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Network Working Group T. Hardjono, Ed.
Internet-Draft MIT
Intended status: Standards Track E. Maler
Expires: October 6, 2015 ForgeRock
M. Machulak
Cloud Identity
D. Catalano
Oracle
April 4, 2015
User-Managed Access (UMA) Profile of OAuth 2.0
draft-hardjono-oauth-umacore-13
Abstract
User-Managed Access (UMA) is a profile of OAuth 2.0. UMA defines how
resource owners can control protected-resource access by clients
operated by arbitrary requesting parties, where the resources reside
on any number of resource servers, and where a centralized
authorization server governs access based on resource owner policies.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 6, 2015.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 6
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
1.3. Achieving Distributed Access Control . . . . . . . . . . 8
1.3.1. Protection API . . . . . . . . . . . . . . . . . . . 8
1.3.2. Authorization API . . . . . . . . . . . . . . . . . . 9
1.3.3. Protected Resource Interface . . . . . . . . . . . . 10
1.3.4. Time-to-Live Considerations . . . . . . . . . . . . . 11
1.4. Authorization Server Configuration Data . . . . . . . . . 11
2. Protecting a Resource . . . . . . . . . . . . . . . . . . . . 15
3. Getting Authorization and Accessing a Resource . . . . . . . 16
3.1. Client Attempts to Access Protected Resource . . . . . . 17
3.1.1. Client Presents No RPT . . . . . . . . . . . . . . . 17
3.1.2. Client Presents RPT . . . . . . . . . . . . . . . . . 18
3.2. Resource Server Registers Requested Permission With
Authorization Server . . . . . . . . . . . . . . . . . . 19
3.3. Resource Server Determines RPT's Status . . . . . . . . . 21
3.3.1. Token Introspection . . . . . . . . . . . . . . . . . 22
3.3.2. RPT Profile: Bearer . . . . . . . . . . . . . . . . . 22
3.4. Client Seeks Authorization for Access . . . . . . . . . . 24
3.4.1. Client Requests Authorization Data . . . . . . . . . 24
3.4.1.1. Authentication Context Flows . . . . . . . . . . 28
3.4.1.2. Claims-Gathering Flows . . . . . . . . . . . . . 28
4. Error Messages . . . . . . . . . . . . . . . . . . . . . . . 33
4.1. OAuth Error Responses . . . . . . . . . . . . . . . . . . 33
4.2. UMA Error Responses . . . . . . . . . . . . . . . . . . . 34
5. Profiles for API Extensibility . . . . . . . . . . . . . . . 35
5.1. Protection API Extensibility Profile . . . . . . . . . . 35
5.2. Authorization API Extensibility Profile . . . . . . . . . 36
5.3. Resource Interface Extensibility Profile . . . . . . . . 37
6. Specifying Additional Profiles . . . . . . . . . . . . . . . 39
6.1. Specifying Profiles of UMA . . . . . . . . . . . . . . . 39
6.2. Specifying RPT Profiles . . . . . . . . . . . . . . . . . 40
6.3. Specifying Claim Token Format Profiles . . . . . . . . . 40
7. Compatibility Notes . . . . . . . . . . . . . . . . . . . . . 40
8. Security Considerations . . . . . . . . . . . . . . . . . . . 41
8.1. Redirection and Impersonation Threats . . . . . . . . . . 41
8.2. Client Authentication . . . . . . . . . . . . . . . . . . 42
8.3. JSON Usage . . . . . . . . . . . . . . . . . . . . . . . 43
8.4. Profiles, Binding Obligations, and Trust Establishment . 44
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9. Privacy Considerations . . . . . . . . . . . . . . . . . . . 44
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 44
10.1. JSON Web Token Claims Registration . . . . . . . . . . . 45
10.1.1. Registry Contents . . . . . . . . . . . . . . . . . 45
10.2. Well-Known URI Registration . . . . . . . . . . . . . . 45
10.2.1. Registry Contents . . . . . . . . . . . . . . . . . 45
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 45
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 46
12.1. Normative References . . . . . . . . . . . . . . . . . . 46
12.2. Informative References . . . . . . . . . . . . . . . . . 47
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 48
1. Introduction
User-Managed Access (UMA) is a profile of OAuth 2.0 [OAuth2]. UMA
defines how resource owners can control protected-resource access by
clients operated by arbitrary requesting parties, where the resources
reside on any number of resource servers, and where a centralized
authorization server governs access based on resource owner policies.
Resource owners configure authorization servers with access policies
that serve as asynchronous authorization grants.
UMA serves numerous use cases where a resource owner uses a dedicated
service to manage authorization for access to their resources,
potentially even without the run-time presence of the resource owner.
A typical example is the following: a web user (an end-user resource
owner) can authorize a web or native app (a client) to gain one-time
or ongoing access to a protected resource containing his home address
stored at a "personal data store" service (a resource server), by
telling the resource server to respect access entitlements issued by
his chosen cloud-based authorization service (an authorization
server). The requesting party operating the client might be the
resource owner, where the app is run by an e-commerce company that
needs to know where to ship a purchased item, or the requesting party
might be resource owner's friend who is using an online address book
service to collect contact information, or the requesting party might
be a survey company that uses an autonomous web service to compile
population demographics. A variety of use cases can be found in
[UMA-usecases] and [UMA-casestudies].
Practical control of access among loosely coupled parties requires
more than just messaging protocols. This specification defines only
the "technical contract" between UMA-conforming entities; a companion
specification, [UMA-obligations], additionally discusses expected
behaviors of parties operating and using these entities. Parties
operating entities that claim to be UMA-conforming should provide
documentation of any rights and obligations between and among them,
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especially as they pertain the concepts and clauses discussed in this
companion specification.
In enterprise settings, application access management sometimes
involves letting back-office applications serve only as policy
enforcement points (PEPs), depending entirely on access decisions
coming from a central policy decision point (PDP) to govern the
access they give to requesters. This separation eases auditing and
allows policy administration to scale in several dimensions. UMA
makes use of a separation similar to this, letting the resource owner
serve as a policy administrator crafting authorization strategies for
resources under their control.
In order to increase interoperable communication among the
authorization server, resource server, and client, UMA defines two
purpose-built APIs related to the outsourcing of authorization,
themselves protected by OAuth (or an OAuth-based authentication
protocol) in embedded fashion.
The UMA protocol has three broad phases, as shown in Figure 1.
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The Three Phases of the UMA Profile of OAuth
+--------------+
| resource |
+---------manage (A)------------ | owner |
| +--------------+
| Phase 1: |
| protect a control (C)
| resource |
v v
+------------+ +----------+--------------+
| | |protection| |
| resource | | API | authorization|
| server |<-protect (B)--| (needs | server |
| | | PAT) | |
+------------+ +----------+--------------+
| protected | | authorization|
| resource | | API |
|(needs RPT) | | (needs AAT) |
+------------+ +--------------+
^ |
| Phases 2 and 3: authorize (D)
| get authorization, |
| access a resource v
| +--------------+
+---------access (E)-------------| client |
+--------------+
requesting party
Figure 1
The phases work as follows:
Protect a resource (Described in Section 2.) The resource owner,
who manages online resources at the resource server ("A"),
introduces it to the authorization server so that the latter can
begin protecting the resources. To accomplish this, the
authorization server presents a protection API ("B") to the
resource server. This API is protected by OAuth (or an OAuth-
based authentication protocol) and requires a protection API token
(PAT) for access. Out of band, the resource owner configures the
authorization server with policies associated with the resource
sets ("C") that the resource registers for protection.
Get authorization (Described in Section 3.) The client approaches
the resource server seeking access to an UMA-protected resource.
In order to access it successfully, the client must first use the
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authorization server's authorization API ("D") to obtain
authorization data and a requesting party token (RPT) on behalf of
its requesting party, and the requesting party may need to supply
identity claims. The API is protected by OAuth (or an OAuth-based
authentication protocol) and requires an authorization API token
(AAT) for access.
Access a resource (Described in Section 3.) The client successfully
presents to the resource server an RPT that has sufficient
authorization data associated with it, gaining access to the
desired resource ("E"). Phase 3 is effectively the "success path"
embedded within phase 2.
Implementers have the opportunity to develop profiles (see Section 6)
that specify and restrict various UMA protocol, RPT, and identity
claim format options, according to deployment and usage conditions.
1.1. Notational Conventions
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL', 'SHALL NOT',
'SHOULD', 'SHOULD NOT', 'RECOMMENDED', 'MAY', and 'OPTIONAL' in this
document are to be interpreted as described in [RFC2119].
Unless otherwise noted, all protocol properties and values are case
sensitive. JSON [JSON] data structures defined by this specification
MAY contain extension properties that are not defined in this
specification. Any entity receiving or retrieving a JSON data
structure SHOULD ignore extension properties it is unable to
understand. Extension names that are unprotected from collisions are
outside the scope of this specification.
1.2. Terminology
UMA introduces the following new terms and enhancements of OAuth term
definitions.
resource owner
An OAuth resource owner that is the "user" in User-Managed
Access. This is typically an end-user (a natural person) but
it can also be a corporation or other legal person.
policy The configuration parameters of an authorization server that
effect resource access management. Authorization policies
typically include elements similar to parts of speech; for
example, "subjects" describe those seeking access (requesting
parties and clients), "verbs" describe operational scopes of
access, and "objects" describe targeted resource sets. Policy
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configuration takes place between the resource owner and the
authorization server, and thus is out of band of UMA.
requesting party
An end-user, or a corporation or other legal person, that uses
a client to seek access to a protected resource. The
requesting party may or may not be the same party as the
resource owner.
client
An application making protected resource requests with the
resource owner's authorization and on the requesting party's
behalf.
claim
A statement of the value or values of one or more identity
attributes of a requesting party. A requesting party may need
to provide claims to an authorization server in order to gain
permission for access to a protected resource.
resource set One or more protected resources that a resource server
manages as a set, abstractly. In authorization policy
terminology, a resource set is the "object" being protected.
This term derives from [OAuth-resource-reg].
scope A bounded extent of access that is possible to perform on a
resource set. In authorization policy terminology, a scope is
one of the potentially many "verbs" that can logically apply to
a resource set ("object"). UMA associates scopes with labeled
resource sets.
authorization data Data associated with an RPT that enables some
combination of the authorization server and resource server to
determine the correct extent of access to allow to a client.
Authorization data is a key part of the definition of an RPT
profile.
authorization server
A server that issues authorization data and RPTs to a client
and protects resources managed at a resource server.
permission A scope of access over a particular resource set at a
particular resource server that is being requested by, or
granted to, a requesting party. In authorization policy
terminology, a permission is an entitlement that includes a
"subject" (requesting party), "verbs" (one or more scopes of
access), and an "object" (resource set). A permission is one
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example of authorization data that an authorization server may
add to a requesting party token.
permission ticket A correlation handle that is conveyed from an
authorization server to a resource server, from a resource
server to a client, and ultimately from a client back to an
authorization server, to enable the authorization server to
assess the correct policies to apply to a request for
authorization data.
token A packaged collection of data meant to be transmitted to
another entity. A token could be used for authorized access
(an "access token" such as an UMA RPT, PAT, or AAT), or could
be used to exchange information about a subject (a "claim
token" such as one that is conveyed by a client to an
authorization server while seeking authorization data).
1.3. Achieving Distributed Access Control
The software components that fill the roles of UMA authorization
servers, resource servers, and clients respectively are intended to
work in an interoperable fashion when each is operated by an
independent party (for example, different organizations). For this
reason, UMA specifies communications channels that the authorization
server MUST implement as HTTP-based APIs that MUST use TLS and OAuth
(or OAuth-based authentication protocol) protection, and that the
resource server MUST implement as an HTTP-based interface. UMA's use
of TLS is governed by Section 1.6 of [OAuth2], which discusses
deployment and adoption characteristics of different TLS versions.
For those OAuth protection use cases where an identity token is
desired in addition to an access token, it is RECOMMENDED that an
OAuth-based authentication protocol such as OpenID Connect be used.
It is also REQUIRED, in turn, for resource servers and clients on the
requesting side of UMA interactions to use these channels, unless a
profile is being used that enables API extensibility. The profiles
that enable such alternatives are provided in Section 5.
1.3.1. Protection API
The authorization server MUST present an HTTP-based protection API,
protected by TLS and OAuth (or an OAuth-based authentication
protocol), for use by resource servers. The authorization server
thus has an OAuth token endpoint and authorization endpoint. The
authorization server MUST declare all of its protection API endpoints
in its configuration data (see Section 1.4).
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The protection API consists of three endpoints:
o Resource set registration endpoint as defined by
[OAuth-resource-reg]
o Permission registration endpoint as defined by Section 3.2
o Token introspection endpoint as defined by [OAuth-introspection]
and Section 3.3.1
An entity seeking protection API access MUST have the scope
"uma_protection". An access token with at least this scope is called
a protection API token (PAT) and an entity that can acquire an access
token with this scope is by definition a resource server. A single
entity can serve in both resource server and client roles if it has
access tokens with the appropriate OAuth scopes. If a request to an
endpoint fails due to an invalid, missing, or expired PAT, or
requires higher privileges at this endpoint than provided by the PAT,
the authorization server responds with an OAuth error.
The authorization server MUST support the OAuth bearer token profile
for PAT issuance, and MAY support other OAuth token profiles. It
MUST declare all supported token profiles and grant types for PAT
issuance in its configuration data. Any OAuth authorization grant
type might be appropriate depending on circumstances; for example,
the client credentials grant is useful in the case of an organization
acting as a resource owner. [UMA-Impl] discusses grant options
further.
A PAT binds a resource owner, a resource server the owner uses for
resource management, and an authorization server the owner uses for
protection of resources at this resource server. It is not specific
to any client or requesting party. The issuance of a PAT represents
the approval of the resource owner for this resource server to use
this authorization server for protecting some or all of the resources
belonging to this resource owner.
1.3.2. Authorization API
The authorization server MUST present an HTTP-based authorization
API, protected by TLS and OAuth (or an OAuth-based authentication
protocol), for use by clients. The authorization server thus has an
OAuth token endpoint and authorization endpoint. The authorization
server MUST declare its authorization API endpoint in its
configuration data (see Section 1.4).
The authorization API consists of one endpoint:
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o RPT endpoint as defined in Section 3.4.1
An entity seeking authorization API access MUST have the scope
"uma_authorization". An access token with at least this scope is
called an authorization API token (AAT) and an entity that can
acquire an access token with this scope is by definition a client. A
single entity can serve in both resource server and client roles if
it has access tokens with the appropriate OAuth scopes. If a request
to an endpoint fails due to an invalid, missing, or expired AAT, or
requires higher privileges at this endpoint than provided by the AAT,
the authorization server responds with an OAuth error.
The authorization server MUST support the OAuth bearer token profile
for AAT issuance, and MAY support other OAuth token profiles. It
MUST declare all supported token profiles and grant types for AAT
issuance in its configuration data. Any OAuth authorization grant
type might be appropriate depending on circumstances; for example,
the client credentials grant is useful in the case of an organization
acting as a requesting party. [UMA-Impl] discusses grant options
further.
An AAT binds a requesting party, a client being used by that party,
and an authorization server that protects resources this client is
seeking access to on this requesting party's behalf. It is not
specific to any resource server or resource owner. The issuance of
an AAT represents the approval of this requesting party for this
client to engage with this authorization server to supply claims, ask
for authorization, and perform any other tasks needed for obtaining
authorization for access to resources at all resource servers that
use this authorization server. The authorization server is able to
manage future processes of authorization and claims-caching
efficiently for this client/requesting party pair across all resource
servers they try to access; however, these management processes are
outside the scope of this specification.
1.3.3. Protected Resource Interface
The resource server MAY present to clients whatever HTTP-based APIs
or endpoints it wishes. To protect any of its resources available in
this fashion using UMA, it MUST require a requesting party token
(RPT) with sufficient authorization data for access.
This specification defines one RPT profile, call "bearer" (see
Section 3.3.2), which the authorization server MUST support. It MAY
support additional RPT profiles, and MUST declare all supported RPT
profiles in its configuration data (see Section 1.4).
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An RPT binds a requesting party, the client being used by that party,
the resource server at which protected resources of interest reside,
and the authorization server that protects those resources. It is
not specific to a single resource owner, though its internal
components are likely to be bound in practice to individual resource
owners, depending on the RPT profile in use.
1.3.4. Time-to-Live Considerations
The authorization server has the opportunity to manage the validity
periods of access tokens that it issues, their corresponding refresh
tokens where applicable, the individual authorization data components
associated with RPTs where applicable, and even the client
credentials that it issues. Different time-to-live strategies may be
suitable for different resource sets and scopes of access, and the
authorization server has the opportunity to give the resource owner
control over lifetimes of tokens and authorization data issued on
their behalf through policy. These options are all outside the scope
of this specification.
1.4. Authorization Server Configuration Data
The authorization server MUST provide configuration data in a JSON
document that resides in an /uma-configuration directory at its host-
meta [hostmeta] location. The configuration data documents
conformance options and endpoints supported by the authorization
server.
The configuration data has the following properties.
version
REQUIRED. The version of the UMA core protocol to which this
authorization server conforms. The value MUST be the string
"1.0".
issuer
REQUIRED. A URI with no query or fragment component that the
authorization server asserts as its issuer identifier. This
value MUST be identical to the web location of the
configuration data minus the host-meta [hostmeta] and /uma-
configuration path components
pat_profiles_supported
REQUIRED. OAuth access token types supported by this
authorization server for PAT issuance. The property value is
an array of string values, where each string value (which MAY
be a URI) is a token type. Non-URI token type strings defined
by OAuth token-defining specifications are privileged. For
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example, the type "bearer" stands for the OAuth bearer token
type defined in [OAuth-bearer]. The authorization server is
REQUIRED to support "bearer", and to supply this value
explicitly. The authorization server MAY declare its support
for additional PAT profiles.
aat_profiles_supported
REQUIRED. OAuth access token types supported by this
authorization server for AAT issuance. The property value is
an array of string values, where each string value (which MAY
be a URI) is a token type. Non-URI token type strings defined
by OAuth token-defining specifications are privileged. For
example, the type "bearer" stands for the OAuth bearer token
type defined in [OAuth-bearer]. The authorization server is
REQUIRED to support "bearer", and to supply this value
explicitly. The authorization server MAY declare its support
for additional AAT profiles.
rpt_profiles_supported
REQUIRED. Profiles supported by this authorization server for
RPT issuance. The property value is an array of string values,
where each string value is a URI identifying an RPT profile.
The authorization server is REQUIRED to support the "bearer"
RPT profile defined in Section 3.3.2, and to supply its
identifying URI explicitly. The authorization server MAY
declare its support for additional RPT profiles.
pat_grant_types_supported
REQUIRED. OAuth grant types supported by this authorization
server in issuing PATs. The property value is an array of
string values, where each string value (which MAY be a URI) is
a grant type. Non-URI token type strings defined by OAuth
grant type-defining specifications are privileged. For
example, the type "authorization_code" stands for the OAuth
authorization code grant type defined in [OAuth2].
aat_grant_types_supported
REQUIRED. OAuth grant types supported by this authorization
server in issuing AATs. The property value is an array of
string values, where each string value (which MAY be a URI) is
a grant type. Non-URI token type strings defined by OAuth
grant type-defining specifications are privileged. For
example, the type "authorization_code" stands for the OAuth
authorization code grant type defined in [OAuth2].
claim_token_profiles_supported
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OPTIONAL. Claim token format profiles supported by this
authorization server. The property value is an array of string
values, where each string value MAY be a URI.
uma_profiles_supported
OPTIONAL. UMA profiles supported by this authorization server.
The property value is an array of string values, where each
string value is a URI identifying an UMA profile. Examples of
UMA profiles are the API extensibility profiles defined in
Section 5.
dynamic_client_endpoint
OPTIONAL. The endpoint to use for performing dynamic client
registration in the case of the use of [DynClientReg], or
alternatively the reserved string "openid" in the case of the
use of [OIDCDynClientReg]. In the latter case, it is presumed
that the resource server or client will discover the dynamic
client registration endpoint from the authorization server's
published OpenID Provider Configuration Information. The
presence of this property indicates authorization server
support for dynamic client registration feature; its absence
indicates a lack of support.
token_endpoint
REQUIRED. The endpoint URI at which the resource server or
client asks the authorization server for a PAT or AAT. A
requested scope of "uma_protection" results in a PAT. A
requested scope of "uma_authorization" results in an AAT.
Usage of this endpoint is defined by [OAuth2].
authorization_endpoint
REQUIRED. The endpoint URI at which the resource server
gathers the consent of the end-user resource owner or the
client gathers the consent of the end-user requesting party for
issuance of a PAT or AAT respectively, if the
"authorization_code" grant type is used. Usage of this
endpoint is defined by [OAuth2].
requesting_party_claims_endpoint
OPTIONAL. The endpoint URI at which the authorization server
interacts with the end-user requesting party to gather claims.
If this property is absent, the authorization server does not
interact with the end-user requesting party for claims
gathering.
introspection_endpoint
REQUIRED. The endpoint URI at which the resource server
introspects an RPT presented to it by a client. Usage of this
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endpoint is defined by [OAuth-introspection] and Section 3.3.1.
A valid PAT MUST accompany requests to this protected endpoint.
resource_set_registration_endpoint
REQUIRED. The endpoint URI at which the resource server
registers resource sets to put them under authorization manager
protection. Usage of this endpoint is defined by
[OAuth-resource-reg] and Section 2. A valid PAT MUST accompany
requests to this protected endpoint.
permission_registration_endpoint
REQUIRED. The endpoint URI at which the resource server
registers a requested permission that would suffice for a
client's access attempt. Usage of this endpoint is defined by
Section 3.2. A valid PAT MUST accompany requests to this
protected endpoint.
rpt_endpoint
REQUIRED. The endpoint URI at which the client asks for
authorization data. Usage of this endpoint is defined in
Section 3.4. A valid AAT and a permission ticket MUST, and an
RPT MAY, accompany requests to this protected endpoint.
Example of authorization server configuration data that resides at
https://example.com/.well-known/uma-configuration (note the use of
https: for endpoints throughout):
{
"version":"1.0",
"issuer":"https://example.com",
"pat_profiles_supported":["bearer"],
"aat_profiles_supported":["bearer"],
"rpt_profiles_supported":
["https://docs.kantarainitiative.org/uma/profiles/uma-token-bearer-1.0"],
"pat_grant_types_supported":["authorization_code"],
"aat_grant_types_supported":["authorization_code"],
"claim_token_profiles_supported":["https://example.com/claims/formats/token1"],
"dynamic_client_endpoint":"https://as.example.com/dyn_client_reg_uri",
"token_endpoint":"https://as.example.com/token_uri",
"authorization_endpoint":"https://as.example.com/authz_uri",
"requesting_party_claims_endpoint":"https://as.example.com/rqp_claims_uri",
"resource_set_registration_endpoint":"https://as.example.com/rs/rsrc_uri",
"introspection_endpoint":"https://as.example.com/rs/status_uri",
"permission_registration_endpoint":"https://as.example.com/rs/perm_uri",
"rpt_endpoint":"https://as.example.com/client/rpt_uri"
}
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Where this specification does not already require optional features
to be documented, it is RECOMMENDED that authorization server
deployers document any profiled or extended features explicitly and
use configuration data to indicate their usage.
2. Protecting a Resource
The resource owner, resource server, and authorization server perform
the following actions to put resources under protection. This list
assumes that the resource server has discovered the authorization
server's configuration data and endpoints as needed.
1. The authorization server issues client credentials to the
resource server. It is OPTIONAL for the client credentials to be
provided dynamically through [DynClientReg] or
[OIDCDynClientReg]; alternatively, they MAY use a static process.
2. The resource server acquires a PAT from the authorization server.
It is OPTIONAL for the resource owner to introduce the resource
server to the authorization server dynamically (for example,
through a "NASCAR"-style user interface where the resource owner
selects a chosen authorization server); alternatively, they MAY
use a static process that may or may not directly involve the
resource owner at introduction time.
3. In an ongoing fashion, the resource server registers any resource
sets with the authorization server for which it intends to
outsource protection, using the resource set registration
endpoint of the protection API (see [OAuth-resource-reg]).
Note: The resource server is free to offer the option to protect any
subset of the resource owner's resources using different
authorization servers or other means entirely, or to protect some
resources and not others. Additionally, the choice of protection
regimes can be made explicitly by the resource owner or implicitly by
the resource server. Any such partitioning by the resource server or
owner is outside the scope of this specification.
Once a resource set has been placed under authorization server
protection through the registration of a resource set description for
it, and until such a description's deletion by the resource server,
the resource server MUST limit access to corresponding resources,
requiring sufficient authorization data associated with client-
presented RPTs by the authorization server (see Section 3.1.2).
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3. Getting Authorization and Accessing a Resource
An authorization server orchestrates and controls clients' access (on
their requesting parties' behalf) to a resource owner's protected
resources at a resource server, under conditions dictated by that
resource owner.
The process of getting authorization and accessing a resource always
begins with the client attempting access at a protected resource
endpoint at the resource server. How the client came to learn about
this endpoint is out of scope for this specification. The resource
owner might, for example, have advertised its availability publicly
on a blog or other website, listed it in a discovery service, or
emailed a link to a particular intended requesting party.
The resource server responds to the client's access request with
whatever its application-specific resource interface defines as a
success response, either immediately if the client has sufficient
authorization, or having first performed one or more embedded
interactions with the authorization server and client in the case of
a failed access attempt.
A high-level summary of the interactions is as follows. The
recipient of each request message SHOULD respond unless it detects a
security concern, such as a suspected denial of service attack that
can be mitigated by rate limiting.
o The client attempts to access a protected resource.
* If the access attempt is unaccompanied by an RPT, the resource
server registers a requested permission at the authorization
server that would suffice for the access attempt, and then
responds with an HTTP 403 (Forbidden) response, a permission
ticket, and instructions on where to go to obtain an RPT and
authorization data.
* If the access attempt is accompanied by an RPT, the resource
server checks the RPT's status.
+ If the RPT is invalid, or if the RPT is valid but has
insufficient authorization data, the resource server
registers a requested permission at the authorization server
that would suffice for the access attempt, and then responds
with an HTTP 403 (Forbidden) response, a permission ticket,
and instructions on where to go to obtain a valid RPT and
authorization data for it.
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+ If the RPT is valid, and if the authorization data
associated with the token is sufficient for allowing access,
the resource server responds with an HTTP 2xx (Success)
response.
o If the client received a 403 response and a permission ticket, it
asks the authorization server for authorization data that matches
the ticket using the RPT endpoint of the authorization API. If
the authorization server needs requesting party claims in order to
assess this client's authorization, it engages in a claims-
gathering flow.
* If the client does not already have an AAT at the appropriate
authorization server to be able to use its authorization API,
it first obtains one.
The interactions are described in detail in the following sections.
3.1. Client Attempts to Access Protected Resource
This interaction assumes that the resource server has previously
registered one or more resource sets that correspond to the resource
the client is attempting to access.
The client attempts to access a protected resource (for example, when
an end-user requesting party clicks on a thumbnail representation of
the resource to retrieve a larger version). It is expected to
discover, or be provisioned or configured with, knowledge of the
protected resource and its location out of band. Further, the client
is expected to acquire its own knowledge about the application-
specific methods made available by the resource server for operating
on this protected resource (such as viewing it with a GET method, or
transforming it with some complex API call).
The access attempt either is or is not accompanied by an RPT.
3.1.1. Client Presents No RPT
Example of a request carrying no RPT:
GET /album/photo.jpg HTTP/1.1
Host: photoz.example.com
...
If the client does not present an RPT with the request, the resource
server uses the protection API to register a requested permission
with the authorization server that would suffice for the access
attempt (see Section 3.2), and receives a permission ticket back in
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response. It then responds to the client. It SHOULD respond with
the HTTP 403 (Forbidden) status code, providing the authorization
server's URI in an "as_uri" property in the header, along with the
just-received permission ticket in the body in a JSON-encoded
"ticket" property. Responses that use any code other than 403 are
undefined by this specification; any common or best practices for
returning other status codes will be documented in the [UMA-Impl].
For example:
HTTP/1.1 403 Forbidden
WWW-Authenticate: UMA realm="example",
as_uri="https://as.example.com"
{
"ticket": "016f84e8-f9b9-11e0-bd6f-0021cc6004de"
}
...
3.1.2. Client Presents RPT
Example of a request carrying an RPT using the UMA "bearer" RPT
profile:
GET /album/photo.jpg HTTP/1.1
Authorization: Bearer vF9dft4qmT
Host: photoz.example.com
...
If the client presents an RPT with its request, the resource server
MUST determine the RPT's status (see Section 3.3) before responding.
If the RPT is invalid, or if the RPT is valid but has insufficient
authorization data for the type of access sought, the resource server
uses the protection API to register a requested permission with the
authorization server that would suffice for the access attempt (see
Section 3.2), and receives a permission ticket back in response. It
then responds to the client with the HTTP 403 (Forbidden) status
code, providing the authorization server's URI in an "as_uri"
property in the header, along with the just-received permission
ticket in the body in a JSON-encoded "ticket" property.
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Example of the resource server's response after having registered a
requested permission and received a ticket:
HTTP/1.1 403 Forbidden
WWW-Authenticate: UMA realm="example",
as_uri="https://as.example.com"
error="insufficient_scope"
{
"ticket": "016f84e8-f9b9-11e0-bd6f-0021cc6004de"
}
If the RPT's status is associated with authorization data that is
sufficient for the access sought by the client, the resource server
MUST give access to the desired resource.
Example of the resource server's response after having determined
that the RPT is valid and associated with sufficient authorization
data:
HTTP/1.1 200 OK
Content-Type: image/jpeg
...
/9j/4AAQSkZJRgABAgAAZABkAAD/7AARRHVja
3kAAQAEAAAAPAAA/+4ADkFkb2JlAGTAAAAAAf
/bAIQABgQEBAUEBgUFBgkGBQYJCwgGBggLDAo
KCwoKDBAMDAwMDAwQDA4PEA8ODBMTFBQTExwb
The resource server MUST NOT give access where the token's status is
not associated with sufficient authorization data for the attempted
scope of access.
3.2. Resource Server Registers Requested Permission With Authorization
Server
The resource server uses the protection API's permission registration
endpoint to register a requested permission with the authorization
server that would suffice for the client's access attempt. The
authorization server returns a permission ticket for the resource
server to give to the client in its response. The PAT provided in
the API request implicitly identifies the resource owner ("subject")
to which the permission applies.
Note: The resource server is free to choose the extent of the
requested permission that it registers, as long as it minimally
suffices for the access attempted by the client. For example, it can
choose to register a permission that covers several scopes or a
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resource set that is greater in extent than the specific resource
that the client attempted to access. Likewise, the authorization
server is ultimately free to choose to partially fulfill the elements
of a permission request based on incomplete satisfaction of policy
criteria, or not to fulfill the request.
The resource server uses the POST method at the endpoint. The body
of the HTTP request message contains a JSON object providing the
requested permission, using a format derived from the scope
description format specified in [OAuth-resource-reg], as follows.
The object has the following properties:
resource_set_id REQUIRED. The identifier for a resource set to
which this client is seeking access. The identifier MUST
correspond to a resource set that was previously registered.
scopes REQUIRED. An array referencing one or more identifiers of
scopes to which access is needed for this resource set. Each
scope identifier MUST correspond to a scope that was registered by
this resource server for the referenced resource set.
Example of an HTTP request that registers a requested permission at
the authorization server's permission registration endpoint, with a
PAT in the header:
POST /host/scope_reg_uri/photoz.example.com HTTP/1.1
Content-Type: application/json
Host: as.example.com
Authorization: Bearer 204c69636b6c69
{
"resource_set_id": "112210f47de98100",
"scopes": [
"http://photoz.example.com/dev/actions/view",
"http://photoz.example.com/dev/actions/all"
]
}
If the registration request is successful, the authorization server
responds with an HTTP 201 (Created) status code and includes the
"ticket" property in the JSON-formatted body.
The permission ticket is a short-lived opaque structure whose form is
determined by the authorization server. The ticket value MUST be
securely random (for example, not merely part of a predictable
sequential series), to avoid denial-of-service attacks. Since the
ticket is an opaque structure from the point of view of the client,
the authorization server is free to include information regarding
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expiration time or any other information within the opaque ticket for
its own consumption. When the client subsequently uses the
authorization API to ask the authorization server for authorization
data to be associated with its RPT, it will submit this ticket to the
authorization server.
For example:
HTTP/1.1 201 Created
Content-Type: application/json
...
{
"ticket": "016f84e8-f9b9-11e0-bd6f-0021cc6004de"
}
If the registration request is authenticated properly but fails due
to other reasons, the authorization server responds with an HTTP 400
(Bad Request) status code and includes one of the following UMA error
codes (see Section 4.2):
invalid_resource_set_id The provided resource set identifier was not
found at the authorization server.
invalid_scope At least one of the scopes included in the request was
not registered previously by this resource server.
3.3. Resource Server Determines RPT's Status
The resource server MUST determine a received RPT's status, including
both whether it is active and, if so, its associated authorization
data, before giving or refusing access to the client. An RPT is
associated with a set of authorization data that governs whether the
client is authorized for access. The token's nature and format are
dictated by its profile; the profile might allow it to be self-
contained, such that the resource server is able to determine its
status locally, or might require or allow the resource server to make
a run-time introspection request of the authorization server that
issued the token.
This specification makes one type of RPT REQUIRED for the
authorization server to support: the UMA bearer token profile, as
defined in Section 3.3.2. Implementers MAY define and use other RPT
profiles.
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3.3.1. Token Introspection
Within any RPT profile, when a resource server needs to introspect a
token in a non-self-contained way to determine its status, it MAY
require, allow, or prohibit use of the OAuth token introspection
endpoint (defined by [OAuth-introspection]) that is part of the
protection API, and MAY profile its usage. The resource server MUST
use the POST method in interacting with the endpoint, not the GET
method also defined by [OAuth-introspection].
3.3.2. RPT Profile: Bearer
This section defines the UMA bearer token profile. Following is a
summary:
o Identifying URI: https://docs.kantarainitiative.org/uma/profiles/
uma-token-bearer-1.0
o Profile author and contact information: Thomas Hardjono
(hardjono@mit.edu)
o Updates or obsoletes: None; this profile is new.
o Keyword in HTTP Authorization header: "Bearer".
o Syntax and semantics of token data: As defined below; an opaque
string value, resolving to an extended JSON Web Token (JWT) [JWT]
format on introspection at the authorization server.
o Token data association: The on-the-wire token is opaque; it is
introspected at run time by the resource server through profiled
use of the OAuth token introspection endpoint
[OAuth-introspection], as defined below.
o Token data processing: As defined in this section and throughout
Section 3 of this specification.
o Grant type restrictions: None.
o Error states: As defined below.
o Security and privacy considerations: As defined in this section,
throughout Section 3, and in Section 8.
An example of a client making a request with an RPT using the
"Bearer" scheme appears in Section 3.1.2.
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On receiving an RPT with the "Bearer" scheme in an authorization
header from a client making an access attempt, the resource server
introspects the token by using the token introspection endpoint of
the protection API. The PAT used by the resource server to make the
introspection request provides resource-owner context to the
authorization server.
The authorization server responds with a JSON object with the
structure dictated by [OAuth-introspection]. If the "active"
property has a Boolean value of true, then the JSON object MUST NOT
contain a "scope" claim, and MUST contain an extension property with
the name "permissions" that contains an array of zero or more values,
each of which is an object consisting of these properties:
resource_set_id REQUIRED. A string that uniquely identifies the
resource set, access to which has been granted to this client on
behalf of this requesting party. The identifier MUST correspond
to a resource set that was previously registered as protected.
scopes REQUIRED. An array referencing one or more URIs of scopes to
which access was granted for this resource set. Each scope MUST
correspond to a scope that was registered by this resource server
for the referenced resource set.
exp OPTIONAL. Integer timestamp, measured in the number of seconds
since January 1 1970 UTC, indicating when this permission will
expire. If the property is absent, the permission does not
expire. If the token-level "exp" value pre-dates a permission-
level "exp" value, the former overrides the latter.
iat OPTIONAL. Integer timestamp, measured in the number of seconds
since January 1 1970 UTC, indicating when this permission was
originally issued. If the token-level "iat" value post-dates a
permission-level "iat" value, the former overrides the latter.
nbf OPTIONAL. Integer timestamp, measured in the number of seconds
since January 1 1970 UTC, indicating the time before which this
permission is not valid. If the token-level "nbf" value post-
dates a permission-level "nbf" value, the former overrides the
latter.
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Example:
HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: no-store
{
"active": true,
"exp": 1256953732,
"iat": 1256912345,
"permissions": [
{
"resource_set_id": "112210f47de98100",
"scopes": [
"http://photoz.example.com/dev/actions/view",
"http://photoz.example.com/dev/actions/all"
],
"exp" : 1256953732
}
]
}
3.4. Client Seeks Authorization for Access
In order to access a protected resource successfully, a client needs
to present a valid RPT with sufficient authorization data for access.
To get to this stage requires a number of previously successful
steps:
1. The authorization server issues client credentials to the client.
It is OPTIONAL for the client credentials to be provided
dynamically through [DynClientReg] or [OIDCDynClientReg];
alternatively, they MAY use a static process.
2. The client acquires an AAT.
3. The client uses the authorization API to acquire an RPT and to
ask for authorization data, providing the permission ticket it
got from the resource server. The authorization server
associates authorization data with the RPT based on the
permission ticket, the resource owner's operative policies, and
the results of any claims-gathering flows.
3.4.1. Client Requests Authorization Data
Once in possession of a permission ticket and an AAT for this
authorization server, the client asks the authorization server to
give it authorization data corresponding to that permission ticket.
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It performs a POST on the RPT endpoint, supplying its own AAT in the
header and a JSON object in the body with a "ticket" property
containing the ticket as its value.
If the client had included an RPT in its failed access attempt, It
MAY also provide that RPT in an "rpt" property in its request to the
authorization server.
In circumstances where the client needs to provide requesting party
claims to the authorization server, it MAY also include a
"claim_tokens" property in its request; see Section 3.4.1.2.1 for
more information.
Example of a request message containing an AAT, an RPT, and a
permission ticket:
POST /authz_request HTTP/1.1
Host: as.example.com
Authorization: Bearer jwfLG53^sad$#f
...
{
"rpt": "sbjsbhs(/SSJHBSUSSJHVhjsgvhsgvshgsv",
"ticket": "016f84e8-f9b9-11e0-bd6f-0021cc6004de"
}
The authorization server uses the ticket to look up the details of
the previously registered requested permission, maps the requested
permission to operative resource owner policies based on the resource
set identifier and scopes associated with it, potentially requests
additional information, and ultimately responds positively or
negatively to the request for authorization data.
The authorization server bases the issuing of authorization data on
resource owner policies. These policies thus amount to an
asynchronous OAuth authorization grant. The authorization server is
also free to enable the resource owner to set policies that require
the owner to interact with the server in near-real time to provide
consent subsequent to an access attempt. All such processes are
outside the scope of this specification.
Once the authorization server adds the requested authorization data,
it returns an HTTP 200 (OK) status code with a response body
containing the RPT with which it associates the requested
authorization data. If the client did not present an RPT in the
request for authorization data, the authorization server creates and
returns a new RPT. If the client did present an RPT in the request,
the authorization server returns the RPT with which it associated the
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requested authorization data, which MAY be either the RPT that was in
the request or a new one. Note: It is entirely an implementation
issue whether the returned RPT is the same one that appeared in the
request or a new RPT, and it is also an implementation issue whether
the AS chooses to invalidate or retain the validity of the original
RPT or any authorization data that was previously added to that RPT;
to assist in client interoperability and token caching expectations,
it is RECOMMENDED that authorization servers document their
practices. [UMA-Impl] discusses the implications.
Example:
HTTP/1.1 200 OK
Content-Type: application/json
{
"rpt": "sbjsbhs(/SSJHBSUSSJHVhjsgvhsgvshgsv"
}
If the authorization server does not add the requested authorization
data, it responds using one of the following UMA error codes and
corresponding HTTP status codes (see Section 4.2):
invalid_ticket The provided ticket was not found at the
authorization server. The authorization server responds with the
HTTP 400 (Bad Request) status code.
expired_ticket The provided ticket has expired. The authorization
server responds with the HTTP 400 (Bad Request) status code.
not_authorized The client is not authorized to have this
authorization data added. The authorization server responds with
the HTTP 403 (Forbidden) status code.
need_info The authorization server needs additional information in
order to determine whether the client is authorized to have this
authorization data. The authorization server responds with the
HTTP 403 (Forbidden) status code. It MAY also respond with an
"error_details" object that contains one or more sub-properties
with hints about the nature of further required information. The
client then has the opportunity to engage in follow-on flows to
continue seeking authorization, in a process sometimes referred as
"trust elevation". This specification defines two nonexclusive
"error_details" sub-properties: "authentication_context",
described in Section 3.4.1.1, and "requesting_party_claims",
described in Section 3.4.1.2.
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request_submitted The authorization server requires intervention by
the resource owner to determine whether the client is authorized
to have this authorization data. Further immediate interaction
between the client and authorization server is out of scope of
this specification.
Example when the ticket has expired:
HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store
...
{
"error": "expired_ticket"
}
Example of a "need_info" response with a full set of "error_details"
hints:
HTTP/1.1 403 Forbidden
Content-Type: application/json
Cache-Control: no-store
...
{
"error": "need_info",
"error_details": {
"authentication_context": {
"required_acr": ["https://example.com/acrs/LOA3.14159"]
},
"requesting_party_claims": {
"required_claims": [
{
"name": "email23423453ou453",
"friendly_name": "email",
"claim_type": "urn:oid:0.9.2342.19200300.100.1.3",
"claim_token_format":
["http://openid.net/specs/openid-connect-core-1_0.html#HybridIDToken"],
"issuer": ["https://example.com/idp"]
}
],
"redirect_user": true,
"ticket": "016f84e8-f9b9-11e0-bd6f-0021cc6004de"
}
}
}
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3.4.1.1. Authentication Context Flows
The "authentication_context" sub-property provides hints about
additional requirements regarding the requesting party's
authentication that underlies the issuance of the currently valid
AAT. On receiving such hints, the client has the opportunity to
redirect the requesting party to the authorization server to
reauthenticate in a manner anticipated to be more successful for
gaining access. Such an action is sometimes referred to as "step-up"
authentication. The "authentication_context" sub-property contains
the following parameter:
required_acr REQUIRED. An array of strings specifying a set of
acceptable authentication context class reference values. Any one
of the referenced authentication context classes (sets of
authentication methods or procedures considered to be equivalent
in a particular context) would satisfy the requesting party
authentication requirements. Each string MAY be a URI, including
one that has been registered through [RFC6711].
3.4.1.2. Claims-Gathering Flows
The "requesting_party_claims" sub-property provides hints about
additional requirements regarding information the authorization
server needs about the requesting party. On receiving such hints,
the client has the opportunity to engage in claims-gathering flows of
various types. The "requesting_party_claims" sub-property MAY
contain the following parameters, where at least one of
"required_claims" or "redirect_user" MUST be supplied:
required_claims An array containing objects that describe
characteristics of the required claims, with the following
properties:
name OPTIONAL. A string (which MAY be a URI) representing the
name of the claim; the "key" in a key-value pair.
friendly_name OPTIONAL. A string that provides a more human-
readable form of the attribute's name, which may be useful as a
"display name" for use in user interfaces in cases where the
actual name is complex or opaque, such as an OID or a UUID.
claim_type OPTIONAL. A string, indicating the expected
interpretation of the provided claim value. The string MAY be
a URI.
claim_token_format OPTIONAL. An array of strings specifying a
set of acceptable formats for a token pushed by the client
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containing this claim (see Section 3.4.1.2.1). Any one of the
referenced formats would satisfy the authorization server's
requirements. Each string MAY be a URI.
issuer OPTIONAL. An array of strings specifying a set of
acceptable issuing authorities for the claim. Any one of the
referenced authorities would satisfy the authorization server's
requirements. Each string MAY be a URI.
redirect_user A Boolean value indicating whether the requesting
party's presence at the authorization server is required for the
process of claims gathering. For example, the authorization
server may require the requesting party to fill out a CAPTCHA to
help prove humanness. The default is false if this parameter is
not present. See Section 1.4 for how the authorization server
declares the requesting party claims endpoint to which the client
has the opportunity to redirect the requesting party. Note that
the word "user" implies a human requesting party; if the
requesting party is not an end-user, then no client action would
be possible on receiving the hint.
ticket The permission ticket that was in the client's request for
authorization data. If the authorization server provides the
"redirect_user" property, it MUST also provide the "ticket"
property. This helps the client avoid maintaining this state
information after the redirect.
An example of the use of these properties appears in Section 3.4.1.
The authorization server has many options for gathering requesting
party claims. For example, it could interact with an end-user
requesting party directly, or accept claims delivered by a client, or
perform a lookup in some external system. The process is extensible
and can have dependencies on the type of requesting party (for
example, natural person or legal person) or client (for example,
browser, native app, or autonomously running web service).
The client and authorization server have two nonexclusive claims-
gathering interaction patterns: push and redirect.
3.4.1.2.1. Client Pushes Claim Tokens to Authorization Server
If the client is ?claims-aware? and the authorization server can
accept pushed claims (for example, as it might have indicated by
providing "requesting_party_claims" hints described in
Section 3.4.1), the client has the option to _push_ claim tokens to
the RPT endpoint. The claim token can reflect the client's role as a
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federated identity provider, a federated relying party, or an
application integrated with a native identity repository.
If the client is aware of the authorization server's requirements for
claims through an out-of-band relationship, the client MAY push claim
tokens in an initial interaction with the RPT endpoint.
The client supplies claim tokens in the body of the authorization
data request message by providing, in addition to the "rpt" and
"ticket" properties, the following property:
claim_tokens REQUIRED. An array of objects with the following
properties:
format REQUIRED. A string specifying the format of the
accompanying claim tokens. The string MAY be a URI.
token REQUIRED. A string containing the claim information in the
indicated format, base64url encoded. If claim token format
features are included that require special interpretation, the
client and authorization server are assumed to have a prior
relationship that establishes how to interpret these features.
For example, if the referenced format equates to SAML 2.0
assertions and the claim token contains audience restrictions,
it is the joint responsibility of the client and authorization
server to determine the proper audience values that enable
successful token consumption.
Example:
POST /rpt_authorization HTTP/1.1
Host: www.example.com
Authorization: Bearer jwfLG53^sad$#f
...
{
"rpt": "sbjsbhs(/SSJHBSUSSJHVhjsgvhsgvshgsv",
"ticket": "016f84e8-f9b9-11e0-bd6f-0021cc6004de",
"claim_tokens": [
{
"format":
"http://openid.net/specs/openid-connect-core-1_0.html#HybridIDToken",
"token": "..."
}
]
}
This specification provides a framework for extensibility through
claim token format profiling. The authorization server MAY support
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any number of claim token profiles, and SHOULD document the claim
token profiles it supports in its configuration data.
3.4.1.2.2. Client Redirects Requesting Party to Authorization Server
If the client is ?claims-unaware? and the authorization server has
declared a requesting party claims endpoint in its configuration
data, or if the authorization server requires direct interaction with
the requesting party as part of its claims-gathering process (for
example, as it might have indicated through the "redirect_user" hint
described in Section 3.4.1), the client has the option to _redirect_
an end-user requesting party to the requesting party claims endpoint.
In this case, the authorization server might be a relying party in a
federated identity interaction, or it might connect to a directory or
other user repository, or even interact with the user in other ways,
such as presenting a questionnaire in a web form. After this process
completes, the authorization server redirects the end-user requesting
party back to the client.
The client constructs the request URI by adding the following
parameters to the query component of the requesting party claims
endpoint URI using the "application/x-www-form-urlencoded" format:
client_id REQUIRED. The client's identifier issued by the
authorization server.
redirect_uri OPTIONAL. The URI to which the client wishes the
authorization server to direct the requesting party's user agent
after completing its interaction. The URI MUST be absolute, MAY
contain an "application/x-www-form-urlencoded" formatted query
parameter component that MUST be retained when adding addition
parameters, and MUST NOT contain a fragment component. The
authorization server SHOULD require all clients to register their
redirection endpoint prior to utilizing the authorization
endpoint. If the URI is pre-registered, this URI MUST exactly
match one of the pre-registered redirection URIs, with the
matching performed as described in Section 6.2.1 of [RFC3986]
(Simple String Comparison).
ticket REQUIRED. The permission ticket associated with the client's
current request for authorization data for this requesting party.
The authorization server MUST return this parameter back to when
the authorization_state is need_info.
state OPTIONAL. An opaque value used by the client to maintain
state between the request and callback. The authorization server
includes this value when redirecting the user agent back to the
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client. The use of this parameter is STRONGLY RECOMMENDED for
preventing cross-site request forgery.
Example of a request issued by a client application (line breaks are
shown only for display convenience):
GET /rqp_claims?client_id=some_client_id&state=abc
&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fredirect HTTP/1.1
Host: as.example.com
At the conclusion of its interaction with the requesting party, the
authorization server returns the user agent to the client adding the
following parameters to the query component of the redirection URI
using the "application/x-www-form-urlencoded" format:
authorization_state REQUIRED. Indicates that the authorization
server completed its claims-gathering interaction with the
requesting party with the indicated state:
claims_submitted The client is free to return to the RPT endpoint
to seek authorization data once again.
not_authorized The client is not authorized to have the desired
authorization data added.
need_info The authorization server needs additional information
in order to determine whether the client is authorized to have
this authorization data. This response directs the client to
return to the RPT endpoint, where it might be provided with
error_details hints about additional information needed.
request_submitted The authorization server requires intervention
by the resource owner to determine whether authorization data
can be added. Further immediate interaction between the
client, requesting party, and authorization server is out of
scope of this specification.
ticket OPTIONAL. The same permission ticket value that the client
provided in the request. It MUST be present if and only if the
authorization_state is need_info.
state OPTIONAL. The same state value that the client provided in
the request. It MUST be present if and only if the client
provided it.
The client MUST ignore unrecognized response parameters. If the
request fails due to a missing, invalid, or mismatching redirection
URI, or if the client identifier is missing or invalid, the
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authorization server SHOULD inform the resource owner of the error
and MUST NOT automatically redirect the user agent to the invalid
redirection URI. If the request fails for reasons other than a
missing or invalid redirection URI, the authorization server informs
the client by adding an "error" parameter to the query component of
the redirection URI using the "application/x-www-form-urlencoded"
format, containing one of the following ASCII error codes:
invalid_request The request is missing a required parameter,
includes an invalid parameter value (such as an invalid or expired
ticket), includes a parameter more than once, or is otherwise
malformed.
server_error The authorization server encountered an unexpected
condition that prevented it from fulfilling the request. (This
error code is needed because an HTTP 500 (Internal Server Error)
status code cannot be returned to the client via an HTTP
redirect.)
temporarily_unavailable The authorization server is currently unable
to handle the request due to a temporary overloading or
maintenance of the server. (This error code is needed because an
HTTP 503 (Service Unavailable) status code cannot be returned to
the client via an HTTP redirect.)
4. Error Messages
Ultimately the resource server is responsible for either granting the
access the client attempted, or returning an error response to the
client with a reason for the failure. [OAuth2] defines several error
responses for a resource server to return. UMA makes use of these
error responses, but requires the resource server to "outsource" the
determination of some error conditions to the authorization server.
This specification defines additional UMA-specific error responses
that the authorization server may give to the resource server and
client as they interact with it, and that the resource server may
give to the client.
4.1. OAuth Error Responses
When a resource server or client attempts to access one of the
authorization server endpoints or a client attempts to access a
protected resource at the resource server, it has to make an
authenticated request by including an OAuth access token in the HTTP
request as described in [OAuth2] Section 7.2.
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If the request failed authentication, the authorization server or the
resource server responds with an OAuth error message as described in
this specification in Section 3.
4.2. UMA Error Responses
When a resource server or client attempts to access one of the
authorization server endpoints or a client attempts to access a
protected resource at the resource server, if the request is
successfully authenticated by OAuth means, but is invalid for another
reason, the authorization server or resource server responds with an
UMA error response by adding the following properties to the entity
body of the HTTP response:
error REQUIRED. A single error code. Values for this property are
defined throughout this specification.
error_description OPTIONAL. Human-readable text providing
additional information.
error_uri OPTIONAL. A URI identifying a human-readable web page
with information about the error.
The following is a common error code that applies to several UMA-
specified request messages:
invalid_request The request is missing a required parameter,
includes an invalid parameter value, includes a parameter more
than once, or is otherwise malformed. The authorization server
MUST respond with the HTTP 400 (Bad Request) status code.
For example:
HTTP/1.1 400 Bad Request
Content-Type: application/json
Cache-Control: no-store
...
{
"error": "invalid_request",
"error_description": "There is already a resource with this identifier.",
"error_uri": "https://as.example.com/errors/resource_exists"
}
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5. Profiles for API Extensibility
In some circumstances, it may be desirable to couple UMA roles
tightly. For example, an authorization server application might also
need to act as a client application in order to retrieve protected
resources so that it can present to resource owners a dashboard-like
user interface that accurately guides the setting of policy; it might
need to access itself-as-authorization server for that purpose. For
another example, the same organization might operate both an
authorization server and a resource server that communicate only with
each other behind a firewall, and it might seek more efficient
communication methods between them.
In other circumstances, it may be desirable to bind UMA flows to
transport mechanisms other than HTTP even if entities remain loosely
coupled. For example, in Internet of Things scenarios, Constrained
Application Protocol (CoAP) may be preferred over HTTP.
This section defines profiles that allow inter-role communications
channels and methods to vary in these circumstances. This
specification still REQUIRES authorization servers to issue PATs,
AATs, and RPTs and associate authorization data with RPTs, and
REQUIRES resource servers to give clients access only when RPTs are
associated with sufficient authorization data. This is because,
although tokens might not always appear on the wire in the normal
fashion, the tokens may represent binding obligations that involve
additional parties unable to take part in these optimization
opportunities (see [UMA-obligations]).
Where alternate communications channels are being used between
independently implemented system entities, it is RECOMMENDED, for
reasons of implementation interoperability, to define concrete
extension profiles that build on these extensibility profiles (see
Section 6.1).
5.1. Protection API Extensibility Profile
This section defines a profile for UMA where the authorization server
and resource server roles either reside in the same system entity or
otherwise have a privileged or specialized communications channel
between them. Following is a summary:
o Identifying URI: https://docs.kantarainitiative.org/uma/profiles/
prot-ext-1.0
o Profile author and contact information: Mark Dobrinic
(mdobrinic@cozmanova.com)
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o Updates or obsoletes: None; this profile is new.
o Security considerations: See below.
o Privacy considerations: See below.
o Error states: None additional.
Using this profile, the resource server MAY use means other than the
HTTP-based protection API that is protected by TLS and OAuth (or an
OAuth-based authentication protocol) to communicate with the
authorization server in all respects, including using software
interfaces and methods rather than network interfaces and APIs. The
authorization server MUST still issue PATs, AATs, and RPTs and
associate authorization data with RPTs, and the resource server MUST
still give clients access only when RPTs are associated with
sufficient authorization data. Interactions with entities other than
the authorization server or resource server MUST be preserved exactly
as they would have if either of them were using standardized UMA
APIs, unless other extensibility profiles are also in use.
An authorization server using any of the opportunities afforded by
this profile MUST declare use of this profile by supplying its
identifying URI for one of its "uma_profiles_supported" values in its
configuration data (see Section 1.4).
Same-entity communication or a tight integration of entities has the
opportunity to make deployments more secure by reducing possible
attack vectors. However, if the entities do not use TLS but
communicate across a transport layer, it is RECOMMENDED to use an
alternate means of transport-layer security, for example, using DTLS
in the case of a CoAP-based UMA profile.
Same-entity communication or a tight integration of entities has the
potential to compromise privacy by promoting the freer exchange of
personal information within a deployment ecosystem. It is
RECOMMENDED to account for privacy impacts in each deployment
scenario.
5.2. Authorization API Extensibility Profile
This section defines a profile for UMA where the authorization server
and client roles either reside in the same system entity or otherwise
have a privileged or specialized communications channel between them.
Following is a summary:
o Identifying URI: https://docs.kantarainitiative.org/uma/profiles/
authz-ext-1.0
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o Profile author and contact information: Mark Dobrinic
(mdobrinic@cozmanova.com)
o Updates or obsoletes: None; this profile is new.
o Security considerations: See below.
o Privacy considerations: See below.
o Error states: None additional.
Using this profile, the client MAY use means other than the HTTP-
based authorization API that is protected by TLS and OAuth (or an
OAuth-based authentication protocol) to communicate with the
authorization server in all respects, including using software
interfaces and methods rather than network interfaces and APIs. The
authorization server MUST still issue PATs, AATs, and RPTs and
associate authorization data with RPTs, and the resource server MUST
still give clients access only when RPTs are associated with
sufficient authorization data. Interactions with entities other than
the authorization server or client MUST be preserved exactly as they
would have if either of them were using standardized UMA APIs, unless
other extensibility profiles are also in use.
An authorization server using any of the opportunities afforded by
this profile MUST declare use of this profile by supplying its
identifying URI for one of its "uma_profiles_supported" values in its
configuration data (see Section 1.4).
Same-entity communication or a tight integration of entities has the
opportunity to make deployments more secure by reducing possible
attack vectors. However, if the entities do not use TLS but
communicate across a transport layer, it is RECOMMENDED to use an
alternate means of transport-layer security, for example, using DTLS
in the case of a CoAP-based UMA profile.
Same-entity communication or a tight integration of entities has the
potential to compromise privacy by promoting the freer exchange of
personal information within a deployment ecosystem. It is
RECOMMENDED to account for privacy impacts in each deployment
scenario.
5.3. Resource Interface Extensibility Profile
This section defines a profile for UMA where the resource server and
client roles either reside in the same system entity or otherwise
have a privileged or specialized communications channel between them.
Following is a summary:
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o Identifying URI: https://docs.kantarainitiative.org/uma/profiles/
rsrc-ext-1.0
o Profile author and contact information: Mark Dobrinic
(mdobrinic@cozmanova.com)
o Updates or obsoletes: None; this profile is new.
o Security considerations: See below.
o Privacy considerations: See below.
o Error states: None additional.
Using this profile, the resource server MAY use means other than an
HTTP-based resource interface to communicate with the authorization
server in all respects, including using software interfaces and
methods rather than network interfaces and APIs. The resource server
MUST still give clients access only when RPTs are associated with
sufficient authorization data. Interactions with entities other than
the resource server or client MUST be preserved exactly as they would
have if either of them were using standardized UMA APIs, unless other
extensibility profiles are also in use.
An authorization server involved in deployments where resource
servers and clients are known to be using opportunities afforded by
the resource interface extensibility profile MAY declare use of this
profile by supplying its identifying URI for one of its
"uma_profiles_supported" values in its configuration data (see
Section 1.4).
Same-entity communication or a tight integration of entities has the
opportunity to make deployments more secure by reducing possible
attack vectors. However, if the entities do not use TLS but
communicate across a transport layer, it is RECOMMENDED to use an
alternate means of transport-layer security, for example, using DTLS
in the case of a CoAP-based UMA profile.
Same-entity communication or a tight integration of entities has the
potential to compromise privacy by promoting the freer exchange of
personal information within a deployment ecosystem. It is
RECOMMENDED to account for privacy impacts in each deployment
scenario.
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6. Specifying Additional Profiles
This specification defines a protocol that has optional features.
For implementation interoperability and to serve particular
deployment scenarios, including sector-specific ones such as
healthcare or e-government, third parties may want to define profiles
of UMA that restrict these options.
Further, this specification creates extensibility points for RPT
profiles and claim token profiles, and third parties may likewise
want to define their own. Different RPT profiles could be used, for
example, to change the dividing line between authorization server and
resource server responsibilities in controlling access. Different
claim token profiles could be used to customize sector-specific or
population-specific (such as individual vs. employee) claim types
that drive the types of policies resource owners could set.
It is not practical for this specification to standardize all desired
profiles. However, to serve overall interoperability goals, this
section provides guidelines for third parties that wish to specify
UMA-related profiles. In all cases, it is RECOMMENDED that profiles
document the following information:
o Specify a URI that uniquely identifies the profile.
o Identify the responsible author and provide postal or electronic
contact information.
o Supply references to any previously defined profiles that the
profile updates or obsoletes.
o Define any additional or changed error states.
o Specify any conformance and interoperability considerations.
o Supply any additional security and privacy considerations.
6.1. Specifying Profiles of UMA
It is RECOMMENDED that profiles of UMA additionally document the
following information:
o Specify the set of interactions between endpoint entities involved
in the profile, calling out any restrictions on ordinary UMA-
conformant operations and any extension properties used in message
formats.
See Section 5 for examples.
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6.2. Specifying RPT Profiles
It is RECOMMENDED that RPT profiles additionally document the
following information:
o Specify the keyword to be used in HTTP Authorization headers with
tokens conforming to this profile.
o Specify the syntax and semantics of the data that the
authorization server associates with the token.
o Specify how the token data is associated with, contained within,
and/or retrieved by means of, the on-the-wire token string.
o Specify processing rules for token data.
o Identify any restrictions on grant types to be used with the token
profile.
See Section 3.3.2 for an example.
6.3. Specifying Claim Token Format Profiles
It is RECOMMENDED that claim token format profiles additionally
document the following information:
o Specify any related or additional error_details hints.
o Specify any constraints on the claim token format vs. a standard
definition for it in a specification.
o Specify any mutual interpretation details of claim token formats
by authorization servers and clients.
7. Compatibility Notes
Implementers should heed the following compatibility notes.
o This specification uses a specific draft of a specification that
is not yet final: [OAuth-introspection] (draft 04); the reference
will be updated until this "UMA V1.0 candidate" specification is
finalized. While every effort will be made to prevent breaking
changes to this specification, should they occur, UMA
implementations should continue to use the specifically referenced
draft version in preference to the final versions, unless using a
possible future UMA profile or specification that updates the
relevant references.
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o In cases where this specification is not prescriptive regarding
conformance or interoperability, any common or best practices for
implementation will be documented in the [UMA-Impl] over time.
8. Security Considerations
As a profile of OAuth, this specification relies mainly on OAuth
security mechanisms as well as transport-level encryption. Thus,
implementers are strongly advised to read the security considerations
in [OAuth2] (Section 10) and [OAuth-bearer] (Section 5) along with
the security considerations of any other OAuth token-defining
specifications in use, along with the entire [OAuth-threat]
specification, and apply the countermeasures described therein. As
well, since this specification builds on [OAuth-resource-reg],
implementers should also take into account the security
considerations in that specification.
The following sections describe additional security considerations.
8.1. Redirection and Impersonation Threats
This section discusses threats related to UMA's nature as an protocol
enabling autonomous (non-resource-owner) requesting parties to gain
authorized access to sensitive resources, including through the
process of claims-gathering redirection.
Like ordinary OAuth redirection, UMA redirection for the purpose of
gathering claims from an end-user requesting party (described in
Section 3.4.1.2.2) creates the potential for cross-site request
forgery (CSRF) through an open redirect if the authorization server
does not force the client to pre-register its redirection endpoint,
and server-side artifact tampering if the client does not avail
itself of the state parameter. The client SHOULD check that the
ticket value returned by an authorization server after a redirect is
completed has not been maliciously changed, for example by a man in
the browser (MITB), by using the state parameter. (See the
[UMA-Impl] for advice on ways to accomplish this.) Sections 4.4.1.8,
4.4.2.5, and 5.3.5 of [OAuth-threat] are apropos for the UMA claims-
gathering redirection flow as well.
When a client redirects an end-user requesting party to the
requesting party claims endpoint, the client provides no a priori
context to the authorization server about which user is appearing at
the endpoint, other than implicitly through the permission ticket.
Since the authorization server is free to gather any claims it
wishes, the effect is to "late-bind" them to the permission ticket
and the state string provided by the client, with the effect of
enabling the authorization server not to trust client-asserted
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claims. This is a desirable result and reflects one reason why the
authorization server might choose to demand use of the redirect flow
over the push flow. However, the client has the opportunity to
switch end-users -- say, enabling malicious end-user Carlos to
impersonate the original end-user Bob who approved the minting of of
the AAT -- after the redirect completes and before it returns to the
RPT endpoint to seek authorization data.
Another issue concerns the exposure of the RPT to an autonomous
requesting party, which could maliciously pass the token to an
unauthorized party.
To mitigate requesting-party switching and RPT exposure threats,
consider the following strategies.
o Require that the Requesting Party (as defined in
[UMA-obligations], meaning this party is able to take on legal
obligations) legitimately represent the wielder of the bearer
token. This solution is based on a legal or contractual approach,
and therefore does not reduce the risk from the technical
perspective.
o The authorization server, possibly with input from the resource
owner, can implement tighter time-to-live strategies around the
authorization data in RPTs. This is a classic approach with
bearer tokens that helps to limit a malicious party's ability to
intercept and use the bearer token. In the same vein, the
authorization server could require claims to have a reasonable
degree of freshness (which would require a custom claims profile).
o The strongest strategy is to disallow bearer-type RPTs within the
UMA profile being deployed, by providing or requiring an RPT
profile that requires use of a holder-of-key approach. In this
way, the wielder of the token must engage in a live session for
proof-of-possession. A less complex version of this strategy is
to "elevate trust" in the requesting party by requiring a stronger
authentication context, forcing step-up authentication by the
requesting party at run time.
8.2. Client Authentication
Along with TLS, UMA requires OAuth, or any OAuth-based authentication
protocol, as the security mechanism for its standardized APIs. The
UMA resource server acts in the role of an OAuth client at the
authorization server's protection API, and the UMA client acts in the
role of an OAuth client at the authorization server's authorization
API. While it is possible to use any profile of OAuth for this
protection, it is RECOMMENDED for the authorization server to use
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OpenID Connect, and to use its mechanisms for stronger client
authentication at the token endpoint, in order to strengthen the
authentication of OAuth clients. Section 16 of [OIDCCore] provides
more information on OpenID Connect security considerations.
Clients using the OAuth implicit grant type carry particular
vulnerabilities in OAuth, and OpenID Connect doesn't help because of
the nature of the implicit grant flow. UMA scenarios are vulnerable
as well. For example, an "implicit client" might require the
retrieval of AATs more frequently, for each browser on each platform.
An attacker can initiate a spear phishing attack on the requesting
party with a link to a malicious website, relying on the requesting
party to authenticate to the authorization server through an email-
based identity provider in order to receive the AAT. The site can
impersonate the requesting party using the browser client's client ID
in an OpenID Connect implicit request to the UMA authorization
server. If the requesting party had previously given consent for an
AAT to be issued, this attempt will likely succeed. The subsequently
issued AAT and permission ticket for an attempted resource access
could potentially be used for RPT retrieval and authorization data
issuance.
A number of mitigation strategies are possible.
o The authorization server could penalize or disallow use of the
implicit grant flow. This could be done at a variety of levels:
* Enabling resource owners to define policies controlling the use
of such clients
* Setting system-default policies controlling their use
* Participating in mutual agreements with other parties that
admit only suitably secure client applications to interact with
service operators
o The authorization server could support dynamic client registration
at the client instance level, such that each instance receives a
unique client_id and secret. The client can then use the
authorization code flow and have at least some form of client
authentication. However, this is easier for a mobile app than for
a browser-based HTML app.
8.3. JSON Usage
This specification defines a number of data formats based on [JSON].
As a subset of the JavaScript scripting language, JSON data SHOULD be
consumed through a process that does not dynamically execute it as
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code, to avoid malicious code execution. One way to achieve this is
to use a JavaScript interpreter rather than the built-in JavaScript
eval() function.
8.4. Profiles, Binding Obligations, and Trust Establishment
Parties operating and using UMA software entities have opportunities
to establish agreements about mutual rights, responsibilities, and
common interpretations of UMA constructs for consistent and expected
software behavior. These agreements can be used to improve the
parties' respective security postures, and written profiles are a key
mechanism for conveying and enforcing these agreements. Section 6
discusses profiling. Section 5 discusses profiling for
extensibility. [UMA-obligations] discusses the development of
binding obligations.
9. Privacy Considerations
The authorization server comes to be in possession of resource set
information that may reveal information about the resource owner,
which the authorization server's trust relationship with the resource
server is assumed to accommodate. However, the client is a less-
trusted party -- in fact, entirely untrustworthy until authorization
data is associated with its RPT. The more information about a
resource set that is registered, the more risk of privacy compromise
there is through a less-trusted authorization server.
The primary privacy duty of UMA's design is to the resource owner.
However, privacy considerations affect the requesting party as well.
This can be seen in the issuance of an AAT, which represents the
approval of a requesting party for a client to engage with an
authorization server to perform tasks needed for obtaining
authorization, possibly including pushing claim tokens.
Parties operating and using UMA software entities have opportunities
to establish agreements about mutual rights, responsibilities, and
common interpretations of UMA constructs for consistent and expected
software behavior. These agreements can be used to improve the
parties' respective privacy postures. For information about the
additional technical, operational, and legal elements of trust
establishment, see [UMA-obligations]. Additional considerations
related to Privacy by Design concepts are discussed in [UMA-PbD].
10. IANA Considerations
This document makes the following requests of IANA.
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10.1. JSON Web Token Claims Registration
This specification registers the claim defined in Section 3.3.2.
10.1.1. Registry Contents
o Claim name: permissions
o Claim description: Array of objects, each describing a set of
scoped, time-limitable entitlements to a resource set
o Change controller: Kantara Initiative User-Managed Access Work
Group - wg-uma@kantarainitiative.org
o Specification document: Section 3.3.2 in this document
10.2. Well-Known URI Registration
This specification registers the well-known URI defined in
Section 1.4.
10.2.1. Registry Contents
o URI suffix: uma-configuration
o Change controller: Kantara Initiative User-Managed Access Work
Group - wg-uma@kantarainitiative.org
o Specification document: Section 1.4 in this document
11. Acknowledgments
The following people made significant text contributions to the
specification:
o Paul C. Bryan, ForgeRock US, Inc. (former editor)
o Mark Dobrinic, Cozmanova
o George Fletcher, AOL
o Lukasz Moren, Cloud Identity Ltd
o Christian Scholz, COMlounge GmbH (former editor)
o Mike Schwartz, Gluu
o Jacek Szpot, Newcastle University
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Additional contributors to this specification include the Kantara UMA
Work Group participants, a list of whom can be found at
[UMAnitarians].
12. References
12.1. Normative References
[DynClientReg]
Richer, J., "OAuth 2.0 Core Dynamic Client Registration",
December 2014,
<http://tools.ietf.org/html/draft-ietf-oauth-dyn-reg>.
[JSON] Bray, T., "The JavaScript Object Notation (JSON) Data
Interchange Format", March 2014,
<https://tools.ietf.org/html/rfc7159>.
[JWT] Jones, M., "JSON Web Token (JWT)", December 2014,
<http://datatracker.ietf.org/doc/
draft-ietf-oauth-json-web-token/>.
[OAuth-bearer]
"The OAuth 2.0 Authorization Framework: Bearer Token
Usage", October 2012,
<http://tools.ietf.org/html/rfc6750>.
[OAuth-introspection]
Richer, J., "OAuth Token Introspection", December 2014,
<http://tools.ietf.org/html/
draft-ietf-oauth-introspection-04>.
[OAuth-resource-reg]
Hardjono, T., "OAuth 2.0 Resource Set Registration",
February 2015, <https://tools.ietf.org/html/draft-
hardjono-oauth-resource-reg>.
[OAuth-threat]
Lodderstedt, T., "OAuth 2.0 Threat Model and Security
Considerations", January 2013,
<http://tools.ietf.org/html/rfc6819>.
[OAuth2] Hardt, D., "The OAuth 2.0 Authorization Framework",
October 2012, <http://tools.ietf.org/html/rfc6749>.
[OIDCCore]
Sakimura, N., "OpenID Connect Core 1.0 incorporating
errata set 1", November 2014,
<http://openid.net/specs/openid-connect-core-1_0.html>.
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[OIDCDynClientReg]
Sakimura, N., "OpenID Connect Dynamic Client Registration
1.0 incorporating errata set 1", November 2014,
<http://openid.net/specs/
openid-connect-registration-1_0.html>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3986] Berners-Lee, T., "Uniform Resource Identifier (URI):
Generic Syntax", January 2005,
<http://www.ietf.org/rfc/rfc3986.txt>.
[RFC6711] Johansson, L., "An IANA Registry for Level of Assurance
(LoA) Profiles", August 2012,
<https://tools.ietf.org/html/rfc6711>.
[hostmeta]
Hammer-Lahav, E., "Web Host Metadata", October 2011,
<http://tools.ietf.org/html/rfc6415>.
12.2. Informative References
[UMA-Impl]
Maler, E., "UMA Implementer's Guide", December 2014,
<http://kantarainitiative.org/confluence/display/uma/
UMA+Implementer%27s+Guide>.
[UMA-PbD] Maler, E., "Privacy by Design Implications of UMA",
December 2013,
<http://kantarainitiative.org/confluence/display/uma/
Privacy+by+Design+Implications+of+UMA>.
[UMA-casestudies]
Maler, E., "UMA Case Studies", April 2014,
<http://kantarainitiative.org/confluence/display/uma/
Case+Studies>.
[UMA-obligations]
Maler, E., "Binding Obligations on UMA Participants",
January 2013, <http://docs.kantarainitiative.org/uma/
draft-uma-trust.html>.
[UMA-usecases]
Maler, E., "UMA Scenarios and Use Cases", October 2010,
<http://kantarainitiative.org/confluence/display/uma/
UMA+Scenarios+and+Use+Cases>.
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[UMAnitarians]
Maler, E., "UMA Participant Roster", December 2014,
<http://kantarainitiative.org/confluence/display/uma/
Participant+Roster>.
Authors' Addresses
Thomas Hardjono (editor)
MIT
Email: hardjono@mit.edu
Eve Maler
ForgeRock
Email: eve.maler@forgerock.com
Maciej Machulak
Cloud Identity
Email: maciej.machulak@cloudidentity.co.uk
Domenico Catalano
Oracle
Email: domenico.catalano@oracle.com
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