Grant Negotiation and Authorization Protocol

Document Charter Grant Negotiation and Authorization Protocol WG (gnap)
Title Grant Negotiation and Authorization Protocol
Last updated 2020-07-10
State Approved
WG State Active
IESG Responsible AD Roman Danyliw
Charter Edit AD Roman Danyliw
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This group is chartered to develop a fine-grained delegation protocol for
authorization, API access, user identifiers, and identity assertions. The 
protocol will also allow the client to present unverified identifiers and 
verifiable assertions to the Authorization Server (AS) as part of its 
request. This protocol enables an authorizing party to delegate access 
to client software to use a Resource Server (RS) with this token. It will 
expand upon the uses cases currently supported by OAuth 2.0 and OpenID 
Connect (itself an extension of OAuth 2.0) to support authorizations 
scoped as narrowly as a single transaction, provide a clear framework for
interaction among all parties involved in the protocol flow, and remove 
unnecessary dependence on a browser or user-agent for coordinating 

The delegation process will be acted upon by multiple parties in the protocol,
each performing a specific role. The protocol will decouple the channels used 
by the protocol participants to communicate from the delegation channel, which
happens directly between the client and the authorization server (in contrast
with OAuth 2.0, which is initiated by the client redirecting the user’s
browser). The protocol will include a means of specifying how the user can 
potentially be involved in an interactive fashion during the delegation 
process. The client and AS will use these interaction mechanisms to involve 
the user, as necessary, to make authorization decisions. This decoupling 
avoids many of the security concerns and technical challenges of OAuth 2.0 
and provides a non-invasive path for supporting future types of clients 
and interaction channels.

The group will define interoperability for this protocol between different
parties, including
 - client and authorization server;
 - client and resource server; and
 - authorization server and resource server.

The group will seek to minimize assumptions about the form of client 
applications, allowing for:
- Fine-grained specification of access
- Approval of AS attestation to identifiers and other identity claims
- Approval of access to multiple resources and APIs in a single interaction
- Multiple access tokens in a single request and response
- AS-directed dispatch of access tokens to the appropriate RS
- Separation between the party authorizing access and the party operating the
client requesting access 

The group will define extension points for this protocol to allow for
flexibility in areas including:

- Cryptographic agility for keys, message signatures, and proof of possession
- User interaction mechanisms including web and non-web methods
- Mechanisms for conveying user, software, organization, and other 
information used in authorization decisions 
- Mechanisms for presenting tokens to resource servers and binding resource 
requests to tokens and associated cryptographic keys 
- Optimized inclusion of additional information related to the identifiers 
and identity assertions about the client
- Optimized inclusion of additional information (including identifiers and 
identity assertions) through the delegation process 

Additionally, the group will provide mechanisms for management of the protocol
lifecycle including:

- Discovery of the authorization server
- Revocation of active tokens
- Data model for granted access and mechanisms for the AS and RS to
communicate the granted access model

Although the artifacts for this work are not intended or expected to be
backwards-compatible with OAuth 2.0 or OpenID Connect, the group will attempt
to simplify migrating from OAuth 2.0 and OpenID Connect to the new protocol
where possible.

This group is not chartered to develop extensions to OAuth 2.0, and as such
will focus on new technological solutions not necessarily compatible with OAuth
2.0. Functionality that builds directly on OAuth 2.0 will be directed to the
OAuth Working Group, including functionality back-ported from the protocol
developed here to OAuth 2.0.

The group is chartered to develop mechanisms for applying cryptographic
methods, such as JOSE and COSE, to the delegation process. This group is not
chartered to develop new cryptographic methods.

The group is chartered to develop mechanisms for conveying identity information
within the protocol including existing identifiers (such as email addresses, 
phone numbers, usernames, and subject identifiers) and assertions (such as 
OpenID Connect ID Tokens, SAML Assertions, and Verifiable Credentials). The 
group is not chartered to develop new formats for identifiers or assertions, 
nor is the group chartered to develop schemas for user information, profiles, 
or other identity attributes.

The initial work will focus on using HTTPS for communication between the client
and the authorization server, taking advantage of optimization features of
HTTP/2 and HTTP/3 where possible, and will strive to enable simple mapping to
other protocols such as CoAP when doing so does not conflict with the primary

Milestones to include:
- Core delegation protocol
- Key presentation mechanism bindings to the core protocol including TLS,
detached HTTP signature, and embedded HTTP signatures 
- Conveyance mechanisms for identifiers and assertions 
- Guidelines for use of protocol extension points
- (if needed) Guidelines on migration paths, implementation, and operations 

Where possible, the group will seek to make use of tools to guide and inform
the standardization process including formal analysis, architecture documents,
and use case documents. These artifacts will not be considered as working group
milestones or deliverables.

The working group will cooperate and coordinate with other IETF WGs such as
OAUTH, and work with external organizations, such as the OpenID Foundation, 
as appropriate.