azapi February 2025
Gazitt, et al. Standards Track [Page]
Workgroup:
OpenID AuthZEN
Published:
Authors:
O. Gazitt, Ed.
Aserto
D. Brossard, Ed.
Axiomatics
A. Tulshibagwale, Ed.
SGNL

Authorization API 1.0 – draft 03

Abstract

The Authorization API enables Policy Decision Points (PDPs) and Policy Enforcement Points (PEPs) to communicate authorization requests and decisions to each other without requiring knowledge of each other's inner workings. The Authorization API is served by the PDP and is called by the PEP. The Authorization API includes an Evaluation endpoint, which provides specific access decisions. Other endpoints may be added in the future for other scenarios, including searching for subjects or resources.

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Table of Contents

1. Introduction

Computational services often implement access control within their components by separating Policy Decision Points (PDPs) from Policy Enforcement Points (PEPs). PDPs and PEPs are defined in XACML ([XACML]) and NIST's ABAC SP 800-162. Communication between PDPs and PEPs follows similar patterns across different software and services that require or provide authorization information. The Authorization API described in this document enables different providers to offer PDP and PEP capabilities without having to bind themselves to one particular implementation of a PDP or PEP.

2. Model

The Authorization API is a transport-agnostic API published by the PDP, to which the PEP acts as a client. Possible bindings of this specification, such as HTTPS or gRPC, are described in Transport (Section 10).

Authorization for the Authorization API itself is out of scope for this document, since authorization for APIs is well-documented elsewhere. For example, the Authorization API's HTTPS binding MAY support authorization using an Authorization header, using a basic or bearer token. Support for OAuth 2.0 ([RFC6749]) is RECOMMENDED.

3. Features

The core feature of the Authorization API is the Access Evaluation API, which enables a PEP to find out if a specific request can be permitted to access a specific resource. The following are non-normative examples:

4. API Version

This document describes the API version 1.0. Any updates to this API through subsequent revisions of this document or other documents MAY augment this API, but MUST NOT modify the API described here. Augmentation MAY include additional API methods or additional parameters to existing API methods, additional authorization mechanisms, or additional optional headers in API requests. All API methods for version 1.0 MUST be immediately preceded by the relative URL path /v1/.

5. Information Model

The information model for requests and responses include the following entities: Subject, Action, Resource, Context, and Decision. These are all defined below.

5.1. Subject

A Subject is the user or robotic principal about whom the Authorization API is being invoked. The Subject may be requesting access at the time the Authorization API is invoked.

A Subject is a JSON ([RFC8259]) object that contains two REQUIRED keys, type and id, which have a value typed string, and an OPTIONAL key, properties, with a value of a JSON object.

type:

REQUIRED. A string value that specifies the type of the Subject.

id:

REQUIRED. A string value containing the unique identifier of the Subject, scoped to the type.

properties:

OPTIONAL. A JSON object containing any number of key-value pairs, which can be used to express additional properties of a Subject.

The following is a non-normative example of a Subject:

{
  "type": "user",
  "id": "alice@acmecorp.com"
}
Figure 1: Example Subject

5.1.1. Subject Properties

Many authorization systems are stateless, and expect the client (PEP) to pass in any properties or attributes that are expected to be used in the evaluation of the authorization policy. To satisfy this requirement, Subjects MAY include zero or more additional attributes as key-value pairs, under the properties object.

An attribute can be single-valued or multi-valued. It can be a primitive type (string, boolean, number) or a complex type such as a JSON object or JSON array.

The following is a non-normative example of a Subject which adds a string-valued department property:

{
  "type": "user",
  "id": "alice@acmecorp.com",
  "properties": {
    "department": "Sales"
  }
}
Figure 2: Example Subject with Additional Property

To increase interoperability, a few common properties are specified below:

5.1.1.1. IP Address

The IP Address of the Subject, identified by an ip_address field, whose value is a textual representation of an IP Address, as defined in Textual Conventions for Internet Network Addresses [RFC4001].

The following is a non-normative example of a subject which adds the ip_address property:

{
  "type": "user",
  "id": "alice@acmecorp.com",
  "properties": {
    "department": "Sales",
    "ip_address": "172.217.22.14"
  }
}
Figure 3: Example Subject with IP Address
5.1.1.2. Device ID

The Device Identifier of the Subject, identified by a device_id field, whose value is a string representation of the device identifier.

The following is a non-normative example of a subject which adds the device_id property:

{
  "type": "user",
  "id": "alice@acmecorp.com",
  "properties": {
    "department": "Sales",
    "ip_address": "172.217.22.14",
    "device_id": "8:65:ee:17:7e:0b"
  }
}
Figure 4: Example Subject with Device ID

5.2. Resource

A Resource is the target of an access request. It is a JSON ([RFC8259]) object that is constructed similar to a Subject entity. It has the follow keys:

type:

REQUIRED. A string value that specifies the type of the Resource.

id:

REQUIRED. A string value containing the unique identifier of the Resource, scoped to the type.

properties:

OPTIONAL. A JSON object containing any number of key-value pairs, which can be used to express additional properties of a Resource.

5.2.1. Examples (non-normative)

The following is a non-normative example of a Resource with a type and a simple id:

{
  "type": "book",
  "id": "123"
}
Figure 5: Example Resource

The following is a non-normative example of a Resource containing a library_record property, that is itself a JSON object:

{
  "type": "book",
  "id": "123",
  "properties": {
    "library_record":{
      "title": "AuthZEN in Action",
      "isbn": "978-0593383322"
    }
  }
}
Figure 6: Example Resource with Additional Property

5.3. Action

An Action is the type of access that the requester intends to perform.

Action is a JSON ([RFC8259]) object that contains a REQUIRED name key with a string value, and an OPTIONAL properties key with a JSON object value.

name:

REQUIRED. The name of the Action.

properties:

OPTIONAL. A JSON object containing any number of key-value pairs, which can be used to express additional properties of an Action.

The following is a non-normative example of an action:

{
  "name": "can_read"
}
Figure 7: Example Action

5.4. Context

The Context object is a set of attributes that represent environmental or contextual data about the request such as time of day. It is a JSON ([RFC8259]) object.

The following is a non-normative example of a Context:

{
  "time": "1985-10-26T01:22-07:00"
}
Figure 8: Example Context

6. Access Evaluation API

The Access Evaluation API defines the message exchange pattern between a client (PEP) and an authorization service (PDP) for executing a single access evaluation.

6.1. The Access Evaluation API Request

The Access Evaluation request is a 4-tuple constructed of the four previously defined entities:

subject:

REQUIRED. The subject (or principal) of type Subject

action:

REQUIRED. The action (or verb) of type Action.

resource:

REQUIRED. The resource of type Resource.

context:

OPTIONAL. The context (or environment) of type Context.

6.1.1. Example (non-normative) 

{
  "subject": {
    "type": "user",
    "id": "alice@acmecorp.com"
  },
  "resource": {
    "type": "account",
    "id": "123"
  },
  "action": {
    "name": "can_read",
    "properties": {
      "method": "GET"
    }
  },
  "context": {
    "time": "1985-10-26T01:22-07:00"
  }
}
Figure 9: Example Request

6.2. The Access Evaluation API Response

The simplest form of a response is simply a boolean representing a Decision, indicated by a "decision" field.

decision:

REQUIRED. A boolean value that specifies whether the Decision is to allow or deny the operation.

In this specification, assuming the evaluation was successful, there are only 2 possible responses:

  • true: The access request is permitted to go forward.

  • false: The access request is denied and MUST NOT be permitted to go forward.

The response object MUST contain this boolean-valued Decision key.

6.2.1. Access Evaluation Decision

The following is a non-normative example of a simple Decision:

{
  "decision": true
}
Figure 10: Example Decision

6.2.2. Additional Context in a Response

In addition to a "decision", a response may contain a "context" field which can be any JSON object. This context can convey additional information that can be used by the PEP as part of the decision evaluation process. Examples include:

  • XACML's notion of "advice" and "obligations"

  • Hints for rendering UI state

  • Instructions for step-up authentication

6.2.3. Example Context

An implementation MAY follow a structured approach to "context", in which it presents the reasons that an authorization request failed.

  • A list of identifiers representing the items (policies, graph nodes, tuples) that were used in the decision-making process.

  • A list of reasons as to why access is permitted or denied.

6.2.3.1. Reasons

Reasons MAY be provided by the PDP.

6.2.3.1.1. Reason Field

A Reason Field is a JSON object that has keys and values of type string. The following are non-normative examples of Reason Field objects:

{
  "en": "location restriction violation"
}
Figure 11: Example Reason
6.2.3.1.2. Reason Object

A Reason Object specifies a particular reason. It is a JSON object that has the following fields:

id:

REQUIRED. A string value that specifies the reason within the scope of a particular response.

reason_admin:

OPTIONAL. The reason, which MUST NOT be shared with the user, but useful for administrative purposes that indicates why the access was denied. The value of this field is a Reason Field object (Section 6.2.3.1.1).

reason_user:

OPTIONAL. The reason, which MAY be shared with the user that indicates why the access was denied. The value of this field is a Reason Field object (Section 6.2.3.1.1).

The following is a non-normative example of a Reason Object:

{
  "id": "0",
  "reason_admin": {
    "en": "Request failed policy C076E82F"
  },
  "reason_user": {
    "en-403": "Insufficient privileges. Contact your administrator",
    "es-403": "Privilegios insuficientes. Póngase en contacto con su administrador"
  }
}
Figure 12: Example of a Reason Object

6.2.4. Sample Response with additional context (non-normative) 

{
  "decision": true,
  "context": {
    "id": "0",
    "reason_admin": {
      "en": "Request failed policy C076E82F"
    },
    "reason_user": {
      "en-403": "Insufficient privileges. Contact your administrator",
      "es-403": "Privilegios insuficientes. Póngase en contacto con su administrador"
    }
  }
}
Figure 13: Example Response with Context

7. Access Evaluations API

The Access Evaluations API defines the message exchange pattern between a client (PEP) and an authorization service (PDP) for evaluating multiple access evaluations within the scope of a single message exchange (also known as "boxcarring" requests).

7.1. The Access Evaluations API Request

The Access Evaluation API Request builds on the information model presented in Section 5 and the 4-tuple defined in the Access Evaluation Request (Section 6.1).

To send multiple access evaluation requests in a single message, the caller MAY add an evaluations key to the request. The evaluations key is an array which contains a list of JSON objects, each typed as a 4-tuple, and specifying a discrete request.

If an evaluations array is NOT present, the Access Evaluations Request behaves in a backwards-compatible manner with the (single) Access Evaluation API Request (Section 6.1).

If an evaluations array IS present and contains one or more objects, these form distinct requests that the PDP will evaluate. These requests are independent from each other, and may be executed sequentially or in parallel, left to the discretion of each implementation.

If the evaluations array IS present and contains one or more objects, the top-level subject, action, resource, and context keys (4-tuple) in the request object MAY be omitted. However, if one or more of these values is present, they provide default values for their respective fields in the evaluation requests. This behavior is described in Section 7.1.1.

The following is a non-normative example for specifying three requests, with no default values:

{
  "evaluations": [
    {
      "subject": {
        "type": "user",
        "id": "alice@acmecorp.com"
      },
      "action": {
        "name": "can_read"
      },
      "resource": {
        "type": "document",
        "id": "boxcarring.md"
      },
      "context":{
        "time": "2024-05-31T15:22-07:00"
      }
    },
    {
      "subject": {
        "type": "user",
        "id": "alice@acmecorp.com"
      },
      "action": {
        "name": "can_read"
      },
      "resource": {
        "type": "document",
        "id": "subject-search.md"
      },
      "context":{
        "time": "2024-05-31T15:22-07:00"
      }
    },
    {
      "subject": {
        "type": "user",
        "id": "alice@acmecorp.com"
      },
      "action": {
        "name": "can_read"
      },
      "resource": {
        "type": "document",
        "id": "resource-search.md"
      },
      "context":{
        "time": "2024-05-31T15:22-07:00"
      }
    }
  ]
}

7.1.1. Default values

While the example above provides the most flexibility in specifying distinct values in each request for every evaluation, it is common for boxcarred requests to share one or more values of the 4-tuple. For example, evaluations MAY all refer to a single subject, and/or have the same contextual (environmental) attributes.

Default values offer a more compact syntax that avoids over-duplication of request data.

If any of the top-level subject, action, resource, and context keys are provided, they are treated as default values for the 4-tuples specified in the evaluations object. Any values specified in the 4-tuples present in the evaluations object take precedence over these default values.

The following is a non-normative example for specifying three requests that refer to a single subject and context:

{
  "subject": {
    "type": "user",
    "id": "alice@acmecorp.com"
  },
  "context":{
    "time": "2024-05-31T15:22-07:00"
  },
  "evaluations": [
    {
      "action": {
        "name": "can_read"
      },
      "resource": {
        "type": "document",
        "id": "boxcarring.md"
      }
    },
    {
      "action": {
        "name": "can_read"
      },
      "resource": {
        "type": "document",
        "id": "subject-search.md"
      }
    },
    {
      "action": {
        "name": "can_read"
      },
      "resource": {
        "type": "document",
        "id": "resource-search.md"
      }
    }
  ]
}

The following is a non-normative example for specifying three requests that refer to a single subject and context, with a default value for action, that is overridden by the third request:

{
  "subject": {
    "type": "user",
    "id": "alice@acmecorp.com"
  },
  "context":{
    "time": "2024-05-31T15:22-07:00"
  },
  "action": {
    "name": "can_read"
  },
  "evaluations": [
    {
      "resource": {
        "type": "document",
        "id": "boxcarring.md"
      }
    },
    {
      "resource": {
        "type": "document",
        "id": "subject-search.md"
      }
    },
    {
      "action": {
        "name": "can_edit"
      },
      "resource": {
        "type": "document",
        "id": "resource-search.md"
      }
    }
  ]
}

7.1.2. Evaluations options

The evaluations request payload includes an OPTIONAL options key, with a JSON value containing a set of key-value pairs.

This provides a general-purpose mechanism for providing caller-supplied metadata on how the request is to be executed.

One such option conrtols evaluation semantics, and is described in Section 7.1.2.1.

A non-normative example of the options field is shown below:

{
  "evaluations": [...],
  "options": {
    "evaluation_semantics": "execute_all",
    "another_option": "value"
  }
}
7.1.2.1. Evaluations semantics

By default, every request in the evaluations array is executed and a response returned in the same array order. This is the most common use-case for boxcarring multiple evaluation requests in a single payload.

With that said, three evaluation semantics are supported:

  1. Execute all of the requests (potentially in parallel), return all of the results. Any failure can be denoted by decision: false and MAY provide a reason code in the context.

  2. Deny on first denial (or failure). This semantic could be desired if a PEP wants to issue a few requests in a particular order, with any denial (error, or decision: false) "short-circuiting" the evaluations call and returning on the first denial. This essentially works like the && operator in programming languages.

  3. Permit on first permit. This is the converse "short-circuiting" semantic, working like the || operator in programming languages.

To select the desired evaluations semantic, a caller can pass in options.evaluations_semantic with exactly one of the following values:

  • execute_all

  • deny_on_first_deny

  • permit_on_first_permit

execute_all is the default semantic, so an evaluations request without the options.evaluations_semantic flag will execute using this semantic.

7.1.2.1.1. Example: Evaluate read action for three documents using all three semantics

Execute all requests:

{
  "subject": {
    "type": "user",
    "id": "alice@example.com"
  },
  "action": {
    "name": "read"
  },
  "options": {
    "evaluations_semantic": "execute_all"
  },
  "evaluations": [
    {
      "resource": {
        "type": "document",
        "id": "1"
      }
    },
    {
      "resource": {
        "type": "document",
        "id": "2"
      }
    },
    {
      "resource": {
        "type": "document",
        "id": "3"
      }
    }
  ]
}

Response:

{
  "evaluations": [
    {
      decision: true
    },
    {
      decision: false
    },
    {
      decision: true
    }
  ]
}

Deny on first deny:

{
  "subject": {
    "type": "user",
    "id": "alice@example.com"
  },
  "action": {
    "name": "read"
  },
  "options": {
    "evaluations_semantic": "deny_on_first_deny"
  },
  "evaluations": [
    {
      "resource": {
        "type": "document",
        "id": "1"
      }
    },
    {
      "resource": {
        "type": "document",
        "id": "2"
      }
    },
    {
      "resource": {
        "type": "document",
        "id": "3"
      }
    }
  ]
}

Response:

{
  "evaluations": [
    {
      decision: true
    },
    {
      decision: false,
      context: {
        "id": "200",
        "reason": "deny_on_first_deny"
      }
    }
  ]
}

Permit on first permit:

{
  "subject": {
    "type": "user",
    "id": "alice@example.com"
  },
  "action": {
    "name": "read"
  },
  "options": {
    "evaluations_semantic": "permit_on_first_permit"
  },
  "evaluations": [
    {
      "resource": {
        "type": "document",
        "id": "1"
      },
    },
    {
      "resource": {
        "type": "document",
        "id": "2"
      }
    },
    {
      "resource": {
        "type": "document",
        "id": "3"
      }
    }
  ]
}

Response:

{
  "evaluations": [
    {
      decision: true
    }
  ]
}

7.2. Access Evaluations API Response

Like the request format, the Access Evaluations Response format for an Access Evaluations Request adds an evaluations array that lists the decisions in the same order they were provided in the evaluations array in the request. Each value of the evaluations array is typed as an Access Evaluation Response (Section 6.2).

In case the evaluations array is present, it is RECOMMENDED that the decision key of the response will be omitted. If present, it can be ignored by the caller.

The following is a non-normative example of a Access Evaluations Response to an Access Evaluations Request containing three evaluation objects:

{
  "evaluations": [
    {
      "decision": true
    },
    {
      "decision": false,
      "context": {
        "reason": "resource not found"
      }
    },
    {
      "decision": false,
      "context": {
        "reason": "Subject is a viewer of the resource"
      }
    }
  ]
}

7.2.1. Errors

There are two types of errors, and they are handled differently: 1. Transport-level errors, or errors that pertain to the entire payload. 2. Errors in individual evaluations.

The first type of error is handled at the transport level. For example, for the HTTP binding, the 4XX and 5XX codes indicate a general error that pertains to the entire payload, as described in Transport (Section 10).

The second type of error is handled at the payload level. Decisions default to closed (i.e. false), but the context field can include errors that are specific to that request.

The following is a non-normative example of a response to an Access Evaluations Request containing three evaluation objects, two of them demonstrating how errors can be returned for two of the evaluation requests:

{
  "evaluations": [
    {
      "decision": true
    },
    {
      "decision": false,
      "context": {
        "error": {
          "status": 404,
          "message": "Resource not found"
        }
      }
    },
    {
      "decision": false,
      "context": {
        "reason": "Subject is a viewer of the resource"
      }
    }
  ]
}

8. Subject Search API

The Subject Search API defines the message exchange pattern between a client (PEP) and an authorization service (PDP) for returning all of the subjects that match the search criteria.

The Subject Search API is based on the Access Evaluation information model, but omits the Subject ID.

8.1. The Subject Search API Request

The Subject Search request is a 3-tuple constructed of three previously defined entities:

subject:

REQUIRED. The subject (or principal) of type Subject. NOTE that the Subject type is REQUIRED but the Subject ID can be omitted, and if present, is IGNORED.

action:

REQUIRED. The action (or verb) of type Action.

resource:

REQUIRED. The resource of type Resource.

page:

OPTIONAL. A page token for paged requests.

8.1.1. Example (non-normative)

The following payload defines a request for the subjects of type user that can perform the can_read action on the resource of type account and ID 123.

{
  "subject": {
    "type": "user"
  },
  "action": {
    "name": "can_read",
  },
  "resource": {
    "type": "account",
    "id": "123"
  }
}
Figure 14: Example Request

8.2. The Subject Search API Response

The response is a paged array of Subjects.

{
  "results": [
    {
      "type": "user",
      "id": "alice@acmecorp.com"
    },
    {
      "type": "user",
      "id": "bob@acmecorp.com"
    }
  ],
  "page": {
    "next_token": ""
  }
}

8.2.1. Paged requests

A response that needs to be split across page boundaries returns a non-empty page.next_token.

8.2.1.1. Example 
{
  "results": [
    {
      "type": "user",
      "id": "alice@acmecorp.com"
    },
    {
      "type": "user",
      "id": "bob@acmecorp.com"
    }
  ],
  "page": {
    "next_token": "alsehrq3495u8"
  }
}

To retrieve the next page, provide page.next_token in the next request:

{
  "subject": {
    "type": "user"
  },
  "action": {
    "name": "can_read",
  },
  "resource": {
    "type": "account",
    "id": "123"
  },
  "page": {
    "next_token": "alsehrq3495u8"
  }
}

Note: page size is implementation-dependent.

9. Resource Search API

The Resource Search API defines the message exchange pattern between a client (PEP) and an authorization service (PDP) for returning all of the resources that match the search criteria.

The Resource Search API is based on the Access Evaluation information model, but omits the Resource ID.

9.1. The Resource Search API Request

The Resource Search request is a 3-tuple constructed of three previously defined entities:

subject:

REQUIRED. The subject (or principal) of type Subject.

action:

REQUIRED. The action (or verb) of type Action.

resource:

REQUIRED. The resource of type Resource. NOTE that the Resource type is REQUIRED but the Resource ID is omitted, and if present, is IGNORED.

page:

OPTIONAL. A page token for paged requests.

9.1.1. Example (non-normative)

The following payload defines a request for the resources of type account on which the subject of type user and ID alice@acmecorp.com can perform the can_read action.

{
  "subject": {
    "type": "user",
    "id": "alice@acmecorp.com"
  },
  "action": {
    "name": "can_read",
  },
  "resource": {
    "type": "account"
  }
}
Figure 15: Example Request

9.2. The Resource Search API Response

The response is a paged array of Resources.

{
  "results": [
    {
      "type": "account",
      "id": "123"
    },
    {
      "type": "account",
      "id": "456"
    }
  ],
  "page": {
    "next_token": ""
  }
}

9.2.1. Paged requests

A response that needs to be split across page boundaries returns a non-empty page.next_token.

9.2.1.1. Example 
{
  "results": [
    {
      "type": "account",
      "id": "123"
    },
    {
      "type": "account",
      "id": "456"
    }
  ],
  "page": {
    "next_token": "alsehrq3495u8"
  }
}

To retrieve the next page, provide page.next_token in the next request:

{
  "subject": {
    "type": "user",
    "id": "alice@acmecorp.com"
  },
  "action": {
    "name": "can_read",
  },
  "resource": {
    "type": "account"
  },
  "page": {
    "next_token": "alsehrq3495u8"
  }
}

Note: page size is implementation-dependent.

10. Transport

This specification defines an HTTPS binding which MUST be implemented by a compliant PDP.

Additional transport bindings (e.g. gRPC) MAY be defined in the future in the form of profiles, and MAY be implemented by a PDP.

10.1. HTTPS Binding

10.1.1. HTTPS Access Evaluation Request

The Access Evaluation Request is an HTTPS request with content-type of application/json. Its body is a JSON object that contains the Access Evaluation Request, as defined in Section 6.1.

The following is a non-normative example of the HTTPS binding of the Access Evaluation Request:

POST /access/v1/evaluation HTTP/1.1
Host: pdp.mycompany.com
Authorization: Bearer <myoauthtoken>
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716

{
  "subject": {
    "type": "user",
    "id": "alice@acmecorp.com"
  },
  "resource": {
    "type": "todo",
    "id": "1",
  },
  "action": {
    "name": "can_read"
  },
  "context": {
    "time": "1985-10-26T01:22-07:00"
  }
}
Figure 16: Example of an HTTPS Access Evaluation Request

10.1.2. HTTPS Access Evaluation Response

The success response to an Access Evaluation Request is an Access Evaluation Response. It is an HTTPS response with a status code of 200, and content-type of application/json. Its body is a JSON object that contains the Access Evaluation Response, as defined in Section 6.2.

Following is a non-normative example of an HTTPS Access Evaluation Response:

HTTP/1.1 OK
Content-type: application/json
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716

{
  "decision": true
}
Figure 17: Example of an HTTP Access Evaluation Response

10.1.3. HTTPS Access Evaluations Request

The Access Evaluations Request is an HTTPS request with content-type of application/json. Its body is a JSON object that contains the Access Evaluations Request, as defined in Section 7.1.

The following is a non-normative example of a the HTTPS binding of the Access Evaluations Request:

POST /access/v1/evaluations HTTP/1.1
Host: pdp.mycompany.com
Authorization: Bearer <myoauthtoken>
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716

{
  "subject": {
    "type": "user",
    "id": "alice@acmecorp.com"
  },
  "context":{
    "time": "2024-05-31T15:22-07:00"
  },
  "action": {
    "name": "can_read"
  },
  "evaluations": [
    {
      "resource": {
        "type": "document",
        "id": "boxcarring.md"
      }
    },
    {
      "resource": {
        "type": "document",
        "id": "subject-search.md"
      }
    },
    {
      "action": {
        "name": "can_edit"
      },
      "resource": {
        "type": "document",
        "id": "resource-search.md"
      }
    }
  ]
}
Figure 18: Example of an HTTPS Access Evaluations Request

10.1.4. HTTPS Access Evaluations Response

The success response to an Access Evaluations Request is an Access Evaluations Response. It is a HTTPS response with a status code of 200, and content-type of application/json. Its body is a JSON object that contains the Access Evaluations Response, as defined in Section 7.2.

The following is a non-normative example of an HTTPS Access Evaluations Response:

HTTP/1.1 OK
Content-type: application/json
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716

{
  "evaluations": [
    {
      "decision": true
    },
    {
      "decision": false,
      "context": {
        "error": {
          "status": 404,
          "message": "Resource not found"
        }
      }
    },
    {
      "decision": false,
      "context": {
        "reason": "Subject is a viewer of the resource"
      }
    }
  ]
}
Figure 19: Example of an HTTPS Access Evaluations Response

10.1.5. HTTPS Subject Search Request

The Subject Search Request is an HTTPS request with content-type of application/json. Its body is a JSON object that contains the Subject Search Request, as defined in Section 8.1.

The following is a non-normative example of the HTTPS binding of the Subject Search Request:

POST /access/v1/subjectsearch HTTP/1.1
Host: pdp.mycompany.com
Authorization: Bearer <myoauthtoken>
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716

{
  "subject": {
    "type": "user"
  },
  "action": {
    "name": "can_read"
  },
  "resource": {
    "type": "account",
    "id": "123",
  }
}
Figure 20: Example of an HTTPS Subject Search Request

10.1.6. HTTPS Subject Search Response

The success response to a Subject Search Request is a Subject Search Response. It is an HTTPS response with a status code of 200, and content-type of application/json. Its body is a JSON object that contains the Subject Search Response, as defined in Section 8.2.

The following is a non-normative example of an HTTPS Subject Search Response:

HTTP/1.1 OK
Content-type: application/json
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716

{
  "results": [
    {
      "type": "user",
      "id": "alice@acmecorp.com"
    },
    {
      "type": "user",
      "id": "bob@acmecorp.com"
    }
  ],
  "page": {
    "next_token": "alsehrq3495u8"
  }
}
Figure 21: Example of an HTTPS Subject Search Response

10.1.7. HTTPS Resource Search Request

The Resource Search Request is an HTTPS request with content-type of application/json. Its body is a JSON object that contains the Resource Search Request, as defined in Section 9.1.

The following is a non-normative example of the HTTPS binding of the Resource Search Request:

POST /access/v1/resourcesearch HTTP/1.1
Host: pdp.mycompany.com
Authorization: Bearer <myoauthtoken>
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716

{
  "subject": {
    "type": "user",
    "id": "alice@acmecorp.com"
  },
  "action": {
    "name": "can_read"
  },
  "resource": {
    "type": "account"
  }
}
Figure 22: Example of an HTTPS Resource Search Request

10.1.8. HTTPS Resource Search Response

The success response to a Resource Search Request is a Resource Search Response. It is an HTTPS response with a status code of 200, and content-type of application/json. Its body is a JSON object that contains the Resource Search Response, as defined in Section 9.2.

The following is a non-normative example of an HTTPS Resource Search Response:

HTTP/1.1 OK
Content-type: application/json
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716

{
  "results": [
    {
      "type": "account",
      "id": "123"
    },
    {
      "type": "account",
      "id": "456"
    }
  ],
  "page": {
    "next_token": "alsehrq3495u8"
  }
}
Figure 23: Example of an HTTPS Resource Search Response

10.1.9. Error Responses

The following error responses are common to all methods of the Authorization API. The error response is indicated by an HTTPS status code (Section 15 of [RFC9110]) that indicates error.

The following errors are indicated by the status codes defined below:

Table 1: HTTPS Error status codes
Code Description HTTPS Body Content
400 Bad Request An error message string
401 Unauthorized An error message string
403 Forbidden An error message string
500 Internal error An error message string

Note: HTTPS errors are returned by the PDP to indicate an error condition relating to the request or its processing, and are unrelated to the outcome of an authorization decision, which is always returned with a 200 status code and a response payload.

To make this concrete:

  • a 401 HTTPS status code indicates that the caller (policy enforcement point) did not properly authenticate to the PDP - for example, by omitting a required Authorization header, or using an invalid access token.

  • the PDP indicates to the caller that the authorization request is denied by sending a response with a 200 HTTPS status code, along with a payload of { "decision": false }.

10.1.10. Request Identification

All requests to the API MAY have request identifiers to uniquely identify them. The API client (PEP) is responsible for generating the request identifier. If present, the request identifier SHALL be provided using the HTTPS Header X-Request-ID. The value of this header is an arbitrary string. The following non-normative example describes this header:

POST /access/v1/evaluation HTTP/1.1
Authorization: Bearer mF_9.B5f-4.1JqM
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716
Figure 24: Example HTTPS request with a Request Id Header

10.1.11. Request Identification in a Response

A PDP responding to an Authorization API request that contains an X-Request-ID header MUST include a request identifier in the response. The request identifier is specified in the HTTPS Response header: X-Request-ID. If the PEP specified a request identifier in the request, the PDP MUST include the same identifier in the response to that request.

The following is a non-normative example of an HTTPS Response with this header:

HTTP/1.1 OK
Content-type: application/json
X-Request-ID: bfe9eb29-ab87-4ca3-be83-a1d5d8305716
Figure 25: Example HTTPS response with a Request Id Header

11. IANA Considerations

This specification does not introduce any new identifiers that would require registration with IANA.

12. Security Considerations

12.1. Communication Integrity and Confidentiality

In the ABAC architecture, the PEP-PDP connection is the most sensitive one and needs to be secured to guarantee:

  • Integrity

  • Confidentiality

As a result, the connection between the PEP and the PDP MUST be secured using the most adequate means given the choice of transport (e.g. TLS for HTTP REST).

12.2. Policy Confidentiality and Sender Authentication

Additionally, the PDP SHOULD authenticate the calling PEP. There are several ways authentication can be established. These ways are out of scope of this specification. They MAY include:

  • Mutual TLS

  • OAuth-based authentication

  • API key

The choice and strength of either mechanism is not in scope.

Authenticating the PEP allows the PDP to avoid common attacks (such as DoS - see below) and/or reveal its internal policies. A malicious actor could craft a large number of requests to try and understand what policies the PDP is configured with. Requesting a client (PEP) be authenticated mitigates that risk.

12.3. Trust

In ABAC, there is occasionally conversations around the trust between PEP and PDP: how can the PDP trust the PEP to send the right values in? This is a misplaced concern. The PDP must trust the PEP as ultimately, the PEP is the one responsible for enforcing the decision the PDP produces.

12.4. Availability & Denial of Service

The PDP SHOULD apply reasonable protections to avoid common attacks tied to request payload size, the number of requests, invalid JSON, nested JSON attacks, or memory consumption. Rate limiting is one such way to address such issues.

13. Normative References

[RFC4001]
Daniele, M., Haberman, B., Routhier, S., and J. Schoenwaelder, "Textual Conventions for Internet Network Addresses", RFC 4001, DOI 10.17487/RFC4001, , <https://www.rfc-editor.org/rfc/rfc4001>.
[RFC6749]
Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", RFC 6749, DOI 10.17487/RFC6749, , <https://www.rfc-editor.org/rfc/rfc6749>.
[RFC8259]
Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, , <https://www.rfc-editor.org/rfc/rfc8259>.
[RFC9110]
Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP Semantics", STD 97, RFC 9110, DOI 10.17487/RFC9110, , <https://www.rfc-editor.org/rfc/rfc9110>.
[XACML]
Godik, S., Ed. and T. M. (Ed.), Ed., "eXtensible Access Control Markup Language (XACML) Version 1.1", , <https://www.oasis-open.org/committees/xacml/repository/cs-xacml-specification-1.1.pdf>.

Appendix A. Terminology

Subject:

The user or robotic principal about whom the Authorization API call is being made.

Resource:

The target of the request; the resource about which the Authorization API is being made.

Action:

The operation the Subject has attempted on the Resource in an Authorization API call.

Context:

The environmental or contextual attributes for this request.

Decision:

The value of the evaluation decision made by the PDP: true for "allow", false for "deny".

PDP:

Policy Decision Point. The component or system that provides authorization decisions over the network interface defined here as the Authorization API.

PEP:

Policy Enforcement Point. The component or system that requests decisions from the PDP and enforces access to specific requests based on the decisions obtained from the PDP.

Appendix B. Acknowledgements

This template uses extracts from templates written by Pekka Savola, Elwyn Davies and Henrik Levkowetz.

Appendix C. Document History

[[ To be removed from the final specification ]]

Appendix D. Notices

Copyright (c) 2025 The OpenID Foundation.

The OpenID Foundation (OIDF) grants to any Contributor, developer, implementer, or other interested party a non-exclusive, royalty free, worldwide copyright license to reproduce, prepare derivative works from, distribute, perform and display, this Implementers Draft, Final Specification, or Final Specification Incorporating Errata Corrections solely for the purposes of (i) developing specifications, and (ii) implementing Implementers Drafts, Final Specifications, and Final Specification Incorporating Errata Corrections based on such documents, provided that attribution be made to the OIDF as the source of the material, but that such attribution does not indicate an endorsement by the OIDF.

The technology described in this specification was made available from contributions from various sources, including members of the OpenID Foundation and others. Although the OpenID Foundation has taken steps to help ensure that the technology is available for distribution, it takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this specification or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any independent effort to identify any such rights. The OpenID Foundation and the contributors to this specification make no (and hereby expressly disclaim any) warranties (express, implied, or otherwise), including implied warranties of merchantability, non-infringement, fitness for a particular purpose, or title, related to this specification, and the entire risk as to implementing this specification is assumed by the implementer. The OpenID Intellectual Property Rights policy (found at openid.net) requires contributors to offer a patent promise not to assert certain patent claims against other contributors and against implementers. OpenID invites any interested party to bring to its attention any copyrights, patents, patent applications, or other proprietary rights that may cover technology that may be required to practice this specification.

Contributors

Marc Jordan
SGNL
Erik Gustavson
SGNL
Alex Babeanu
3Edges

Authors' Addresses

Omri Gazitt (editor)
Aserto
David Brossard (editor)
Axiomatics
Atul Tulshibagwale (editor)
SGNL