The XAuth Protocol
draft-hardt-xauth-protocol-01
The information below is for an old version of the document.
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| Author | Dick Hardt | ||
| Last updated | 2020-01-30 | ||
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draft-hardt-xauth-protocol-01
Network Working Group D. Hardt, Ed.
Internet-Draft SignIn.Org
Intended status: Standards Track 29 January 2020
Expires: 1 August 2020
The XAuth Protocol
draft-hardt-xauth-protocol-01
Abstract
Client software often desires resources or identity claims that are
managed independent of the client. This protocol allows a user and/
or resource owner to delegate resource authorization and/or release
of identity claims to an authorization server. Client software can
then request access to resources and/or identity claims by calling
the authorization server. The authorization server acquires consent
and authorization from the user and/or resource owner if required,
and then returns the authorization and identity claims that were
approved. This protocol can be extended to support alternative
client authentication mechanisms, authorizations, claims, and
interactions.
[Editor: suggestions on how to improve this are welcome!]
[Editor: suggestions for other names than XAuth are welcome!]
Note to Readers
Source for this draft and an issue tracker can be found at
https://github.com/dickhardt/hardt-xauth-protocol
(https://github.com/dickhardt/hardt-xauth-protocol).
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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Internet-Drafts are draft documents valid for a maximum of six months
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time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on 1 August 2020.
Copyright Notice
Copyright (c) 2020 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 (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Parties . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Handles . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. Reused Terms . . . . . . . . . . . . . . . . . . . . . . 5
2.4. Sequence . . . . . . . . . . . . . . . . . . . . . . . . 6
3. AS Request JSON . . . . . . . . . . . . . . . . . . . . . . . 8
3.1. Top Level Attributes . . . . . . . . . . . . . . . . . . 11
3.2. "client" Object . . . . . . . . . . . . . . . . . . . . . 11
3.3. "user" Object . . . . . . . . . . . . . . . . . . . . . . 12
3.4. "authentication" Object . . . . . . . . . . . . . . . . . 13
3.5. "authorizations" Object . . . . . . . . . . . . . . . . . 13
3.6. "claims" Object . . . . . . . . . . . . . . . . . . . . . 14
3.7. Authorization Types . . . . . . . . . . . . . . . . . . . 14
4. Interaction Response JSON . . . . . . . . . . . . . . . . . . 14
4.1. "user" Object . . . . . . . . . . . . . . . . . . . . . . 15
4.2. "interaction" Object . . . . . . . . . . . . . . . . . . 15
4.3. "authorization" Object . . . . . . . . . . . . . . . . . 16
4.4. "authentication" Object . . . . . . . . . . . . . . . . . 16
5. Interaction Types . . . . . . . . . . . . . . . . . . . . . . 16
5.1. "popup" Type . . . . . . . . . . . . . . . . . . . . . . 16
5.2. "redirect" Type . . . . . . . . . . . . . . . . . . . . . 17
5.3. "qrcode" Type . . . . . . . . . . . . . . . . . . . . . . 17
6. AS Response JSON . . . . . . . . . . . . . . . . . . . . . . 17
6.1. Top Level Attributes . . . . . . . . . . . . . . . . . . 18
6.2. "authorizations" Object . . . . . . . . . . . . . . . . . 18
6.3. "claims" Object . . . . . . . . . . . . . . . . . . . . . 19
6.4. Access Methods . . . . . . . . . . . . . . . . . . . . . 20
7. Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8. JOSE Client Authentication . . . . . . . . . . . . . . . . . 20
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8.1. JOSE Headers . . . . . . . . . . . . . . . . . . . . . . 21
8.2. Authentication Request Token . . . . . . . . . . . . . . 23
8.3. Authorization Request Token . . . . . . . . . . . . . . . 24
8.4. Refresh Token . . . . . . . . . . . . . . . . . . . . . . 25
8.5. JOSE Access Token . . . . . . . . . . . . . . . . . . . . 25
8.6. HTTP Authorization JOSE Header . . . . . . . . . . . . . 26
8.7. JOSE Token Verification . . . . . . . . . . . . . . . . . 26
8.8. AS Request . . . . . . . . . . . . . . . . . . . . . . . 26
8.9. Interaction Response . . . . . . . . . . . . . . . . . . 26
8.10. Deletion Request . . . . . . . . . . . . . . . . . . . . 27
8.11. Authentication Request . . . . . . . . . . . . . . . . . 27
8.12. Authentication Response . . . . . . . . . . . . . . . . . 27
8.13. Authorization Request . . . . . . . . . . . . . . . . . . 27
8.14. AS Response . . . . . . . . . . . . . . . . . . . . . . . 28
8.15. Bearer Token RS Access . . . . . . . . . . . . . . . . . 28
8.16. Proof-of-possession RS Access . . . . . . . . . . . . . . 29
8.17. JOSE Body RS Access . . . . . . . . . . . . . . . . . . . 29
8.18. Access Refresh . . . . . . . . . . . . . . . . . . . . . 29
9. Error Messages . . . . . . . . . . . . . . . . . . . . . . . 30
10. AS Initiated Sequence . . . . . . . . . . . . . . . . . . . . 30
10.1. Initiation Token . . . . . . . . . . . . . . . . . . . . 32
11. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 32
12. Rational . . . . . . . . . . . . . . . . . . . . . . . . . . 33
13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 36
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36
15. Security Considerations . . . . . . . . . . . . . . . . . . . 36
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 36
16.1. Normative References . . . . . . . . . . . . . . . . . . 36
16.2. Informative References . . . . . . . . . . . . . . . . . 38
Appendix A. Document History . . . . . . . . . . . . . . . . . . 39
A.1. draft-hardt-xauth-protocol-00 . . . . . . . . . . . . . . 39
A.2. draft-hardt-xauth-protocol-01 . . . . . . . . . . . . . . 39
Appendix B. Comparison with OAuth 2.0 and OpenID Connect . . . . 39
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction
This protocol supports the widely deployed use cases supported by
OAuth 2.0 [RFC6749] & [RFC6750], and OpenID Connect [OIDC], an
extension of OAuth 2.0, as well as other extensions, and other use
cases that are not supported, such as requesting multiple
authorizations in one request. This protocol also addresses many of
the security issues in OAuth 2.0 by having parameters securely sent
directly between parties, rather than via a browser redirection.
The technology landscape has changed since OAuth 2.0 was initially
drafted. More interactions happen on mobile devices than PCs.
Modern browsers now directly support asymetric cryptographic
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functions. Standards have emerged for signing and encrypting tokens
with rich payloads (JOSE) that are widely deployed.
Additional use cases are now being served with extensions to OAuth
2.0: OpenID Connect added support for authentication and releasing
identity claims; [RFC8252] added support for native apps; [RFC8628]
added support for smart devices; and support for [browser_based_apps]
is being worked on. There are numerous efforts on adding proof-of-
possession to resource access.
This protocol simplifies the overall architectural model, takes
advantage of today's technology landscape, provides support for all
the widely deployed use cases, and offers numerous extension points.
The
While this protocol is not backwards compatible with OAuth 2.0, it
strives to minimize the migration effort.
2. Protocol
2.1. Parties
* *Authorization Server* (AS) - manages Client authorization to API
resources and release of identity claims about the User. The AS
may require explicit consent from the RO or User to provide these
to the Client.
* *Client* - requests authorization to API resources, and/or
identity claims about the User. There are two types of Clients:
Registered Clients and Dynamic Clients. An AS may support only
one or both types. All Clients have a key to authenticate with
the AS.
* *Registered Client* - a Client that has registered with the AS and
has a Client ID to identify itself, and can prove it possesses a
key that is linked to the Client ID. The AS may have different
policies for what different Registered Clients can request. The
Client MAY be interacting with a User.
* *Dynamic Client* - a Client that has not been registered with the
AS, and each instance will generate it's own key pair so it can
prove it is the same instance of the Client on subsequent
requests. A single-page application with no server is an example
of a Dynamic Client. The Client MUST be interacting with a User.
* *User* - the person who has delegated making identity claims about
themselves to the AS, and is interacting with the Client.
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* *Resource Server* (RS) - has API resources that require an access
token from the AS for access.
* *Resource Owner* (RO) - owns the RS, and has delegated RS access
token creation to the AS. The RO may be the same entity as the
User, or may be a different entity that the AS interacts with
independent of the Client.
2.2. Handles
Handles are strings issued by the AS to the Client that are opaque to
the Client.
* *authorization handle* - represents the client request. Presented
back to the AS in an Authorization Request.
* *authentication handle* - represents the client request for
authentication first. Presented back to the AS in an
Authentication Request, or in the subsequent AS Request.
* *access handle* - represents the access the AS has granted the
Client to the RS. The Client proves possession of its key when
presenting an access handle to access an RS. The RS is able to
understand the authorizations represented by the access handle
directly, or through an introspection call. The RS is able to
verify the access handle was issued to the Client that presented
it.
* *refresh handle* - represents the access the AS has granted the
Client to a RS. Presented back to the AS when the Client wants a
fresh access token or access handle.
When presenting any of the above handles, the Client always proves
possession of its key.
2.3. Reused Terms
* *access token* - an access token as defined in [RFC6749]
Section 1.4.
* *Claims* - Claims as defined in [OIDC] Section 5.
* *Client ID* - an AS unique identifier for a Registered Client as
defined in [RFC6749] Section 2.2.
* *ID Token* - an ID Token as defined in [OIDC] Section 2.
* *NumericDate* - a NumericDate as defined in [RFC7519] Section 2.
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2.4. Sequence
1. *AS Discovery* (Section 7) The Client discovers the AS end
point, keys, supported claims and authorizations, and other
capabilities. Some, or all of this information could be
manually preconfigured, or dynamically obtained. Dynamic AS
discovery is out of scope of this document.
2. *AS Request* (Section 8.8) The Client creates an AS Request
(Section 3) for authorization to API resources and/or identity
claims about the User and sends it with an HTTP POST to the AS
endpoint. The Client includes requests authentication first if
the Client wants the AS to authenticate the User prior to
requesting additional claims and authorizations.
3. *AS Request Evaluation* The AS processes the request and
determines if it needs to interact with the RO or User. If
interaction is required, the AS returns an Interaction Response
(Section 4), if no interaction is required it returns an AS
Response (Section 6).
4. *Interaction Response* (Section 8.9) The AS will send an
authentication object unless the Client sent authentication
first, in which case the AS will send an authentication object.
If the AS wants the Client to initiate the User interaction, it
will include an interaction object. If authentication first,
the Client will next send (6) Authentication Request, otherwise
an Authorization Request.
5. *Authorization Request* (Section 8.13) The Client creates an
authorization request token Section 8.3 and does a GET of the
authorization uri, after waiting for any authorization wait
time. The Client then listens for (13) AS Response.
6. *Authentication Request* (Section 8.11) The Client creates an
authentication request token and does a GET of the
authentication uri. The Client then listens for (9)
Authentication Response.
7. *Interaction* If the AS sent interaction instructions to the
Client, the Client executes them.
8. *User Authentication* The AS authenticates the User. If Client
requested authentication first, the AS responds to the
Authentication Request with an (9) Authentication Response,
otherwise the AS performs any needed authorizations per step
(10).
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9. *Authentication Response* (Section 8.12) The AS sends an AS
Response containing the identity claims the Client requested.
10. *AS Request 2* The Client uses the returned identity claims to
look up the User in its internal database and determines what,
if any, claims and/or authorizations it would like to request
and includes them in a new AS Request, as well as the
authentication handle. If Client wants not additional claims
and/or authorizations, the Client sets the claims object to the
JSON null value. The Client then listens for (13) AS Response.
11. *Authorization* If required, the AS interacts with the User and/
or RO to determine which of any of the authorizations and
identity claims requests made by the Client are to be granted.
12. *Redirect* If the Client did a full browser redirect to the AS,
the AS redirects the User back to the redirect_uri supplied by
the Client, otherwise the AS closes its popup window, or informs
the User the interaction is complete.
13. *AS Response* (Section 8.14) The AS responds to the Client with
a AS Response (Section 6) containing authorized RS access tokens
and User identity claims. The AS may provide refresh handles
and uris for each access token if they are authorized. If
proof-of-possession is required for accessing the RS, the AS
will provide access handles instead of access tokens. If the AS
has not completed the interaction, it will instead return a
retry response for the Client to make a new Authorization
Request.
14. *Resource Request* (Section 8.15, Section 8.16, & Section 8.17)
The Client access the RS using a bearer token, a proof-of-
possession token, or a signed request.
15. *Access Refresh* (Section 8.18) If the Client received a refresh
handle and uri, it sends the refresh handle to the refresh uri,
and receives a fresh access token or handle.
*Sequence Diagram*
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+--------+ +---------------+
| |<-(1)------- Discovery ------------------->| Authorization |
| | | Server |
| |--(2)------- AS Request ------------------>| |
| | | (3) Request |
| | | Evaluation |
| |<-(4)------- Interaction Response ---------| |
| | | |
| |--(5)------- Authorization Request ------->| -------+ |
| | or | | |
| |--(6)------- Authentication Request ------>| ---+ | |
| | | | | |
| | +--------+ | | | |
| |--(7)--------->| User |<------------(8)--| | | |
| | Interaction +--------+ Authentication | | | |
| Client | | | | |
| | | | | |
| |<-(9)------- Authentication Response ------|<---+ | |
| | | | |
| |--(10)------ AS Request 2 ---------------->| -------+ |
| | | | |
| | +--------+ | | |
| |<-(12)---------| User |<-----------(11)--| | |
| | Redirect | / RO | Authorization | | |
| | +--------+ | | |
| | | | |
| |<-(13)------ AS Response ------------------|<-------+ |
| | | |
| | +----------+ | |
| |--(14)-- Resource Request -->| Resource | | |
| |<------ Resource Response ---| Server | | |
| | +----------+ | |
| | | |
| |--(15)------- Refresh Request ------------>| |
| |<----------- Refresh Response -------------| |
+--------+ +---------------+
3. AS Request JSON
Following is a non-normative JSON [RFC8259] document example where
the Client wants to interact with the User with a popup and is
requesting identity claims about the User and read access to the
User's contacts:
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Example 1
{
"as" :"https://as.example",
"iat" :"1579046092",
"nonce" :"f6a60810-3d07-41ac-81e7-b958c0dd21e4",
"client": {
"display": {
"name" :"SPA Display Name",
"uri" :"https://spa.example/about"
},
"interaction": {
"type" :"popup"
}
},
"authorizations": {
"type" :"oauth_scope",
"scope" :"read_contacts"
},
"claims": {
"oidc": {
"id_token" : {
"email" : { "essential" : true },
"email_verified" : { "essential" : true }
},
"userinfo" : {
"name" : { "essential" : true },
"picture" : null
}
}
}
}
Following is a non-normative example where the Client has previously
authenticated the User, and is requesting additional authorization:
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Example 2
{
"as" :"https://as.example",
"iat" :"1579046092",
"nonce" :"0d1998d8-fbfa-4879-b942-85a88bff1f3b",
"client": {
"id" : "di3872h34dkJW",
"interaction": {
"type" : "redirect",
"uri" : "https://web.example/return"
}
},
"user": {
"identifiers": {
"oidc": {
"iss" :"https://as.example",
"sub" :"123456789"
}
}
},
"authorizations": {
"type" :"oauth_scope",
"scope" :"read_calendar write_calendar"
}
}
Following is a non-normative example where the Client is requesting
authorization first:
Example 3
{
"as" :"https://as.example",
"iat" :"1579046092",
"nonce" :"5c9360a5-9065-4f7b-a330-5713909e06c6",
"client": {
"id" : "di3872h34dkJW",
"interaction": {
"type" : "redirect",
"uri" : "https://web.example/return"
}
},
"authentication": {
"first": true
},
"claims": { "oidc": { "id_token" : {} } }
}
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Following is a non-normative example where the Client previously
requested authorization first (Example 3), the response was a new
User, and now makes the following AS Request:
Example 4
{
"as" :"https://as.example",
"iat" :"1579046092",
"nonce" :"0a74f51f-514a-4821-b71f-01c252223f2f",
"authentication": {
"handle": "eyJhb958.example.authentication.handle.9yf3szM"
},
"claims": {
"oidc": {
"userinfo" : {
"email" : { "essential" : true },
"phone_number" : { "essential" : true },
"name" : { "essential" : true },
"picture" : null
}
}
}
}
3.1. Top Level Attributes
*as* - the unique string identifier for the AS. This attribute is
REQUIRED.
*iat* - the time of the request as a NumericDate.
*nonce* - a unique identifier for this request. This attribute is
REQUIRED. Note the AS Response MUST contain a matching nonce
attribute.
3.2. "client" Object
The client object MUST contain either the client_id attribute for
Registered Clients, or the display object for Dynamic Clients. If
the Client can interact with the User, then an interaction object
MUST be included. If there is an authentication handle, then the
client object MUST not be included.
*client_id* - the identifier the AS has for the Registered Client.
*display* - the display object contains the following attributes:
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* *name* - a string that represents the Dynamic Client
[Editor: a max length for the name?]
* *uri* - a URI representing the Dynamic Client
[Editor: a max length for the URI?]
The name and uri will be displayed by the AS when prompting for
authorization.
*interaction* - the interaction object contains the type of
interaction the Client will provide the User. Other attributes are
dependent on the interaction type value.
* *type* - contains one of the following values: "popup",
"redirect", or "qrcode". Details in Section 5.
* *redirect_uri* - this attribute is included if the type is
"redirect". It is the URI that the Client requests the AS to
redirect the User to after the AS has completed interacting with
the User. If the Client manages session state in URIs, then the
redirect_uri should contain that state.
* *ui_locales* - End-User's preferred languages and scripts for the
user interface, represented as a space-separated list of [RFC5646]
language tag values, ordered by preference.
[Editor: do we need max pixels or max chars for qrcode interaction?
Either passed to AS, or max specified values here?]
[Editor: other possible interaction models could be a "webview",
where the Client can display a web page, or just a "message", where
the client can only display a text message]
[Editor: we may need to include interaction types for iOS and Android
as the mobile OS APIs evolve.]
[Editor: does the Client include parameters if it wants the AS
Response signed and/or encrypted?]
3.3. "user" Object
The user object is optional.
*identifiers* - the identifiers object contains one or more of the
following identifiers for the User:
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* *phone_number* - contains a phone number per Section 5 of
[RFC3966].
* *email* - contains an email address per [RFC5322].
* *oidc* - is an object containing both the "iss" and "sub"
attributes from an OpenID Connect ID Token per [OIDC] Section 2.
The user and identifiers objects MAY be included to improve the user
experience by the AS. The AS MUST authenticate the User independent
of these values. The user object MUST not be included if there is an
authentication handle.
*discovery* - MUST contain the JSON true value. Indicates the Client
requests the AS to return a "discovered" attribute in the Interaction
Response if the AS has a User at the AS with one or more of the
identifiers. This attribute is OPTIONAL. Support of the discovery
attribute by the AS is OPTIONAL. The AS MAY return the [TBD] error
if discovery is not supported, or ignore the request.
3.4. "authentication" Object
This OPTIONAL object MUST contain one of the following attributes:
* *first* - Must have the JSON value true. Indicates the Client is
requesting authentication first, and an authentication object in
the Interaction Response. If present, the AS will ignore the
authorizations object. [Editor: any use case where the Client
needs an authorization at Authentication?] The Client SHOULD
limit the claims requested to only those needed to identify the
User at the Client. [Editor: this works if it is only a directed
identifier, but consent would be required to return a verified
phone or email. Hmmm.]
* *handle* - the authentication handle. MUST be included in the AS
Request following an Authentication Response.
3.5. "authorizations" Object
The optional authorizations object contains a dictionary of resource
objects the Client is requesting authorization to access. The
authorizations object may contain one or more of:
* *type* - one of the following values: "oauth_scope", "oauth_rich",
or "oauth_rich_list". See Section 3.7 for details.
* *scope* - a string containing the OAuth 2.0 scope per [RFC6749]
section 3.3. Present if type is "oauth_scope" or "oauth_rich".
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* *authorization_details* - an authorization_details object per
[RAR]. Present if type is "oauth_rich".
* *list* - an array of objects containing "scope" and
"authorization_details". Present if type is "oauth_rich_list".
Used when requesting multiple access tokens and/or handles.
[Editor: details may change as the [RAR] document evolves]
3.6. "claims" Object
The optional claims object contains one or more identity claims being
requested. The claims may contain:
* *oidc* - an object that contains one or both of the following
objects:
- *userinfo* - Claims that will be returned as a JSON object
- *id_token* - Claims that will be included in the returned ID
Token. If the null value, an ID Token will be returned
containing no additional Claims.
The contents of the userinfo and id_token objects are Claims as
defined in [OIDC] Section 5.
* *oidc4ia* - OpenID Connect for Identity Assurance claims request
per [OIDC4IA].
* *vc* - [Editor: define how W3C Verifiable Credentials [W3C_VC] can
be requested.]
3.7. Authorization Types
* *oauth_scope* - an OAuth 2.0 authorization request per [RFC6749]
section 3.3
* *oauth_rich* - a rich authorization request per [RAR]
* *oauth_rich_list* - a list of rich authorization requests
4. Interaction Response JSON
A non-normative example of an Interaction Response follows:
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{
"user": {
"discovered": true
},
"interaction": {
"type" : "popup",
"uri" : "https://as.example/endpoint/ey5gs32..."
},
"authorization": {
"handle" : "eyJhb958.example.authorization.handle.9yf3szM",
"uri" : "https://as.example/authorization/ey7snHGs",
"wait" : "10"
}
}
4.1. "user" Object
MUST contain one of "authorization" object, or "authentication"
object.
* *discovery* - if the AS Request included a discovery attribute,
then the AS MAY return a "user" object with the "discovered"
property set to the JSON value true if one or more of the
identifiers provided in the AS Request identify a User at the AS,
or the JSON value false if not. If the Client received a false
return, it may
[Editor: reference a security consideration for this functionality.]
4.2. "interaction" Object
If the AS wants the Client to start the interaction, the AS MUST
select one of the interaction mechanisms provided by the Client in
the AS Request, and include the matching attribute in the interaction
object:
* *type* - this MUST match the type provided by the Client in the AS
Request client.interaction object.
* *uri* - the URI to interact with the User per the type. This may
be a temporary short URL if the type is qrcode so that it is easy
to scan.
* *message* - a text string to display to the User if type is
qrcode.
[Editor: do we specify a maximum length for the uri and message so
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that a device knows the maximum it needs to support? A smart device
may have limited screen real estate.]
4.3. "authorization" Object
The authorization object has the following attributes:
* *handle* - the authorization handle. This attribute is REQUIRED.
* *uri* - the authorization URI. This attribute is REQUIRED.
* *wait* - the amount of time in integer seconds the Client MUST
wait before making the Authorization Request. This attribute is
OPTIONAL.
4.4. "authentication" Object
Returned if the Client requested authentication first. The
authentication object has the following attributes:
* *handle* - the authentication handle. This attribute is REQUIRED.
* *uri* - the authentication URI. This attribute is REQUIRED.
5. Interaction Types
If the AS wants the Client to initiate the interaction with the User,
then the AS will return an interaction object Section 4.2 so that the
Client can can hand off interactions with the User to the AS. The
Client will initiate the interaction with the User in one of the
following ways:
5.1. "popup" Type
The Client will create a new popup child browser window containing
the value of the uri attribute of the interaction object. [Editor:
more details on how to do this]
The AS will close the window when the interactions with the User are
complete. [Editor: confirm AS can do this still on all browsers, or
does Client need to close]
The AS MAY respond to an outstanding Authorization Request
Section 8.13 before the popup window has been closed.
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5.2. "redirect" Type
The Client will redirect the User to the value of the uri attribute
of the interaction object. When the AS interactions with the User
are complete, the AS will redirect the User to the redirect_uri the
Client provided in the AS Request.
If the Client made a Authorization Request when starting the
interaction, the AS MAY respond to the Authorization Request
Section 8.13 before the User has been redirected back to the Client.
5.3. "qrcode" Type
The Client will create a [QR_Code] of the uri attribute of the
interaction object and display the resulting graphic and the message
attribute of the interaction object as a text string.
6. AS Response JSON
Example non-normative AS Response JSON document for Example 1 in
Section 3:
{
"iat":"15790460234",
"nonce":"f6a60810-3d07-41ac-81e7-b958c0dd21e4",
"authorizations": {
"type" : "oauth_scope",
"scope" : "read_contacts",
"expires_in" : "3600",
"method" : "bearer",
"token" : "eyJJ2D6.example.access.token.mZf9p"
},
"claims": {
"oidc": {
"id_token" : "eyJhbUzI1N.example.id.token.YRw5DFdbW",
"userinfo" : {
"name" : "John Doe",
"picture" : "https://photos.example/p/eyJzdkiO"
}
}
}
}
Example non-normative AS Response JSON document for Example 2 in
Section 3:
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{
"iat" :"15790460234",
"nonce" :"0d1998d8-fbfa-4879-b942-85a88bff1f3b",
"authorizations": {
"type" : "oauth_scope",
"scope" : "read_calendar write_calendar",
"expires_in" : "3600",
"method" : "pop",
"access": {
"handle" : "ey.example.access.handle.9yf3szM",
"jwk": {
"x5u" : "https://as.example/jwk/VBUEOIQA82"
}
},
"refresh": {
"handle" : "ey.example.refresh.handle.Jl4FzM",
"uri" : "https://as.example/refresh/eyj34"
}
}
}
Details of the JSON document:
6.1. Top Level Attributes
*iat* - the time of the response as a NumericDate.
*nonce* - the nonce that was included in the AS Request JSON
Section 3.
6.2. "authorizations" Object
There is an authorizations object in the AS Response if there was an
authorizations object in the AS Request.
* *type* - the type of claim request: "oauth_scope", "oauth_rich",
or "oauth_rich_list". See Section 3.7 for details.
* *list* - an array of objects if the type was "oauth_rich_list".
The objects have the following attributes just as if the type was
"oauth_rich"
* *scope* - the scopes the Client was granted authorization for.
This will be all, or a subset, of what was requested.
* *authorization_details* - the authorization details granted. Only
returned for "oauth_rich" and "oauth_rich_list".
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* *method* - the access method: "bearer", "pop", or "jws". See
Section 6.4 for details.
* *token* - an access token for accessing the resource(s). Included
if the access method is "bearer".
* *expires_in* - an optional value specifying how many seconds until
the access token or handle expire.
* *refresh* - an optional object containing parameters required to
refresh an access token or handle. See refresh request
Section 8.18.
- *handle* - an refresh handle used to create the JSON refresh
token.
- *uri* - the refresh uri the Client will use to refresh.
* *access* - an object containing the parameters needed to access
resources requiring proof-of-possession. Included if the access
method is "pop".
- *handle* - the access handle.
- *jwk* - the jwk object to use.
6.3. "claims" Object
There is a claims object in the AS Response if there was a claims
object in the AS Request.
* *oidc*
- *id_token* - an OpenID Connect ID Token containing the Claims
the User consented to be released.
- *userinfo* - the Claims the User consented to be released.
Claims are defined in [OIDC] Section 5.
* *oidc4ia* - OpenID Connect for Identity Assurance claims response
per [OIDC4IA].
* *vc*
The verified claims the user consented to be released. [Editor:
details TBD]
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6.4. Access Methods
The are three different methods for the Client to access an RS:
* *bearer* - the AS provides a bearer access token that the Client
can use to access an RS per Section 8.15.
* *pop* - the AS provides an access handle that the Client presents
in a proof-of-possession RS access request per Section 8.16.
* *pop_body* - the Client signs the JSON payload sent to the RS per
Section 8.17.
In the AS Response, the AS will return the method the Client MUST use
when accessing the RS.
7. Discovery
The Client obtains the following metadata about the AS prior to
initiating a request:
*Endpoint* - the endpoint of the AS.
*"as"* - the unique string identifier for the AS.
*Algorithms* - the asymetric cryptographic algorithms supported by
the AS.
*Authorizations* - the authorizations the Client may request, if any.
*Identity Claims* - the identity claims the Client may request, if
any, and what public keys the claims will be signed with.
The client may also obtain information about how the AS will sign
and/or encrypt the AS Response, as well as any other metadata
required for extensions to this protocol, as defined in those
extension specifications.
8. JOSE Client Authentication
The default mechanism for the Client to authenticate to the AS and
the RS is signing a JSON document with JWS per [RFC7515]. The
resulting tokens always use compact serialization.
It is expected that extensions to this protocol that specify a
different mechanism for the Client to authenticate, would over ride
this section.
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The Authorization Request JSON is signed with JWS and passed as the
body of the POST.
The authorization, refresh, and access handles are signed with JWS
resulting in authorization request, refresh, and access tokens
respectively. These JOSE tokens are passed in the HTTP Authorization
header with the "JOSE" parameter per Section 8.6.
The Client will use the same private key to create all tokens.
The Client and the AS MUST both use HTTP/2 ([RFC7540]) or later, and
TLS 1.3 ([RFC8446]) or later, when communicating with each other.
[Editor: too aggressive to mandate HTTP/2 and TLS 1.3?]
8.1. JOSE Headers
A non-normative example of a JOSE header for a Registered Client
using a key id to identify the Client's public key:
{
"alg":"ES256",
"typ":"JOSE",
"kid":"1"
}
A non-normative example of a JOSE header for a Registered Client
using a certificate to assert the Client's public key:
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{
"alg":"ES256",
"typ":"JOSE",
"jwk":
{"kty":"RSA",
"use":"sig",
"kid":"1b94c",
"n":"vrjOfz9Ccdgx5nQudyhdoR17V-IubWMeOZCwX_jj0hgAsz2J_pqYW08
PLbK_PdiVGKPrqzmDIsLI7sA25VEnHU1uCLNwBuUiCO11_-7dYbsr4iJmG0Q
u2j8DsVyT1azpJC_NG84Ty5KKthuCaPod7iI7w0LK9orSMhBEwwZDCxTWq4a
YWAchc8t-emd9qOvWtVMDC2BXksRngh6X5bUYLy6AyHKvj-nUy1wgzjYQDwH
MTplCoLtU-o-8SNnZ1tmRoGE9uJkBLdh5gFENabWnU5m1ZqZPdwS-qo-meMv
VfJb6jJVWRpl2SUtCnYG2C32qvbWbjZ_jBPD5eunqsIo1vQ",
"e":"AQAB",
"x5c":
["MIIDQjCCAiqgAwIBAgIGATz/FuLiMA0GCSqGSIb3DQEBBQUAMGIxCzAJB
gNVBAYTAlVTMQswCQYDVQQIEwJDTzEPMA0GA1UEBxMGRGVudmVyMRwwGgYD
VQQKExNQaW5nIElkZW50aXR5IENvcnAuMRcwFQYDVQQDEw5CcmlhbiBDYW1
wYmVsbDAeFw0xMzAyMjEyMzI5MTVaFw0xODA4MTQyMjI5MTVaMGIxCzAJBg
NVBAYTAlVTMQswCQYDVQQIEwJDTzEPMA0GA1UEBxMGRGVudmVyMRwwGgYDV
QQKExNQaW5nIElkZW50aXR5IENvcnAuMRcwFQYDVQQDEw5CcmlhbiBDYW1w
YmVsbDCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAL64zn8/QnH
YMeZ0LncoXaEde1fiLm1jHjmQsF/449IYALM9if6amFtPDy2yvz3YlRij66
s5gyLCyO7ANuVRJx1NbgizcAblIgjtdf/u3WG7K+IiZhtELto/A7Fck9Ws6
SQvzRvOE8uSirYbgmj6He4iO8NCyvaK0jIQRMMGQwsU1quGmFgHIXPLfnpn
fajr1rVTAwtgV5LEZ4Iel+W1GC8ugMhyr4/p1MtcIM42EA8BzE6ZQqC7VPq
PvEjZ2dbZkaBhPbiZAS3YeYBRDWm1p1OZtWamT3cEvqqPpnjL1XyW+oyVVk
aZdklLQp2Btgt9qr21m42f4wTw+Xrp6rCKNb0CAwEAATANBgkqhkiG9w0BA
QUFAAOCAQEAh8zGlfSlcI0o3rYDPBB07aXNswb4ECNIKG0CETTUxmXl9KUL
+9gGlqCz5iWLOgWsnrcKcY0vXPG9J1r9AqBNTqNgHq2G03X09266X5CpOe1
zFo+Owb1zxtp3PehFdfQJ610CDLEaS9V9Rqp17hCyybEpOGVwe8fnk+fbEL
2Bo3UPGrpsHzUoaGpDftmWssZkhpBJKVMJyf/RuP2SmmaIzmnw9JiSlYhzo
4tpzd5rFXhjRbg4zW9C+2qok+2+qDM1iJ684gPHMIY8aLWrdgQTxkumGmTq
gawR+N5MDtdPTEQ0XfIBc2cJEUyMTY5MPvACWpkA6SdS4xSvdXK3IVfOWA=="]
}
}
[Editor: the jwk above was copy and pasted from the JWK example.
Replace? ]
The certificate could be signed by the AS, allowing the AS to verify
the signature using the AS public key, or the certificate could be
signed by a private key the AS has bound to the Registered Client,
allowing each instance of the Registered Client to have its own
asymetric key pair.
A non-normative example of a JOSE header for a Dynamic Client
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including the public key generated by the Client that matches its its
private key:
{
"alg":"ES256",
"typ":"JOSE",
"jwk":{
"kty":"EC",
"crv":"P-256",
"x":"Kgl5DJSgLyV-G32osmLhFKxJ97FoMW0dZVEqDG-Cwo4",
"y":"GsL4mOM4x2e6iON8BHvRDQ6AgXAPnw0m0SfdlREV7i4"
}
}
A non-normative example of a JOSE header for a JOSE access token for
a Client accessing an RS that requires proof-of-possession:
{
"alg":"ES256",
"typ":"JOSE",
"jwk":{
"x5u":"https://as.example/jwk/VBUEOIQA82"
}
}
The "jwk" object in a JOSE access token Section 8.5 MUST be the AS
jwk object the AS provided with the access handle.
This decouples how the AS communicates the Client's public key to the
RS from how the AS asserts the Client's public key. The RS can have
a consistent mechanism assert the Client's public key across all
Clients.
One advantage of this is the AS can create a certificate of a Dynamic
Client's public key, and pass it by value or reference to the Client
to present to the RS.
All JOSE headers MUST have: + the "alg" attribute. + the "typ"
attribute set to "jose". + either a "kid" or "jwk" attribute.
[Editor: should we use indicate the type of token (authorization,
refresh, access) using "typ" or "cty"?]
8.2. Authentication Request Token
A non-normative example of a payload follows:
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{
"as" :"https://as.example",
"type" :"authentication",
"iat" :"1579046092",
"jti" :"f6d72254-4f23-417f-b55e-14ad323b1dc1",
"handle":"eyJhb958.example.authentication.handle.9yf3szM"
}
The payload of the authentication token contains:
*as* - the unique string identifier for the AS.
*type* - the string "authentication", indicating the type of token.
*iat* - the time the authentication token was created as a
NumericDate.
*jti* - a unique identifier for the authentication token per
[RFC7519] section 4.1.7.
*handle* the authentication handle the AS provided the Client in the
Interaction Response Section 4.
8.3. Authorization Request Token
A non-normative example of a payload follows:
{
"as" :"https://as.example",
"type" :"authorization",
"iat" :"1579046092",
"jti" :"f6d72254-4f23-417f-b55e-14ad323b1dc1",
"handle":"eyJhb958.example.authorization.handle.9yf3szM"
}
The payload of the authorization token contains:
*as* - the unique string identifier for the AS.
*type* - the string "authorization", indicating the type of token.
*iat* - the time the authorization token was created as a
NumericDate.
*jti* - a unique identifier for the authorization token per [RFC7519]
section 4.1.7.
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*handle* the authorization handle the AS provided the Client in the
Interaction Response Section 4.
8.4. Refresh Token
A non-normative example of a payload follows:
{
"as" :"https://as.example",
"type" :"refresh",
"iat" :"1579049876",
"jti" :"4342046d-83c4-4725-8c72-e9a49245f791",
"handle":"eyJhb958.example.refresh.handle.9yf3szM"
}
The payload of the authorization token contains:
*as* - the unique string identifier for the AS.
*type* - the string "refresh", indicating the type of token.
*iat* - the time the refresh request token was created as a
NumericDate.
*jti* - a unique identifier for the refresh request token.
*handle* the refresh handle the AS provided the Client in the AS
Response Section 6 or access refresh response Section 8.18.
8.5. JOSE Access Token
The "jwk" object in a JOSE access token header MUST be set to the
"jwk" value the AS provided for the access handle.
A non-normative example of a payload follows:
{
"type" :"access",
"iat" :"1579046092",
"jti" :"5ef47057-08f9-4763-be8d-162824d43dfb",
"handle":"eyJhb958.example.access.handle.9yf3szM"
}
The payload of the JOSE access token contains:
*type* - the string "access", indicating the type of token.
*iat* - the time the JOSE access token was created as a NumericDate.
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*jti* - a unique identifier for the JOSE access token.
*handle* the access handle the AS provided the Client in the AS
Response Section 6 or access refresh response Section 8.18.
[Editor: should we include the called URI in the token?]
8.6. HTTP Authorization JOSE Header
The Client authenticates requests by setting the HTTP Authorization
header to include the "JOSE" parameter, followed by one or more space
characters, followed by the appropriate JOSE token.
A non-normative example:
Authorization: JOSE eyJhb.example.authorization.token.haDwskpFDBW
The authorization request token, refresh request token, and the JOSE
access token are all passed in this manner.
8.7. JOSE Token Verification
TBD
8.8. AS Request
The Client creates a JSON document per Section 3, signs it using JWS
[RFC7515], and sends the JWS token to the AS end point using HTTP
POST, with a content-type of application/jose.
* *Payload Encryption*
The AS may require the AS Request to be encrypted. If so, the JWS
token is encrypted per JWE [RFC7516] using the public key and
algorithm specified by the AS.
8.9. Interaction Response
If the Client set the authenticate_first flag, the response includes
an authentication object, otherwise it includes an authorization
object. If the AS wants the Client to initiate the User interaction,
it sends an interaction object.
If no interaction is required the AS will return an AS Response per
Section 8.14, otherwise the AS will return an Interaction Response
per Section 4.
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If the AS wants the Client to start the interaction, an interaction
object will be returned in the response.
* *Error Responses*
The AS MAY respond with one of the following errors defined in
Section 9:
TBD
8.10. Deletion Request
The Client MAY delete an outstanding request using the authorization
token by making an HTTP DELETE call to the authorization uri, setting
the HTTP Authorization header per Section 8.6 with the authorization
request token.
A non-normative deletion request example:
DELETE /authorization/ey7snHGs HTTP/2
Host: as.example
Authorization: JOSE eyJhb.example.authorization.token.haDwskpFDBW
* *Error Responses*
The AS MAY respond with one of the following errors defined in
Section 9:
TBD
8.11. Authentication Request
Section 8.2
8.12. Authentication Response
8.13. Authorization Request
The Client makes an HTTP GET call to the authorization uri, setting
the HTTP Authorization header per Section 8.6 with the authorization
request token.
A non-normative Authorization Request example:
GET /authorization/ey7snHGs HTTP/2
Host: as.example
Authorization: JOSE eyJhb.example.authorization.token.haDwskpFDBW
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8.14. AS Response
The AS verifies the authorization request token, and then provides a
response according to what the User and/or RO have authorized if
required. If no signature or encryption was required, the AS will
respond with a JSON document with content-type set to application/
json.
* *Response Signing*
The AS MAY sign the response with a JWS per [RFC7515] and the private
key matching the public key the AS defined as its AS Response signing
key. The AS will respond with the content-type set to application/
jose.
* *Response Encryption*
The AS MAY encrypt the response using the public key provided by the
Client, using JWE per [RFC7516]. The AS will respond with the
content-type set to application/jose.
* *Error Responses*
The AS MAY respond with one of the following errors defined in
Section 9:
TBD
8.15. Bearer Token RS Access
If the access method in the AS Response authorizations object
Section 6.2 was "bearer", then the Client accesses the RS per
Section 2.1 of [RFC6750]
A non-normative example of the HTTP request headers follows:
GET /calendar HTTP/2
Host: calendar.example
Authorization: bearer eyJJ2D6.example.access.token.mZf9pTSpA
* *Error Responses*
TBD
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8.16. Proof-of-possession RS Access
If the access method in the AS Response authorizations object
Section 6.2 was "pop", then the Client creates a JOSE access token
per Section 8.5 for each call to the RS, setting the HTTP
Authorization header per Section 8.6 with the JOSE access token.
A non-normative example of the HTTP request headers follows:
GET /calendar HTTP/2
Host: calendar.example
Authorization: JOSE eyJhbG.example.JOSE.access.token.kwwQb958
* *Error Responses*
TBD
8.17. JOSE Body RS Access
If the access method in the AS Response authorizations object
Section 6.2 was "pop_body", then the Client creates a JOSE access
token per Section 8.5 for each call to the RS, setting the HTTP
Authorization header per Section 8.6 with the JOSE access token.
The Client creates a JSON document per the RS requirements. The
document MUST include the access handle. The CLient then signs the
document using JWS [RFC7515], and sends the resulting compact
notation JWS token to the RS end point using HTTP POST, with a
content-type of application/jose. Note this is similar to the AS
Request Section 8.8.
[Editor: any isues here? Anything missing that MUST be in the
payload? Would an HTTP Authorization header make sense?]
8.18. Access Refresh
If the Client received a refresh handle and uri from the AS in the
Interaction Response, and it wants a fresh access token or handle, it
creates a refresh request token per Section 8.4. setting the HTTP
Authorization header per Section 8.6 with the refresh request token.
The AS will then respond with a refresh response.
* *Refresh Response*
A non-normative example refresh response with an access handle:
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{
"type" : "oauth_scope",
"scope" : "read_calendar write_calendar",
"expires_in" : "3600",
"method" : "pop",
"access": {
"handle" : "ey.example.access.handle.9yf3iWszM",
"jwk": {
"x5u" : "https://as.example/jwk/VBUEOIQA82"
}
},
"refresh": {
"handle" : "ey.example.refresh.handle.4SkjIi",
"uri" : "https://as.example/refresh/eyJl4FzM"
}
}
The refresh response is the same as the authorizations object
Section 6.2 in the AS Response.
If a new refresh handle and/or refresh uri is returned, the Client
MUST use the new refresh handle and/or refresh uri
[Editor: are there other results relevant for [RAR]?]
* *Error Responses*
The AS MAY respond with one of the following errors defined in
Section 9:
TBD
9. Error Messages
[Editor: return "wait" time in AS Response when AS wants Client to
wait before retying a Authorization Request. The Client MUST
generate a fresh authorization token when retrying the Authorization
Request. ]
TBD
10. AS Initiated Sequence
[Editor: AS initiated flows have been challenging to implement as
OAuth 2.0 did not directly support them, so deployments bounced back
and forth between the Client and AS to create a Client initiated
flow. Here is a proposal to support AS initiated: authentication;
just-in-time (JIT) provisioning; and authorization]
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In this sequence the User starts at the AS, and then based on User
input, the AS redirects the User to a Client, passing an initiation
token Section 10.1, and then the Client retrieves authorizations and/
or identity claims about the User. The Client MUST be a Registered
Client. The sequence follows:
1. The User is interacting at the AS and wants to use the Client,
and provide the Client identity claims and/or authorizations from
the AS that the Client has pre-configured.
2. The AS creates a authorization handle and uri representing the
identity claims and authorizations to be provided to the Client.
The AS creates an initiation token containing the AS identifier,
the authorization handle, and the authorization uri.
3. The AS redirects the User to a URI the Client has configured to
accept initiation tokens, passing the initiation token as a query
parameters with the name "token".
4. The Client verifies the initiation token.
5. The Client makes an Authorization Request per Section 8.13.
6. The AS responds with an AS Response JSON document Section 6 per
Section 8.14.
The Client now has the User identity claims and/or authorizations.
If Client policy permits, the Client can perform JIT provisioning if
the User is new to the Client.
*AS Initiated Sequence Diagram*
+--------+ +-------------+ +---------------+
| | | | | |
| | | User |-------(1)-->| |
| | | | | |
| | +-------------+ | (2) |
| | /\ | |
| Client |<--- initiation ---/ \-------------(3)---| Authorization |
| | token | Server |
| (4) | | |
| | | |
| |--(5)------- Authorization Request ------>| |
| | | |
| |<-(6)------- AS Response -----------------| |
| | | |
+--------+ +---------------+
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10.1. Initiation Token
A non-normative example of an initiation token payload follows:
{
"as": "https://as.example",
"authorization": {
"handle" : "eyJhb958.example.authorization.handle.9yf3szM",
"uri" : "https://as.example/authorization/ey7snHGs"
}
}
* *as* - the "as" identifier for the AS. This attribute is
REQUIRED.
* *authorization* - the authorization object has the following
attributes:
- *handle* - the authorization handle. This attribute is
REQUIRED.
- *uri* - the authorization URI. This attribute is REQUIRED.
The initiation token is signed with JWS and uses the compact
serialization.
11. Extensibility
This standard can be extended in a number of areas:
* *Client Authentication Mechanisms*
An extension could define other mechanisms for the Client to
authenticate and replace JOSE in Section 8 with Mutual TLS or HTTP
Signing. Constrained environments could use CBOR [RFC7049] instead
of JSON, and COSE [RFC8152] instead of JOSE, and CoAP [RFC8323]
instead of HTTP/2.
* *AS Request*
An additional top level object could be added to the AS Request
payload if the AS can manage delegations other than authorizations or
claims, or some other functionality.
* *"client" Object*
Additional information about the Client that the AS would require
related to an extension.
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* *"user" Object*
Additional information about the Client that the AS would require
related to an extension.
* *"authorizations" Object*
Additional types of authorizations in addition to OAuth 2.0 scopes
and RAR.
* *"claims" Object*
Additional types of identity claims in addition to OpenID Connect
claims and Verified Credentials.
* *Interaction*
Additional mechanisms for the Client to start an interaction with the
User.
* *Access Methods*
Additional mechanisms for the Client to present authorization to a
resource.
* *Continuous Authentication*
An extension could define a new handle for the Client to use to
regularly provide continuous authentication signals and receive
responses.
[Editor: do we specify access token / handle introspection in this
document, or leave that to an extension?]
[Editor: do we specify access token / handle revocation in this
document, or leave that to an extension?]
12. Rational
1. *Why is there only one mechanism for the Client to authenticate
with the AS? Why not support other mechanisms?*
Having choices requires implementers to understand which choice
is preferable for them. Having one default mechanism in the
document for the Client to authenticate simplifies most
implementations. Extensions can specify other mechanisms that
are preferable in specific environments.
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2. *Why is the default Client authentication JOSE rather than
MTLS?*
MTLS cannot be used today by a Dynamic Client. MTLS requires
the application to have access below what is typically the
application layer, that is often not available on some
platforms. JOSE is done at the application layer. Many AS
deployments will be an application behind a proxy performing
TLS, and there are risks in the proxy passing on the results of
MTLS.
3. *Why is the default Client authentication JOSE rather than HTTP
signing?*
There is currently no widely deployed open standard for HTTP
signing. Additionally, HTTP signing requires passing all the
relevant parts of the HTTP request to downstream services within
an AS that may need to independently verify the Client identity.
4. *What are the advantages of using JOSE for the Client to
authenticate to the AS and a resource?*
Both Registered Clients and Dynamic Clients can have a private
key, eliminating the public Client issues in OAuth 2.0, as a
Dynamic Client can create an ephemeral key pair. Using
asymetric cryptography also allows each instance of a Registered
Client to have its own private key if it can obtain a
certificate binding its public key to the public key the AS has
for the Client. Signed tokens can be passed to downstream
components in a AS or RS to enable independent verification of
the Client and its request. The AS Initiated Sequence
Section 10 requires a URL safe parameter, and JOSE is URL safe.
5. *Why does the AS not return parameters to the Client in the
redirect url?*
Passing parameters via a browser redirection is the source of
many of the security risks in OAuth 2.0. It also presents a
challenge for smart devices. In this protocol, the redirection
from the Client to the AS is to enable the AS to interact with
the User, and the redirection back to the Client is to hand back
interaction control to the Client if the redirection was a full
browser redirect. Unlike OAuth 2.0, the identity of the Client
is independent of the URI the AS redirects to.
6. *Why is there not a UserInfo endpoint as there is with OpenID
Connect?*
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In OpenID Connect, obtaining claims over the redirect or the
Token Endpoint are problematic. The redirect is limited in
size, and is not secure. The Token Endpoint is intended to
return tokens, and is limited by the "application/x-www-form-
urlencoded" format. A UserInfo endpoint returns "application/
json", and can return rich claims, just as the authorization uri
in this protocol.
[Editor: is there some other reason to have the UserInfo
endpoint? What are industry best practices now? ]
7. *Why is there still a Client ID? Could we not use a fingerprint
of the public key to identify the Client?*
Some AS deployments do not allow calls from Registered Clients,
and provide different functionality to different Clients. A
permanent identifier for the Client is needed for the Client
developer and the AS admin to ensure they are referring to the
same Client. The Client ID was used in OAuth 2.0, and it served
the same purpose.
8. *Why have both claims and authorizations?*
There are use cases for each that are independent:
authenticating a user vs granting access to a resource. A
request for an authorization returns an access token or handle,
while a request for a claim returns the claim.
9. *Why specify HTTP/2 or later and TLS 1.3 or later for Client and
AS communication in ?*Section 8
Knowing the AS supports HTTP/2 enables a Client to set up a
connection faster. HTTP/2 will be more efficient when Clients
have large numbers of access tokens and are frequently
refreshing them at the AS as there will be less network traffic.
Mandating TLS 1.3 similarly improves the performance and
security of Clients and AS when setting up a TLS connection.
10. *Why do some of the JSON objects only have one child, such as
the identifiers object in the user object in the AS Request?*
It is difficult to forecast future use cases. Having more
resolution may mean the difference between a simple extension,
and a convoluted extension.
11. *Why is the "iss" included in the "oidc" identifier object?
Would the "sub" not be enough for the AS to identify the User?*
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The AS may use another AS to authenticate Users. The "iss" and
"sub" combination is required to uniquely identify the User for
any AS.
12. *Why complicate the sequence with authentication first?*
A common pattern is to use an AS to authenticate the User at the
Client. The Client does not know a priori if the User is a new
User, or a returning User. Asking a returning User to consent
releasing identity claims and/or authorizations they have
already provided is a poor User experience, as is sending the
User back to the AS. The Client requesting identity first
enables the Client to get a response from the AS while the AS is
still interacting with the User, so that the Client can request
any identity claims/or authorizations required or desired.
13. *Why is there a JOSE Body access method for the
Client?*Section 8.17
There are numerous use cases where the RS wants non-repudiation
and providence of API calls. For example, the UAS Service
Supplier Framework for Authentication and Authorization [UTM].
13. Acknowledgments
This draft derives many of its concepts from Justin Richer's
Transactional Authorization draft [TxAuth].
Additional thanks to Justin Richer for his strong critique of earlier
drafts.
14. IANA Considerations
[ JOSE parameter for Authorization HTTP header ]
TBD
15. Security Considerations
TBD
16. References
16.1. Normative References
[RFC3966] Schulzrinne, H., "The tel URI for Telephone Numbers",
RFC 3966, DOI 10.17487/RFC3966, December 2004,
<https://www.rfc-editor.org/info/rfc3966>.
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[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008,
<https://www.rfc-editor.org/info/rfc5322>.
[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
September 2009, <https://www.rfc-editor.org/info/rfc5646>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/info/rfc6749>.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750,
DOI 10.17487/RFC6750, October 2012,
<https://www.rfc-editor.org/info/rfc6750>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
[RFC7516] Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
RFC 7516, DOI 10.17487/RFC7516, May 2015,
<https://www.rfc-editor.org/info/rfc7516>.
[RFC7519] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
(JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
<https://www.rfc-editor.org/info/rfc7519>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/info/rfc7540>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[OIDC] Sakimora, N., Bradley, J., Jones, M., de Medeiros, B., and
C. Mortimore, "OpenID Connect Core 1.0", November 2014,
<https://openiD.net/specs/openiD-connect-core-1_0.html>.
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[OIDC4IA] Lodderstedt, T. and D. Fett, "OpenID Connect for Identity
Assurance 1.0", October 2019, <https://openid.net/specs/
openid-connect-4-identity-assurance-1_0.html>.
16.2. Informative References
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[RFC8252] Denniss, W. and J. Bradley, "OAuth 2.0 for Native Apps",
BCP 212, RFC 8252, DOI 10.17487/RFC8252, October 2017,
<https://www.rfc-editor.org/info/rfc8252>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>.
[RFC8323] Bormann, C., Lemay, S., Tschofenig, H., Hartke, K.,
Silverajan, B., and B. Raymor, Ed., "CoAP (Constrained
Application Protocol) over TCP, TLS, and WebSockets",
RFC 8323, DOI 10.17487/RFC8323, February 2018,
<https://www.rfc-editor.org/info/rfc8323>.
[RFC8628] Denniss, W., Bradley, J., Jones, M., and H. Tschofenig,
"OAuth 2.0 Device Authorization Grant", RFC 8628,
DOI 10.17487/RFC8628, August 2019,
<https://www.rfc-editor.org/info/rfc8628>.
[browser_based_apps]
Parecki, A. and D. Waite, "OAuth 2.0 for Browser-Based
Apps", September 2019, <https://tools.ietf.org/html/draft-
ietf-oauth-browser-based-apps-04>.
[RAR] Lodderstedt, T., Richer, J., and B. Campbell, "OAuth 2.0
Rich Authorization Requests", January 2020,
<https://tools.ietf.org/html/draft-ietf-oauth-rar-00>.
[W3C_VC] Sporny, M., Noble, G., and D. Chadwick, "Verifiable
Credentials Data Model 1.0", November 2019,
<https://w3c.github.io/vc-data-model/>.
[QR_Code] "ISO/IEC 18004:2015 - Information technology - Automatic
identification and data capture techniques - QR Code bar
code symbology specification", February 2015,
<https://www.iso.org/standard/62021.html>.
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[TxAuth] Richer, J., "Transactional Authorization", December 2019,
<https://tools.ietf.org/html/draft-richer-transactional-
authz-04>.
[UTM] Rios, J., Smith, I., and P. Venkatesen, "UAS Service
Supplier Framework for Authentication and Authorization",
September 2019, <https://utm.arc.nasa.gov/docs/2019-
UTM_Framework-NASA-TM220364.pdf>.
Appendix A. Document History
A.1. draft-hardt-xauth-protocol-00
* Initial version
A.2. draft-hardt-xauth-protocol-01
* text clean up
* added OIDC4IA claims
* added "jws" method for accessing a resource.
* renamed Initiation Request -> AS Request
* renamed Initiation Response -> Interaction Response
* renamed Completion Request -> Authorization Request
* renamed Completion Response -> AS Request
* renamed completion handle -> authorization handle
* added Authentication Request, Authentication Response,
authentication handle
Appendix B. Comparison with OAuth 2.0 and OpenID Connect
*Changed Features*
The major differences between this protocol and OAuth 2.0 and OpenID
Connect are:
* The Client uses a private key to authenticate in this protocol
instead of the client secret in OAuth 2.0 and OpenID Connect.
* The Client initiates the protocol by making a signed request
directly to the AS instead of redirecting the User to the AS.
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* The Client does not receive any parameters from a redirection of
the User back from the AS.
* Refreshing an access token requires creating a refresh token from
a refresh handle, rather than an authenticated call with a refresh
token.
* The Client can request identity claims to be returned independent
of the ID Token. There is no UserInfo endpoint to query claims as
there is in OpenID Connect.
*Preserved Features*
* This protocol reuses the OAuth 2.0 scopes, Client IDs, and access
tokens of OAuth 2.0.
* This protocol reuses the Client IDs, Claims and ID Token of OpenID
Connect.
* No change is required by the Client or the RS for existing APIs.
Author's Address
Dick Hardt (editor)
SignIn.Org
United States
Email: dick.hardt@gmail.com
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