of OAuth for when such a credential leaks. A significant benefit of OAuth for
usage in those clients is that the password is replaced by a token. usage in those clients is that the password is replaced by a token.
Tokens typically provided limited access rights and can be managed Tokens typically provided limited access rights and can be managed
and revoked separately from the user's long-term credential and revoked separately from the user's long-term credential
(password). (password).
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 21, 2013. This Internet-Draft will expire on June 20, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. OAuth SASL Mechanism Specifications . . . . . . . . . . . . . 8 3. OAuth SASL Mechanism Specifications . . . . . . . . . . . . . 8
3.1. Initial Client Response . . . . . . . . . . . . . . . . . 9 3.1. Initial Client Response . . . . . . . . . . . . . . . . . 9
3.1.1. Reserved Key/Values . . . . . . . . . . . . . . . . . 10 3.1.1. Reserved Key/Values . . . . . . . . . . . . . . . . . 10
3.1.2. Use of the gs2-header . . . . . . . . . . . . . . . . 10 3.1.2. Use of the gs2-header . . . . . . . . . . . . . . . . 10
3.2. Server's Response . . . . . . . . . . . . . . . . . . . . 10 3.2. Server's Response . . . . . . . . . . . . . . . . . . . . 10
3.2.1. OAuth Identities in the SASL Context . . . . . . . . . 11 3.2.1. OAuth Identifiers in the SASL Context . . . . . . . . 11
3.2.2. Canonicalization . . . . . . . . . . . . . . . . . . . 11 3.2.2. Server Response to Failed Authentication . . . . . . . 11
3.2.3. Server response to failed authentication. . . . . . . 11 3.2.3. Completing an Error Message Sequence . . . . . . . . . 12
3.2.4. Completing an error message sequence. . . . . . . . . 12 3.3. OAuth Access Token Types using Digital Signatures and
3.3. Use of Signature Type Authorization . . . . . . . . . . . 12 Keyed Message Digests . . . . . . . . . . . . . . . . . . 12
3.4. Channel Binding . . . . . . . . . . . . . . . . . . . . . 13 3.4. Channel Binding . . . . . . . . . . . . . . . . . . . . . 13
4. GSS-API OAuth Mechanism Specification . . . . . . . . . . . . 15 4. GSS-API OAuth Mechanism Specification . . . . . . . . . . . . 14
5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.1. Successful Bearer Token Exchange . . . . . . . . . . . . . 17 5.1. Successful Bearer Token Exchange . . . . . . . . . . . . . 16
5.2. OAuth 1.0a Authorization with Channel Binding . . . . . . 18 5.2. OAuth 1.0a Authorization with Channel Binding . . . . . . 17
5.3. Failed Exchange . . . . . . . . . . . . . . . . . . . . . 19 5.3. Failed Exchange . . . . . . . . . . . . . . . . . . . . . 18
5.4. Failed Channel Binding . . . . . . . . . . . . . . . . . . 20 5.4. Failed Channel Binding . . . . . . . . . . . . . . . . . . 19
5.5. SMTP Example of a failed negotiation. . . . . . . . . . . 20 5.5. SMTP Example of a Failed Negotiation . . . . . . . . . . . 19
6. Security Considerations . . . . . . . . . . . . . . . . . . . 22 6. Security Considerations . . . . . . . . . . . . . . . . . . . 21
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 7. Internationalization Considerations . . . . . . . . . . . . . 22
7.1. SASL Registration . . . . . . . . . . . . . . . . . . . . 23 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23
7.2. GSS-API Registration . . . . . . . . . . . . . . . . . . . 24 8.1. SASL Registration . . . . . . . . . . . . . . . . . . . . 23
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25 8.2. GSS-API Registration . . . . . . . . . . . . . . . . . . . 24
8.1. Normative References . . . . . . . . . . . . . . . . . . . 25 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25
8.2. Informative References . . . . . . . . . . . . . . . . . . 26 9.1. Normative References . . . . . . . . . . . . . . . . . . . 25
Appendix A. Acknowlegements . . . . . . . . . . . . . . . . . . . 27 9.2. Informative References . . . . . . . . . . . . . . . . . . 26
Appendix B. Document History . . . . . . . . . . . . . . . . . . 28 Appendix A. Acknowlegements . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 30 Appendix B. Document History . . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 31
1. Introduction 1. Introduction
OAuth [I-D.ietf-oauth-v2] enables a third-party application to obtain OAuth [RFC6749] enables a third-party application to obtain limited
limited access to a protected resource, either on behalf of a access to a protected resource, either on behalf of a resource owner
resource owner by orchestrating an approval interaction, or by by orchestrating an approval interaction, or by allowing the third-
allowing the third-party application to obtain access on its own party application to obtain access on its own behalf. The core OAuth
behalf. The core OAuth specification [I-D.ietf-oauth-v2] does not 2.0 specification [RFC6749] does not define the interaction between
define the interaction between the client and the resource server the client and the resource server with the access to a protected
with the access to a protected resource using an Access Token. This resource using an Access Token. This functionality is described in
functionality is described in separate specifications, for example separate specifications, for example bearer tokens [RFC6750], OAuth
Bearer tokens [I-D.ietf-oauth-v2-bearer], MAC tokens 2.0 MAC tokens [I-D.ietf-oauth-v2-http-mac]. OAuth 1.0a [RFC5849],
[I-D.ietf-oauth-v2-http-mac], and OAuth 1.0a [RFC5849]. In each of the predecessor of OAuth 2.0, has a similar design. The main use
these are defined in an HTTP-based environment only. cases for OAuth 2.0 and OAuth 1.0 have so far focused on an HTTP-
based environment only.
Figure 1 shows the abstract message flow as shown in Figure 1 of Figure 1 shows the abstract message flow as shown in Figure 1 of
[I-D.ietf-oauth-v2]. OAuth 2.0 [RFC6749].
+--------+ +---------------+ +--------+ +---------------+
| |--(A)- Authorization Request ->| Resource | | |--(A)- Authorization Request ->| Resource |
| | | Owner | | | | Owner |
| |<-(B)-- Authorization Grant ---| | | |<-(B)-- Authorization Grant ---| |
| | +---------------+ | | +---------------+
| | | |
| | +---------------+ | | +---------------+
| |--(C)-- Authorization Grant -->| Authorization | | |--(C)-- Authorization Grant -->| Authorization |
| Client | | Server | | Client | | Server |
| |<-(D)----- Access Token -------| | | |<-(D)----- Access Token -------| |
| | +---------------+ | | +---------------+
| | | |
| | +---h------------+ | | +---------------+
| |--(E)----- Access Token ------>| Resource | | |--(E)----- Access Token ------>| Resource |
| | | Server | | | | Server |
| |<-(F)--- Protected Resource ---| | | |<-(F)--- Protected Resource ---| |
+--------+ +---------------+ +--------+ +---------------+
Figure 1: Abstract OAuth 2.0 Protocol Flow Figure 1: Abstract OAuth 2.0 Protocol Flow
This document takes advantage of the OAuth protocol and its This document takes advantage of the OAuth protocol and its
deployment base to provide a way to use SASL [RFC4422] as well as the deployment base to provide a way to use SASL [RFC4422] as well as the
GSS-API [RFC2743] to gain access to resources when using non-HTTP- GSS-API [RFC2743] to gain access to resources when using non-HTTP-
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protocol exchanges within a data security layer. protocol exchanges within a data security layer.
The Generic Security Service Application Program Interface (GSS-API) The Generic Security Service Application Program Interface (GSS-API)
[RFC2743] provides a framework for applications to support multiple [RFC2743] provides a framework for applications to support multiple
authentication mechanisms through a unified interface. authentication mechanisms through a unified interface.
This document defines SASL mechanisms for OAuth, and it conforms to This document defines SASL mechanisms for OAuth, and it conforms to
the new bridge between SASL and the GSS-API called GS2 [RFC5801]. the new bridge between SASL and the GSS-API called GS2 [RFC5801].
This means that this document defines both SASL and GSS-API This means that this document defines both SASL and GSS-API
mechanisms. Implementers may be interested in either the SASL, the mechanisms. Implementers may be interested in either the SASL, the
GSS-API, or even both mechanisms. To faciliate these two variants, GSS-API, or even both mechanisms. To facilitate these two variants,
the description has been split into two parts, one part that provides the description has been split into two parts, one part that provides
normative references for those interested in the SASL OAuth mechanism normative references for those interested in the SASL OAuth mechanism
(see Section 3), and a second part for those implementers that wish (see Section 3), and a second part for those implementers that wish
to implement the GSS-API portion (see Section 4). to implement the GSS-API portion (see Section 4).
When OAuth is integrated into SASL and the GSS-API the high-level When OAuth is integrated into SASL and the GSS-API the high-level
steps are as follows: steps are as follows:
(A) The client requests authorization from the resource owner. (A) The client requests authorization from the resource owner.
The authorization request can be made directly to the resource The authorization request can be made directly to the resource
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(D) The authorization server authenticates the client and (D) The authorization server authenticates the client and
validates the authorization grant, and if valid issues an access validates the authorization grant, and if valid issues an access
token. token.
(E) The client requests the protected resource from the resource (E) The client requests the protected resource from the resource
server and authenticates by presenting the access token. server and authenticates by presenting the access token.
(F) The resource server validates the access token, and if valid, (F) The resource server validates the access token, and if valid,
indicates a successful authentication. indicates a successful authentication.
Steps (E) and (F) are not defined in [I-D.ietf-oauth-v2] and are the Steps (E) and (F) are not defined in [RFC6749] and are the main
main functionality specified within this document. Consequently, the functionality specified within this document. Consequently, the
message exchange shown in Figure 2 is the result of this message exchange shown in Figure 2 is the result of this
specification. The client will genrally need to determine the specification. The client will generally need to determine the
authentication endpoints (and perhaps the service endpoints) before authentication endpoints (and perhaps the service endpoints) before
the OAuth 2.0 protocol exchange messages in steps (A)-(D) are the OAuth 2.0 protocol exchange messages in steps (A)-(D) are
executed. The discovery of the resource owner and authorization executed. The discovery of the resource owner and authorization
server endpoints is outside the scope of this specification. The server endpoints is outside the scope of this specification. The
client must discover those endpoints using a discovery mechanisms client must discover those endpoints using a discovery mechanisms
such as Webfinger using host-meta [I-D.jones-appsawg-webfinger]. In such as Webfinger using host-meta [I-D.ietf-appsawg-webfinger]. In
band discovery is not tenable if clients support the OAuth 2.0 band discovery is not tenable if clients support the OAuth 2.0
password grant. Once credentials are obtained the client proceeds to password grant. Once credentials are obtained the client proceeds to
steps (E) and (F) defined in this specification. steps (E) and (F) defined in this specification.
----+ ----+
+--------+ +---------------+ | +--------+ +---------------+ |
| |--(A)-- Authorization Request --->| Resource | | | |--(A)-- Authorization Request --->| Resource | |
| | | Owner | |Plain | | | Owner | |Plain
| |<-(B)------ Access Grant ---------| | |OAuth | |<-(B)------ Access Grant ---------| | |OAuth
| | +---------------+ |2.0 | | +---------------+ |2.0
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Figure 2: OAuth SASL Architecture Figure 2: OAuth SASL Architecture
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
The reader is assumed to be familiar with the terms used in the OAuth The reader is assumed to be familiar with the terms used in the OAuth
2.0 specification [I-D.ietf-oauth-v2]. 2.0 specification [RFC6749].
In examples, "C:" and "S:" indicate lines sent by the client and In examples, "C:" and "S:" indicate lines sent by the client and
server respectively. Line breaks have been inserted for readability. server respectively. Line breaks have been inserted for readability.
Note that the IMAP SASL specification requires base64 encoding Note that the IMAP SASL specification requires base64 encoding, see
message, not this memo. Section 4 of [RFC4648], not this memo.
3. OAuth SASL Mechanism Specifications 3. OAuth SASL Mechanism Specifications
SASL is used as a generalized authentication method in a variety of SASL is used as an authentication framework in a variety of
application layer protocols. This document defines the following application layer protocols. This document defines the following
SASL mechanisms for usage with OAuth: SASL mechanisms for usage with OAuth:
OAUTHBEARER Authorization using Bearer tokens. OAUTHBEARER: Authorization using OAuth 2.0 bearer tokens as
described in [RFC6750].
OAUTH10A Authorization using OAuth 1.0a tokens. OAUTH10A: Authorization using OAuth 1.0a MAC tokens (using the
HMAC-SHA1 keyed message digest) as described in Section 3.4.2
of [RFC5849].
OAUTH10A-PLUS Adds channel binding [RFC5056] capability to OAUTH10A-PLUS: Adds channel binding [RFC5056] capability to
OAUTH10A for additional security guarantees. OAUTH10A for protection against man-in-the-middle attacks.
Any new OAuth token scheme MAY define a new SASL mechanism compatible New extensions may be defined to add additional OAuth Access Token
with the mechanisms defined here by simply registering the new Types. Such a new SASL OAuth mechanism can be added by simply
name(s) and citing this specification for the further definition. registering the new name(s) and citing this specification for the
New channel binding enabled "-PLUS" mechanisms defined in this way further definition. New channel binding enabled "-PLUS" mechanisms
MUST include message integrity protection. A newly defined mechanism defined in this way MUST include message integrity protection. A
would also need to register a new GS2 OID. newly defined mechanism would also need to register a new GS2 OID.
These mechanisms are client initiated and lock-step, the server These mechanisms are client initiated and lock-step, the server
always replying to a client message. In the case where the client always replying to a client message. In the case where the client
has and correctly uses a valid token the flow is: has and correctly uses a valid token the flow is:
o Client sends a valid and correct initial client response. o Client sends a valid and correct initial client response.
o Server responds with a successful authentication. o Server responds with a successful authentication.
In the case where authorization fails the server sends an error In the case where authorization fails the server sends an error
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server in order to allow the server to finish the exchange. Some server in order to allow the server to finish the exchange. Some
protocols and common SASL implementations do not support both sending protocols and common SASL implementations do not support both sending
a SASL message and finalizing a SASL negotiation, the additional a SASL message and finalizing a SASL negotiation, the additional
client message in the error case deals with this problem. This client message in the error case deals with this problem. This
exchange is: exchange is:
o Client sends an invalid initial client response. o Client sends an invalid initial client response.
o Server responds with an error message. o Server responds with an error message.
o Client sends a dummy client reponse. o Client sends a dummy client response.
o Server fails the authentication. o Server fails the authentication.
3.1. Initial Client Response 3.1. Initial Client Response
Client responses are a key/value pair sequence. The initial client Client responses are a key/value pair sequence. The initial client
response includes a gs2-header as defined in GS2 [RFC5801], which response includes a gs2-header as defined in GS2 [RFC5801], which
carries the authorization ID. These key/value pairs carry the carries the authorization ID. These key/value pairs carry the
equivalent values from an HTTP context in order to be able to equivalent values from an HTTP context in order to be able to
complete an OAuth style HTTP authorization. The ABNF [RFC5234] complete an OAuth style HTTP authorization. Unknown key/value pairs
syntax is: MUST be ignored by the server. The ABNF [RFC5234] syntax is:
kvsep = %x01 kvsep = %x01
key = 1*ALPHA key = 1*ALPHA
value = *(VCHAR | SP | HTAB | CR | LF ) value = *(VCHAR / SP / HTAB / CR / LF )
kvpair = key "=" value kvsep kvpair = key "=" value kvsep
client_resp = 0*kvpair kvsep client_resp = 0*kvpair kvsep
;; gs2-header = As defined in GSS-API ;; gs2-header = As defined in GSS-API
initial_client_resp = gs2-header kvsep client_resp initial_client_resp = gs2-header kvsep client_resp
The following key/value pairs are defined in the client response: The following key/value pairs are defined in the client response:
auth (REQUIRED): The payload of the HTTP Authorization header for auth (REQUIRED): The payload of the HTTP Authorization header for
an equivalent HTTP OAuth authroization. an equivalent HTTP OAuth authorization.
host: Contains the host name to which the client connected. host: Contains the host name to which the client connected.
port: Contains the port number represented as a decimal positive port: Contains the port number represented as a decimal positive
integer string without leading zeros to which the client integer string without leading zeros to which the client
connected. connected.
qs: The HTTP query string. In non-channel binding mechanisms qs: The HTTP query string. In non-channel binding mechanisms
this is reserved, the client SHOUD NOT send it, and has the this is reserved, the client SHOUD NOT send it, and has the
default value of "". In "-PLUS" variants this carries a single default value of "". In "-PLUS" variants this carries a single
key value pair "cbdata" for the channel binding data payload key value pair "cbdata" for the channel binding data payload
formatted as an HTTP query string. formatted as an HTTP query string.
In authorization schemes that use signatures, the client MUST send For OAuth Access Token Types that use digital signatures or keyed
host and port number key/values, and the server MUST fail an message digests the client MUST send host and port number key/values,
authorization request requiring signatures that does not have host and the server MUST fail an authorization request requiring
and port values. For authorization schemes that require a URI scheme signatures or keyed message digests that do not have host and port
as part of the data being signed "http" is always used. In OAuth values. For authorization schemes that require a URI scheme as part
1.0a for example, the signature base string includes the of the data being signed "http" is always used. In OAuth 1.0a for
example, the so-called signature base string calculation includes the
reconstructed HTTP URL. reconstructed HTTP URL.
3.1.1. Reserved Key/Values 3.1.1. Reserved Key/Values
In these mechanisms values for path, query string and post body are In these mechanisms values for path, query string and post body are
assigned default values. OAuth authorization schemes MAY define assigned default values. OAuth authorization schemes MAY define
usage of these in the SASL context and extend this specification. usage of these in the SASL context and extend this specification.
For OAuth schemes that use request signatures the default values MUST For OAuth Access Token Types that use request signatures the default
be used unless explict values are provided in the client response. values MUST be used unless explicit values are provided in the client
The following key values are reserved for future use: response. The following key values are reserved for future use:
mthd (RESERVED): HTTP method for use in signatures, the default mthd (RESERVED): HTTP method for use in signatures, the default
value is "POST". value is "POST".
path (RESERVED): HTTP path data, the default value is "/". path (RESERVED): HTTP path data, the default value is "/".
post (RESERVED): HTTP post data, the default value is "". post (RESERVED): HTTP post data, the default value is "".
3.1.2. Use of the gs2-header 3.1.2. Use of the gs2-header
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credential, if it does not the server MUST fail the negotiation. credential, if it does not the server MUST fail the negotiation.
In the non "-PLUS" mechanisms the "gs2-cb-flag" MUST be set to "n" In the non "-PLUS" mechanisms the "gs2-cb-flag" MUST be set to "n"
because channel-binding [RFC5056] data is not expected. In the because channel-binding [RFC5056] data is not expected. In the
OAUTH10A-PLUS mechanism (or other -PLUS variants based on this OAUTH10A-PLUS mechanism (or other -PLUS variants based on this
specification) the "gs2-cb-flag" MUST be set appropriately by the specification) the "gs2-cb-flag" MUST be set appropriately by the
client. client.
3.2. Server's Response 3.2. Server's Response
The server validates the response per the specification for the The server validates the response per the specification for the OAuth
authorization scheme used. If the authorization scheme used includes Access Token Types used. If the OAuth Access Token Type utilizes a
signing of the request parameters the client must provide a client digital signature or a keyed message digest of the request parameters
response that satisfies the data requirements for the scheme in use. then the client must provide a client response that satisfies the
data requirements for the scheme in use.
In a "-PLUS" mechanism the server examines the channel binding data, In a "-PLUS" mechanism the server examines the channel binding data,
extracts the channel binding unique prefix, and extracts the raw extracts the channel binding unique prefix, and extracts the raw
channel biding data based on the channel binding type used. It then channel biding data based on the channel binding type used. It then
computes it's own copy of the channel binding payload and compares 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. that to the payload sent by the client in the cbdata key/value.
Those two must be equal for channel binding to succeed. Those two must be equal for channel binding to succeed.
The server responds to a successfully verified client message by The server responds to a successfully verified client message by
completing the SASL negotiation. The authenticated identity reported completing the SASL negotiation. The authenticated identity reported
by the SASL mechanism is the identity securely established for the by the SASL mechanism is the identity securely established for the
client with the OAuth credential. The application, not the SASL client with the OAuth credential. The application, not the SASL
mechanism, based on local access policy determines whether the mechanism, based on local access policy determines whether the
identity reported by the mechanism is allowed access to the requested identity reported by the mechanism is allowed access to the requested
resource. Note that the semantics of the authz-id is specified by resource. Note that the semantics of the authz-id is specified by
the SASL framework [RFC4422]. the SASL framework [RFC4422].
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The server responds to a successfully verified client message by The server responds to a successfully verified client message by
completing the SASL negotiation. The authenticated identity reported completing the SASL negotiation. The authenticated identity reported
by the SASL mechanism is the identity securely established for the by the SASL mechanism is the identity securely established for the
client with the OAuth credential. The application, not the SASL client with the OAuth credential. The application, not the SASL
mechanism, based on local access policy determines whether the mechanism, based on local access policy determines whether the
identity reported by the mechanism is allowed access to the requested identity reported by the mechanism is allowed access to the requested
resource. Note that the semantics of the authz-id is specified by resource. Note that the semantics of the authz-id is specified by
the SASL framework [RFC4422]. the SASL framework [RFC4422].
3.2.1. OAuth Identities in the SASL Context 3.2.1. OAuth Identifiers in the SASL Context
Some OAuth schemes can carry both an owner or resource identity and a OAuth access tokens may carry the authenticated identifier of the
"proxy" identity, for example an OAuth 1.0a [RFC5849] mechanism where resource owner and client authentication provides the authenticated
the consumer key (oauth_consumer_key) identifies the entity using the identity of the client issuing the request to the resource server.
token and the token itself identifies the owner or resouce. If both
identities are needed by an application the developer will need to If both identities are needed by an application the developer will
provide a way to communicate that from the SASL mechanism back to the need to provide a way to communicate that from the SASL mechanism
application such as a GSS-API [RFC2473] named type like back to the application such as a GSS-API [RFC2743] named type like
GSS_C_NT_USER_NAME or a comparable newly defined GSS-API name type or GSS_C_NT_USER_NAME or a comparable newly defined GSS-API name type or
name attribute [RFC6680]. name attribute [RFC6680].
3.2.2. Canonicalization 3.2.2. Server Response to Failed Authentication
The identity asserted by the OAuth authorization server is canonical
for display. The server MAY provide a different canonical form based
on local data.
3.2.3. Server response to failed authentication.
For a failed authentication the server returns a JSON [RFC4627] For a failed authentication the server returns a JSON [RFC4627]
formatted error result, and fails the authentication. The error formatted error result, and fails the authentication. The error
result consists of the following values: result consists of the following values:
status (REQUIRED): The authorization error code. Valid error status (REQUIRED): The authorization error code. Valid error
codes are defined in the IANA [[need registry name]] registry codes are defined in the IANA [[need registry name]] registry
specified in the OAuth 2 core specification. specified in the OAuth 2 core specification.
scope (OPTIONAL): An OAuth scope which is valid to access the scope (OPTIONAL): An OAuth scope which is valid to access the
service. This may be empty which implies that unscoped tokens service. This may be empty which implies that unscoped tokens
are required, or a space separated list. Use of a space are required, or a space separated list. Use of a space
separated list is NOT RECOMMENDED. separated list is NOT RECOMMENDED.
If the resource server provides a scope the client SHOULD always If the resource server provides a scope then the client MUST always
request scoped tokens from the token endpoint. The client MAY use a request scoped tokens from the token endpoint. If the resource
scope other than the one provided by the resource server. Scopes server provides no scope to the client then the client SHOULD presume
other than those advertised by the resource server are be defined by an empty scope (unscoped token) is needed.
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.
If channel binding is in use and the channel binding fails the server 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 responds with a status code set to 412 to indicate that the channel
binding precondition failed. If the authentication scheme in use binding precondition failed. If the authentication scheme in use
does not include signing the server SHOULD revoke the presented does not include signing the server SHOULD revoke the presented
credential and the client SHOULD discard that credential. credential and the client SHOULD discard that credential.
3.2.4. Completing an error message sequence. 3.2.3. Completing an Error Message Sequence
Section 3.6 of [RFC4422] explicitly prohibits additional information Section 3.6 of [RFC4422] explicitly prohibits additional information
in an unsuccessful authentication outcome. Therefor, the error in an unsuccessful authentication outcome. Therefore, the error
message is sent in a normal message. The client MUST then send an message is sent in a normal message. The client MUST then send an
additional client response consisting of a single %x01 (control A) additional client response consisting of a single %x01 (control A)
character to the server in order to allow the server to finish the character to the server in order to allow the server to finish the
exchange. exchange.
3.3. Use of Signature Type Authorization 3.3. OAuth Access Token Types using Digital Signatures and Keyed
Message Digests
Some OAuth mechanisms support authorization using signatures, which OAuth Access Token Types may use digital signatures or keyed message
requires that both client and server construct the string to be digests. The client and the resource server need to perform a
signed. OAuth 2 is designed for authentication/authorization to cryptographic computation for integrity protection and data origin
access specific URIs. SASL is designed for user authentication, and authentication.
has no facility for being more specific. In this mechanism we
require or define default values for the data elements from an HTTP OAuth is designed for access to resources identified by URIs. SASL
request which allow the signature base string to be constructed is designed for user authentication, and has no facility for more
properly. The default HTTP path is "/" and the default post body is fine-grained access control. In this specification we require or
empty. These atoms are defined as extension points so that no define default values for the data elements from an HTTP request
changes are needed if there is a revision of SASL which supports more which allow the signature base string to be constructed properly.
specific resource authorization, e.g. IMAP access to a specific The default HTTP path is "/" and the default post body is empty.
folder or FTP access limited to a specific directory. 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.
Using the example in the OAuth 1.0a specification as a starting Using the example in the OAuth 1.0a specification as a starting
point, on an IMAP server running on port 143 and given the OAuth 1.0a point, on an IMAP server running on port 143 and given the OAuth 1.0a
style authorization request (with %x01 shown as ^A and line breaks style authorization request (with %x01 shown as ^A and line breaks
added for readability) below: added for readability) below:
n,a=user@example.com^A n,a=user@example.com^A
host=example.com^A host=example.com^A
user=user@example.com^A user=user@example.com^A
port=143^A port=143^A
skipping to change at page 13, line 42 skipping to change at page 13, line 31
POST&http%3A%2F%2Fexample.com:143%2F&oauth_consumer_key%3D9djdj82h4 POST&http%3A%2F%2Fexample.com:143%2F&oauth_consumer_key%3D9djdj82h4
8djs9d2%26oauth_nonce%3D7d8f3e4a%26oauth_signature_method%3DHMAC-SH 8djs9d2%26oauth_nonce%3D7d8f3e4a%26oauth_signature_method%3DHMAC-SH
A1%26oauth_timestamp%3D137131201%26oauth_token%3Dkkk9d7dh3k39sjv7 A1%26oauth_timestamp%3D137131201%26oauth_token%3Dkkk9d7dh3k39sjv7
3.4. Channel Binding 3.4. Channel Binding
The channel binding data is carried in the "qs" (query string) key The channel binding data is carried in the "qs" (query string) key
value pair formatted as a standard HTTP query parameter with the name value pair formatted as a standard HTTP query parameter with the name
"cbdata". Channel binding requires that the channel binding data be "cbdata". Channel binding requires that the channel binding data be
integrity protected end-to-end in order to protect against man-in- integrity protected end-to-end in order to protect against man-in-
the-middle attacks. All authorization schemes offered with "-PLUS" the-middle attacks. All SASL OAuth mechanisms with a "-PLUS" postfix
mechanisms MUST provide integrity protection. It should be noted MUST provide integrity protection. It should be noted that while the
that while the Bearer token scheme specifies SSL for normal usage it Bearer Access Token Type mandates TLS it does not create keying
offers no integrity protection and is not suitable for use with material at the application layer and is not suitable for use with
channel binding. channel bindings.
The channel binding data is computed by the client based on it's The channel binding data is computed by the client based on it's
choice of preferred channel binding type. As specified in [RFC5056], choice of preferred channel binding type. As specified in [RFC5056],
the channel binding information MUST start with the channel binding the channel binding information MUST start with the channel binding
unique prefix, followed by a colon (ASCII 0x3A), followed by a base64 unique prefix, followed by a colon (ASCII 0x3A), followed by a base64
encoded channel binding payload. The channel binding payload is the encoded channel binding payload. The channel binding payload is the
raw data from the channel binding type. For example, if the client raw data from the channel binding type. For example, if the client
is using tls-unique for channel binding then the raw channel binding is using tls-unique for channel binding then the raw channel binding
data is the TLS finished message as specified in section 3.1 of data is the TLS finished message as specified in Section 3.1 of
[RFC5929]. [RFC5929].
4. GSS-API OAuth Mechanism Specification 4. GSS-API OAuth Mechanism Specification
Note: The normative references in this section are informational for Note: The normative references in this section are informational for
SASL implementers, but they are normative for GSS-API implementers. SASL implementers, but they are normative for GSS-API implementers.
A SASL OAuth mechanism is also a GSS-API mechanism and the messages A SASL OAuth mechanism is also a GSS-API mechanism and the messages
described in Section 3 are the same with the following changes to the described in Section 3 are the same with the following changes to the
GS2 related elements: GS2 related elements:
skipping to change at page 15, line 38 skipping to change at page 14, line 38
(GSS_C_MUTUAL_FLAG) set to TRUE. OAuth supports credential (GSS_C_MUTUAL_FLAG) set to TRUE. OAuth supports credential
delegation, therefore security contexts may have the deleg_state flag delegation, therefore security contexts may have the deleg_state flag
(GSS_C_DELEG_FLAG) set to either TRUE or FALSE. (GSS_C_DELEG_FLAG) set to either TRUE or FALSE.
The mutual authentication property of this mechanism relies on The mutual authentication property of this mechanism relies on
successfully comparing the TLS server identity with the negotiated successfully comparing the TLS server identity with the negotiated
target name. Since the TLS channel is managed by the application target name. Since the TLS channel is managed by the application
outside of the GSS-API mechanism, the mechanism itself is unable to outside of the GSS-API mechanism, the mechanism itself is unable to
confirm the name while the application is able to perform this confirm the name while the application is able to perform this
comparison for the mechanism. For this reason, applications MUST comparison for the mechanism. For this reason, applications MUST
match the TLS server identity with the target name, as discussed in match the TLS server identity with the target name using the
[RFC6125]. appropriate application profile, as discussed in [RFC6125]. For
example, when SASL OAuth is run over IMAP then the IMAP profile of
RFC 6125 is used.
OAuth mechanisms do not support per-message tokens or OAuth mechanisms do not support per-message tokens or
GSS_Pseudo_random. GSS_Pseudo_random.
OAuth supports a standard generic name syntax for acceptors, such as OAuth supports a standard generic name syntax for acceptors, such as
GSS_C_NT_HOSTBASED_SERVICE (see [RFC2743], Section 4.1). These GSS_C_NT_HOSTBASED_SERVICE (see [RFC2743], Section 4.1). These
service names MUST be associated with the "entityID" claimed by the service names MUST be associated with the "entityID" claimed by the
RP. OAuth mechanisms support only a single name type for initiators: RP. OAuth mechanisms support only a single name type for initiators:
GSS_C_NT_USER_NAME. GSS_C_NT_USER_NAME is the default name type. 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 The query, display, and exported name syntaxes for OAuth principal
skipping to change at page 17, line 10 skipping to change at page 16, line 10
Section 4). The exported name token does, of course, conform to Section 4). The exported name token does, of course, conform to
[RFC2743], Section 3.2, but the "NAME" part of the token should be [RFC2743], Section 3.2, but the "NAME" part of the token should be
treated as a potential input string to the OAuth name normalization treated as a potential input string to the OAuth name normalization
rules. rules.
5. Examples 5. Examples
These examples illustrate exchanges between an IMAP and SMTP clients These examples illustrate exchanges between an IMAP and SMTP clients
and servers. and servers.
Note to implementers: Authorization scheme names are case Note to implementers: The SASL OAuth method names are case
insensitive. One example uses "Bearer" but that could as easily be insensitive. One example uses "Bearer" but that could as easily be
"bearer", "BEARER", or "BeArEr". "bearer", "BEARER", or "BeArEr".
5.1. Successful Bearer Token Exchange 5.1. Successful Bearer Token Exchange
This example shows a successful OAuth 2.0 bearer token exchange. This example shows a successful OAuth 2.0 bearer token exchange.
Note that line breaks are inserted for readability. Note that line breaks are inserted for readability.
S: * IMAP4rev1 Server Ready S: * OK IMAP4rev1 Server Ready
C: t0 CAPABILITY C: t0 CAPABILITY
S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER SASL-IR
S: t0 OK Completed S: t0 OK Completed
C: t1 AUTHENTICATE OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20BaG9zdD1zZX C: t1 AUTHENTICATE OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20BaG9zdD1zZX
J2ZXIuZXhhbXBsZS5jb20BcG9ydD0xNDMBYXV0aD1CZWFyZXIgdkY5ZGZ0NHFtV J2ZXIuZXhhbXBsZS5jb20BcG9ydD0xNDMBYXV0aD1CZWFyZXIgdkY5ZGZ0NHFtV
GMyTnZiM1JsY2tCaGJIUmhkbWx6ZEdFdVkyOXRDZz09AQE= GMyTnZiM1JsY2tCaGJIUmhkbWx6ZEdFdVkyOXRDZz09AQE=
S: t1 OK SASL authentication succeeded S: t1 OK SASL authentication succeeded
As required by IMAP [RFC3501], the payloads are base64-encoded. The As required by IMAP [RFC3501], the payloads are base64-encoded. The
decoded initial client response (with %x01 represented as ^A and long decoded initial client response (with %x01 represented as ^A and long
lines wrapped for readability) is: lines wrapped for readability) is:
skipping to change at page 18, line 13 skipping to change at page 17, line 13
0x0D and 0x0A), these are not displayed explicitly in the example. 0x0D and 0x0A), these are not displayed explicitly in the example.
[connection begins] [connection begins]
S: 220 mx.example.com ESMTP 12sm2095603fks.9 S: 220 mx.example.com ESMTP 12sm2095603fks.9
C: EHLO sender.example.com C: EHLO sender.example.com
S: 250-mx.example.com at your service,[172.31.135.47] S: 250-mx.example.com at your service,[172.31.135.47]
S: 250-SIZE 35651584 S: 250-SIZE 35651584
S: 250-8BITMIME S: 250-8BITMIME
S: 250-AUTH LOGIN PLAIN OAUTHBEARER S: 250-AUTH LOGIN PLAIN OAUTHBEARER
S: 250-ENHANCEDSTATUSCODES S: 250-ENHANCEDSTATUSCODES
S: 250-PIPELINING S: 250 PIPELINING
C: t1 AUTHENTICATE OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20BaG9zdD1zZX C: t1 AUTHENTICATE OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20BaG9zdD1zZX
J2ZXIuZXhhbXBsZS5jb20BcG9ydD0xNDMBYXV0aD1CZWFyZXIgdkY5ZGZ0NHFtV J2ZXIuZXhhbXBsZS5jb20BcG9ydD0xNDMBYXV0aD1CZWFyZXIgdkY5ZGZ0NHFtV
GMyTnZiM1JsY2tCaGJIUmhkbWx6ZEdFdVkyOXRDZz09AQE= GMyTnZiM1JsY2tCaGJIUmhkbWx6ZEdFdVkyOXRDZz09AQE=
S: 235 Authentication successful. S: 235 Authentication successful.
[connection continues...] [connection continues...]
5.2. OAuth 1.0a Authorization with Channel Binding 5.2. OAuth 1.0a Authorization with Channel Binding
This example shows channel binding in the context of an OAuth 1.0a This example shows channel binding in the context of an OAuth 1.0a
signed authorization request. Note that line breaks are inserted for request using a keyed message digest. Note that line breaks are
readability. inserted for readability.
S: * CAPABILITY IMAP4rev1 AUTH=OAUTH10A-PLUS SASL-IR IMAP4rev1 Server S: * OK [CAPABILITY IMAP4rev1 AUTH=OAUTH10A-PLUS SASL-IR]
Ready IMAP4rev1 Server Ready
S: t0 OK Completed
C: t1 AUTHENTICATE OAUTH10A-PLUS cD10bHMtdW5pcXVlLGE9dXNlckBleGFtcGxlL C: t1 AUTHENTICATE OAUTH10A-PLUS cD10bHMtdW5pcXVlLGE9dXNlckBleGFtcGxlL
mNvbQFob3N0PXNlcnZlci5leGFtcGxlLmNvbQFwb3J0PTE0MwFhdXRoPU9BdXRoI mNvbQFob3N0PXNlcnZlci5leGFtcGxlLmNvbQFwb3J0PTE0MwFhdXRoPU9BdXRoI
HJlYWxtPSJFeGFtcGxlIixvYXV0aF9jb25zdW1lcl9rZXk9IjlkamRqODJoNDhka HJlYWxtPSJFeGFtcGxlIixvYXV0aF9jb25zdW1lcl9rZXk9IjlkamRqODJoNDhka
nM5ZDIiLG9hdXRoX3Rva2VuPSJra2s5ZDdkaDNrMzlzanY3IixvYXV0aF9zaWduY nM5ZDIiLG9hdXRoX3Rva2VuPSJra2s5ZDdkaDNrMzlzanY3IixvYXV0aF9zaWduY
XR1cmVfbWV0aG9kPSJITUFDLVNIQTEiLG9hdXRoX3RpbWVzdGFtcD0iMTM3MTMxM XR1cmVfbWV0aG9kPSJITUFDLVNIQTEiLG9hdXRoX3RpbWVzdGFtcD0iMTM3MTMxM
jAxIixvYXV0aF9ub25jZT0iN2Q4ZjNlNGEiLG9hdXRoX3NpZ25hdHVyZT0iU1Nkd jAxIixvYXV0aF9ub25jZT0iN2Q4ZjNlNGEiLG9hdXRoX3NpZ25hdHVyZT0iU1Nkd
ElHRWdiR2wwZEd4bElIUmxZU0J3YjNRdSIBcXM9Y2JkYXRhPXRscy11bmlxdWU6U ElHRWdiR2wwZEd4bElIUmxZU0J3YjNRdSIBcXM9Y2JkYXRhPXRscy11bmlxdWU6U
0c5M0lHSnBaeUJwY3lCaElGUk1VeUJtYVc1aGJDQnRaWE56WVdkbFB3bz0BAQ== 0c5M0lHSnBaeUJwY3lCaElGUk1VeUJtYVc1aGJDQnRaWE56WVdkbFB3bz0BAQ==
S: t1 OK SASL authentication succeeded S: t1 OK SASL authentication succeeded
skipping to change at page 20, line 41 skipping to change at page 19, line 41
The decoded server response is: The decoded server response is:
{ {
"status":"412", "status":"412",
"scope":"example_scope" "scope":"example_scope"
} }
The client responds with the required dummy response. The client responds with the required dummy response.
5.5. SMTP Example of a failed negotiation. 5.5. SMTP Example of a Failed Negotiation
This example shows an authorization failure in an SMTP exchange. This example shows an authorization failure in an SMTP exchange.
Note that line breaks are inserted for readability, and that the SMTP Note that line breaks are inserted for readability, and that the SMTP
protocol terminates lines with CR and LF characters (ASCII values protocol terminates lines with CR and LF characters (ASCII values
0x0D and 0x0A), these are not displayed explicitly in the example. 0x0D and 0x0A), these are not displayed explicitly in the example.
[connection begins] [connection begins]
S: 220 mx.example.com ESMTP 12sm2095603fks.9 S: 220 mx.example.com ESMTP 12sm2095603fks.9
C: EHLO sender.example.com C: EHLO sender.example.com
S: 250-mx.example.com at your service,[172.31.135.47] S: 250-mx.example.com at your service,[172.31.135.47]
S: 250-SIZE 35651584 S: 250-SIZE 35651584
S: 250-8BITMIME S: 250-8BITMIME
S: 250-AUTH LOGIN PLAIN OAUTHBEARER S: 250-AUTH LOGIN PLAIN OAUTHBEARER
S: 250-ENHANCEDSTATUSCODES S: 250-ENHANCEDSTATUSCODES
S: 250-PIPELINING S: 250 PIPELINING
C: AUTH OAUTHBEARER bixhPT1zb21ldXNlckBleGFtcGxlLmNvbQFhdXRoPUJlYXJlciB2 C: AUTH OAUTHBEARER bixhPT1zb21ldXNlckBleGFtcGxlLmNvbQFhdXRoPUJlYXJlciB2
RjlkZnQ0cW1UYzJOdmIzUmxja0JoZEhSaGRtbHpkR0V1WTI5dENnPT0BAQ== RjlkZnQ0cW1UYzJOdmIzUmxja0JoZEhSaGRtbHpkR0V1WTI5dENnPT0BAQ==
S: 334 eyJzdGF0dXMiOiI0MDEiLCJzY2hlbWVzIjoiYmVhcmVyIG1hYyIsInNjb3BlIjoia S: 334 eyJzdGF0dXMiOiI0MDEiLCJzY2hlbWVzIjoiYmVhcmVyIG1hYyIsInNjb3BlIjoia
HR0cHM6Ly9tYWlsLmdvb2dsZS5jb20vIn0K HR0cHM6Ly9tYWlsLmdvb2dsZS5jb20vIn0K
C: AQ== C: AQ==
S: 535-5.7.1 Username and Password not accepted. Learn more at S: 535-5.7.1 Username and Password not accepted. Learn more at
S: 535 5.7.1 http://support.example.com/mail/oauth S: 535 5.7.1 http://support.example.com/mail/oauth
[connection continues...] [connection continues...]
The server returned an error message in the 334 SASL message, the The server returned an error message in the 334 SASL message, the
client responds with the required dummy response, and the server client responds with the required dummy response, and the server
finalizes the negotiation. finalizes the negotiation.
6. Security Considerations 6. Security Considerations
This mechanism does not provide a security layer, but does provide a OAuth 1.0a and OAuth 2 allows for a variety of deployment scenarios,
provision for channel binding. The OAuth 2 specification and the security properties of these profiles vary. Application
[I-D.ietf-oauth-v2] allows for a variety of usages, and the security developers therefore need to understand the needs of their
properties of these profiles vary. The usage of bearer tokens, for applications before selecting a specific SASL OAuth mechanism.
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.
The channel binding in this mechanism has different properties based The channel binding in this mechanism has different properties based
on the authentication scheme used. The integrity guarantee for on the Access Token Type used.
channel binding depends on the quality of the guarantee in the the
authorization scheme.
It is possible that SASL will be authenticating a connection and the 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 life of that connection may outlast the life of the access token used
authenticate it. This is a common problem in application protocols to establish it. This is a common problem in application protocols
where connections are long-lived, and not a problem with this where connections are long-lived, and not a problem with this
mechanism per se. Servers MAY unilaterally disconnect clients in mechanism per se. Servers MAY unilaterally disconnect clients in
accordance with the application protocol. accordance with the application protocol.
An OAuth credential is not equivalent to the password or primary The OAuth access token (and related keying material) is not
account credential. There are protocols like XMPP that allow actions equivalent to the user's long term password. As such, care has to be
like change password. The server SHOULD ensure that actions taken in taken when these OAuth credentials are used for actions like changing
the authenticated channel are appropriate to the strength of the passwords (as it is possible with some protocols, e.g., XMPP). The
presented credential. server SHOULD ensure that actions taken in the authenticated channel
are appropriate to the strength of the presented credential.
Tokens have a lifetime associated with them. Reducing the lifetime Access tokens have a lifetime. Reducing the lifetime of an access
of a token provides security benefits in the case that tokens leak. token provides security benefits, as described in
In addition a previously obtained token MAY be revoked or rendered [I-D.ietf-oauth-v2-threatmodel], and OAuth 2.0 introduces refresh
invalid at any time. The client MAY request a new access token for tokens to obtain new access token on the fly. Additionally, a
each connection to a resource server, but it SHOULD cache and re-use previously obtained access 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. access credentials that appear to be valid.
7. IANA Considerations 7. Internationalization Considerations
7.1. SASL Registration The identifer asserted by the OAuth authorization server about the
resource owner inside the access token may be displayed to a human.
For example, when SASL is used in the context of IMAP the resource
server may assert the resource owner's email address to the IMAP
server for usage in an email-based application. The identifier may
therefore contain internationalized characters and an application
needs to ensure that the mapping between the identifier provided by
OAuth is suitable for use with the application layer protocol SASL is
incorporated into.
At the time of writing the standardization of the assertion format
(in JSON format) is still ongoing, see
[I-D.ietf-oauth-json-web-token].
8. IANA Considerations
8.1. SASL Registration
The IANA is requested to register the following SASL profile: The IANA is requested to register the following SASL profile:
SASL mechanism profile: OAUTHBEARER SASL mechanism profile: OAUTHBEARER
Security Considerations: See this document Security Considerations: See this document
Published Specification: See this document Published Specification: See this document
For further information: Contact the authors of this document. For further information: Contact the authors of this document.
skipping to change at page 24, line 5 skipping to change at page 24, line 5
Security Considerations: See this document Security Considerations: See this document
Published Specification: See this document Published Specification: See this document
For further information: Contact the authors of this document. For further information: Contact the authors of this document.
Owner/Change controller: the IETF Owner/Change controller: the IETF
Note: None Note: None
7.2. GSS-API Registration 8.2. GSS-API Registration
IANA is further requested to assign an OID for thESE GSS mechanismS IANA is further requested to assign an OID for these GSS mechanisms
in the SMI numbers registry, with the prefix of in the SMI numbers registry, with the prefix of
iso.org.dod.internet.security.mechanisms (1.3.6.1.5.5) and to iso.org.dod.internet.security.mechanisms (1.3.6.1.5.5) and to
reference this specification in the registry. reference this specification in the registry.
8. References 9. References
8.1. Normative References
[I-D.ietf-oauth-v2]
Hardt, D., "The OAuth 2.0 Authorization Framework",
draft-ietf-oauth-v2-31 (work in progress), August 2012.
[I-D.ietf-oauth-v2-bearer] 9.1. Normative References
Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage",
draft-ietf-oauth-v2-bearer-23 (work in progress),
August 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in
IPv6 Specification", RFC 2473, December 1998. IPv6 Specification", RFC 2473, December 1998.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
skipping to change at page 25, line 46 skipping to change at page 25, line 36
[RFC3174] Eastlake, D. and P. Jones, "US Secure Hash Algorithm 1 [RFC3174] Eastlake, D. and P. Jones, "US Secure Hash Algorithm 1
(SHA1)", RFC 3174, September 2001. (SHA1)", RFC 3174, September 2001.
[RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and [RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and
Security Layer (SASL)", RFC 4422, June 2006. Security Layer (SASL)", RFC 4422, June 2006.
[RFC4627] Crockford, D., "The application/json Media Type for [RFC4627] Crockford, D., "The application/json Media Type for
JavaScript Object Notation (JSON)", RFC 4627, July 2006. JavaScript Object Notation (JSON)", RFC 4627, July 2006.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006.
[RFC5056] Williams, N., "On the Use of Channel Bindings to Secure [RFC5056] Williams, N., "On the Use of Channel Bindings to Secure
Channels", RFC 5056, November 2007. Channels", RFC 5056, November 2007.
[RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008. (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, [RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
skipping to change at page 26, line 33 skipping to change at page 26, line 26
Verification of Domain-Based Application Service Identity Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509 within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer (PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, March 2011. Security (TLS)", RFC 6125, March 2011.
[RFC6680] Williams, N., Johansson, L., Hartman, S., and S. [RFC6680] Williams, N., Johansson, L., Hartman, S., and S.
Josefsson, "Generic Security Service Application Josefsson, "Generic Security Service Application
Programming Interface (GSS-API) Naming Extensions", Programming Interface (GSS-API) Naming Extensions",
RFC 6680, August 2012. RFC 6680, August 2012.
8.2. Informative References [RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework",
RFC 6749, October 2012.
[I-D.ietf-oauth-v2-http-mac] [RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Hammer-Lahav, E., "HTTP Authentication: MAC Access Framework: Bearer Token Usage", RFC 6750, October 2012.
Authentication", draft-ietf-oauth-v2-http-mac-01 (work in
progress), February 2012.
[I-D.jones-appsawg-webfinger] 9.2. Informative References
[I-D.ietf-appsawg-webfinger]
Jones, P., Salgueiro, G., and J. Smarr, "WebFinger", Jones, P., Salgueiro, G., and J. Smarr, "WebFinger",
draft-jones-appsawg-webfinger-06 (work in progress), draft-ietf-appsawg-webfinger-07 (work in progress),
June 2012. December 2012.
[I-D.ietf-oauth-json-web-token]
Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", draft-ietf-oauth-json-web-token-05 (work in
progress), November 2012.
[I-D.ietf-oauth-v2-http-mac]
Richer, J., Mills, W., and H. Tschofenig, "OAuth 2.0
Message Authentication Code (MAC) Tokens",
draft-ietf-oauth-v2-http-mac-02 (work in progress),
November 2012.
[I-D.ietf-oauth-v2-threatmodel]
Lodderstedt, T., McGloin, M., and P. Hunt, "OAuth 2.0
Threat Model and Security Considerations",
draft-ietf-oauth-v2-threatmodel-08 (work in progress),
October 2012.
[RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION [RFC3501] Crispin, M., "INTERNET MESSAGE ACCESS PROTOCOL - VERSION
4rev1", RFC 3501, March 2003. 4rev1", RFC 3501, March 2003.
Appendix A. Acknowlegements Appendix A. Acknowlegements
The authors would like to thank the members of the Kitten working The authors would like to thank the members of the Kitten working
group, and in addition and specifically: Simon Josefson, Torsten group, and in addition and specifically: Simon Josefson, Torsten
Lodderstadt, Ryan Troll, and Nico Williams. Lodderstadt, Ryan Troll, Alexey Melnikov, and Nico Williams.
This document was produced under the chairmanship of Alexey Melnikov,
Tom Yu, Shawn Emery, Josh Howlett, Sam Hartman. The area directors
included Stephen Farrell.
Appendix B. Document History Appendix B. Document History
[[ to be removed by RFC editor before publication as an RFC ]] [[ to be removed by RFC editor before publication as an RFC ]]
-09
o Incorporated review by Alexey and Hannes.
o Clarified the three OAuth SASL mechanisms.
o Updated references
o Extended acknowledgements
-08 -08
o Fixed the channel binding examples for p=$cbtype o Fixed the channel binding examples for p=$cbtype
o More tuning of the authcid language and edited and renamed 3.2.1. o More tuning of the authcid language and edited and renamed 3.2.1.
-07 -07
o Struck the MUST langiage from authzid. o Struck the MUST langiage from authzid.
 End of changes. 66 change blocks. 
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