draft-ietf-kitten-sasl-oauth-19.txt   draft-ietf-kitten-sasl-oauth-20.txt 
KITTEN W. Mills KITTEN W. Mills
Internet-Draft Microsoft Internet-Draft Microsoft
Intended status: Standards Track T. Showalter Intended status: Standards Track T. Showalter
Expires: July 24, 2015 Expires: October 18, 2015
H. Tschofenig H. Tschofenig
ARM Ltd. ARM Ltd.
January 20, 2015 April 16, 2015
A set of SASL Mechanisms for OAuth A set of SASL Mechanisms for OAuth
draft-ietf-kitten-sasl-oauth-19.txt draft-ietf-kitten-sasl-oauth-20.txt
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
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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 July 24, 2015. This Internet-Draft will expire on October 18, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2015 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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3.1.1. Reserved Key/Values . . . . . . . . . . . . . . . . . 8 3.1.1. Reserved Key/Values . . . . . . . . . . . . . . . . . 8
3.2. Server's Response . . . . . . . . . . . . . . . . . . . . 8 3.2. Server's Response . . . . . . . . . . . . . . . . . . . . 8
3.2.1. OAuth Identifiers in the SASL Context . . . . . . . . 9 3.2.1. OAuth Identifiers in the SASL Context . . . . . . . . 9
3.2.2. Server Response to Failed Authentication . . . . . . 9 3.2.2. Server Response to Failed Authentication . . . . . . 9
3.2.3. Completing an Error Message Sequence . . . . . . . . 10 3.2.3. Completing an Error Message Sequence . . . . . . . . 10
3.3. OAuth Access Token Types using Keyed Message Digests . . 10 3.3. OAuth Access Token Types using Keyed Message Digests . . 10
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.1. Successful Bearer Token Exchange . . . . . . . . . . . . 12 4.1. Successful Bearer Token Exchange . . . . . . . . . . . . 12
4.2. Successful OAuth 1.0a Token Exchange . . . . . . . . . . 13 4.2. Successful OAuth 1.0a Token Exchange . . . . . . . . . . 13
4.3. Failed Exchange . . . . . . . . . . . . . . . . . . . . . 13 4.3. Failed Exchange . . . . . . . . . . . . . . . . . . . . . 13
4.4. SMTP Example of a Failed Negotiation . . . . . . . . . . 15 4.4. SMTP Example of a Failed Negotiation . . . . . . . . . . 14
5. Security Considerations . . . . . . . . . . . . . . . . . . . 15 5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6. Internationalization Considerations . . . . . . . . . . . . . 17 6. Internationalization Considerations . . . . . . . . . . . . . 16
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
7.1. SASL Registration . . . . . . . . . . . . . . . . . . . . 17 7.1. SASL Registration . . . . . . . . . . . . . . . . . . . . 17
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. Normative References . . . . . . . . . . . . . . . . . . 18 8.1. Normative References . . . . . . . . . . . . . . . . . . 17
8.2. Informative References . . . . . . . . . . . . . . . . . 19 8.2. Informative References . . . . . . . . . . . . . . . . . 18
Appendix A. Acknowlegements . . . . . . . . . . . . . . . . . . 19 Appendix A. Acknowlegements . . . . . . . . . . . . . . . . . . 19
Appendix B. Document History . . . . . . . . . . . . . . . . . . 20 Appendix B. Document History . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
OAuth 1.0a [RFC5849] and OAuth 2.0 [RFC6749] are protocol frameworks OAuth 1.0a [RFC5849] and OAuth 2.0 [RFC6749] are protocol frameworks
that enable a third-party application to obtain limited access to a that enable 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.
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between the OAuth client and the authorization server; it does not between the OAuth client and the authorization server; it does not
define the interaction between the OAuth client and the resource define the interaction between the OAuth client and the resource
server for the access to a protected resource using an Access Token. server for the access to a protected resource using an Access Token.
Instead, the OAuth client to resource server interaction is described Instead, the OAuth client to resource server interaction is described
in separate specifications, such as the bearer token specification in separate specifications, such as the bearer token specification
[RFC6750]. OAuth 1.0a included the protocol specification for the [RFC6750]. OAuth 1.0a included the protocol specification for the
communication between the OAuth client and the resource server in communication between the OAuth client and the resource server in
[RFC5849]. [RFC5849].
The main use cases for OAuth 2.0 and OAuth 1.0a have so far focused The main use cases for OAuth 2.0 and OAuth 1.0a have so far focused
on an HTTP-based [RFC2616] environment only. This document on an HTTP-based [RFC7230] environment only. This document
integrates OAuth 1.0a and OAuth 2.0 into non-HTTP-based applications integrates OAuth 1.0a and OAuth 2.0 into non-HTTP-based applications
using the integration into SASL. Hence, this document takes using the integration into SASL. Hence, this document takes
advantage of the OAuth protocol and its deployment base to provide a advantage of the OAuth protocol and its deployment base to provide a
way to use the Simple Authentication and Security Layer (SASL) way to use the Simple Authentication and Security Layer (SASL)
[RFC4422] to gain access to resources when using non-HTTP-based [RFC4422] to gain access to resources when using non-HTTP-based
protocols, such as the Internet Message Access Protocol (IMAP) protocols, such as the Internet Message Access Protocol (IMAP)
[RFC3501] and the Simple Mail Transfer Protocol (SMTP) [RFC5321], [RFC3501] and the Simple Mail Transfer Protocol (SMTP) [RFC5321],
which is what this memo uses in the examples. which is what this memo uses in the examples.
To illustrate the impact of integrating this specification into an To illustrate the impact of integrating this specification into an
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+--------+ +---------------+ | +--------+ +---------------+ |
----+ ----+
Figure 1: OAuth 2.0 Protocol Flow Figure 1: OAuth 2.0 Protocol Flow
The Simple Authentication and Security Layer (SASL) is a framework The Simple Authentication and Security Layer (SASL) is a framework
for providing authentication and data security services in for providing authentication and data security services in
connection-oriented protocols via replaceable authentication connection-oriented protocols via replaceable authentication
mechanisms. It provides a structured interface between protocols and mechanisms. It provides a structured interface between protocols and
mechanisms. The resulting framework allows new protocols to reuse mechanisms. The resulting framework allows new protocols to reuse
existing authentication protocols and allows old protocols to make existing authentication mechanisms and allows old protocols to make
use of new authentication mechanisms. The framework also provides a use of new authentication mechanisms. The framework also provides a
protocol for securing subsequent exchanges within a data security protocol for securing subsequent exchanges within a data security
layer. layer.
When OAuth is integrated into SASL the high-level steps are as When OAuth is integrated into SASL the high-level steps are as
follows: 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
owner (as shown), or preferably indirectly via the authorization owner (as shown), or preferably indirectly via the authorization
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support the Dynamic Client Registration protocol support the Dynamic Client Registration protocol
[I-D.ietf-oauth-dyn-reg]. [I-D.ietf-oauth-dyn-reg].
OAuth 1.0 follows a similar model but uses a different terminology OAuth 1.0 follows a similar model but uses a different terminology
and does not separate the resource server from the authorization and does not separate the resource server from the authorization
server. server.
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", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [RFC2119]. "OPTIONAL" in this 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 [RFC6749] and SASL [RFC4422]. 2.0 specification [RFC6749] and SASL [RFC4422].
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, see Note that the IMAP SASL specification requires base64 encoding, see
Section 4 of [RFC4648], not this memo. Section 4 of [RFC4648], not this memo.
3. OAuth SASL Mechanism Specifications 3. OAuth SASL Mechanism Specifications
SASL is used as an authentication framework 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: OAuth 2.0 bearer tokens, as described in [RFC6750]. OAUTHBEARER: OAuth 2.0 bearer tokens, as described in [RFC6750].
RFC 6750 uses Transport Layer Security (TLS) to secure the RFC 6750 uses Transport Layer Security (TLS) [RFC5246] to
protocol interaction between the client and the resource secure the protocol interaction between the client and the
server. resource server.
OAUTH10A: OAuth 1.0a MAC tokens (using the HMAC-SHA1 keyed OAUTH10A: OAuth 1.0a MAC tokens (using the HMAC-SHA1 keyed
message digest), as described in Section 3.4.2 of [RFC5849]. message digest), as described in Section 3.4.2 of [RFC5849].
New extensions may be defined to add additional OAuth Access Token New extensions may be defined to add additional OAuth Access Token
Types. Such a new SASL OAuth mechanism can be added by simply Types. Such a new SASL OAuth mechanism can be added by simply
registering the new name(s) and citing this specification for the registering the new name(s) and citing this specification for the
further definition. further definition.
These mechanisms are client initiated and lock-step, the server These mechanisms are client initiated and lock-step, the server
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3. Client sends a dummy client response. 3. Client sends a dummy client response.
4. Server fails the authentication. 4. Server fails the authentication.
3.1. Initial Client Response 3.1. Initial Client Response
Client responses are a GS2 [RFC5801] header followed by zero or more Client responses are a GS2 [RFC5801] header followed by zero or more
key/value pairs, or may be empty. The gs2-header is defined here for key/value pairs, or may be empty. The gs2-header is defined here for
compatibility with GS2 if a GS2 mechanism is formally defined, but compatibility with GS2 if a GS2 mechanism is formally defined, but
this document does not define one. These key/value pairs take the this document does not define one. The key/value pairs take the
place of the corresponding HTTP headers and values to convey the place of the corresponding HTTP headers and values to convey the
information necessary to complete an OAuth style HTTP authorization. information necessary to complete an OAuth style HTTP authorization.
Unknown key/value pairs MUST be ignored by the server. The ABNF Unknown key/value pairs MUST be ignored by the server. The ABNF
[RFC5234] syntax is: [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
;;gs2-header = See RFC 5801 ;;gs2-header = See RFC 5801
client_resp = (gs2-header kvsep 0*kvpair kvsep) / kvsep client_resp = (gs2-header kvsep *kvpair kvsep) / kvsep
The GS2 header MAY include the user name associated with the resource The GS2 header MAY include the user name associated with the resource
being accessed, the "authzid". It is worth noting that application being accessed, the "authzid". It is worth noting that application
protocols are allowed to require an authzid, as are specific server protocols are allowed to require an authzid, as are specific server
implementations. implementations.
The client response consisting of only a single kvsep is used only The client response consisting of only a single kvsep is used only
when authentication fails, and is only valid in that context. If when authentication fails, and is only valid in that context. If
sent as the first message from the client the server MAY simply fail sent as the first message from the client the server MAY simply fail
the authentication without returning discovery information since the authentication without returning discovery information since
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utilizes a keyed message digest of the request parameters then the utilizes a keyed message digest of the request parameters then the
client must provide a client response that satisfies the data client must provide a client response that satisfies the data
requirements for the scheme in use. requirements for the scheme in use.
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 authorization identity is resource. Note that the semantics of the authzid is specified by the
specified by the SASL framework [RFC4422]. SASL framework [RFC4422].
3.2.1. OAuth Identifiers in the SASL Context 3.2.1. OAuth Identifiers in the SASL Context
In the OAuth framework the client may be authenticated by the In the OAuth framework the client may be authenticated by the
authorization server and the resource owner is authenticated to the authorization server and the resource owner is authenticated to the
authorization server. OAuth access tokens may contain information authorization server. OAuth access tokens may contain information
about the authentication of the resource owner and about the client about the authentication of the resource owner and about the client
and may therefore make this information accessible to the resource and may therefore make this information accessible to the resource
server. server.
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For a failed authentication the server returns a JSON [RFC7159] For a failed authentication the server returns a JSON [RFC7159]
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 "OAuth Extensions Error Registry" codes are defined in the IANA "OAuth Extensions Error 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 omitted which implies that unscoped
are required, or a scope value. If a scope is specified then a tokens are required. If a scope is specified then a single
single scope is preferred, use of a space separated list of scope is preferred, use of a space separated list of scopes is
scopes is NOT RECOMMENDED. NOT RECOMMENDED.
openid-configuration (OPTIONAL): The URL for a document following openid-configuration (OPTIONAL): The URL for a document following
the OpenID Provider Configuration Information schema as the OpenID Provider Configuration Information schema as
described in OpenID Connect Discovery (OIDCD) described in OpenID Connect Discovery (OIDCD)
[OpenID.Discovery] section 3 that is appropriate for the user. [OpenID.Discovery] section 3 that is appropriate for the user.
As specified in OIDCD this will have the "https" URL scheme. As specified in OIDCD this will have the "https" URL scheme.
This document MUST have all OAuth related data elements This document MUST have all OAuth related data elements
populated. The server MAY return different URLs for users in populated. The server MAY return different URLs for users in
different domains and the client SHOULD NOT cache a single different domains and the client SHOULD NOT cache a single
returned value and assume it applies for all users/domains that returned value and assume it applies for all users/domains that
the server suports. The returned discovery document SHOULD the server suports. The returned discovery document SHOULD
have all data elements required by the OpenID Connect Discovery have all data elements required by the OpenID Connect Discovery
specification populated. In addition, the discovery document specification populated. In addition, the discovery document
SHOULD contain the 'registration_endpoint' element to learn SHOULD contain the 'registration_endpoint' element to identify
about the endpoint to be used with the Dynamic Client the endpoint to be used with the Dynamic Client Registration
Registration protocol [I-D.ietf-oauth-dyn-reg] to obtain the protocol [I-D.ietf-oauth-dyn-reg] to obtain the minimum number
minimum number of parameters necessary for the OAuth protocol of parameters necessary for the OAuth protocol exchange to
exchange to function. Another comparable discovery or client function. Another comparable discovery or client registration
registration mechanism MAY be used if available. mechanism MAY be used if available.
The use of the 'offline_access' scope, as defined in The use of the 'offline_access' scope, as defined in
[OpenID.Core] is RECOMMENDED to give clients the capability to [OpenID.Core] is RECOMMENDED to give clients the capability to
explicitly request a refresh token. explicitly request a refresh token.
If the resource server provides a scope then the client MUST always If the resource server provides a scope then the client MUST always
request scoped tokens from the token endpoint. If the resource request scoped tokens from the token endpoint. If the resource
server provides no scope to the client then the client SHOULD presume server does not return a scope the client SHOULD presume an empty
an empty scope (unscoped token) is required to access the resource. scope (unscoped token) is required to access the resource.
Since clients may interact with a number of application servers, such Since clients may interact with a number of application servers, such
as email servers and XMPP servers, they need to have a way to as email servers and XMPP [RFC6120] servers, they need to have a way
determine whether dynamic client registration has been performed to determine whether dynamic client registration has been performed
already and whether an already available refresh token can be re-used already and whether an already available refresh token can be re-used
to obtain an access token for the desired resource server. This to obtain an access token for the desired resource server. This
specification RECOMMENDs that a client uses the information in the specification RECOMMENDs that a client uses the information in the
'iss' element defined in OpenID Connect Core [OpenID.Core] to make 'iss' element defined in OpenID Connect Core [OpenID.Core] to make
this determination. this determination.
3.2.3. Completing an Error Message Sequence 3.2.3. Completing an Error Message Sequence
Section 3.6 of SASL [RFC4422] explicitly prohibits additional Section 3.6 of SASL [RFC4422] explicitly prohibits additional
information in an unsuccessful authentication outcome. Therefore, information in an unsuccessful authentication outcome. Therefore,
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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
4. Examples 4. Examples
These examples illustrate exchanges between IMAP and SMTP clients and These examples illustrate exchanges between IMAP and SMTP clients and
servers. All IMAP examples use SASL-IR [RFC4959] and send payload in servers. All IMAP examples use SASL-IR [RFC4959] and send payload in
the initial client response. The Bearer Token examples assume the initial client response. The Bearer Token examples assume
encrypted transport, if the underlying connection is not already TLS encrypted transport; if the underlying connection is not already TLS
then STARTTLS MUST be used as TLS is required in the Bearer Token then STARTTLS MUST be used as TLS is required in the Bearer Token
specification. specification.
Note to implementers: The SASL OAuth method 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".
4.1. Successful Bearer Token Exchange 4.1. Successful Bearer Token Exchange
This example shows a successful OAuth 2.0 bearer token exchange in This example shows a successful OAuth 2.0 bearer token exchange in
IMAP. Note that line breaks are inserted for readability. The IMAP. Note that line breaks are inserted for readability. The
underlying TLS establishment is not shown but is required for using underlying TLS establishment is not shown but is required for using
Bearer Tokens per that specification. Bearer Tokens per that specification.
S: * OK IMAP4rev1 Server Ready S: * OK IMAP4rev1 Server Ready
C: t0 CAPABILITY C: t0 CAPABILITY
S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER SASL-IR S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER SASL-IR
S: t0 OK Completed S: t0 OK Completed
C: t1 AUTH OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20sAWhvc3Q9c2 C: t1 AUTH OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20sAWhvc3Q9c2Vy
VydmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9QmVhcmVyIHZGOWRmdDRxb dmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9QmVhcmVyIHZGOWRmd
VRjMk52YjNSbGNrQmhiSFJoZG1semRHRXVZMjl0Q2c9PQEB DRxbVRjMk52YjNSbGNrQmhiSFJoZG1semRHRXVZMjl0Q2c9PQEB
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:
n,a=user@example.com,^Ahost=server.example.com^Aport=143^A n,a=user@example.com,^Ahost=server.example.com^Aport=143^A
auth=Bearer vF9dft4qmTc2Nvb3RlckBhbHRhdmlzdGEuY29tCg==^A^A auth=Bearer vF9dft4qmTc2Nvb3RlckBhbHRhdmlzdGEuY29tCg==^A^A
The same credential used in an SMTP exchange is shown below. Note The same credential used in an SMTP exchange is shown below. Note
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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-STARTTLS S: 250-STARTTLS
S: 250 PIPELINING S: 250 PIPELINING
[Negotiate TLS...] [Negotiate TLS...]
C: t1 AUTH OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20sAWhvc3Q9c C: t1 AUTH OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20sAWhvc3Q9c2Vy
2VydmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9QmVhcmVyIHZGOWRmdDR dmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9QmVhcmVyIHZGOWRmd
xbVRjMk52YjNSbGNrQmhiSFJoZG1semRHRXVZMjl0Q2c9PQEB DRxbVRjMk52YjNSbGNrQmhiSFJoZG1semRHRXVZMjl0Q2c9PQEB
S: 235 Authentication successful. S: 235 Authentication successful.
[connection continues...] [connection continues...]
4.2. Successful OAuth 1.0a Token Exchange 4.2. Successful OAuth 1.0a Token Exchange
This IMAP example shows a successful OAuth 1.0a token exchange. Note This IMAP example shows a successful OAuth 1.0a token exchange. Note
that line breaks are inserted for readability. This example assumes that line breaks are inserted for readability. This example assumes
that TLS is already established. Signature computation is discussed that TLS is already established. Signature computation is discussed
in Section 3.3. in Section 3.3.
skipping to change at page 14, line 13 skipping to change at page 14, line 13
scope. Note that line breaks are inserted for readability. scope. Note that line breaks are inserted for readability.
S: * OK IMAP4rev1 Server Ready S: * OK IMAP4rev1 Server Ready
C: t0 CAPABILITY C: t0 CAPABILITY
S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER SASL-IR S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER SASL-IR
S: t0 OK Completed S: t0 OK Completed
C: t1 AUTH OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20sAW C: t1 AUTH OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20sAW
hvc3Q9c2VydmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9AQE= hvc3Q9c2VydmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9AQE=
S: + eyJzdGF0dXMiOiJpbnZhbGlkX3Rva2VuIiwic2NvcGUiOiJleGFtcGxl S: + eyJzdGF0dXMiOiJpbnZhbGlkX3Rva2VuIiwic2NvcGUiOiJleGFtcGxl
X3Njb3BlIiwib3BlbmlkLWNvbmZpZ3VyYXRpb24iOiJodHRwczovL2V4 X3Njb3BlIiwib3BlbmlkLWNvbmZpZ3VyYXRpb24iOiJodHRwczovL2V4
YW1wbGUuY29tLy53ZWxsLWtub3duL29wZW5pZC1jb25maWd1cmF0aW9u YW1wbGUuY29tLy53ZWxsLWtub3duL29wZW5pZC1jb25maWcifQ==
In0=
C: AQ== C: AQ==
S: t1 NO SASL authentication failed S: t1 NO SASL authentication failed
The decoded initial client response is: The decoded initial client response is:
n,a=user@example.com,^Ahost=server.example.com^A n,a=user@example.com,^Ahost=server.example.com^A
port=143^Aauth=^A^A port=143^Aauth=^A^A
The decoded server error response is: The decoded server error response is:
{ {
"status":"invalid_token", "status":"invalid_token",
"scope":"example_scope", "scope":"example_scope",
"openid-configuration":"https://example.com/.well-known/openid-configuration" "openid-configuration":"https://example.com/.well-known/openid-config"
} }
The client responds with the required dummy response, "AQ==" is the The client responds with the required dummy response, "AQ==" is the
base64 encoding of the ASCII value 0x01. The same exchange using the base64 encoding of the ASCII value 0x01. The same exchange using the
IMAP specific method of cancelling an AUTHENTICATE command sends "*" IMAP specific method of cancelling an AUTHENTICATE command sends "*"
and is shown below. and is shown below.
S: * OK IMAP4rev1 Server Ready S: * OK IMAP4rev1 Server Ready
C: t0 CAPABILITY C: t0 CAPABILITY
S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER SASL-IR IMAP4rev1 S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER SASL-IR IMAP4rev1
S: t0 OK Completed S: t0 OK Completed
skipping to change at page 15, line 25 skipping to change at page 15, line 19
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 bix1c2VyPXNvbWV1c2VyQGV4YW1wbGUuY29tLAFhdXRoPUJlYXJl C: AUTH OAUTHBEARER bix1c2VyPXNvbWV1c2VyQGV4YW1wbGUuY29tLAFhdXRoPUJlYXJl
ciB2RjlkZnQ0cW1UYzJOdmIzUmxja0JoZEhSaGRtbHpkR0V1WTI5dENnPT0BAQ== ciB2RjlkZnQ0cW1UYzJOdmIzUmxja0JoZEhSaGRtbHpkR0V1WTI5dENnPT0BAQ==
S: 334 eyJzdGF0dXMiOiI0MDEiLCJzY2hlbWVzIjoiYmVhcmVyIG1hYyIsInNjb3BlIjoia S: 334 eyJzdGF0dXMiOiJpbnZhbGlkX3Rva2VuIiwic2NoZW1lcyI6ImJlYXJlciBtYWMiL
HR0cHM6Ly9tYWlsLmdvb2dsZS5jb20vIn0K CJzY29wZSI6Imh0dHBzOi8vbWFpbC5nb29nbGUuY29tLyJ9
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.
5. Security Considerations 5. Security Considerations
OAuth 1.0a and OAuth 2 allows for a variety of deployment scenarios, OAuth 1.0a and OAuth 2 allow for a variety of deployment scenarios,
and the security properties of these profiles vary. As shown in and the security properties of these profiles vary. As shown in
Figure 1 this specification is aimed to be integrated into a larger Figure 1 this specification is aimed to be integrated into a larger
OAuth deployment. Application developers therefore need to OAuth deployment. Application developers therefore need to
understand the needs of their security requirements based on a threat understand their security requirements based on a threat assessment
assessment before selecting a specific SASL OAuth mechanism. For before selecting a specific SASL OAuth mechanism. For OAuth 2.0 a
OAuth 2.0 a detailed security document [RFC6819] provides guidance to detailed security document [RFC6819] provides guidance to select
select those OAuth 2.0 components that help to mitigate threats for a those OAuth 2.0 components that help to mitigate threats for a given
given deployment. For OAuth 1.0a Section 4 of RFC 5849 [RFC5849] deployment. For OAuth 1.0a Section 4 of RFC 5849 [RFC5849] provides
provides guidance specific to OAuth 1.0. guidance specific to OAuth 1.0.
This document specifies two SASL Mechanisms for OAuth and each comes This document specifies two SASL Mechanisms for OAuth and each comes
with different security properties. with different security properties.
OAUTHBEARER: This mechanism borrows from OAuth 2.0 bearer tokens OAUTHBEARER: This mechanism borrows from OAuth 2.0 bearer tokens
[RFC6750]. It relies on the application using TLS to protect the [RFC6750]. It relies on the application using TLS to protect the
OAuth 2.0 Bearer Token exchange; without TLS usage at the OAuth 2.0 Bearer Token exchange; without TLS usage at the
application layer this method is completely insecure. application layer this method is completely insecure.
Consequently, TLS MUST be provided by the application when Consequently, TLS MUST be provided by the application when
choosing this authentication mechanism. choosing this authentication mechanism.
OAUTH10A: This mechanism re-uses OAuth 1.0a MAC tokens (using the OAUTH10A: This mechanism re-uses OAuth 1.0a MAC tokens (using the
HMAC-SHA1 keyed message digest), as described in Section 3.4.2 of HMAC-SHA1 keyed message digest), as described in Section 3.4.2 of
[RFC5849]. To compute the keyed message digest in the same way [RFC5849]. To compute the keyed message digest in the same way as
was in RFC 5839 this specification conveys additional parameters in RFC 5839 this specification conveys additional parameters
between the client and the server. This SASL mechanism only between the client and the server. This SASL mechanism only
supports client authentication. If server-side authentication is supports client authentication. If server-side authentication is
desireable then it must be provided by the application underneath desireable then it must be provided by the application underneath
the SASL layer. The use of TLS is strongly RECOMMENDED. the SASL layer. The use of TLS is strongly RECOMMENDED.
Additionally, the following aspects are worth pointing out: Additionally, the following aspects are worth pointing out:
An access token is not equivalent to the user's long term password. An access token is not equivalent to the user's long term password.
Care has to be taken when these OAuth credentials are used for Care has to be taken when these OAuth credentials are used for
skipping to change at page 18, line 21 skipping to change at page 18, line 12
Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
C. Mortimore, "OpenID Connect Core 1.0", February 2014. C. Mortimore, "OpenID Connect Core 1.0", February 2014.
[OpenID.Discovery] [OpenID.Discovery]
Sakimura, N., Bradley, J., Jones, M., and E. Jay, "OpenID Sakimura, N., Bradley, J., Jones, M., and E. Jay, "OpenID
Connect Discovery 1.0", July 2011. Connect Discovery 1.0", July 2011.
[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.
[RFC2244] Newman, C. and J. Myers, "ACAP -- Application
Configuration Access Protocol", RFC 2244, November 1997.
[RFC3174] Eastlake, D. and P. Jones, "US Secure Hash Algorithm 1
(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.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, October 2006. Encodings", RFC 4648, October 2006.
[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
skipping to change at page 19, line 13 skipping to change at page 18, line 46
Framework: Bearer Token Usage", RFC 6750, October 2012. Framework: Bearer Token Usage", RFC 6750, October 2012.
[RFC7159] Bray, T., "The JavaScript Object Notation (JSON) Data [RFC7159] Bray, T., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, March 2014. Interchange Format", RFC 7159, March 2014.
8.2. Informative References 8.2. Informative References
[I-D.ietf-oauth-dyn-reg] [I-D.ietf-oauth-dyn-reg]
Richer, J., Jones, M., Bradley, J., Machulak, M., and P. Richer, J., Jones, M., Bradley, J., Machulak, M., and P.
Hunt, "OAuth 2.0 Dynamic Client Registration Protocol", Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
draft-ietf-oauth-dyn-reg-22 (work in progress), January draft-ietf-oauth-dyn-reg-27 (work in progress), March
2015. 2015.
[I-D.ietf-oauth-json-web-token] [I-D.ietf-oauth-json-web-token]
Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", draft-ietf-oauth-json-web-token-32 (work in (JWT)", draft-ietf-oauth-json-web-token-32 (work in
progress), December 2014. progress), December 2014.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[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.
[RFC4959] Siemborski, R. and A. Gulbrandsen, "IMAP Extension for [RFC4959] Siemborski, R. and A. Gulbrandsen, "IMAP Extension for
Simple Authentication and Security Layer (SASL) Initial Simple Authentication and Security Layer (SASL) Initial
Client Response", RFC 4959, September 2007. Client Response", RFC 4959, September 2007.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, [RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008. October 2008.
[RFC6120] Saint-Andre, P., "Extensible Messaging and Presence [RFC6120] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", RFC 6120, March 2011. Protocol (XMPP): Core", RFC 6120, March 2011.
[RFC6819] Lodderstedt, T., McGloin, M., and P. Hunt, "OAuth 2.0 [RFC6819] Lodderstedt, T., McGloin, M., and P. Hunt, "OAuth 2.0
Threat Model and Security Considerations", RFC 6819, Threat Model and Security Considerations", RFC 6819,
January 2013. January 2013.
[RFC7033] Jones, P., Salgueiro, G., Jones, M., and J. Smarr, [RFC7033] Jones, P., Salgueiro, G., Jones, M., and J. Smarr,
"WebFinger", RFC 7033, September 2013. "WebFinger", RFC 7033, September 2013.
[RFC7230] Fielding, R. and J. Reschke, "Hypertext Transfer Protocol
(HTTP/1.1): Message Syntax and Routing", RFC 7230, June
2014.
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, Alexey Melnikov, Jeffrey Hutzelman, Nico Lodderstadt, Ryan Troll, Alexey Melnikov, Jeffrey Hutzelman, Nico
Williams, Matt Miller, and Benjamin Kaduk. Williams, Matt Miller, and Benjamin Kaduk.
This document was produced under the chairmanship of Alexey Melnikov, This document was produced under the chairmanship of Alexey Melnikov,
Tom Yu, Shawn Emery, Josh Howlett, Sam Hartman. The supervising area Tom Yu, Shawn Emery, Josh Howlett, Sam Hartman. The supervising area
director was Stephen Farrell. director was Stephen Farrell.
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