OAuth 2.0 Token ExchangeMicrosoftmbj@microsoft.comhttp://self-issued.info/Microsofttonynad@microsoft.comPing Identitybrian.d.campbell@gmail.comPing Identityve7jtb@ve7jtb.comSalesforcecmortimore@salesforce.com
Security
OAuth Working GroupRFCRequest for CommentsI-DInternet-DraftJSON Web TokenJWTDelegationImpersonationSTSSecurity Token ServiceExchangeTokenOAuth
This specification defines a protocol for an HTTP- and JSON- based
Security Token Service (STS) by defining how to request and obtain
security tokens from OAuth 2.0 authorization servers,
including security tokens employing impersonation and delegation.
A security token is a set of information that facilitates
the sharing of identity and security information in heterogeneous environments or across security domains.
Examples of security tokens include
JSON Web Tokens (JWTs) and
SAML Assertions .
Security tokens are typically signed to achieve integrity
and sometimes also encrypted to achieve confidentiality.
Security tokens are also sometimes described as Assertions, such as in
.
A Security Token Service (STS) is a service capable of validating and issuing
security tokens, which enables clients to obtain appropriate
access credentials for resources in heterogeneous environments or across security
domains.
Web Service clients have used WS-Trust
as the protocol to interact with an STS for token exchange.
While WS-Trust
uses XML and SOAP, the trend in modern Web development
has been towards RESTful patterns and JSON.
The OAuth 2.0 Authorization Framework
and OAuth 2.0 Bearer Tokens
have emerged as popular standards for authorizing and securing access to HTTP and
RESTful resources but do not provide everything necessary to facilitate
token exchange interactions.
This specification defines a protocol extending OAuth 2.0 that enables
clients to request and obtain security tokens from authorization servers acting in
the role of an STS.
Similar to OAuth 2.0, this specification focuses on client developer simplicity and
requires only an HTTP client and JSON parser, which are nearly universally available
in modern development environments. The STS protocol defined in this specification
is not itself RESTful (an STS doesn't lend itself particularly well to a REST
approach) but does utilize communication patterns and data formats that should be
familiar to developers accustomed to working with RESTful systems.
A new grant type for a token exchange request and the associated specific parameters for
such a request to the token endpoint are defined by this specification.
A token exchange response is a normal OAuth 2.0 response from the token endpoint
with a few additional parameters defined herein to provide information to the client.
The entity that makes the request to exchange tokens is considered the client in the
context of the token exchange interaction. However, that does not restrict
usage of this profile to traditional OAuth clients. An OAuth resource server, for example,
might assume the role of the client during token exchange in order to trade an access token,
which it received in a protected resource request, for a new token that is appropriate to include in a
call to a backend service. The new token might be an access token that is more
narrowly scoped for the downstream service or it could be an entirely different kind
of token.
The scope of this specification is limited to the definition of a
basic request and response protocol for an STS-style token exchange utilizing OAuth 2.0.
Although a few new JWT claims are defined that enable delegation semantics to be expressed,
the specific syntax, semantics and security characteristics of the tokens themselves
(both those presented to the AS and those obtained by the client)
are explicitly out of scope and no requirements are placed on the trust model in
which an implementation might be deployed. Additional profiles may provide
more detailed requirements around the specific nature of the parties and trust involved,
such as whether signing and/or encryption of tokens is needed or if proof-of-possession style
tokens will be required or issued; however, such details
will often be policy decisions made with respect to the specific needs of individual
deployments and will be configured or implemented accordingly.
The security tokens obtained may be used in a number of contexts,
the specifics of which are also beyond the scope of this specification.
When principal A impersonates principal B, A is given all
the rights that B has within some defined rights context
and is indistinguishable from B in that context.
Thus, when principal A impersonates principal B, then in
so far as any entity receiving such a token is concerned, they are
actually dealing with B. It is true that some members of the
identity system might have awareness that impersonation is
going on, but it is not a requirement. For all intents and
purposes, when A is impersonating B, A is B.
Delegation semantics are different than
impersonation semantics, though the two are closely related.
With delegation semantics, principal A still has its own identity
separate from B and it is explicitly understood that while B
may have delegated some of its rights to A, any actions taken are
being taken by A representing B. In a sense, A is an agent for B.
Delegation and impersonation are not inclusive of all situations.
When a principal is acting directly on its own behalf, for example,
neither delegation nor impersonation are in play. They are, however,
the more common semantics operating for token exchange and, as such, are
given more direct treatment in this specification.
Delegation semantics are typically expressed in a token by including information about both the
primary subject of the token as well as the actor to whom that subject has delegated some of its rights.
Such a token is sometimes referred to as a composite token because it is composed of information
about multiple subjects. Typically, in the request, the subject_token
represents the identity of the party on
behalf of whom the token is being requested while the actor_token represents
the identity of the party to whom the access rights of the issued token are being delegated.
A composite token issued by the authorization server will contain information about both parties.
When and if a composite token is issued is at the discretion of the authorization server and
applicable policy and configuration.
The specifics of representing a composite token and even whether or not such a token will be issued depend on the details of the implementation and the kind of token.
The representations of composite tokens that are not JWTs are beyond the scope of this specification.
The actor_token request parameter, however, does provide a means
for providing information about the desired actor and the JWT act claim
can provide a representation of a chain of delegation.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL"
in this document are to be interpreted as described in
RFC 2119.
This specification uses the terms
"access token type", "authorization server", "client", "client identifier",
"resource server", "token endpoint", "token request", and "token response"
defined by OAuth 2.0,
and the terms "Claim" and "JWT Claims Set" defined by
JSON Web Token (JWT).
A client requests a security token by making a token request to the authorization
server's token endpoint using the extension grant type mechanism defined
in Section 4.5 of OAuth 2.0.
Client authentication to the authorization server is done using the normal
mechanisms provided by OAuth 2.0.
Section 2.3.1 of The OAuth 2.0 Authorization Framework
defines password-based authentication of the client,
however, client authentication is extensible and other mechanisms are possible.
For example, defines client authentication using
JSON Web Tokens (JWTs) .
The supported methods of client authentication and whether or not to allow
unauthenticated or unidentified clients are deployment decisions that are
at the discretion of the authorization server.
The client makes a token exchange request to the token endpoint with an extension
grant type by including the
following parameters using the application/x-www-form-urlencoded
format with a character encoding of UTF-8 in the HTTP request entity-body:
REQUIRED. The value
urn:ietf:params:oauth:grant-type:token-exchange
indicates that a token exchange is being performed.
OPTIONAL.
Indicates the physical location of the target service or resource where the client intends to use
the requested security token. This enables the authorization server to apply policy as appropriate
for the target, such as determining the type and content of the token to be issued or if and how
the token is to be encrypted.
In many cases, a client will not have knowledge of the logical organization of the systems with
which it interacts and will only know the location of the service where it intends to use the token.
The resource parameter allows the client to indicate to the authorization server
where it intends to use the issued token by providing the location, typically as an https URL, in the
token exchange request in the same form that will be used to access that resource.
The authorization server will typically have the capability to map from a resource URI value to
an appropriate policy. The value of the resource parameter MUST be an
absolute URI, as specified by Section 4.3 of ,
which MAY include a query component and MUST NOT include a fragment component.
Multiple resource parameters may be used to indicate
that the issued token is intended to be used at the multiple resources listed.
OPTIONAL.
The logical name of the target service where the client intends to use
the requested security token. This serves a purpose similar to the
resource parameter, but with the client providing a logical name
rather than a physical location. Interpretation of the name requires that the value be something
that both the client and the authorization server understand. An OAuth client identifier,
a SAML entity identifier ,
an OpenID Connect Issuer Identifier ,
or a URI are examples of things that
might be used as audience parameter values.
Multiple audience parameters may be used to indicate
that the issued token is intended to be used at the multiple audiences listed.
The audience and resource parameters may
be used together to indicate multiple target services with a mix of logical names and physical locations.
OPTIONAL.
A list of space-delimited, case-sensitive strings that allow the client to
specify the desired scope of the requested security token in the context of the
service or resource where the token will be used.
OPTIONAL.
An identifier, as described in , for the type of the requested security token.
If the requested type is unspecified, the issued token type is at
the discretion of the authorization server and may be dictated by
knowledge of the requirements of the service or resource
indicated by the resource or
audience parameter.
REQUIRED.
A security token that represents the
identity of the party on behalf of whom the request is being made.
Typically, the subject of this token will be the subject of
the security token issued in response to this request.
REQUIRED.
An identifier, as described in , that indicates the type of the security token in
the subject_token parameter.
OPTIONAL.
A security token that represents
the identity of the acting party. Typically this will be the party that is authorized to use the requested security token and act on behalf of the subject.
An identifier, as described in , that indicates the type of the security token in the
actor_token parameter.
This is REQUIRED when the actor_token parameter
is present in the request but MUST NOT be included otherwise.
In the absence of one-time-use or other semantics specific to the token type, the act of performing
a token exchange has no impact on the validity of the subject token or actor token.
Furthermore, the validity of the subject token or actor token have no impact on the
validity of the issued token after the exchange has occurred.
When requesting a token, the client can indicate the desired target service(s)
where it intends to use that token
by way of the audience and resource
parameters, as well as indicating the
desired scope of the requested token using the scope parameter.
The semantics of such a request are that the client is asking for a token with the requested
scope that is usable at all the requested target services. Effectively, the requested access rights of
the token are the cartesian product of all the scopes at all the target services.
An authorization server may be unwilling or unable to fulfill any token request but the likelihood
of an unfulfillable request is significantly higher when very broad access rights are being solicited.
As such, in the absence of specific knowledge about the relationship of systems in a deployment,
clients should exercise discretion in the breadth of the access requested, particularly the
number of target services. An authorization server can use the invalid_target
error code, defined in , to inform a client that it requested access to
too many target services simultaneously.
The authorization server responds to a token exchange request with a normal
OAuth 2.0 response from the token endpoint, as specified in
Section 5 of . Additional details and
explanation are provided in the following subsections.
If the request is valid and meets all policy and other criteria of the authorization server,
a successful token response is constructed by adding the following parameters
to the entity-body of the HTTP response using the "application/json"
media type, as specified by , and an HTTP 200 status code. The
parameters are serialized into a JavaScript Object Notation (JSON)
structure by adding each parameter at the top level.
Parameter names and string values are included as JSON strings.
Numerical values are included as JSON numbers. The order of
parameters does not matter and can vary.
REQUIRED. The security token issued by the authorization server in response
to the token exchange request.
The access_token parameter from
Section 5.1 of is used here to carry the requested
token, which allows this token exchange protocol to use the existing OAuth 2.0 request
and response constructs defined for the token endpoint.
The identifier access_token is used for historical
reasons and the issued token need not be an OAuth access token.
REQUIRED. An identifier, as described in ,
for the representation of the issued security token.
REQUIRED.
A case-insensitive value specifying the method of using of the access token issued,
as specified in Section 7.1 of .
It provides the client
with information about how to utilize the access token to access protected resources.
For example, a value of Bearer,
as specified in , indicates that
the security token is a bearer token and the client can simply present it as is without any
additional proof of eligibility beyond the contents of the token itself.
Note that the meaning of this parameter is different from the meaning of
the issued_token_type parameter,
which declares the representation of the issued security token;
the term "token type" is typically used with this meaning, as it is in
all *_token_type parameters in this specification.
If the issued token is not an access token or usable as an access token,
then the token_type value N_A is used
to indicate that an OAuth 2.0
token_type identifier is not applicable in that context.
RECOMMENDED. The validity lifetime, in seconds, of the token issued by the
authorization server. Oftentimes the client will not have the inclination or capability
to inspect the content of the token and this parameter provides a consistent and token type
agnostic indication of how long the token can be expected to be valid.
For example, the value 1800 denotes that the token will
expire in thirty minutes from the time the response was generated.
OPTIONAL, if the scope of the issued security token is identical to the scope requested by the client;
otherwise, REQUIRED.
OPTIONAL.
A refresh token will typically not be issued when the the exchange is of one temporary
credential (the subject_token) for a different temporary credential (the issued token)
for use in some other context.
A refresh token can be issued in cases where the client of the token exchange needs the
ability to access a resource even when the original credential is no longer valid
(e.g. user-not-present or offline scenarios where there is no longer any user entertaining
an active session with the client).
Profiles or deployments of this specification should clearly document the conditions
under which a client should expect a refresh token in response to
urn:ietf:params:oauth:grant-type:token-exchange
grant type requests.
If either the subject_token or actor_token
are invalid for any reason, or are unacceptable based on policy, the authorization server
MUST construct an error response, as specified in Section 5.2 of .
The value of the error
parameter MUST be the invalid_request error code.
If the authorization server is unwilling or unable to issue a token for all the target services
indicated by the resource or audience parameters,
the invalid_target error code SHOULD be used in the error response.
The authorization
server MAY include additional information regarding the reasons for the error
using the error_description and/or error_uri parameters.
Other error codes may also be used, as appropriate.
The following example demonstrates a hypothetical token exchange in which
an OAuth resource server
assumes the role of the client during token exchange in order to
trade an access token that it received in a protected resource request for a
token that it will use to call to a backend service
(extra line breaks and indentation in the examples are for display purposes only).
The resource server receives the following request containing
an OAuth access token in the Authorization request header, as specified in
Section 2.1 of .
The resource server assumes the role of the client for the token exchange
and the access token from the request above is sent
to the authorization
server using a request as specified in .
The value of the subject_token parameter carries the
access token and the value of
the subject_token_type parameter indicates that it is
an OAuth 2.0 access token.
The resource server, acting in the roll of the client, uses its identifier and secret to authenticate to
the authorization server using the HTTP Basic authentication scheme.
The resource parameter indicates the location
of the backend service, https://backend.example.com/api,
where the issued token will be used.
The authorization server validates the client credentials and the
subject_token presented in the token
exchange request. From the resource
parameter, the authorization server is able to determine the
appropriate policy to apply to the request and issues a token
suitable for use at https://backend.example.com.
The access_token parameter of the
response contains the new token, which is itself a bearer OAuth
access token that is valid for one minute. The token happens to be
a JWT; however, its structure and format are opaque to
the client so the issued_token_type
indicates only that it is an access token.
The resource server can then use the newly acquired access token in making
a request to the backend server.
Additional examples can be found in .
Several parameters in this specification utilize an identifier as the value to
describe the token in question.
Specifically, they are the
requested_token_type,
subject_token_type, actor_token_type
parameters of the request and the issued_token_type member of the response.
Token type identifiers are URIs.
Token Exchange can work with both tokens issued by other parties and tokens from
the given authorization server. For the former the token type identifier indicates
the syntax (e.g. JWT or SAML) so the AS can parse it; for the latter it indicates
what the AS issued it for (e.g. access_token or refresh_token).
This specification defines the token type identifiers
urn:ietf:params:oauth:token-type:access_token and
urn:ietf:params:oauth:token-type:refresh_token to indicate
that the token is an OAuth 2.0 access token or refresh token, respectively.
The value urn:ietf:params:oauth:token-type:jwt defined in
Section 9 of indicates that the token is a JWT.
This specification also defines the token type identifier
urn:ietf:params:oauth:token-type:id_token to indicate
that the token is an ID Token, as defined in Section 2 of .
Other URIs to indicate other token types MAY be used.
The distinction between an access token and a JWT is subtle.
An access token represents a delegated authorization decision, whereas JWT is a token format.
An access token can be formatted as a JWT but doesn't necessarily have to be. And a
JWT might well be an access token but not all JWTs are access tokens.
The intent of this specification is that urn:ietf:params:oauth:token-type:access_token
be an indicator that the token is a typical OAuth access token issued by the authorization server in question, opaque to the client,
and usable the same manner as any other access token obtained from that authorization server
(it could well be a JWT but the client isn't and needn't be aware of that fact).
Whereas urn:ietf:params:oauth:token-type:jwt is to indicate specifically that a JWT is
being requested or sent (perhaps in a cross-domain use-case where the JWT is used as an authorization grant to
obtain an access token from a different authorization server as is facilitated by ).
It is useful to have defined mechanisms to express delegation within a token as well as to express
authorization to delegate or impersonate. Although the token exchange protocol described
herein can be used with any type of token, this section defines claims to express such
semantics specifically for JWTs and in an OAuth 2.0 Token Introspection response.
Similar definitions for other types of tokens are possible but
beyond the scope of this specification.
The act (actor) claim provides a means within a JWT
to express that delegation has occurred and identify the acting party to whom authority has been delegated.
The act claim value is a JSON object and
members in the JSON object are claims that identify the actor.
The claims that make up the act
claim identify and possibly provide additional information about the actor.
For example, the combination of the two claims iss
and sub might be necessary to uniquely identify an actor.
However, claims within the act claim pertain only to the identity of the actor
and are not relevant to the validity of the containing JWT in the same manner as the top-level claims.
Consequently, non-identity claims (e.g. exp, nbf,
and aud) are not meaningful when used within an
act claim, and therefore must not be used.
A chain of delegation can be expressed by nesting one act claim within
another. The outermost act claim represents the current actor while nested
act claims represent prior actors. The least recent actor is the most deeply
nested.
When included as a top-level member of an OAuth token introspection response, act
has the same semantics and format as the the claim of the same name.
The scp claim is an array of strings, each of which
represents an OAuth scope granted for the issued security token.
Each array entry of the claim value is a scope-token, as defined in
Section 3.3 of OAuth 2.0.
OAuth 2.0 Token Introspection defines the scope
parameter to convey the scopes associated with the token.
The cid claim carries the
client identifier of the OAuth 2.0 client that
requested the token.
OAuth 2.0 Token Introspection defines the client_id
parameter as the client identifier for the OAuth 2.0 client that requested the token.
The may_act claim makes a statement that one party is authorized to
become the actor and act on behalf of another party.
The claim value is a JSON object and members in the JSON object are claims that identify the party that
is asserted as being eligible to act for the party identified by
the JWT containing the claim.
The claims that make up the may_act
claim identify and possibly provide additional information about the authorized actor.
For example, the combination of the two claims iss
and sub are sometimes necessary to uniquely identify an authorized actor,
while the email claim might be used to provide additional useful information about
that party.
However, claims within the may_act claim pertain only to the identity of that party
and are not relevant to the validity of the containing JWT
in the same manner as top level claims.
Consequently, claims such as exp, nbf, and
aud are not meaningful when used within a may_act
claim, and therefore should not be used.
When included as a top-level member of an OAuth token introspection response, may_act
has the same semantics and format as the the claim of the same name.
This specification registers the following values in the
IANA "OAuth URI" registry
established by .
URN: urn:ietf:params:oauth:grant-type:token-exchangeCommon Name: Token exchange grant type for OAuth 2.0Change controller: IESGSpecification Document: of [[ this specification ]]URN: urn:ietf:params:oauth:token-type:access_tokenCommon Name: Token type URI for an OAuth 2.0 access tokenChange controller: IESGSpecification Document: of [[this specification]]URN: urn:ietf:params:oauth:token-type:refresh_tokenCommon Name: Token Type URI for an OAuth 2.0 refresh tokenChange controller: IESGSpecification Document: of [[this specification]]URN: urn:ietf:params:oauth:token-type:id_tokenCommon Name: Token Type URI for an ID TokenChange controller: IESGSpecification Document: of [[this specification]]
This specification registers the following values
in the IANA "OAuth Parameters" registry
established by .
Parameter name: resourceParameter usage location: token requestChange controller: IESGSpecification document(s): of [[ this specification ]]Parameter name: audienceParameter usage location: token requestChange controller: IESGSpecification document(s): of [[ this specification ]]Parameter name: requested_token_typeParameter usage location: token requestChange controller: IESGSpecification document(s): of [[ this specification ]]Parameter name: subject_tokenParameter usage location: token requestChange controller: IESGSpecification document(s): of [[ this specification ]]Parameter name: subject_token_typeParameter usage location: token requestChange controller: IESGSpecification document(s): of [[ this specification ]]Parameter name: actor_tokenParameter usage location: token requestChange controller: IESGSpecification document(s): of [[ this specification ]]Parameter name: actor_token_typeParameter usage location: token requestChange controller: IESGSpecification document(s): of [[ this specification ]]Parameter name: issued_token_typeParameter usage location: token responseChange controller: IESGSpecification document(s): of [[ this specification ]]
This specification registers the following access token type
in the IANA "OAuth Access Token Types" registry
established by .
Type name: N_AAdditional Token Endpoint Response Parameters: (none)HTTP Authentication Scheme(s): (none)Change controller: IESGSpecification document(s): of [[ this specification ]]
This specification registers the following Claims
in the IANA "JSON Web Token Claims" registry
established by .
Claim Name: actClaim Description: ActorChange Controller: IESGSpecification Document(s): of [[ this specification ]]Claim Name: scpClaim Description: Scope ValuesChange Controller: IESGSpecification Document(s): of [[ this specification ]]Claim Name: cidClaim Description: Client IdentifierChange Controller: IESGSpecification Document(s): of [[ this specification ]]Claim Name: may_actClaim Description: May Act ForChange Controller: IESGSpecification Document(s): of [[ this specification ]]
This specification registers the following values
in the IANA "OAuth Token Introspection Response" registry
established by .
Claim Name: actClaim Description: ActorChange Controller: IESGSpecification Document(s): of [[ this specification ]]Claim Name: may_actClaim Description: May Act ForChange Controller: IESGSpecification Document(s): of [[ this specification ]]
This specification registers the following values
in the IANA "OAuth Extensions Error" registry
established by .
Error Name: invalid_targetError Usage Location: token error responseRelated Protocol Extension: OAuth 2.0 Token ExchangeChange Controller: IETFSpecification Document(s): of [[ this specification ]]
All of the normal security issues that are discussed in ,
especially in relationship to comparing URIs and dealing with unrecognized values,
also apply here.
In addition, both delegation and impersonation introduce unique security
issues. Any time one principal is delegated the rights of
another principal, the potential for abuse is a concern.
The use of the scp claim is suggested to mitigate
potential for such abuse, as it restricts the contexts in which
the delegated rights can be exercised.
Tokens typically carry personal information and their usage in Token Exchange may reveal details
of the target services being accessed. As such, tokens should only be requested and
sent according to the privacy policies at the respective organizations.
JSON Web Token (JWT)MicrosoftPing IdentityNomura Research Institute, Ltd.JSON Web Token ClaimsIANAOAuth ParametersIANAWS-Trust 1.4
Two example token exchanges are provided in the following sections
illustrating impersonation and delegation, respectively
(with extra line breaks and indentation for display purposes only).
In the following token exchange request, a client is requesting a token
with impersonation semantics.
The client tells the authorization server that it needs a token for use at
the target service with the logical name
urn:example:cooperation-context.
The subject_token in the prior request is a JWT and
the decoded JWT Claims Set is shown here. The JWT is
intended for consumption by the authorization server within a specific time window.
The subject of the JWT (bc@example.net) is
the party on behalf of whom the new token is being requested.
The access_token parameter of the token exchange
response shown below contains the new token that the client requested.
The other parameters of the response indicate that the token is a bearer access token
that expires in an hour.
The decoded JWT Claims Set of the issued token is shown below. The new JWT is
issued by the authorization server and intended for consumption by a system entity
known by the logical name urn:example:cooperation-context
any time before its expiration.
The subject (sub) of the JWT
is the same as the subject the token used to make the request,
which effectively enables the client to impersonate that subject
at the system entity known by the logical name of
urn:example:cooperation-context by using the token.
In the following token exchange request, a client is requesting a token
and providing both a subject_token and an actor_token.
The client tells the authorization server that it needs a token for use at
the target service with the logical name
urn:example:cooperation-context. Policy at the
authorization server dictates that the issued token be a composite.
The subject_token in the prior request is a JWT and
the decoded JWT Claims Set is shown here. The JWT is
intended for consumption by the authorization server
before a specific expiration time.
The subject of the JWT
(user@example.net) is
the party on behalf of whom the new token is being requested.
The actor_token in the prior request is a JWT and
the decoded JWT Claims Set is shown here. This JWT is also
intended for consumption by the authorization server
before a specific expiration time.
The subject of the JWT
(admin@example.net) is
the actor that will wield the security token being requested.
The access_token parameter of the token exchange
response shown below contains the new token that the client requested.
The other parameters of the response indicate that the token is a JWT
that expires in an hour and that the access token type is not applicable
since the issued token is not an access token.
The decoded JWT Claims Set of the issued token is shown below. The new JWT is
issued by the authorization server and intended for consumption by a system entity
known by the logical name
urn:example:cooperation-context
any time before its expiration.
The subject (sub)
of the JWT
is the same as the subject of
the subject_token used to make the request.
The actor (act) of the JWT is the same as the subject
of the actor_token used to make the request.
This indicates delegation and identifies
admin@example.net as the current actor to whom authority
has been delegated to act on behalf of user@example.net.
This specification was developed within the OAuth Working Group, which
includes dozens of active and dedicated participants.
It was produced under the chairmanship of
Hannes Tschofenig and Derek Atkins
with Kathleen Moriarty and Stephen Farrell serving as
Security Area Directors.
The following individuals contributed ideas, feedback, and wording
to this specification:
Caleb Baker,
Vittorio Bertocci,
Thomas Broyer,
William Denniss,
Vladimir Dzhuvinov,
Phil Hunt,
Benjamin Kaduk,
Jason Keglovitz,
Torsten Lodderstedt,
Adam Lewis,
James Manger,
Nov Matake,
Matt Miller,
Matthew Perry,
Justin Richer,
Rifaat Shekh-Yusef,
Scott Tomilson,
and
Hannes Tschofenig.
[[ to be removed by the RFC Editor before publication as an RFC ]]
-09
Changed "security tokens obtained could be used in a number of contexts" to
"security tokens obtained may be used in a number of contexts" per a WGLC suggestion.Clarified that the validity of the subject or actor token have no impact on the validity
of the issued token after the exchange has occurred per a WGLC comment.Changed use of invalid_target error code to a SHOULD per a WGLC comment.Clarified text about non-identity claims within the "act" claim being meaningless
per a WGLC comment.Added brief Privacy Considerations section per WGLC comments.
-08
Use the bibxml reference for OpenID.Core rather than defining it inline.Added editor role for Campbell.Minor clarification of the text for actor_token.
-07
Fixed typo (desecration -> discretion).
Added an explanation of the relationship between scope, audience and resource in the request
and added an "invalid_target" error code enabling the AS to tell the client that the requested audiences/resources were too broad.
-06
Drop "An STS for the REST of Us" from the title.Drop "heavyweight" and "lightweight" from the abstract and introduction.Clarifications on the language around xxxxxx_token_type.Remove the want_composite parameter.
Add a short mention of proof-of-possession style tokens to the introduction
and remove the respective open issue.
-05
Defined the JWT claim cid to express
the OAuth 2.0 client identifier of the client that requested the token.
Defined and requested registration for act and
may_act as Token introspection response parameters
(in addition to being JWT claims).
Loosen up the language about refresh_token in the response to OPTIONAL from NOT RECOMMENDED
based on feedback form real world deployment experience.
Add clarifying text about the distinction between JWT and access token URIs.
Close out (remove) some of the Open Issues bullets that have been resolved.
-04
Clarified that the "resource" and "audience" request parameters can be used at the same
time (via http://www.ietf.org/mail-archive/web/oauth/current/msg15335.html).
Clarified subject/actor token validity after token exchange and explained a
bit more about the recommendation to not issue refresh tokens
(via http://www.ietf.org/mail-archive/web/oauth/current/msg15318.html).
Updated the examples appendix to use an issuer value that doesn't imply
that the client issued and signed the tokens and used "Bearer" and
"urn:ietf:params:oauth:token-type:access_token" in one of the responses
(via http://www.ietf.org/mail-archive/web/oauth/current/msg15335.html).
Defined and registered urn:ietf:params:oauth:token-type:id_token,
since some use cases perform token exchanges for ID Tokens
and no URI to indicate that a token is an ID Token had previously been defined.
-03
Updated the document editors (adding Campbell, Bradley, and Mortimore).Added to the title.Added to the abstract and introduction.
Updated the format of the request to use application/x-www-form-urlencoded
request parameters and the response to use the existing token endpoint
JSON parameters defined in OAuth 2.0.
Changed the grant type identifier to urn:ietf:params:oauth:grant-type:token-exchange.
Added RFC 6755 registration requests for
urn:ietf:params:oauth:token-type:refresh_token,
urn:ietf:params:oauth:token-type:access_token, and
urn:ietf:params:oauth:grant-type:token-exchange.
Added RFC 6749 registration requests for request/response parameters.
Removed the Implementation Considerations and the requirement to support JWTs.
Clarified many aspects of the text.
Changed on_behalf_of to
subject_token,
on_behalf_of_token_type to
subject_token_type,
act_as to
actor_token, and
act_as_token_type to
actor_token_type.
Added an audience request parameter used to
indicate the logical names of the target services at which the client
intends to use the requested security token.
Added a want_composite request parameter used to
indicate the desire for a composite token rather than trying to infer it from the
presence/absence of token(s) in the request.
Added a resource request parameter used to
indicate the URLs of resources at which the client
intends to use the requested security token.
Specified that multiple audience and
resource request parameter values may be used.
Defined the JWT claim act (actor) to express
the current actor or delegation principal.
Defined the JWT claim may_act to express
that one party is authorized to act on behalf of another party.
Defined the JWT claim scp (scopes) to express
OAuth 2.0 scope-token values.
Added the N_A (not applicable)
OAuth Access Token Type definition for use in contexts in which
the token exchange syntax requires a token_type
value, but in which the token being issued is not an access token.
Added examples.
-02
Enabled use of Security Token types other than JWTs for
act_as and
on_behalf_of request values.
Referenced the JWT and OAuth Assertions RFCs.
-01
Updated references.
-00
Created initial working group draft from draft-jones-oauth-token-exchange-01.