draft-ietf-kitten-sasl-oauth-22.txt   draft-ietf-kitten-sasl-oauth-23.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: November 1, 2015 Expires: November 30, 2015
H. Tschofenig H. Tschofenig
ARM Ltd. ARM Ltd.
April 30, 2015 May 29, 2015
A set of SASL Mechanisms for OAuth A set of SASL Mechanisms for OAuth
draft-ietf-kitten-sasl-oauth-22.txt draft-ietf-kitten-sasl-oauth-23.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 November 1, 2015. This Internet-Draft will expire on November 30, 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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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. OAuth SASL Mechanism Specifications . . . . . . . . . . . . . 6 3. OAuth SASL Mechanism Specifications . . . . . . . . . . . . . 6
3.1. Initial Client Response . . . . . . . . . . . . . . . . . 7 3.1. Initial Client Response . . . . . . . . . . . . . . . . . 7
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 . . . . . . . . 11
3.3. OAuth Access Token Types using Keyed Message Digests . . 11 3.3. OAuth Access Token Types using Keyed Message Digests . . 11
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 12 4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 12
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 . . . . . . . . . . . . . . . . . . . . . 14 4.3. Failed Exchange . . . . . . . . . . . . . . . . . . . . . 14
4.4. SMTP Example of a Failed Negotiation . . . . . . . . . . 15 4.4. SMTP Example of a Failed Negotiation . . . . . . . . . . 15
5. Security Considerations . . . . . . . . . . . . . . . . . . . 16 5. Security Considerations . . . . . . . . . . . . . . . . . . . 16
6. Internationalization Considerations . . . . . . . . . . . . . 17 6. Internationalization Considerations . . . . . . . . . . . . . 17
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
7.1. SASL Registration . . . . . . . . . . . . . . . . . . . . 17 7.1. SASL Registration . . . . . . . . . . . . . . . . . . . . 18
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1. Normative References . . . . . . . . . . . . . . . . . . 18 8.1. Normative References . . . . . . . . . . . . . . . . . . 18
8.2. Informative References . . . . . . . . . . . . . . . . . 19 8.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. Acknowlegements . . . . . . . . . . . . . . . . . . 20 Appendix A. Acknowlegements . . . . . . . . . . . . . . . . . . 20
Appendix B. Document History . . . . . . . . . . . . . . . . . . 20 Appendix B. Document History . . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
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.
The core OAuth 2.0 specification [RFC6749] specifies the interaction The core OAuth 2.0 specification [RFC6749] specifies the interaction
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[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 [RFC7230] 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. This document gives examples of use in IMAP and SMTP.
To illustrate the impact of integrating this specification into an To illustrate the impact of integrating this specification into an
OAuth-enabled application environment, Figure 1 shows the abstract OAuth-enabled application environment, Figure 1 shows the abstract
message flow of OAuth 2.0 [RFC6749]. As indicated in the figure, message flow of OAuth 2.0 [RFC6749]. As indicated in the figure,
this document impacts the exchange of messages (E) and (F) since SASL this document impacts the exchange of messages (E) and (F) since SASL
is used for interaction between the client and the resource server is used for interaction between the client and the resource server
instead of HTTP. instead of HTTP.
----+ ----+
+--------+ +---------------+ | +--------+ +---------------+ |
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existing authentication mechanisms 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 indirectly via the authorization server as an
server as an intermediary. intermediary.
(B) The client receives an authorization grant which is a (B) The client receives an authorization grant which is a
credential representing the resource owner's authorization, credential representing the resource owner's authorization,
expressed using one of the grant types defined in [RFC6749] or expressed using one of the grant types defined in [RFC6749] or
[RFC5849] or using an extension grant type. The authorization [RFC5849] or using an extension grant type. The authorization
grant type depends on the method used by the client to request grant type depends on the method used by the client to request
authorization and the types supported by the authorization server. authorization and the types supported by the authorization server.
(C) The client requests an access token by authenticating with the (C) The client requests an access token by authenticating with the
authorization server and presenting the authorization grant. authorization server and presenting the authorization grant.
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [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, as
Section 4 of [RFC4648], not this memo. specified in Section 4 of [RFC4648].
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) [RFC5246] to RFC 6750 uses Transport Layer Security (TLS) [RFC5246] to
secure the protocol interaction between the client and the secure the protocol interaction between the client and the
resource 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 registering
registering the new name(s) and citing this specification for the the new name(s) with IANA in the SASL Mechanisms registry and citing
further definition. this specification for the further definition.
SASL mechanisms using this document as their definition do not SASL mechanisms using this document as their definition do not
provide a data security layer; that is, they cannot provide integrity provide a data security layer; that is, they cannot provide integrity
or confidentiality protection for application messages after the or confidentiality protection for application messages after the
initial authentication. If such protection is needed, TLS or some initial authentication. If such protection is needed, TLS or some
similar solution should be used. Additionally, for the two similar solution should be used. Additionally, for the two
mechanisms specified in this document, TLS MUST be used for mechanisms specified in this document, TLS MUST be used for
OAUTHBEARER to protect the bearer token; for OAUTH10A the use of TLS OAUTHBEARER to protect the bearer token; for OAUTH10A the use of TLS
is RECOMMENDED. is RECOMMENDED.
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The following keys and corresponding values are defined in the client The following keys and corresponding values are defined in the client
response: response:
auth (REQUIRED): The payload that would be in the HTTP auth (REQUIRED): The payload that would be in the HTTP
Authorization header if this OAuth exchange was being carried Authorization header if this OAuth exchange was being carried
out over HTTP. out over HTTP.
host: Contains the host name to which the client connected. In host: Contains the host name to which the client connected. In
an HTTP context this is the value of the HTTP Host header. an HTTP context this is the value of the HTTP Host header.
port: Contains the port number represented as a decimal positive port: Contains the destination port that the client connected to,
integer string without leading zeros to which the client represented as a decimal positive integer string without
connected. leading zeros.
For OAuth token types such as OAuth 1.0a that use keyed message For OAuth token types such as OAuth 1.0a that use keyed message
digests the client MUST send host and port number key/values, and the digests the client MUST send host and port number key/values, and the
server MUST fail an authorization request requiring keyed message server MUST fail an authorization request requiring keyed message
digests that are not accompanied by host and port values. In OAuth digests that are not accompanied by host and port values. In OAuth
1.0a for example, the so-called "signature base string calculation" 1.0a for example, the so-called "signature base string calculation"
includes the reconstructed HTTP URL. includes the reconstructed HTTP URL.
3.1.1. Reserved Key/Values 3.1.1. Reserved Key/Values
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usage of these in the SASL context and extend this specification. usage of these in the SASL context and extend this specification.
For OAuth Access Token Types that include a keyed message digest of For OAuth Access Token Types that include a keyed message digest of
the request the default values MUST be used unless explicit values the request the default values MUST be used unless explicit values
are provided in the client response. The following key values are are provided in the client response. The following key values are
reserved for future use: reserved for future use:
mthd (RESERVED): HTTP method, the default value is "POST". mthd (RESERVED): HTTP method, the default 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 the empty
string ("").
qs (RESERVED): The HTTP query string, the default value is "". qs (RESERVED): The HTTP query string, the default value is the
empty string ("").
3.2. Server's Response 3.2. Server's Response
The server validates the response according the specification for the The server validates the response according to the specification for
OAuth Access Token Types used. If the OAuth Access Token Type the OAuth Access Token Types used. If the OAuth Access Token Type
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 fully validates the client response before generating a The server fully validates the client response before generating a
server response; this will necessarily include the validation steps server response; this will necessarily include the validation steps
listed in the specification for the OAuth Access Token Type used. listed in the specification for the OAuth Access Token Type used.
However, additional validation steps may be needed, depending on the However, additional validation steps may be needed, depending on the
particular application protocol making use of SASL. In particular, particular application protocol making use of SASL. In particular,
values included as kvpairs in the client response (such as host and values included as kvpairs in the client response (such as host and
port) which correspond to values known to the application by some port) which correspond to values known to the application server by
other mechanism (such as an application protocol data unit or pre- some other mechanism (such as an application protocol data unit or
configured values) MUST be validated to match between the initial pre-configured values) MUST be validated to match between the initial
client response and the the other source(s) of such information. As client response and the the other source(s) of such information. As
a concrete example, when SASL is used over IMAP to an IMAP server for a concrete example, when SASL is used over IMAP to an IMAP server for
a single domain the hostname can be vaialble via configuration; this a single domain the hostname can be available via configuration; this
hostname must be validated to match the value sent in the 'host' hostname must be validated to match the value sent in the 'host'
kvpair. kvpair.
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 authzid is specified by the resource. Note that the semantics of the authzid is specified by the
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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 omitted which implies that unscoped service. This may be omitted which implies that unscoped
tokens are required. If a scope is specified then a single tokens are required. If a scope is specified then a single
scope is preferred, use of a space separated list of scopes is scope is preferred. At the time this document was written
NOT RECOMMENDED. there are several implementations that do not properly support
space separated lists of scopes, so the use of a space
separated list of scopes is 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
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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.
underlying TLS establishment is not shown but is required for using
Bearer Tokens per that specification.
[Initial connection and TLS establishment...]
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 bixhPXVzZXJAZXhhbXBsZS5jb20sAWhvc3Q9c2Vy C: t1 AUTH OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20sAWhvc3Q9c2Vy
dmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9QmVhcmVyIHZGOWRmd dmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9QmVhcmVyIHZGOWRmd
DRxbVRjMk52YjNSbGNrQmhiSFJoZG1semRHRXVZMjl0Q2c9PQEB 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. Again
The same credential used in an SMTP exchange is shown below. Note this example assumes that TLS is already established per the Bearer
that line breaks are inserted for readability, and that the SMTP Token specification requirements.
protocol terminates lines with CR and LF characters (ASCII values
0x0D and 0x0A), these are not displayed explicitly in the example.
Again this example assumes that TLS is already established per the
Bearer Token specification requirements.
[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-STARTTLS S: 250-STARTTLS
S: 250 PIPELINING S: 250 PIPELINING
[Negotiate TLS...] [Negotiate TLS...]
C: t1 AUTH OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20sAWhvc3Q9c2Vy C: t1 AUTH OAUTHBEARER bixhPXVzZXJAZXhhbXBsZS5jb20sAWhvc3Q9c2Vy
dmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9QmVhcmVyIHZGOWRmd dmVyLmV4YW1wbGUuY29tAXBvcnQ9NTg3AWF1dGg9QmVhcmVyIHZGOWRmd
DRxbVRjMk52YjNSbGNrQmhiSFJoZG1semRHRXVZMjl0Q2c9PQEB DRxbVRjMk52YjNSbGNrQmhiSFJoZG1semRHRXVZMjl0Q2c9PQEB
S: 235 Authentication successful. S: 235 Authentication successful.
[connection continues...] [connection continues...]
The decoded initial client response is:
n,a=user@example.com,^Ahost=server.example.com^Aport=587^A
auth=Bearer vF9dft4qmTc2Nvb3RlckBhbHRhdmlzdGEuY29tCg==^A^A
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.
S: * OK IMAP4rev1 Server Ready S: * OK IMAP4rev1 Server Ready
C: t0 CAPABILITY C: t0 CAPABILITY
S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER OAUTH10A SASL-IR S: * CAPABILITY IMAP4rev1 AUTH=OAUTHBEARER OAUTH10A SASL-IR
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hvc3Q9c2VydmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9AQE= hvc3Q9c2VydmVyLmV4YW1wbGUuY29tAXBvcnQ9MTQzAWF1dGg9AQE=
S: + eyJzdGF0dXMiOiJpbnZhbGlkX3Rva2VuIiwic2NvcGUiOiJleGFtcGxl S: + eyJzdGF0dXMiOiJpbnZhbGlkX3Rva2VuIiwic2NvcGUiOiJleGFtcGxl
X3Njb3BlIiwib3BlbmlkLWNvbmZpZ3VyYXRpb24iOiJodHRwczovL2V4 X3Njb3BlIiwib3BlbmlkLWNvbmZpZ3VyYXRpb24iOiJodHRwczovL2V4
YW1wbGUuY29tLy53ZWxsLWtub3duL29wZW5pZC1jb25maWd1cmF0aW9u YW1wbGUuY29tLy53ZWxsLWtub3duL29wZW5pZC1jb25maWd1cmF0aW9u
In0= In0=
C: * C: *
S: t1 NO SASL authentication failed S: t1 NO SASL authentication failed
4.4. SMTP Example of a Failed Negotiation 4.4. 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. TLS
Note that line breaks are inserted for readability, and that the SMTP negotiation is not shown but as noted above it is required for the
protocol terminates lines with CR and LF characters (ASCII values use of Bearer Tokens.
0x0D and 0x0A), these are not displayed explicitly in the example.
TLS negotiation is not shown but as noted above it is required for
the use of Bearer Tokens.
[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
[Negotiate TLS...]
C: AUTH OAUTHBEARER bix1c2VyPXNvbWV1c2VyQGV4YW1wbGUuY29tLAFhdXRoPUJlYXJl C: AUTH OAUTHBEARER bix1c2VyPXNvbWV1c2VyQGV4YW1wbGUuY29tLAFhdXRoPUJlYXJl
ciB2RjlkZnQ0cW1UYzJOdmIzUmxja0JoZEhSaGRtbHpkR0V1WTI5dENnPT0BAQ== ciB2RjlkZnQ0cW1UYzJOdmIzUmxja0JoZEhSaGRtbHpkR0V1WTI5dENnPT0BAQ==
S: 334 eyJzdGF0dXMiOiJpbnZhbGlkX3Rva2VuIiwic2NoZW1lcyI6ImJlYXJlciBtYWMiL S: 334 eyJzdGF0dXMiOiJpbnZhbGlkX3Rva2VuIiwic2NoZW1lcyI6ImJlYXJlciBtYWMiL
CJzY29wZSI6Imh0dHBzOi8vbWFpbC5nb29nbGUuY29tLyJ9 CJzY29wZSI6Imh0dHBzOi8vbWFpbC5leGFtcGxlLmNvbS8ifQ==
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 initial client response is:
n,user=someuser@example.com,^A
auth=Bearer vF9dft4qmTc2Nvb3RlckBhdHRhdmlzdGEuY29tCg==^A^A
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.
{
"status":"invalid_token",
"schemes":"bearer mac",
"scope":"https://mail.example.com/"
}
5. Security Considerations 5. Security Considerations
OAuth 1.0a and OAuth 2 allow 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 their security requirements based on a threat assessment understand their security requirements based on a threat assessment
before selecting a specific SASL OAuth mechanism. For OAuth 2.0 a before selecting a specific SASL OAuth mechanism. For OAuth 2.0 a
detailed security document [RFC6819] provides guidance to select detailed security document [RFC6819] provides guidance to select
those OAuth 2.0 components that help to mitigate threats for a given those OAuth 2.0 components that help to mitigate threats for a given
skipping to change at page 16, line 47 skipping to change at page 17, line 8
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
actions like changing passwords (as it is possible with some actions like changing passwords (as it is possible with some
protocols, e.g., XMPP [RFC6120]). The resource server should protocols, e.g., XMPP [RFC6120]). The resource server should
ensure that actions taken in the authenticated channel are ensure that actions taken in the authenticated channel are
appropriate to the strength of the presented credential. appropriate to the strength of the presented credential.
Lifetime of the appliation sessions. Lifetime of the application sessions.
It is possible that SASL will be authenticating a connection and It is possible that SASL will be used to authenticate a connection
the life of that connection may outlast the life of the access and the life of that connection may outlast the life of the access
token used to establish it. This is a common problem in token used to establish it. This is a common problem in
application protocols where connections are long-lived, and not a application protocols where connections are long-lived, and not a
problem with this mechanism per se. Resource servers may problem with this mechanism per se. Resource servers may
unilaterally disconnect clients in accordance with the application unilaterally disconnect clients in accordance with the application
protocol. protocol.
Access tokens have a lifetime. Access tokens have a lifetime.
Reducing the lifetime of an access token provides security Reducing the lifetime of an access token provides security
benefits and OAuth 2.0 introduces refresh tokens to obtain new benefits and OAuth 2.0 introduces refresh tokens to obtain new
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Intended usage: common Intended usage: common
Owner/Change controller: the IESG Owner/Change controller: the IESG
Note: None Note: None
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-oauth-dyn-reg]
Richer, J., Jones, M., Bradley, J., Machulak, M., and P.
Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
draft-ietf-oauth-dyn-reg-27 (work in progress), March
2015.
[OpenID.Core] [OpenID.Core]
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.
skipping to change at page 19, line 24 skipping to change at page 19, line 47
6749, October 2012. 6749, October 2012.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization [RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
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]
Richer, J., Jones, M., Bradley, J., Machulak, M., and P.
Hunt, "OAuth 2.0 Dynamic Client Registration Protocol",
draft-ietf-oauth-dyn-reg-27 (work in progress), March
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.
[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
skipping to change at page 20, line 27 skipping to change at page 20, line 44
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.
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 ]]
-23
o AD feedback from IESG review and comments.
o Fixed port number in SMTP examples.
o Minor editorial changes.
o Dyn-Reg draft becomes normative.
o Added explicit TLS start indicator in all examples, removed text
that said we assume that.
-19 -19
o Last call feedback agaiun. o Last call feedback agaiun.
o Clarified usage of TLS in examples and fixed them some more. o Clarified usage of TLS in examples and fixed them some more.
Adding reference to RFC4422 and cancellation token and an example Adding reference to RFC4422 and cancellation token and an example
for that. for that.
-18 -18
 End of changes. 33 change blocks. 
56 lines changed or deleted 81 lines changed or added

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