OpenID Connect 1.0 draft-01

Abstract

OpenID Connect 1.0 is a simple identity layer on top of the OAuth 2.0 [RFC6749] protocol. It allows Clients to verify the identity of the End-User based on the authentication performed by an Authorization Server, as well as to obtain basic profile information about the End-User in an interoperable and REST-like manner. It does so by extending Authorization Endoint and Token Endpoint by defining standardized scope and a new token type called ID Token. In perticular, it introduces a standard scope called openid, which asks the server to provide the authentication event information through a new token type called ID Token, which is a JSON Web Token. In addition, it defines a new OAuth Bearer Token [RFC6750] endpoint called Userinfo Endpoint, from which the client may obtain user profile data.

It is very simple to implement as well as it can be very secure and privacy observing. For security, it leverages on various cryptographic techniques leveraging on JSON Web Signature and JSON Web Encryption as well as other industrially proven techniques. For privacy, it supports anti-collusion techniques such as pseudonymous identifier as well as a Self-Issued provider that may act as a privacy proxy.

Table of Contents

1.  Introduction
    1.1.  Requirements Notation and Conventions
2.  Terms, Concepts, and Requirements to them (Normative)
    2.1.  End User
    2.2.  Entity
    2.3.  Identity
    2.4.  Claim
    2.5.  Authentication
    2.6.  ID Token
    2.7.  Identifier
    2.8.  Issuer
    2.9.  Issuer Identifier
    2.10.  OpenID Provider (OP)
    2.11.  Relying Party (RP)
    2.12.  Validation
3.  Authentication - Code Flow
    3.1.  Authorization Endpoint
    3.2.  Token Endpoint
4.  Authentication - Implicit Flows
    4.1.  Request Parameters
    4.2.  Server Processings
    4.3.  Authorization Response
5.  Initiating Login at Client from Third Party
6.  Claims Framework
    6.1.  Requesting Claims
    6.2.  Standard Claims
    6.3.  Claim Types
    6.4.  UserInfo Endpoint
    6.5.  Offline Access
7.  Request by JSON
    7.1.  Authorization Request by JSON
    7.2.  Validation
    7.3.  Authorization Error Response
8.  Self-Issued OpenID Provider
    8.1.  Self-Issued OpenID Provider Discovery
    8.2.  Self-Issued OpenID Provider Registration
    8.3.  Self-Issued OpenID Provider Request
    8.4.  Self-Issued OpenID Provider Response
    8.5.  Self-Issued ID Token Validation
9.  Client Authentication
10.  Signatures and Encryption
    10.1.  Supported Algorithms
    10.2.  Keys
    10.3.  Signing
    10.4.  Encryption
11.  String Operations and Serializations
    11.1.  String Operations
    11.2.  Serializations
12.  Implementation Considerations
    12.1.  Mandatory to Implement Features for All OpenID Providers
    12.2.  Mandatory to Implement Features for Dynamic OpenID Providers
    12.3.  Related Specifications
13.  Security Considerations
    13.1.  TLS Version
    13.2.  Request Disclosure
    13.3.  Server Masquerading
    13.4.  Token Manufacture/Modification
    13.5.  Server Response Disclosure
    13.6.  Server Response Repudiation
    13.7.  Request Repudiation
    13.8.  Access Token Redirect
    13.9.  Token Reuse
    13.10.  Eavesdropping or Leaking Authorization Codes (Secondary Authenticator Capture)
    13.11.  Token Substitution
    13.12.  Timing Attack
    13.13.  Other Crypto Related Attacks
    13.14.  Signing and Encryption Order
    13.15.  Issuer Identifier
    13.16.  TLS Requirements
    13.17.  Lifetimes of Access Tokens and Refresh Tokens
    13.18.  Symmetric Key Entropy
    13.19.  Need for Signed Requests
    13.20.  Need for Encrypted Requests
14.  Privacy Considerations
    14.1.  Personally Identifiable Information
    14.2.  Data Access Monitoring
    14.3.  Correlation
    14.4.  Offline Access
15.  IANA Considerations
    15.1.  JSON Web Token Claims Registry
    15.2.  OAuth Parameters Registry
    15.3.  OAuth Extensions Error Registry
16.  References
    16.1.  Normative References
    16.2.  Informative References
Appendix A.  Examples
Appendix B.  Acknowledgements
Appendix C.  Notices
§  Authors' Addresses

1.  Introduction

OpenID Connect 1.0 defines how to perfom federated login using OAuth 2.0. It does so by extending Authorization Endoint and Token Endpoint by defining standardized scope and a new token type called ID Token. In perticular, it introduces a standard scope called openid, which asks the server to provide the authentication event information through a new token type called ID Token, which is a JSON Web Token.

As this specification is built on top of OAuth 2.0, it trys to avoid duplicating the normative text of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749]. As the result, the readers are expected to be familiar witth to read this specification.

1.1.  Requirements Notation and Conventions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] (Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels,” March 1997.).

Throughout this document, values are quoted to indicate that they are to be taken literally. When using these values in protocol messages, the quotes MUST NOT be used as part of the value.

All uses of JSON Web Signature (JWS) (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] data structures in this specification utilize the JWS Compact Serialization; the JWS JSON Serialization is not used.

When the RFC 2119 language applies to the behavior of OpenID Providers, it is in this specification for explanatory value to help Client implementers understand the expected behavior of OpenID Providers.

2.  Terms, Concepts, and Requirements to them (Normative)

This section explains the basic concept and terms that are required to read this specification. This section is a normative portion of this specification, imposing requirements upon implementations. All the capitalized words in the text of this specification, such as "Issuer Identifier", reference these defined terms. Whenever the reader encounters them, their definitions found in this section must be followed.

In this specification, the term and definitions are organized in the following way.

2.x. Defined Term (Abbreviation)

Definition of the term in once sentence without an article to start and a trailing punctuation so that the term can be replaced with the definition when it is found in the main text

[SOURCE: Reference to the Source document when applicable]

NOTE: Clarification note is written in the NOTE: section as needed. It may have multiple note section.

NOTE: As explained above, the terms defined in this specification can be and should be expanded by the reader when they are encountered in the main text. However, this does not apply to the terms imported from OAuth 2.0, such as "Access Token".

As this specification is an extension to OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749], it uses the terms used there: i.e., "Access Token", "Refresh Token", "Authorization Code", "Authorization Grant", "Authorization Server", "Authorization Endpoint", "Client", "Client Identifier", "Client Secret", "Protected Resource", "Resource Owner", "Resource Server", "Authorization Request", and "Token Endpoint".

This specification also defines the following terms:

2.1.  End User

Human Resource Owner

2.2.  Entity

Something that has a separate and distinct existence and that can be identified in a context

[SOURCE: ITU-T X.1252]

NOTE: An End User (End User) is one example of an Entity.

2.3.  Identity

Set of attributes related to an Entity

[SOURCE: ISO/IEC 24760-1 (International Organization for Standardization, “ISO/IEC 24760-1 -- Information technology - Security techniques - A framework for identity management -- Part 1: Terminology and concepts,” December 2011.) [ISO24760‑1]]

2.4.  Claim

Piece of information asserted about an Entity (Entity)

2.5.  Authentication

Provision of assurance in the identity of an Entity (Entity)

[SOURCE: ISO/IEC 18014-2 (International Organization for Standardization, “ISO/IEC 18014-2 -- Information technology -- Security techniques -- Time-stamping services -- Part 2: Mechanisms producing independent tokens,” December 2009.) [ISO18014‑2]]

2.6.  ID Token

JSON Web Token (JWT) (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT] that contains Claims about the Authentication (Authentication) event

NOTE: It MAY contain other Claims. The actual format and the standard claims included in the ID Token are explained in Section 3.2.4 (ID Token).

2.7.  Identifier

Value that uniquely characterizes an Entity (Entity) in a specific context

2.8.  Issuer

Entity (Entity) that issues a set of Claims

2.9.  Issuer Identifier

Case sensitive URL using the https scheme that contains scheme, host, and OPTIONALLY, port number and path components and no query or fragment components that acts as a verifiable Identifier for an Issuer

2.10.  OpenID Provider (OP)

OAuth 2.0 Authorization Server that is capable of providing Claims to a Relying Party

2.11.  Relying Party (RP)

OAuth 2.0 Client application requiring Claims from an OpenID Provider (OpenID Provider (OP))

2.12.  Validation

Process intended to establish the soundness or correctness of a construct

3.  Authentication - Code Flow

3.1.  Authorization Endpoint

For the purpose of this specification, it is assumed that the Relying Party knows the location of the Authorization Endpoint in one way or another. It could be through out-of-band information sharing or through some form of discovery operation such as OpenID Connect Discovery (Sakimura, N., Bradley, J., Jones, M., and E. Jay, “OpenID Connect Discovery 1.0,” July 2013.) [OpenID.Discovery], which is out of scope of this specification.

To start the Authentication process for the End User, the RP sends the User-Agent to the Authorization Endpoint through HTTP redirection or other mechanisms. The parameters that are sent are that of the OAuth 2.0 Authorization Request plus some OpenID Connect specific parameters. They are sent to the Authorization Endpoint using HTTPS and the server MUST be able to process these parameters.

3.1.1.  Request Parameters

Followings are the OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749] parameters.

scope

REQUIRED. The value MUST contain the openid. This scope value requests ID Token, which is a JWT that includes the Claims about the End-User Authentication event.

response_type

REQUIRED. The value MUST be code.

client_id

REQUIRED. OAuth 2.0 Client Identifier.

redirect_uri

REQUIRED. Redirection URI to which the response will be sent. This MUST be pre-registered with the OpenID Provider. This URI MUST exactly match one of the redirect_uris registered for the Client, with the matching performed as described in Section 6.2.1 of [RFC3986] (Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.) (Simple String Comparison).The redirection URI MAY use the http scheme, provided that the Client Type is confidential, as defined in Section 2.1 of OAuth 2.0, though the use of TLS is strongly RECOMMENDED.

state

RECOMMENDED. Opaque value used to maintain state between the request and the callback. Typically, Cross-Site Request Forgery (CSRF, XSRF) mitigation is done by cryptographically binding the value of this parameter with the browser cookie.

Followings are the extension parameters that this specification defines. All of them are OPTIONAL.

nonce

OPTIONAL. String value used to associate a Client session with an ID Token, and to mitigate replay attacks. The value is passed through unmodified from the Authorization Request to the ID Token. Sufficient entropy MUST be present in the nonce values used to prevent attackers from guessing values.

display

OPTIONAL. ASCII string value that specifies how the Authorization Server displays the authentication and consent user interface pages to the End-User. The defined values are:

page

The Authorization Server SHOULD display authentication and consent UI consistent with a full User-Agent page view. If the display parameter is not specified this is the default display mode.

popup

The Authorization Server SHOULD display authentication and consent UI consistent with a popup User-Agent window. The popup User-Agent window SHOULD be 450 pixels wide and 500 pixels tall.

touch

The Authorization Server SHOULD display authentication and consent UI consistent with a device that leverages a touch interface. The Authorization Server MAY attempt to detect the touch device and further customize the interface.

wap

The Authorization Server SHOULD display authentication and consent UI consistent with a "feature phone" type display.

prompt

OPTIONAL. Space delimited, case sensitive list of ASCII string values that specifies whether the Authorization Server prompts the End-User for reauthentication and consent. The defined values are:

none

The Authorization Server MUST NOT display any authentication or consent user interface pages. An error is returned if the End-User is not already authenticated or the Client does not have pre-configured consent for the requested Claims or does not fulfill other conditions for processing. This can be used as a method to check for existing authentication and/or consent.

login

The Authorization Server SHOULD prompt the End-User for reauthentication. If it cannot prompt the End-User, it MUST return an error.

consent

The Authorization Server SHOULD prompt the End-User for consent before returning information to the Client.

select_account

The Authorization Server SHOULD prompt the End-User to select a user account. This allows an End-User who has multiple accounts at the Authorization Server to select amongst the multiple accounts that they might have current sessions for. If it cannot prompt the End-User, it MUST return an error.

The prompt parameter can be used by the Client to make sure that the End-User is still present for the current session or to bring attention to the request. If this parameter contains none with any other value, an error is returned.

max_age

OPTIONAL. Maximum Authentication Age. Specifies the allowable elapsed time in seconds since the last time the End-User was actively authenticated. If the elapsed time is greater than this value, the OP MUST attempt to actively re-authenticate the End-User. When max_age is used, the ID Token returned MUST include an auth_time Claim Value.

ui_locales

OPTIONAL. End-User's preferred languages and scripts for the user interface, represented as a space-separated list of BCP47 (Phillips, A. and M. Davis, “Tags for Identifying Languages,” September 2009.) [RFC5646] language tag values, ordered by preference. For instance, the value "fr-CA fr en" represents a preference for French as spoken in Canada, then French (without a region designation), followed by English (without a region designation). An error SHOULD NOT result if some or all of the requested locales are not supported by the OpenID Provider.

id_token_hint

OPTIONAL. Previously issued ID Token passed to the Authorization Server as a hint about the End-User's current or past authenticated session with the Client. This SHOULD be present when prompt=none is used. If the End-User identified by the ID Token is logged in or is logged in by the request, then the Authorization Server returns a positive response; otherwise, it SHOULD return a negative response. The Authorization Server need not be listed as an audience of the ID Token when it is used as an id_token_hint value.

login_hint

OPTIONAL. Hint to the Authorization Server about the login identifier the End-User might use to log in (if necessary). This hint can be used by an RP if it first asks the End-User for their e-mail address (or other identifier) and then wants to pass that value as a hint to the discovered authorization service. It is RECOMMENDED that the hint value match the value used for discovery. This value MAY also be a phone number in the format specified for the phone_number Claim. The use of this parameter is left to the OP's discretion.

acr_values

OPTIONAL. Requested Authentication Context Class Reference values. Space-separated string that specifies the acr values that the Authorization Server is being requested to use for processing this authentication request, with the values appearing in order of preference. The Authentication Context Class satisfied by the authentication performed is returned as the acr Claim Value, as specified in ID Token section of OpenID Connect Messages. The acr Claim is requested as a Voluntary Claim by this parameter.

Following is a non-normative example using HTTP redirect (with line wraps within values for display purposes only):

  HTTP/1.1 302 Found
  Location: https://server.example.com/authorize?
    response_type=code
    &client_id=s6BhdRkqt3
    &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
    &scope=openid
    &state=af0ifjsldkj

3.1.2.  Server Processings

Upon receipt of the parameters, the server MUST perform the following.

1. Check if scope includes openid. If it does not, just proceed with normal OAuth processing;
2. Authenticate the user and obtain authorization from the user as needed;
3. Record the enough information to be able to create the id_token;
4. Find out what response_type the request was using and send the result back accordingly;

3.1.3.  Authorization Response

If the Resource Owner authenticates and authorizes, the Authorization Endpoint returns the OAuth 2.0 response as follows:

3.1.3.1.  Authorization Successful Response

The Authorization Server saves the association between code and id_token, and returns code and other OAuth 2.0 parameters as defined in Section 4.1.2 of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749].

The following is a non-normative example (with line wraps for the display purposes only):

  HTTP/1.1 302 Found
  Location: https://client.example.org/cb?
    code=SplxlOBeZQQYbYS6WxSbIA
    &state=af0ifjsldkj

3.1.3.2.  Code Validation

To validate a code issued from the Authorization Endpoint with an ID Token in response to a request containing a response_type of code id_token or code id_token token, the Client SHOULD do the following:

1. Hash the octets of the ASCII representation of the code with the hash algorithm specified in JWS (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) [JWA] for the alg parameter in the ID Token's JWS (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] header.
2. Take the left-most half of the hash and base64url encode it.
3. The value of c_hash in the ID Token MUST match the value produced in the previous step if c_hash is present in the ID Token.

3.1.3.3.  Authorization Error Response

If the End-User denies the access request or if the request fails, the OP (Authorization Server) informs the RP (Client) by using the Error Response parameters defined in Sections 4.1.2.1 of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749].

In addition to the error codes defined in Sections 4.1.2.1 of OAuth 2.0, this specification also defines the following error codes:

interaction_required

The Authorization Server requires End-User interaction of some form to proceed. This error MAY be returned when the prompt parameter in the Authorization Request is set to none to request that the Authorization Server SHOULD NOT display any user interfaces to the End-User, but the Authorization Request cannot be completed without displaying a user interface for End-User interaction.

login_required

The Authorization Server requires End-User authentication. This error MAY be returned when the prompt parameter in the Authorization Request is set to none to request that the Authorization Server SHOULD NOT display any user interfaces to the End-User, but the Authorization Request cannot be completed without displaying a user interface for user authentication.

session_selection_required

The End-User is REQUIRED to select a session at the Authorization Server. The End-User MAY be authenticated at the Authorization Server with different associated accounts, but the End-User did not select a session. This error MAY be returned when the prompt parameter in the Authorization Request is set to none to request that the Authorization Server SHOULD NOT display any user interfaces to the End-User, but the Authorization Request cannot be completed without displaying a user interface to prompt for a session to use.

consent_required

The Authorization Server requires End-User consent. This error MAY be returned when the prompt parameter in the Authorization Request is set to none to request that the Authorization Server SHOULD NOT display any user interfaces to the End-User, but the Authorization Request cannot be completed without displaying a user interface for End-User consent.

invalid_request_uri

The request_uri in the Authorization Request returns an error or contains invalid data.

invalid_request_object

The request parameter contains an invalid Request Object.

registration_not_supported

The OP does not support use of the registration parameter.

request_not_supported

The OP does not support use of the request parameter.

request_uri_not_supported

The OP does not support use of the request_uri parameter.

3.2.  Token Endpoint

As in OAuth 2.0, if the response type was code, the Client interacts with the Token Endpoint.

In OpenID Connect, this communication MUST be over TLS. See OpenID Connect Messages for more information on using TLS.

3.2.1.  Access Token Request

To obtain an Access Token, Refresh Token or ID Token, the Client sends Access Token Request as defined in OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749]. It the client is a confidential client, then it MUST Authenticate to the Token Endpoint using the authentication method that is agreed between the client and the server for its client_id.

NOTE: Various Client Authentication methods are documented in Section 2.2.1 of OpenID Connect Messages 1.0.

The following is a non-normative example of an Access Token Request:

  POST /token HTTP/1.1
  Host: server.example.com
  Content-Type: application/x-www-form-urlencoded
  Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW

  grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
    &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb

3.2.2.  Access Token Request Validation

Upon receipt of the request, the Authorization Server MUST:

• Authenticate any Clients that were issued Client Credentials (or for which other Client Authentication methods can be used);
• Ensure the Authorization Code was issued to the authenticated Client;
• Verify that the Authorization Code is valid, and
• Ensure that the Scheme, Host, Path, and Query Parameter segments in the redirect_uri parameter are identical to the redirect_uri parameter value that was included in the initial Authorization Request. If the redirect_uri parameter value not be present when there is only one registered redirect_uri value, the Authorization Server MAY return an error (since the Client should have included the parameter) or MAY proceed without an error (since OAuth 2.0 permits the parameter to be omitted in this case); and
• Check if the received code is associated with a previously created ID Token;

NOTE: The code may have a special structure that indicates what was to be included in the ID Token, or the server might pull them from the database that stored such information using the code.

3.2.3.  Access Token Response

After receiving and validating a valid and authorized Access Token Request from the Client, the Authorization Server returns a successful response that includes an Access Token and an ID Token. The parameters in the successful response are defined in Section 4.1.4 of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749].

This specification only describes OAuth 2.0 Bearer Token Usage (Jones, M. and D. Hardt, “The OAuth 2.0 Authorization Framework: Bearer Token Usage,” October 2012.) [RFC6750]. The OAuth 2.0 response parameter token_type MUST be set to Bearer unless another Token Type has been negotiated with the Client. Servers SHOULD support OAuth 2.0 Bearer Token Usage (Jones, M. and D. Hardt, “The OAuth 2.0 Authorization Framework: Bearer Token Usage,” October 2012.) [RFC6750] for interoperability. For security reasons Servers MAY only allow Clients to register specific token_type.

Clients MUST support OAuth 2.0 Bearer Token Usage (Jones, M. and D. Hardt, “The OAuth 2.0 Authorization Framework: Bearer Token Usage,” October 2012.) [RFC6750] and MAY support other token_type.

In addition to the OAuth 2.0 response parameters, the following parameters MUST be included in the response:

id_token

ID Token value associated with the authenticated session.

Following is a non-normative example:

HTTP/1.1 200 OK

  {
   "access_token": "SlAV32hkKG",
   "token_type": "Bearer",
   "refresh_token": "8xLOxBtZp8",
   "expires_in": 3600,
   "id_token": "eyJ0 ... NiJ9.eyJ1c ... I6IjIifX0.DeWt4Qu ... ZXso"
  }

As in the OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749], Clients SHOULD ignore unrecognized response parameters.

For the case where a Refresh Token was used in the request instead of the Access Token, refer to Section 3.2.6 (Refresh Token Response).

3.2.4.  ID Token

The ID Token is a security token that contains Claims about the authentication event and other requested Claims. The ID Token is represented as a JSON Web Token (JWT) (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT].

The ID Token is used to manage the authentication event and user identifier and is scoped to a particular Client via the aud (audience) and nonce Claims.

The following Claims are used within the ID Token:

iss

REQUIRED. Issuer Identifier for the Issuer of the response. The iss value is a case sensitive URL using the https scheme that contains scheme, host, and OPTIONALLY, port number and path components and no query or fragment components.

sub

REQUIRED. Subject identifier. A locally unique and never reassigned identifier within the Issuer for the End-User, which is intended to be consumed by the Client, e.g., 24400320 or AItOawmwtWwcT0k51BayewNvutrJUqsvl6qs7A4. It MUST NOT exceed 255 ASCII characters in length. The sub value is a case sensitive string.

aud

REQUIRED. Audience(s) that this ID Token is intended for. It MUST contain the OAuth 2.0 client_id of the Relying Party as an audience value. It MAY also contain identifiers for other audiences. In the general case, the aud value is an array of case sensitive strings. In the special case when there is one audience, the aud value MAY be a single case sensitive string.

exp

REQUIRED. Expiration time on or after which the ID Token MUST NOT be accepted for processing. The processing of this parameter requires that the current date/time MUST be before the expiration date/time listed in the value. Implementers MAY provide for some small leeway, usually no more than a few minutes, to account for clock skew. The time is represented as the number of seconds from 1970-01-01T0:0:0Z as measured in UTC until the date/time. See RFC 3339 (Klyne, G., Ed. and C. Newman, “Date and Time on the Internet: Timestamps,” July 2002.) [RFC3339] for details regarding date/times in general and UTC in particular. The exp value is a number.

iat

REQUIRED. Time at which the JWT was issued. The time is represented as the number of seconds from 1970-01-01T0:0:0Z as measured in UTC until the date/time. The iat value is a number.

auth_time

OPTIONAL or REQUIRED. Time when the End-User authentication occurred. The time is represented as the number of seconds from 1970-01-01T0:0:0Z as measured in UTC until the date/time. When a max_age request is made or when auth_time is requested as an Essential Claim, then this Claim is REQUIRED. (The auth_time Claim semantically corresponds to the OpenID 2.0 PAPE (Recordon, D., Jones, M., Bufu, J., Ed., Daugherty, J., Ed., and N. Sakimura, “OpenID Provider Authentication Policy Extension 1.0,” December 2008.) [OpenID.PAPE] auth_time response parameter.) The auth_time value is a number.

nonce

OPTIONAL or REQUIRED. String value used to associate a Client session with an ID Token, and to mitigate replay attacks. The value is passed through unmodified from the Authorization Request to the ID Token. If present in the ID Token, Clients MUST verify that the nonce Claim Value is equal to the value of the nonce parameter sent in the Authorization Request. If present in the Authorization Request, Authorization Servers MUST include a nonce Claim in the ID Token with the Claim Value being the nonce value sent in the Authorization Request. Authorization Servers SHOULD perform no other processing on nonce values used. Use of the nonce is REQUIRED for all requests where an ID Token is returned directly from the Authorization Endpoint. It is OPTIONAL when the ID Token is returned from the Token Endpoint. The nonce value is a case sensitive string.

at_hash

OPTIONAL or REQUIRED. Access Token hash value. If the ID Token is issued from the Authorization Endpoint with an access_token, this is REQUIRED. This is OPTIONAL when the ID Token is issued from the Token Endpoint. Its value is the base64url encoding of the left-most half of the hash of the octets of the ASCII representation of the access_token value, where the hash algorithm used is the hash algorithm used in the alg parameter of the ID Token's JWS (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] header. For instance, if the alg is RS256, hash the access_token value with SHA-256, then take the left-most 128 bits and base64url encode them. The at_hash value is a case sensitive string.

c_hash

Sometimes REQUIRED. Code hash value. If the ID Token is issued from the Authorization Endpoint with a code, this is REQUIRED. Its value is the base64url encoding of the left-most half of the hash of the octets of the ASCII representation of the code value, where the hash algorithm used is the hash algorithm used in the alg parameter of the ID Token's JWS (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] header. For instance, if the alg is HS512, hash the code value with SHA-512, then take the left-most 256 bits and base64url encode them. The c_hash value is a case sensitive string.

acr

OPTIONAL. Authentication Context Class Reference. String specifying an Authentication Context Class Reference value that identifies the Authentication Context Class that the authentication performed satisfied. The value "0" indicates the End-User authentication did not meet the requirements of ISO/IEC 29115 (International Organization for Standardization, “ISO/IEC 29115:2013 -- Information technology - Security techniques - Entity authentication assurance framework,” March 2013.) [ISO29115] level 1. Authentication using a long-lived browser cookie, for instance, is one example where the use of "level 0" is appropriate. Authentications with level 0 SHOULD never be used to authorize access to any resource of any monetary value. (This corresponds to the OpenID 2.0 PAPE (Recordon, D., Jones, M., Bufu, J., Ed., Daugherty, J., Ed., and N. Sakimura, “OpenID Provider Authentication Policy Extension 1.0,” December 2008.) [OpenID.PAPE] nist_auth_level 0.) An absolute URI or a registered name (Johansson, L., “An IANA Registry for Level of Assurance (LoA) Profiles,” August 2012.) [RFC6711] SHOULD be used as the acr value; registered names MUST NOT be used with a different meaning than that which is registered. Parties using this claim will need to agree upon the meanings of the values used, which may be context-specific. The acr value is a case sensitive string.

amr

OPTIONAL. Authentication Methods References. JSON array of strings that are identifiers for authentication methods used in the authentication. For instance, values might indicate that both password and OTP authentication methods were used. The definition of particular values to be used in the amr Claim is beyond the scope of this specification. Parties using this claim will need to agree upon the meanings of the values used, which may be context-specific. The amr value is an array of case sensitive strings.

azp

OPTIONAL or REQUIRED. Authorized Party - the party to which the ID Token was issued. If present, it MUST contain the OAuth 2.0 client_id of the party that will be using it. This Claim is only REQUIRED when the party requesting the ID Token is not the same as the sole audience of the ID Token. It MAY be included even when the Authorized Party is the same as the sole audience. The azp value is a case sensitive string containing a StringOrURI value.

sub_jwk

NOT RECOMMENDED or REQUIRED. Public key value used to check the signature of an ID Token issued by a Self-Issued OpenID Provider, as specified in [OpenID.SelfIssued] (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Self Issued Provider 1.0,” July 2013.). The key is a bare key in JWK [JWK] (Jones, M., “JSON Web Key (JWK),” May 2013.) format (not an X.509 certificate value). Use of the sub_jwk Claim is REQUIRED when the OP is a Self-Issued OP and is NOT RECOMMENDED when the OP is not Self-Issued. The iss value is a JSON object.

[Editor's Note] Perhaps sub_jwk should be moved to [OpenID.SelfIssued] (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Self Issued Provider 1.0,” July 2013.).

ID Tokens MAY contain other Claims. Any Claims used that are not understood MUST be ignored.

ID Tokens MUST be signed using JWS (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] and OPTIONALLY both signed and then encrypted using JWS (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] and JWE (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” May 2013.) [JWE] respectively, thereby providing authentication, integrity, non-repudiation, and optionally, confidentiality. ID Tokens MUST NOT use none as the alg value.

ID Tokens SHOULD NOT use the JWS or JWE x5u, x5c, jku, or jwk header parameter fields. Instead, key values and key references used for ID Tokens are communicated in advance using Discovery and Registration parameters.

The following is a non-normative example of a base64url decoded ID Token:

  {
   "iss": "https://server.example.com",
   "sub": "24400320",
   "aud": "s6BhdRkqt3",
   "nonce": "n-0S6_WzA2Mj",
   "exp": 1311281970,
   "iat": 1311280970,
   "auth_time": 1311280969,
   "acr": "urn:mace:incommon:iap:silver",
   "at_hash": "MTIzNDU2Nzg5MDEyMzQ1Ng"
  }

3.2.5.  ID Token Validation by the Client

To validate the ID Token in the Authorization or Token Endpoint Response, the Client MUST do the following:

1. If the Client has negotiated the encryption algorithm to be used for ID Token, then the Client MUST decrypt the ID Token using the key pair specified for it according to JWE (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” May 2013.) [JWE] and JWA (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) [JWA].

   NOTE:

   The Client and the Server MAY utilize [OpenID.Registration] (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Dynamic Client Registration 1.0,” July 2013.) for this purpose, which allows the client to provided the algorithm through id_token_encrypted_response_alg parameter and the associated key pair.

2. The Client MUST validate that the aud (audience) Claim contains its client_id value registered at the Issuer identified by the iss (issuer) Claim as an audience. The aud (audience) Claim MAY contain an array with more than one element. The ID Token MUST be rejected if the ID Token does not list the Client as a valid audience, or if it contains additional audiences not trusted by the Client.
3. If the ID Token contains multiple audiences, the Client SHOULD verify that an azp Claim is present.
4. If an azp (authorized party) Claim is present, the Client SHOULD verify and that its client_id is the Claim value.
5. Validation the issuer through TLS server validation MUST be performed.
6. Optionally, the Client MAY perform ID Token signature Validation for added security. In this case, the Client MUST validate the signature of all other ID Tokens according to JWS (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] using the algorithm specified in the alg parameter of the JWT (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT] header. When checking the signature:
   1. The alg value SHOULD be the default of RS256 or the algorithm sent by the Client during the registration process. If the Client used the OpenID Connect Dynamic Registration 1.0, then it is in the id_token_signed_response_alg parameter.
   2. If the alg parameter of the JWT header is a MAC based algorithm such as HS256, HS384, or HS512, the octets of the UTF-8 representation of the client_secret corresponding to the client_id contained in the aud (audience) Claim are used as the key to validate the signature. Multiple audiences are not supported for MAC based algorithms.
   3. For other Signing algorithms, the Client MUST use the signing key provided in Discovery by the Issuer. The issuer MUST exactly match the value of the iss (issuer) Claim.
7. The current time MUST be less than the value of the exp Claim.
8. The iat Claim can be used to reject tokens that were issued too far away from the current time, limiting the amount of time that nonces need to be stored to prevent attacks. The acceptable range is Client specific.
9. If a nonce value was sent in the Authorization Request, a nonce Claim MUST be present and its value checked to verify that it is the same value as the one that was sent in the Authorization Request. The Client SHOULD check the nonce value for replay attacks. The precise method for detecting replay attacks is Client specific.
10. If the acr Claim was requested, the Client SHOULD check that the asserted Claim Value is appropriate. The meaning and processing of acr Claim Values is out of scope for this specification.
11. If the auth_time Claim was requested, either through a specific request for this Claim or by using the max_age parameter, the Client SHOULD check the auth_time Claim value and request re-authentication if it determines too much time has elapsed since the last End-User authentication.

3.2.6.  Refresh Token Response

If an ID Token is returned as a result of a token refresh request, the following requirements apply:

• its iss Claim value MUST be the same as in the ID Token issued when the original authentication occurred,
• its sub Claim value MUST be the same as in the ID Token issued when the original authentication occurred,
• its iat Claim MUST represent the time that the new ID Token is issued,
• its aud Claim value MUST be the same as in the ID Token issued when the original authentication occurred,
• if the ID Token contains an auth_time Claim, its value MUST represent the time of the original authentication - not the time that the new ID token is issued,
• its azp Claim value MUST be the same as in the ID Token issued when the original authentication occurred; if no azp Claim was present in the original ID Token, one MUST NOT be present in the new ID Token, and
• otherwise, the same rules apply as apply when issuing an ID Token at the time of the original authentication.

4.  Authentication - Implicit Flows

In Implicit Flows, all the tokens are returned from the authorization endpoint.

4.1.  Request Parameters

Follwoings are the OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749] parametes.

scope

REQUIRED. The value MUST contain the openid. This scope value requests ID Token, which is a JWT that includes the Claims about the End-User Authentication event.

response_type

REQUIRED. The value MUST be token id_token or code token id_token as defined in OAuth 2.0 Multiple Response Type Encoding Practices (de Medeiros, B., Ed., Scurtescu, M., and P. Tarjan, “OAuth 2.0 Multiple Response Type Encoding Practices,” June 2013.) [OAuth.Responses].

client_id

REQUIRED. OAuth 2.0 Client Identifier.

redirect_uri

REQUIRED. Redirection URI to which the response will be sent. This MUST be pre-registered with the OpenID Provider. This URI MUST exactly match one of the redirect_uris registered for the Client, with the matching performed as described in Section 6.2.1 of [RFC3986] (Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax,” January 2005.) (Simple String Comparison).The redirection URI MUST use the https scheme.

state

RECOMMENDED. Opaque value used to maintain state between the request and the callback. Typically, Cross-Site Request Forgery (CSRF, XSRF) mitigation is done by cryptographically binding the value of this parameter with the browser cookie.

The OpenID Connect parameter nonce is REQUIRED for this specification.

nonce

REQUIRED. String value used to associate a Client session with an ID Token, and to mitigate replay attacks. The value is passed through unmodified from the Authorization Request to the ID Token. Sufficient entropy MUST be present in the nonce values used to prevent attackers from guessing values. One method to achieve this is to store a random value as a signed session cookie, and pass the value in the nonce parameter. In that case, the nonce in the returned ID Token can be compared to the signed session cookie to detect ID Token replay by third parties.

Other OPTIONAL parameters defined in [OpenID.Core] (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Authentication Core 1.0,” July 2013.) such as display, prompt, max_age, ui_locales, etc. can be used as well.

Following is a non-normative example using HTTP redirect (with line wraps within values for display purposes only):

  HTTP/1.1 302 Found
  Location: https://server.example.com/authorize?
    response_type=token%20id_token
    &client_id=s6BhdRkqt3
    &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
    &scope=openid
    &state=af0ifjsldkj

4.2.  Server Processings

Upon receipt of the parameters, the server MUST perform the following.

1. Check if scope includes openid. If it does not, just proceed with normal OAuth processing;
2. Chekc that response_type is token id_token.
3. Authenticate the user and obtain authorization from the user as needed;

4.3.  Authorization Response

If the Resource Owner authenticates and authorizes, the Authorization Endpoint returns the OAuth 2.0 response as follows:

4.3.1.  Authorization Successful Response

The Authorization Server returns OAuth 2.0 parameters as defined in Section 4.2.2 of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749] together with ID Token. The Client MUST follow the validation rule set by OAuth 2.0.

The following is a non-normative example (with line wraps for the display purposes only):

  HTTP/1.1 302 Found
  Location: https://client.example.org/cb#
    access_token=jHkWEdUXMU1BwAsC4vtUsZwnNvTIxEl0z9K3vx5KF0Y
    &token_type=Bearer
    &id_token=eyJhbGciOiJSUzI1NiJ9.ew0KICJpc3MiOiAiaHR0cDovL3NlcnZlc
    i5leGFtcGxlLmNvbSIsDQogInN1YiI6ICIyNDgyODk3NjEwMDEiLA0KICJhdWQiO
    iAiczZCaGRSa3F0MyIsDQogIm5vbmNlIjogIm4tMFM2X1d6QTJNaiIsDQogImV4c
    CI6IDEzMTEyODE5NzAsDQogImlhdCI6IDEzMTEyODA5NzAsDQogImF0X2hhc2giO
    iAiNzdRbVVQdGpQZnpXdEYyQW5wSzlSUSINCn0.g7UR4IDBNIjoPFV8exQCosUNV
    eh8bNUTeL4wdQp-2WXIWnly0_4ZK0sh4A4uddfenzo4Cjh4wuPPrSw6lMeujYbGy
    zKspJrRYL3iiYWc2VQcl8RKdHPz_G-7yf5enut1YE8v7PhKucPJCRRoobMjqD73f
    1nJNwQ9KBrfh21Ggbx1p8hNqQeeLLXb9b63JD84hVOXwyHmmcVgvZskge-wExwnh
    Ivv_cxTzxIXsSxcYlh3d9hnu0wdxPZOGjT0_nNZJxvdIwDD4cAT_LE5Ae447qB90
    ZF89Nmb0Oj2b1GdGVQEIr8-FXrHlyD827f0N_hLYPdZ73YK6p10qY9oRtMimg
    &state=af0ifjsldkj

4.3.2.  Authorization Error Response

If the End-User denies the access request or if the request fails, the OP (Authorization Server) informs the RP (Client) by using the Error Response parameters defined in Sections 4.2.2.1 of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749].

In addition to the error codes defined in Sections 4.2.2.1 of OAuth 2.0, the server MUST support the Authorization Error Response defined in [OpenID.Core] (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Authentication Core 1.0,” July 2013.).

5.  Initiating Login at Client from Third Party

In some cases, the login flow can start at the Authorization Server or another party by contacting the Client via a stored link. The target resource at the Client can be a deep link, rather than a default landing page.

The Client MAY optionally register (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Dynamic Client Registration 1.0,” July 2013.) [OpenID.Registration] an initiate_login_uri that can be used by the Authorization Server or another party to initiate a login for an End-User at the Client.

The Authorization Server or a third party sends a Login Initiation Request to the Client Initiation URI with the following parameters:

login_hint

OPTIONAL. Hint to the Authorization Server about the login identifier the End-User might use to log in. If the client receives a value for this string-valued parameter, it MUST include it in the subsequent authorization request as the login_hint parameter value.

iss

REQUIRED. Issuer Identifier for the Issuer that the Client is to send the authentication request to. Its value MUST be a URL using the https scheme.

target_link_uri

OPTIONAL. URI that the Client is requested to redirect to after authentication. Clients MUST verify the value of the target_link_uri to prevent being used as an open redirector to external sites.

Other parameters MAY be sent, if defined by extensions. Any parameters used that are not understood MUST be ignored by the Client.

Clients SHOULD employ frame busting and other techniques to prevent End-Users from being logged in by third party sites without their knowledge.

6.  Claims Framework

This section defines a framework in which the client may obtain the claims about the End User. It can be done through the pre-defined scopes values or through more granular claims parameter. The claims can come from a single source or distributed sources as well.

6.1.  Requesting Claims

In addition to obtaining the authentication event information about the End-User, the Client often wants to obtain other Claims about the user. To request such, the Client sends the request through either scope values or claims parameter as defined in Claims Request (Requesting Claims via claims parameter).

6.1.1.  Requesting Claims via Scope values

OpenID Connect Clients use scope values as defined in 3.3 of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749] to specify what access privileges are being requested for Access Tokens. The scopes associated with Access Tokens determine what resources will be available when they are used to access OAuth 2.0 protected endpoints. For OpenID Connect, scopes can be used to request that specific sets of information be made available as Claim Values. This specification describes only the scope values used by OpenID Connect.

OpenID Connect allows additional scope values to be defined and used. Scope values used that are not understood by an implementation SHOULD be ignored.

Claims requested by the following scopes are treated by Authorization Servers as Voluntary Claims.

OpenID Connect defines the following scope values:

openid

REQUIRED. Informs the Authorization Server that the Client is making an OpenID Connect request. If the openid scope value is not present, the behavior is entirely unspecified.

profile

OPTIONAL. This scope value requests access to the End-User's default profile Claims, which are: name, family_name, given_name, middle_name, nickname, preferred_username, profile, picture, website, gender, birthdate, zoneinfo, locale, and updated_at.

email

OPTIONAL. This scope value requests access to the email and email_verified Claims.

address

OPTIONAL. This scope value requests access to the address Claim.

phone

OPTIONAL. This scope value requests access to the phone_number and phone_number_verified Claims.

offline_access

OPTIONAL. This scope value requests that an OAuth 2.0 Refresh Token be issued that can be used to obtain an Access Token that grants access to the End-User's UserInfo Endpoint even when the End-User is not present (not logged in).

Multiple scope values MAY be used by creating a space delimited, case sensitive list of ASCII scope values.

The Claims requested by the profile, email, address, and phone scope values are returned from the UserInfo Endpoint, when a response_type value is used that results in an Access Token being issued. However, when the response_type value used is id_token (which issues no Access Token), the resulting Claims are returned in the ID Token.

In some cases, the End-User will be given the option to have the OpenID Provider decline to provide some or all information requested by Clients. To minimize the amount of information that the End-User is being asked to disclose, a Client can elect to only request a subset of the information available from the UserInfo Endpoint.

The following is a non-normative example of a scope Request.

  https://server.example.com/op/authorize?
    response_type=code
    &client_id=s6BhdRkqt3
    &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
    &scope=openid%20profile%20email%20phone
    &nonce=n-0S6_WzA2Mj
    &state=af0ifjsldkj

6.1.2.  Requesting Claims via claims parameter

As a way to request a more granular set of claims, this specification defines the following request parameter to the Authorization Endpoint.

claims

OPTIONAL. This parameter is used to request that specific Claims be returned. The value is a JSON object, as specified in Section 6.1.2 (Requesting Claims via claims parameter).

claims_locales

End-User's preferred languages and scripts for Claims being returned, represented as a space-separated list of BCP47 (Phillips, A. and M. Davis, “Tags for Identifying Languages,” September 2009.) [RFC5646] language tag values, ordered by preference. An error SHOULD NOT result if some or all of the requested locales are not supported by the OpenID Provider.

The claims parameter requests that specific Claims be returned from the UserInfo Endpoint and/or in the ID Token. It is represented as a JSON object containing lists of Claims being requested from these locations. Properties of the Claims being requested MAY also be specified.

Support for the claims parameter is OPTIONAL. Should an OP not support this parameter and an RP uses it, the OP SHOULD return a set of Claims to the RP that it believes would be useful to the RP and the End-User using whatever heuristics it believes are appropriate. The claims_parameter_supported Discovery result indicates whether the OP supports this parameter.

The claims parameter value is represented in an OAuth 2.0 request as UTF-8 encoded JSON (which ends up being form-urlencoded when passed as an OAuth parameter). When used in a Request Object value, the JSON is used as the value of the claims member.

The top-level members of the Claims request JSON object are:

userinfo

OPTIONAL. Requests that the listed individual Claims be returned from the UserInfo Endpoint. If present, the listed Claims are being requested to be added to any Claims that are being requested using scope values. If not present, the Claims being requested from the UserInfo Endpoint are only those requested using scope values.

When the userinfo member is used, the request MUST also use a response_type value that results in an Access Token being issued to use at the UserInfo Endpoint.

id_token

OPTIONAL. Requests that the listed individual Claims be returned in the ID Token. If present, the listed Claims are being requested to be added to the default Claims in the ID Token. If not present, the default ID Token Claims are requested.

Other members MAY be present. Any members used that are not understood MUST be ignored.

An example Claims request is as follows:

  {
   "userinfo":
    {
     "given_name": {"essential": true},
     "nickname": null,
     "email": {"essential": true},
     "email_verified": {"essential": true},
     "picture": null,
     "http://example.info/claims/groups": null
    },
   "id_token":
    {
     "auth_time": {"essential": true},
     "acr": {"values": ["urn:mace:incommon:iap:silver"] }
    }
  }

6.1.2.1.  Individual Claims Requests

The userinfo and id_token members of the claims request both are JSON objects with the names of the individual Claims being requested as the member names. The member values MUST be one of the following:

null

Indicates that this Claim is being requested in the default manner. In particular, this is a Voluntary Claim. For instance, the Claim request:

  "given_name": null

requests the given_name Claim in the default manner.

JSON Object

Used to provide additional information about the Claim being requested. This specification defines the following members:

essential

OPTIONAL. Indicates whether the Claim being requested is an Essential Claim. If the value is true, this indicates that the Claim is an Essential Claim. For instance, the Claim request:

  "auth_time": {"essential": true}

can be used to specify that it is Essential to return an auth_time Claim Value.

If the value is false, it indicates that it is a Voluntary Claim. The default is false.

By requesting Claims as Essential Claims the Client indicates to the End-User that releasing these Claims will ensure a smooth authorization for the specific task requested by the End-User. Note that even if the Claims are not available because the End-User did not authorize their release or they are not present, the Authorization Server MUST NOT generate an error when Claims are not returned, whether they are Essential or Voluntary.

value

OPTIONAL. Requests that the Claim be returned with a particular value. For instance the Claim request:

  "sub": {"value": "248289761001"}

can be used to specify that the request apply to the End-User with subject identifier 248289761001.

The value of the value member MUST be a valid value for the Claim being requested. Definitions of individual Claims can include requirements on how and whether the value qualifier is to be used when requesting that Claim.

values

OPTIONAL. Requests that the Claim be returned with one of a set of values, with the values appearing in order of preference. For instance the Claim request:

  "acr": {"essential": true,
          "values": ["urn:mace:incommon:iap:silver",
                     "urn:mace:incommon:iap:bronze"]}

specifies that it is Essential that the acr Claim be returned with either the value urn:mace:incommon:iap:silver or urn:mace:incommon:iap:bronze.

The values in the values member array MUST be valid values for the Claim being requested. Definitions of individual Claims can include requirements on how and whether the values qualifier is to be used when requesting that Claim.

Other members MAY be defined to provide additional information about the requested Claims. Any members used that are not understood MUST be ignored.

Note that when the claims request parameter is supported, the scope values that request Claims, as defined in Section 6.1.1 (Requesting Claims via Scope values), are effectively shorthand methods for requesting sets of individual Claims. For example, using the scope value openid email and a response_type that returns an Access Token is equivalent to using the scope value openid and the following request for individual Claims.

Equivalent of using the email scope value:

  {
   "userinfo":
    {
     "email": null,
     "email_verified": null
    }
  }

6.1.2.2.  Languages and Scripts for Individual Claims

As described in Section 6.2.2 (Claims Languages and Scripts), human-readable Claims values and Claim Values that reference human-readable values MAY be represented in multiple languages and scripts. Within a request for individual Claims, requested languages and scripts for particular Claims MAY be requested by including Claim Names that contain #-separated BCP47 (Phillips, A. and M. Davis, “Tags for Identifying Languages,” September 2009.) [RFC5646] language tags in the Claims request, using the Claim Name syntax specified in Section 6.2.2 (Claims Languages and Scripts). For example, a Family Name in Katakana in Japanese can be requested using the Claim Name family_name#ja-Kana-JP and a Kanji representation of the Family Name in Japanese can be requested using the Claim Name family_name#ja-Hani-JP. A German-language Web site can be requested with the Claim Name website#de.

If an OP receives a request for human-readable Claims in a language and script that it doesn't have, any versions of those Claims returned that don't use the requested language and script SHOULD use a language tag in the Claim Name.

6.2.  Standard Claims

This specification defines a set of standard Claims. They can be requested to be returned either in the UserInfo Response or in the ID Token.

For privacy reasons, OpenID Providers MAY elect to not return values for some requested Claims.

The sub (subject) Claim in the UserInfo Endpoint response MUST exactly match the sub Claim in the ID Token, before using additional UserInfo Endpoint Claims.

The UserInfo Endpoint MUST return Claims in JSON format unless a different format was specified during Registration [OpenID.Registration] (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Dynamic Client Registration 1.0,” July 2013.). The UserInfo Endpoint MAY return Claims in JWT format, which can be signed and/or encrypted. The UserInfo Endpoint MUST return a content-type header to indicate which format is being returned. The following are accepted content types:

The following is a non-normative example of such a response:

  {
   "sub": "248289761001",
   "name": "Jane Doe",
   "given_name": "Jane",
   "family_name": "Doe",
   "preferred_username": "j.doe",
   "email": "janedoe@example.com",
   "picture": "http://example.com/janedoe/me.jpg"
  }

6.2.1.  Address Claim

The Address Claim represents a physical mailing address. Implementations MAY return only a subset of the fields of an address, depending upon the information available and the End-User's privacy preferences. For example, the country and region might be returned without returning more fine-grained address information.

Implementations MAY return just the full address as a single string in the formatted sub-field, or they MAY return just the individual component fields using the other sub-fields, or they MAY return both. If both variants are returned, they SHOULD be describing the same address, with the formatted address indicating how the component fields are combined.

formatted

Full mailing address, formatted for display or use on a mailing label. This field MAY contain multiple lines, separated by newline characters.

street_address

Full street address component, which MAY include house number, street name, Post Office Box, and multi-line extended street address information. This field MAY contain multiple lines, separated by newline characters.

locality

City or locality component.

region

State, province, prefecture or region component.

postal_code

Zip code or postal code component.

country

Country name component.

6.2.2.  Claims Languages and Scripts

Human-readable Claim Values and Claim Values that reference human-readable values MAY be represented in multiple languages and scripts. To specify the languages and scripts, BCP47 (Phillips, A. and M. Davis, “Tags for Identifying Languages,” September 2009.) [RFC5646] language tags are added to member names, delimited by a # character. For example, family_name#ja-Kana-JP expresses the Family Name in Katakana in Japanese, which is commonly used to index and represent the phonetics of the Kanji representation of the same represented as family_name#ja-Hani-JP. As another example, both website and website#de Claim Values might be returned, referencing a Web site in an unspecified language and a Web site in German.

Since Claim Names are case sensitive, it is strongly RECOMMENDED that language tag values used in Claim Names be spelled using the character case with which they are registered in the IANA Language Subtag Registry (Internet Assigned Numbers Authority (IANA), “Language Subtag Registry,” 2005.) [IANA.Language]. In particular, normally language names are spelled with lowercase characters, region names are spelled with uppercase characters, and scripts are spelled with mixed case characters. However, since BCP47 language tag values are case insensitive, implementations SHOULD interpret the language tag values supplied in a case insensitive manner.

Per the recommendations in BCP47, language tag values for Claims SHOULD only be as specific as necessary. For instance, using fr might be sufficient in many contexts, rather than fr-CA or fr-FR. Where possible, OPs SHOULD try to match requested Claim locales with Claims it has. For instance, if the Client asks for a Claim with a de (German) language tag and the OP has a value tagged with de-CH (Swiss German) and no generic German value, it would be appropriate for the OP to return the Swiss German value to the Client. (This intentionally moves as much of the complexity of language tag matching to the OP as possible, to simplify Clients.)

A claims_locales request can be used to specify the preferred languages and scripts to use for the returned Claims. Section 6.1.2.2 (Languages and Scripts for Individual Claims) describes how to request that specific Claims use particular languages and scripts.

When the OP determines, either through the claims_locales parameter, or by other means, that the End-User and Client are requesting Claims in only one set of languages and scripts, it is RECOMMENDED that OPs return Claims without language tags when they employ this language and script. It is also RECOMMENDED that Clients be written in a manner that they can handle and utilize Claims using language tags.

6.2.3.  Claim Stability and Uniqueness

The sub (subject) and iss (issuer) Claims are the only Claims that a Client can rely upon as a stable identifier for the End-User, since the sub Claim MUST be locally unique and never reassigned within the Issuer for a particular End-User, as described in this specification. Therefore, the only guaranteed unique identifier for a given End-User is the combination of the iss Claim and the sub Claim.

All other Claims carry no such guarantees across different issuers in terms of stability over time or uniqueness across users, and Issuers are permitted to apply local restrictions and policies. For instance, an Issuer MAY re-use an email Claim value across different End-Users at different points in time, and the claimed email address for a given End-User MAY change over time. Therefore, other Claims such as email, phone_number, and preferred_username and MUST NOT be used as unique identifiers for the End-User.

6.2.4.  Additional Claims

While this specification defines only small set of Claims as standard Claims, other Claims MAY be used in conjunction with the standard Claims. When using such Claims, it is RECOMMENDED that collision resistant names be used for the Claim Names, as described in Section 4.2 (Public Claim Names) of the JSON Web Token (JWT) (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT] specification. Alternatively, Private Claim Names can be safely used when naming conflicts are unlikely to arise, as described in 4.3 of the JWT specification. Or, if specific additional Claims will have broad and general applicability, they can be registered with Reserved Claim Names, per Sections 4.1 and 9.1 of the JWT specification.

6.2.5.  new section

6.3.  Claim Types

The UserInfo Endpoint MAY return the following three types of Claims:

Normal Claims

Claims that are directly asserted by the OpenID Provider.

Aggregated Claims

Claims that are asserted by a Claims Provider other than the OpenID Provider but are returned by OpenID Provider.

Distributed Claims

Claims that are asserted by a Claims Provider other than the OpenID Provider but are returned as references by the OpenID Provider.

The UserInfo Endpoint MUST support Normal Claims.

Aggregated and Distributed Claims support is OPTIONAL.

6.3.1.  Normal Claims

Normal Claims are represented as members in a JSON object. The Claim Name is the member name and the Claim Value is the member value.

The following is a non-normative response containing Normal Claims:

  {
   "name": "Jane Doe",
   "given_name": "Jane",
   "family_name": "Doe",
   "email": "janedoe@example.com",
   "picture": "http://example.com/janedoe/me.jpg"
  }

6.3.2.  Aggregated and Distributed Claims

Aggregated and distributed Claims are represented by using special _claim_names and _claim_sources members of the JSON object containing the Claims.

_claim_names

JSON object whose member names are the Claim Names for the Aggregated and Distributed Claims. The member values are references to the member names in the _claim_sources member from which the actual Claim Values can be retrieved.

_claim_sources

JSON object whose member names are referenced by the member values of the _claim_names member. The member values contain sets of Aggregated Claims or reference locations for Distributed Claims. The member values can have one of the following formats depending on whether it is providing Aggregated or Distributed Claims:

Aggregated Claims

JSON object that MUST contain the JWT member whose value is a JWT (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT] that MUST contain all the Claims in the _claim_names object that references the corresponding _claim_sources member. Other members MAY be present. Any members used that are not understood MUST be ignored.

JWT

REQUIRED. JWT containing Claim Values.

The JWT SHOULD NOT contain a sub (subject) Claim unless its value is an identifier for the End-User at the Claims Provider (and not for the OpenID Provider or another party); this typically means that a sub Claim SHOULD NOT be provided.

Distributed Claims

JSON object that contains the following members and values:

endpoint

REQUIRED. OAuth 2.0 resource endpoint from which the associated Claim can be retrieved. The endpoint URL MUST return the Claim as a JWT.

access_token

OPTIONAL. Access Token enabling retrieval of the Claims from the endpoint URL by using the OAuth 2.0 Bearer Token Usage (Jones, M. and D. Hardt, “The OAuth 2.0 Authorization Framework: Bearer Token Usage,” October 2012.) [RFC6750] protocol. Claims SHOULD be requested using the Authorization Request header field and Claims Providers MUST support this method. If the Access Token is not available, Clients MAY need to retrieve the Access Token out of band or use an a priori Access Token that was negotiated between the Claims Provider and Client, or the Claims Provider MAY reauthenticate the End-User and/or reauthorize the Client.

A sub (subject) Claim SHOULD NOT be returned from the Claims Provider unless its value is an identifier for the End-User at the Claims Provider (and not for the OpenID Provider or another party); this typically means that a sub Claim SHOULD NOT be provided.

6.3.2.1.  Example of Aggregated Claims

In this non-normative example, Claims from Claims Provider A are combined with other Claims held by the OpenID provider, with the Claims from Claims Provider A being returned as Aggregated Claims.

In this example, these Claims about Jane Doe have been issued by Claims Provider A:

  {
   "address": {
     "street_address": "1234 Hollywood Blvd.",
     "locality": "Los Angeles",
     "region": "CA",
     "postal_code": "90210",
     "country": "US"},
   "phone_number": "+1 (310) 123-4567"
  }

Claims Provider A signs the JSON Claims, representing them in a signed JWT: jwt_header.jwt_part2.jwt_part3. It is this JWT that is used by the OpenID Provider.

In this example, this JWT containing Jane Doe's Aggregated Claims from Claims Provider A is combined with other Normal Claims, and returned as the following set of Claims:

  {
   "name": "Jane Doe",
   "given_name": "Jane",
   "family_name": "Doe",
   "birthdate": "0000-03-22",
   "eye_color": "blue",
   "email": "janedoe@example.com",
   "_claim_names": {
     "address": "src1",
     "phone_number": "src1"
   },
   "_claim_sources": {
     "src1": {"JWT": "jwt_header.jwt_part2.jwt_part3"}
   }
  }

6.3.2.2.  Example of Distributed Claims

In this non-normative example, the OpenID Provider combines Normal Claims that it holds with references to Claims held by two different Claims Providers, B and C, incorporating references to some of the Claims held by B and C as Distributed Claims.

In this example, these Claims about Jane Doe are held by Claims Provider B (Jane Doe's bank):

  {
   "shipping_address": {
     "street_address": "1234 Hollywood Blvd.",
     "locality": "Los Angeles",
     "region": "CA",
     "postal_code": "90210",
     "country": "US"},
   "payment_info": "Some_Card 1234 5678 9012 3456",
   "phone_number": "+1 (310) 123-4567"
  }

Also in this example, this Claim about Jane Doe is held by Claims Provider C (a credit agency):

  {
   "credit_score": 650
  }

The OpenID Provider returns Jane Doe's Claims along with references to the Distributed Claims from Claims Provider B and Claims Provider C by sending the Access Tokens and URLs of locations from which the Distributed Claims can be retrieved:

  {
   "name": "Jane Doe",
   "given_name": "Jane",
   "family_name": "Doe",
   "email": "janedoe@example.com",
   "birthdate": "0000-03-22",
   "eye_color": "blue",
   "_claim_names": {
     "payment_info": "src1",
     "shipping_address": "src1",
     "credit_score": "src2"
    },
   "_claim_sources": {
     "src1": {"endpoint":
                "https://bank.example.com/claim_source"},
     "src2": {"endpoint":
                "https://creditagency.example.com/claims_here",
              "access_token": "ksj3n283dke"}
   }
  }

6.4.  UserInfo Endpoint

The UserInfo Endpoint is an OAuth 2.0 Bearer Token Usage (Jones, M. and D. Hardt, “The OAuth 2.0 Authorization Framework: Bearer Token Usage,” October 2012.) [RFC6750] Protected Resource that returns Claims about the authenticated End-User. To obtain the requested Claims about the End-User, the Client makes a GET or POST request to the UserInfo Endpoint as stated below.

Communication between the Client and the UserInfo Endpoint MUST utilize TLS. See TLS Requirements in OpenID Connect Messages for more information on using TLS.

The UserInfo Endpoint MUST support the use of the HTTP GET and HTTP POST methods defined in RFC 2616 (Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.) [RFC2616] at the UserInfo Endpoint.

The UserInfo Endpoint MUST accept Access Tokens as OAuth 2.0 Bearer Token Usage (Jones, M. and D. Hardt, “The OAuth 2.0 Authorization Framework: Bearer Token Usage,” October 2012.) [RFC6750].

The UserInfo Endpoint SHOULD support the use of Cross Origin Resource Sharing (CORS) (Opera Software ASA, “Cross-Origin Resource Sharing,” July 2010.) [CORS] and or other methods as appropriate to enable Java Script Clients to access the endpoint.

6.4.1.  UserInfo Request

Clients sends either an HTTPS GET or POST request to the UserInfo Endpoint to obtain Claims about the End-User request as specified in section 2 of the OAuth 2.0 Bearer Token Usage (Jones, M. and D. Hardt, “The OAuth 2.0 Authorization Framework: Bearer Token Usage,” October 2012.) [RFC6750] specification. The Access Token that is sent MUST be the one obtained from OpenID Connect Authentication.

It is RECOMMENDED that the Client use the Authorization header field method for all requests and that they use the GET method.

The following is a non-normative example of a UserInfo request:

  GET /userinfo HTTP/1.1
  Host: server.example.com
  Authorization: Bearer SlAV32hkKG

6.4.2.  UserInfo Response

The UserInfo Claims MUST be returned as the members of a JSON object unless a signed or encrypted response was requested during Client Registration. The Standard Claims defined in OpenID Connect Messages (Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., Mortimore, C., and E. Jay, “OpenID Connect Messages 1.0,” July 2013.) [OpenID.Messages] can be returned, as can additional Claims not specified there. It MUST be returned in the HTTP response body unless a different format was specified during Registration [OpenID.Registration] (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Dynamic Client Registration 1.0,” July 2013.). The content-type of the HTTP response MUST be set to application/json if the response body is a text JSON structure; the response body SHOULD be encoded using UTF-8. If the JSON response is signed or encrypted, then the content-type MUST be set to application/jwt.

If a Claim is not returned, that Claim Name SHOULD be omitted from the JSON object representing the Claims; it SHOULD NOT be present with a null or empty string value.

The sub (subject) Claim MUST always be returned in the UserInfo Response.

NOTE: The UserInfo Endpoint response is not guaranteed to be about the End-User identified by the sub (subject) element of the ID Token. The sub Claim in the UserInfo Endpoint response MUST be verified to exactly match the sub Claim in the ID Token before using additional UserInfo Endpoint Claims.

Upon receipt of the UserInfo Response, the Client MUST verify the response in accordance with Section 6.4.3 (UserInfo Response Validation).

Following is a non-normative example of such response:

  HTTP/1.1 200 OK
  Content-Type: application/json

  {
   "sub": "248289761001",
   "name": "Jane Doe",
   "given_name": "Jane",
   "family_name": "Doe",
   "email": "janedoe@example.com",
   "picture": "http://example.com/janedoe/me.jpg"
  }

6.4.3.  UserInfo Response Validation

To validate the UserInfo Response, the Client MUST do the following:

1. If the Client has provided a userinfo_encrypted_response_alg parameter during Registration, decrypt the UserInfo Response using the key pair specified during Registration.
2. If the response was signed, the Client SHOULD validate the signature according to JWS (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS].
3. Check that the OP that responded was the intended OP through a TLS server certificate check, per RFC 6125 (Saint-Andre, P. and J. Hodges, “Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS),” March 2011.) [RFC6125].

6.4.4.  UserInfo Error Response

When an error condition occurs, the UserInfo Endpoint returns an Error Response as defined in Section 3 of the OAuth 2.0 Bearer Token Usage (Jones, M. and D. Hardt, “The OAuth 2.0 Authorization Framework: Bearer Token Usage,” October 2012.) [RFC6750] specification utilizing an error code as specified in Section 2.3.3 of OpenID Connect Messages 1.0 (Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., Mortimore, C., and E. Jay, “OpenID Connect Messages 1.0,” July 2013.) [OpenID.Messages].

Following is a non-normative example of an error response:

  HTTP/1.1 401 Unauthorized
  WWW-Authenticate: Bearer realm="example.com",
                       error="invalid_token",
                       error_description="The Access Token expired"

6.5.  Offline Access

The offline_access scope value requests that an OAuth 2.0 Refresh Token be issued that can be used to obtain an Access Token that grants access to the End-User's UserInfo Endpoint even when the End-User is not present (not logged in). When offline access is requested, a prompt parameter value of consent MUST be used unless other conditions for processing permitting offline access to the requested resources are in place. The OP MUST always obtain consent to returning a Refresh Token that enables offline access to the requested resources. A previously saved user consent is not always sufficient to grant offline access.

Upon receipt of a scope parameter containing the offline_access value, the Authorization Server:

• MUST ensure that the prompt parameter contains consent unless other conditions for processing permitting offline access to the requested resources are in place; unless one or both of these conditions are fulfilled, then it MUST ignore the offline_access request,
• MUST ignore the offline_access request unless the Client is using a response_type value that would result in an Authorization Code being returned,
• MUST explicitly receive or have consent for all Clients when the registered application_type is web,
• SHOULD explicitly receive or have consent for all Clients when the registered application_type is native.

The use of Refresh Tokens is not exclusive to the offline_access use case. The Authorization Server MAY grant Refresh Tokens in other contexts that are beyond the scope of this specification.

7.  Request by JSON

While OAuth 2.0's Form Encoded requests are simple to code, it has a disadvantage that it is not being signed and thus pronte to the tampering. Also, no method to encrypt the payload is defined so the confidentiality of the request is not warranted.

This specification defines an alternative request format based on JSON Web Token. It can be signed and encrypted to achieve integrity, non-repudiation, and confidentiality. Since such requests are largely static, such a request can be created once and used many times.

Further, it defines a method that passes such request via reference. In this case, the signed request can be created once and registered to the server and the client can chose from one of them by specifying the URI of the request, making the request small as well as allowing the serverside optimization.

7.1.  Authorization Request by JSON

This specification defines following OAuth 2.0 extension parameters to send the Authorization Request by JWT encoded JSON by value and by reference. If one of them is used, the other MUST NOT be used in the same request.

request

This parameter enables OpenID Connect requests to be passed in a single, self-contained parameter and to be signed and optionally encrypted. The parameter value is a Request Object value, as specified in Section 7.1.1 (Passing the Request Object by value). It represents the request as a JWT whose Claims are the request parameters above.

When the request parameter is used, the OpenID Connect request parameter values contained in the JWT supersede those passed using the OAuth 2.0 request syntax. Even if a scope parameter is present in the Request Object value, a scope parameter MUST always be passed using the OAuth 2.0 request syntax containing the openid scope value to indicate to the underlying OAuth 2.0 logic that this is an OpenID Connect request.

request_uri

This parameter enables OpenID Connect requests to be passed by reference, rather than by value. The request_uri value is a URL using the https scheme referencing a resource containing a Request Object value, which is a JWT containing the request parameters. This parameter is used identically to the request parameter, other than that the Request Object value is retrieved from the specified URL, rather than passed by value. See Section 7.1.2 (Passing the Request Object by Reference) for more information on using the request_uri parameter.

7.1.1.  Passing the Request Object by value

The request parameter enables OpenID Connect requests to be passed in a single, self-contained parameter and to be signed and optionally encrypted. It represents the request as a JWT whose Claims are the request parameters to the Authorization Endpoint. This JWT is called a Request Object.

Support for the request parameter is OPTIONAL. The request_parameter_supported Discovery result indicates whether the OP supports this parameter. Should an OP not support this parameter and an RP uses it, the OP MUST return the request_not_supported error.

When the request parameter is used, the OpenID Connect request parameter values contained in the JWT supersede those passed using the OAuth 2.0 request syntax. However, some parameters MAY be passed using the OAuth 2.0 request syntax even when a Request Object is used; this would typically be done to enable a cached, pre-signed (and possibly pre-encrypted) Request Object value to be used containing the fixed request parameters, while parameters that can vary with each request, such as state and nonce, are passed as OAuth 2.0 parameters.

Even if a scope parameter is present in the Request Object value, a scope parameter MUST always be passed using the OAuth 2.0 request syntax containing the openid scope value to indicate to the underlying OAuth 2.0 logic that this is an OpenID Connect request.

The Request Object MAY be signed or unsigned (plaintext). When it is plaintext, this is indicated by use of the none algorithm [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) in the JWS header. If signed, the Request Object SHOULD contain the Claims iss (issuer) and aud (audience) as members, with their semantics being as defined in the JWT (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT] specification.

The Request Object MAY also be encrypted using JWE (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” May 2013.) [JWE], with nested signing and encryption performed as described in the JWT [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) specification.

request and request_uri parameters MUST NOT be included in Request Objects.

An example set of Request Object Claims before base64url encoding and JWS signing is as follows:

  {
   "response_type": "code id_token",
   "client_id": "s6BhdRkqt3",
   "redirect_uri": "https://client.example.org/cb",
   "scope": "openid",
   "state": "af0ifjsldkj",
   "login_hint": "janedoe@example.org",
   "max_age": 86400,
   "claims":
    {
     "userinfo":
      {
       "given_name": {"essential": true},
       "nickname": null,
       "email": {"essential": true},
       "email_verified": {"essential": true},
       "picture": null
      },
     "id_token":
      {
       "auth_time": {"essential": true},
       "acr": { "values":["urn:mace:incommon:iap:silver"] }
      }
    }
  }

7.1.2.  Passing the Request Object by Reference

The request_uri parameter enables OpenID Connect requests to be passed by reference, rather than by value. This parameter is used identically to the request parameter, other than that the Request Object value is retrieved from the resource at the specified URL, rather than passed by value.

The request_uri_parameter_supported Discovery result indicates whether the OP supports this parameter. Should an OP not support this parameter and an RP uses it, the OP MUST return the request_uri_not_supported error.

When the request_uri parameter is used, the OpenID Connect request parameter values contained in the referenced JWT supersede those passed using the OAuth 2.0 request syntax. However, some parameters MAY be passed using the OAuth 2.0 request syntax even when a request_uri is used; this would typically be done to enable a cached, pre-signed (and possibly pre-encrypted) Request Object value to be used containing the fixed request parameters, while parameters that can vary with each request, such as state and nonce, are passed as OAuth 2.0 parameters.

Even if a scope parameter is present in the referenced Request Object, a scope parameter MUST always be passed using the OAuth 2.0 request syntax containing the openid scope value to indicate to the underlying OAuth 2.0 logic that this is an OpenID Connect request.

Servers MAY cache the contents of the resources referenced by request URIs. If the contents of the referenced resource could ever change, the URI SHOULD include the base64url encoded SHA-256 hash of the referenced resource contents as the fragment component of the URI. If the fragment value used for a URI changes, that signals the server that any cached value for that URI with the old fragment value is no longer valid.

Note that Clients MAY pre-register request_uri values using the request_uris parameter defined in Section 2 of the OpenID Connect Dynamic Client Registration 1.0 (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Dynamic Client Registration 1.0,” July 2013.) [OpenID.Registration] specification.

7.1.2.1.  "request_uri" Rationale

There are several reasons that one might choose to use the request_uri parameter:

1. The set of request parameters can become large, and can exceed browser URI size limitations. Passing the request parameters by reference can solve this problem.
2. Passing a request_uri value, rather than a complete request by value, can reduce request latency.
3. Most requests for Claims from an RP are constant. The request_uri is a way of creating and sometimes also signing and encrypting a constant set of request parameters in advance. (The request_uri value becomes an "artifact" representing a particular fixed set of request parameters.)
4. Pre-registering a fixed set of request parameters at registration time enables OPs to cache and pre-validate the request parameters at registration time, meaning they need not be retrieved at request time.
5. Pre-registering a fixed set of request parameters at registration time enables OPs to vet the contents of the request from consumer protection and other points of views, either itself or by utilizing a third party.

7.2.  Validation

If any of the validation procedures defined in this specification fail, any operations requiring the information that failed to correctly validate MUST be aborted and the information that failed to validate MUST NOT be used.

7.2.1.  Authorization Request Validation

Authorization Request Validation consists of two main steps: (1) decryption and signature validation of the value of request or the content of request_uri, and (2) parameter validation. If a Request Object value was sent in the request parameter or by reference in the request_uri parameter, the Request Object MUST validate as JWS (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] or JWE (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” May 2013.) [JWE] encoded objects, for which nested encryption and signing can be utilized in the manner described in the JWT (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT] specification.

7.2.1.1.  Encrypted Request Object

If the Authorization Server has advertised JWE encryption algorithms in the request_object_encryption_alg_values_supported and request_object_encryption_enc_values_supported elements of its Discovery Document, these are used by the Client to encrypt the JWT.

The Authorization Server MUST decode the JWT in accordance with the JSON Web Encryption (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” May 2013.) [JWE] specification. The result MAY be either a signed or unsigned (plaintext) Request Object. In the former case, signature validation MUST be performed as defined in Section 7.2.1.2 (Signed Request Object).

The Authorization Server MUST return the error if there is a decryption error.

7.2.1.2.  Signed Request Object

To perform Signature Validation, the alg parameter in the JWS header MUST match the value of the request_object_signing_alg set during Client Registration (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Dynamic Client Registration 1.0,” July 2013.) [OpenID.Registration] or a value that was pre-registered by other means.

The signature MUST be validated against the key registered for that client_id and algorithm, in accordance with the JSON Web Signature (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] specification.

The Authorization Server MUST return the Authorization Error Response if there is a signature validation error.

7.2.1.3.  Parameter Validation

The Authorization Server MUST construct the Authorization Request Message from the Request Object value and the OAuth 2.0 Authorization Request parameters. If the same parameter exists both in the Request Object and the OAuth Authorization Request parameters, the parameter in the Request Object is used. Using this Authorization Request Message, the Authorization Server performs the following steps of the request validation:

1. The Authorization Server MUST validate all the OAuth 2.0 parameters according to the OAuth 2.0 specification.
2. The Authorization Server MUST verify that all the REQUIRED parameters are present.
3. If the sub (subject) Claim as a member of id_token element is requested with a specific value, the Authorization Server MUST only send a positive response if that user has an active session with the Authorization Server. The Authorization Server MUST NOT reply with an ID Token or Access Token for a different user, even if they have an active session with the Authorization Server.
4. If the acr Claim is requested as an Essential Claim for the ID Token with a values parameter requesting specific Authentication Context Class Reference values, then the Authorization Server MUST return an acr Claim Value that matches one of the requested values. The Authorization Server MAY ask the End-User to re-authenticate with additional factors to meet this requirement. If this is an Essential Claim and the requirement cannot be met, then the Authorization Server MUST treat that outcome as a failed authentication attempt.
5. The Client MAY request this Claim as a Voluntary Claim by using the acr_values request parameter or by not including "essential": true in the individual acr Claim request. If the Claim is not Essential and the requested value cannot be provided, the Authorization Server SHOULD return the session's current acr as the value of the acr Claim. If the Claim is not Essential, the Authorization Server is not required to provide this Claim in its response.

If the Authorization Server encounters any error, it MUST return the error response.

7.3.  Authorization Error Response

If the End-User denies the access request or if the request fails, the OP (Authorization Server) informs the RP (Client) by using the Error Response parameters defined in Sections 4.1.2.1 of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749].

In addition to the error codes defined in Sections 4.1.2.1 and 4.2.2.1 of OAuth 2.0 and that of OpenID Connect Authentication Core 1.0, this specification also defines the following error codes:

invalid_request_uri

The request_uri in the Authorization Request returns an error or contains invalid data.

invalid_request_object

The request parameter contains an invalid Request Object.

request_not_supported

The OP does not support use of the request parameter.

request_uri_not_supported

The OP does not support use of the request_uri parameter.

8.  Self-Issued OpenID Provider

OpenID Connect supports Self-Issued OpenID Providers: personal OPs that issue self-signed ID Tokens. Self-Issued OPs use the special Issuer Identifier https://self-issued.me.

8.1.  Self-Issued OpenID Provider Discovery

If the input identifier for the discovery process contains the domain self-issued.me, dynamic discovery is not performed. Instead, then the following static configuration values are used:

  {
   "authorization_endpoint":
     "openid:",
   "issuer":
     "https://self-issued.me",
   "scopes_supported":
     ["openid", "profile", "email", "address", "phone"],
   "response_types_supported":
     ["id_token"],
   "subject_types_supported":
     ["pairwise"],
   "id_token_signing_alg_values_supported":
     ["RS256"],
   "request_object_signing_alg_values_supported":
     ["none", "RS256"]
  }

Note: The OpenID Foundation may consider hosting a site https://self-issued.me/ that returns the above static configuration file so that the Client would not need any special treatment for discovery of the Self-Issued OP.

8.2.  Self-Issued OpenID Provider Registration

When using a Self-Issued OP, the Client is deemed to have registered with the OP and obtained following Client Registration Response.

client_id

redirect_uri value of the Client.

client_secret_expires_at

0

Note: The OpenID Foundation may consider hosting the (stateless) endpoint https://self-issued.me/registration/1.0/ that returns the response above so that the Client would not need to perform any special processing for registration of a Self-Issued OP.

8.2.1.  Providing Additional Registration Information

The registration request parameter is used by the Client to provide information about itself to a Self-Issued OP that would normally be provided to an OP during Dynamic Client Registration. The value is a JSON object containing name/value pairs defined in Section 2.1 of the OpenID Connect Dynamic Client Registration 1.0 (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Dynamic Client Registration 1.0,” July 2013.) [OpenID.Registration] specification. None of this information is REQUIRED by Self-Issued OPs, so the use of this parameter is OPTIONAL.

The registration parameter value is represented in an OAuth 2.0 request as UTF-8 encoded JSON (which ends up being form-urlencoded when passed as an OAuth parameter). When used in a Request Object value, per defined in OpenID Connect Messages, the JSON is used as the value of the registration member.

The Registration parameters that would typically be used in requests to Self-Issued OPs are policy_uri, tos_uri, and logo_uri. If the Client uses more than one redirection URI, the redirect_uris parameter would be used to register them. Finally, if the Client is requesting encrypted responses, it would use the jwks_uri, id_token_encrypted_response_alg and id_token_encrypted_response_enc parameters.

8.3.  Self-Issued OpenID Provider Request

The Client sends the Authorization Request to the Authorization Endpoint with the following parameters:

response_type

REQUIRED. Constant string value id_token.

client_id

REQUIRED. Client ID value for the Client, which in this case contains the redirect_uri value of the Client. Since the Client's redirect_uri URI value is communicated as the Client ID, a redirect_uri parameter is NOT REQUIRED to also be included in the request.

scope

REQUIRED. scope parameter value, as specified in OpenID Connect UserInfo.

id_token_hint

OPTIONAL. Previously issued ID Token passed to the Authorization Server as a hint about the End-User's current or past authenticated session with the Client. This SHOULD be present when prompt=none is used. If the End-User identified by the ID Token is logged in or is logged in by the request, then the Authorization Server returns a positive response; otherwise, it SHOULD return a negative response.

If the ID Token received by the RP is encrypted, the Client MUST decrypt the signed ID Token contained within the encrypted ID Token. The Client MAY re-encrypt the signed ID token to the Authentication Server using a key that enables the server to decrypt the ID Token. In this case, the sub (subject) of the signed ID Token MUST be sent as the kid (Key ID) of the JWE. Encrypting content to Self-Issued OPs is currently only supported when the OP's JWK key type is RSA and the encryption algorithm used is RSA1_5.

claims

OPTIONAL. This parameter is used to request that specific Claims be returned. The value is a JSON object, as specified in OpenID Connect Messages.

registration

OPTIONAL. This parameter is used by the Client to provide information about itself to a Self-Issued OP that would normally be provided to an OP during Dynamic Client Registration, as specified in Section 8.2.1 (Providing Additional Registration Information).

request

OPTIONAL. Request Object value, as specified in OpenID Connect Messages. The Request Object MAY be encrypted in a JWE by the Client. In this case, the sub (subject) of a previously issued ID Token for this Client MUST be sent as the kid (Key ID) of the JWE. Encrypting content to Self-Issued OPs is currently only supported when the OP's JWK key type is RSA and the encryption algorithm used is RSA1_5.

Other parameters MAY be sent. Note that all Claims are returned in the ID Token.

The entire URL MUST NOT exceed 2048 ASCII characters.

Following is a non-normative example (with line wraps within values for display purposes only):

  HTTP/1.1 302 Found
  Location: openid://
    ?response_type=id_token
    &client_id=https%3A%2F%2Fclient.example.org%2Fcb
    &scope=openid%20profile
    &state=af0ifjsldkj
    &nonce=n-0S6_WzA2Mj
    registration=&%7B%22logo_uri%22%3A%22https%3A%2F%2F
      client.example.org%2Flogo.png%22%7D

8.4.  Self-Issued OpenID Provider Response

The Self-Issued OpenID Provider response is the same as the normal implicit flow response with the following refinements. Since it is an implicit flow response, the response parameters will be returned in the URL fragment component.

1. The iss (issuer) Claim Value is https://self-issued.me.
2. A sub_jwk Claim is present, with its value being the public key value used to check the signature of the ID Token.
3. The sub (subject) Claim value is the base64url encoded SHA-256 hash of the concatenation of the octets of the UTF-8 representations of the base64url encoded key values in the sub_jwk Claim. When the kty value is RSA, the key values n and e are concatenated in that order. When the kty value is EC, the key values crv, x, and y are concatenated in that order.
4. No Access Token is returned for accessing a UserInfo Endpoint, so all Claims returned MUST be in the ID Token.

8.5.  Self-Issued ID Token Validation

If any of the validation procedures defined in this specification fail, any operations requiring the information that failed to correctly validate MUST be aborted and the information that failed to validate MUST NOT be used.

To validate the ID Token in the Authorization or Token Endpoint Response, the Client MUST do the following:

1. The Client MUST validate that the value of the iss (issuer) Claim is https://self-isued.me. If iss contains a different value, the ID Token is not Self-Issued, and instead it MUST be validated according to ID Token Validation defined in OpenID Connect Authentication Basic.
2. The Client MUST validate that the aud (audience) Claim contains the value of the redirect_uri that the Client sent in the authentication request as an audience.
3. The Client MUST validate the signature of the ID Token according to JWS (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] using the algorithm specified in the alg parameter of the JWT header [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.), using the key in the sub_jwk Claim; the key is a bare key in JWK format (not an X.509 certificate value).
4. The alg value SHOULD be the default of RS256. It MAY also be ES256.
5. The Client MUST validate that the sub (subject) Claim value is the base64url encoded SHA-256 hash of the concatenation of the octets of the UTF-8 representations of the base64url encoded key values in the sub_jwk Claim. When the kty value is RSA, the key values n and e are concatenated in that order. When the kty value is EC, the key values crv, x, and y are concatenated in that order.
6. The current time MUST be less than the value of the exp Claim (possibly allowing for some small leeway to account for clock skew).
7. The iat Claim can be used to reject tokens that were issued too far away from the current time, limiting the amount of time that nonces need to be stored to prevent attacks. The acceptable range is Client specific.
8. If a nonce value was sent in the Authorization Request, a nonce Claim MUST be present and its value of the checked to verify that it is the same value as the one that was sent in the Authorization Request. The Client SHOULD check the nonce value for replay attacks. The precise method for detecting replay attacks is Client specific.

The following is a non-normative example of a base64url decoded Self-Issued ID Token (with line wraps within values for display purposes only):

  {
   "iss": "https://self-issued.me",
   "sub": "wBy8QvHbPzUnL0x63h13QqvUYcOur1X0cbQpPVRqX5k",
   "aud": "https://client.example.org/cb",
   "nonce": "n-0S6_WzA2Mj",
   "exp": 1311281970,
   "iat": 1311280970,
   "sub_jwk": {
     "kty":"RSA",
     "n": "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx
     4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMs
     tn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2
     QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbI
     SD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqb
     w0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",
     "e":"AQAB"
    }
  }

9.  Client Authentication

During Client Registration, the RP (Client) MAY register an authentication method. If no method is registered, the default method of client_secret_basic MUST be used.

The Supported options are:

client_secret_basic

Clients that have received a client_secret value from the Authorization Server, authenticate with the Authorization Server in accordance with Section 3.2.1 of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749] using HTTP Basic authentication scheme.

client_secret_post

Clients that have received a client_secret value from the Authorization Server, authenticate with the Authorization Server in accordance with Section 3.2.1 of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749] by including the Client Credentials in the request body.

client_secret_jwt

Clients that have received a client_secret value from the Authorization Server create a JWT using an HMAC SHA algorithm, such as HMAC SHA-256. The HMAC (Hash-based Message Authentication Code) is calculated using the octets of the UTF-8 representation of the client_secret as the shared key.

The Client authenticates in accordance with Section 2.2 of OAuth JWT Bearer Token Profiles (Jones, M., Campbell, B., and C. Mortimore, “JSON Web Token (JWT) Bearer Token Profiles for OAuth 2.0,” March 2013.) [OAuth.JWT] and OAuth 2.0 Assertion Profile (Campbell, B., Mortimore, C., Jones, M., and Y. Goland, “Assertion Framework for OAuth 2.0,” March 2013.) [OAuth.Assertions]. The JWT MUST contain the following REQUIRED Claim Values and MAY contain the following OPTIONAL Claim Values:

iss

REQUIRED. Issuer. This MUST contain the client_id of the OAuth Client.

sub

REQUIRED. Subject. This MUST contain the client_id of the OAuth Client.

aud

REQUIRED. Audience. The aud (audience) Claim. Value that identifies the Authorization Server as an intended audience. The Authorization Server MUST verify that it is an intended audience for the token. The Audience SHOULD be the URL of the Authorization Server's Token Endpoint.

jti

REQUIRED. JWT ID. A unique identifier for the token. The JWT ID MAY be used by implementations requiring message de-duplication for one-time use assertions.

exp

REQUIRED. Expiration time on or after which the ID Token MUST NOT be accepted for processing.

iat

OPTIONAL. Time at which the JWT was issued.

ID Tokens MAY contain other Claims. Any Claims used that are not understood MUST be ignored.

The authentication token MUST be sent as the value of the [OAuth.Assertions] (Campbell, B., Mortimore, C., Jones, M., and Y. Goland, “Assertion Framework for OAuth 2.0,” March 2013.) client_assertion parameter.

The value of the [OAuth.Assertions] (Campbell, B., Mortimore, C., Jones, M., and Y. Goland, “Assertion Framework for OAuth 2.0,” March 2013.) client_assertion_type parameter MUST be "urn:ietf:params:oauth:client-assertion-type:jwt-bearer", per [OAuth.JWT] (Jones, M., Campbell, B., and C. Mortimore, “JSON Web Token (JWT) Bearer Token Profiles for OAuth 2.0,” March 2013.).

private_key_jwt

Clients that have registered a public key sign a JWT using that key. The Client authenticates in accordance with Section 2.2 of OAuth JWT Bearer Token Profiles (Jones, M., Campbell, B., and C. Mortimore, “JSON Web Token (JWT) Bearer Token Profiles for OAuth 2.0,” March 2013.) [OAuth.JWT] and OAuth 2.0 Assertion Profile (Campbell, B., Mortimore, C., Jones, M., and Y. Goland, “Assertion Framework for OAuth 2.0,” March 2013.) [OAuth.Assertions]. The JWT MUST contain the following REQUIRED Claim Values and MAY contain the following OPTIONAL Claim Values:

iss

REQUIRED. Issuer. This MUST contain the client_id of the OAuth Client.

sub

REQUIRED. Subject. This MUST contain the client_id of the OAuth Client.

aud

REQUIRED. Audience. The aud (audience) Claim. Value that identifies the Authorization Server as an intended audience. The Authorization Server MUST verify that it is an intended audience for the token. The Audience SHOULD be the URL of the Authorization Server's Token Endpoint.

jti

REQUIRED. JWT ID. A unique identifier for the token. The JWT ID MAY be used by implementations requiring message de-duplication for one-time use assertions.

exp

REQUIRED. Expiration time on or after which the ID Token MUST NOT be accepted for processing.

iat

OPTIONAL. Time at which the JWT was issued.

The JWT MAY contain other Claims. Any Claims used that are not understood MUST be ignored.

The authentication token MUST be sent as the value of the [OAuth.Assertions] (Campbell, B., Mortimore, C., Jones, M., and Y. Goland, “Assertion Framework for OAuth 2.0,” March 2013.) client_assertion parameter.

The value of the [OAuth.Assertions] (Campbell, B., Mortimore, C., Jones, M., and Y. Goland, “Assertion Framework for OAuth 2.0,” March 2013.) client_assertion_type parameter MUST be "urn:ietf:params:oauth:client-assertion-type:jwt-bearer", per [OAuth.JWT] (Jones, M., Campbell, B., and C. Mortimore, “JSON Web Token (JWT) Bearer Token Profiles for OAuth 2.0,” March 2013.).

For example (with line wraps within values for display purposes only):

  POST /token HTTP/1.1
  Host: server.example.com
  Content-Type: application/x-www-form-urlencoded

  grant_type=authorization_code&
    code=i1WsRn1uB1&
    client_id=s6BhdRkqt3&
    client_assertion_type=
    urn%3Aietf%3Aparams%3Aoauth%3Aclient-assertion-type%3Ajwt-bearer&
    client_assertion=PHNhbWxwOl ... ZT

10.  Signatures and Encryption

Depending on the transport through which the messages are sent, the integrity of the message might not be guaranteed and the originator of the message might not be authenticated. To mitigate these risks, Request Object, Token Request, ID Token, and UserInfo Response values MAY utilize JSON Web Signature (JWS) (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) [JWS] to sign the contents.

To achieve message confidentiality, Request Object, Token Request, ID Token, and UserInfo Response values MAY use JSON Web Encryption (JWE) (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” May 2013.) [JWE] to encrypt the content.

When the message is both signed and encrypted, it MUST be signed first and then encrypted, per Section 13.14 (Signing and Encryption Order), with nesting performed in the same manner as specified for JWTs [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.). Note that all JWE encryption methods perform integrity checking.

10.1.  Supported Algorithms

The server advertises its supported signing and encryption algorithms in its discovery document. The algorithm identifiers are specified in JWA (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) [JWA]. The related elements are:

userinfo_signing_alg_values_supported

JSON array containing a list of the JWS [JWS] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Signature (JWS),” May 2013.) signing algorithms (alg values) [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) supported by the UserInfo Endpoint to encode the Claims in a JWT [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.).

userinfo_encryption_alg_values_supported

JSON array containing a list of the JWE [JWE] (Jones, M., Rescorla, E., and J. Hildebrand, “JSON Web Encryption (JWE),” May 2013.) encryption algorithms (alg values) [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) supported by the UserInfo Endpoint to encode the Claims in a JWT [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.).

userinfo_encryption_enc_values_supported

JSON array containing a list of the JWE encryption algorithms (enc values) [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) supported by the UserInfo Endpoint to encode the Claims in a JWT [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.).

id_token_signing_alg_values_supported

JSON array containing a list of the JWS signing algorithms (alg values) supported by the Authorization Server for the ID Token to encode the Claims in a JWT [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.).

id_token_encryption_alg_values_supported

JSON array containing a list of the JWE encryption algorithms (alg values) supported by the Authorization Server for the ID Token to encode the Claims in a JWT [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.).

id_token_encryption_enc_values_supported

JSON array containing a list of the JWE encryption algorithms (enc values) supported by the Authorization Server for the ID Token to encode the Claims in a JWT [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.).

request_object_signing_alg_values_supported

JSON array containing a list of the JWS signing algorithms (alg values) supported by the Authorization Server for Request Object values. Servers SHOULD support none and RS256.

request_object_encryption_alg_values_supported

JSON array containing a list of the JWE encryption algorithms (alg values) supported by the Authorization Server for Request Object values.

request_object_encryption_enc_values_supported

JSON array containing a list of the JWE encryption algorithms (enc values) supported by the Authorization Server for Request Object values.

token_endpoint_auth_signing_alg_values_supported

JSON array containing a list of the JWS signing algorithms (alg values) supported by the Token Endpoint for the private_key_jwt and client_secret_jwt methods to encode the JWT [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.). Servers SHOULD support RS256.

The Client registers its REQUIRED algorithms for Signing and Encryption using the following Registration parameters:

request_object_signing_alg

OPTIONAL. JWS signature algorithm [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) REQUIRED for Request Objects by the Authorization Server. All Request Objects from this client_id MUST be rejected if not signed by this algorithm. Servers SHOULD support RS256.

userinfo_signed_response_alg

OPTIONAL. JWS signature algorithm [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) REQUIRED for UserInfo Responses. If this is specified the response will be JWT (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT] serialized.

userinfo_encrypted_response_alg

OPTIONAL. JWE alg algorithm [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) REQUIRED for UserInfo Responses. If this is requested in combination with signing, the response MUST be signed first then encrypted, per Section 13.14 (Signing and Encryption Order). If this is specified, the response will be JWT (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT] serialized.

userinfo_encrypted_response_enc

OPTIONAL. JWE enc algorithm [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) REQUIRED for UserInfo Responses. If userinfo_encrypted_response_alg is specified the default for this value is A128CBC-HS256.

id_token_signed_response_alg

OPTIONAL. JWS signature algorithm [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) REQUIRED for ID Tokens issued to this client_id. The default if not specified is RS256. The public key for validating the signature is provided by retrieving the JWK Set referenced by the jwks_uri element from Discovery.

id_token_encrypted_response_alg

OPTIONAL. JWE alg algorithm [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) REQUIRED for ID Tokens issued to this client_id. If this is requested, the response MUST be signed then encrypted. The default if not specified is no encryption.

id_token_encrypted_response_enc

OPTIONAL. JWE enc algorithm [JWA] (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) REQUIRED for ID Tokens issued to this client_id. If id_token_encrypted_response_alg is specified the default for this value is A128CBC-HS256.

10.2.  Keys

The OpenID Provider provides its public keys during Discovery using the following element:

jwks_uri

REQUIRED. URL of the OP's JSON Web Key Set [JWK] (Jones, M., “JSON Web Key (JWK),” May 2013.) document. This contains the signing key(s) the Client uses to validate signatures from the OP. The JWK Set MAY also contain the Server's encryption key(s), which are used by Clients to encrypt requests to the Server. When both signing and encryption keys are made available, a use (Key Use) parameter value is REQUIRED for all keys in the document to indicate each key's intended usage.

Likewise, the Client can provide its public keys during Registration using the following element:

jwks_uri

OPTIONAL. URL for the Client's JSON Web Key Set [JWK] (Jones, M., “JSON Web Key (JWK),” May 2013.) document. If the Client signs requests to the Server, it contains the signing key(s) the Server uses to validate signatures from the Client. The JWK Set MAY also contain the Client's encryption keys(s), which are used by the Server to encrypt responses to the Client. When both signing and encryption keys are made available, a use (Key Use) parameter value is REQUIRED for all keys in the document to indicate each key's intended usage.

When both signing and encryption keys are made available, the use (Key Use) parameter value is REQUIRED for all keys in the JWK Set at the jwks_uri to indicate each key's intended usage. Although some algorithms allow the same key pair to be used for both signatures and encryption, doing so is NOT RECOMMENDED, as it is less secure.

In both cases, the JWK x5c parameter MAY be used to provide X.509 representations of keys provided. When used, the bare key values MUST still be present and MUST match those in the certificate.

10.3.  Signing

The signing party MUST select a signature algorithm based on the supported algorithms of the recipient in Section 10.1 (Supported Algorithms).

Asymmetric Signatures

When using RSA or ECDSA Signatures, the alg Claim of the JWS header MUST be set to the appropriate algorithm as defined in JSON Web Algorithms (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) [JWA]. The private key MUST be the one associated with the Public Signing Key provided in Section 10.2 (Keys). If there are multiple keys in the referenced JWK document, a kid value MUST be provided in the JWS header. The key usage of the respective keys MUST support signature.

Symmetric Signatures

When using MAC-based signatures, the alg Claim of the JWS header MUST be set to a MAC algorithm, as defined in JSON Web Algorithms (Jones, M., “JSON Web Algorithms (JWA),” May 2013.) [JWA]. The MAC key used is the octets of the UTF-8 representation of the client_secret value. See Section 13.18 (Symmetric Key Entropy) for a discussion of entropy requirements for client_secret values. Symmetric signatures MUST never be used by public (non-confidential) Clients because of their inability to keep secrets.

See Section 13.19 (Need for Signed Requests) for Security Considerations about the need for signed requests.

10.3.1.  Rotation of Asymmetric Signing Keys

Rotation of signing keys can be accomplished with the following approach. The signer publishes its keys in a JWK Set at the jwks_uri location and includes the kid of the signing key in the JWS header of each message to indicate to the verifier which key is to be used to validate the signature. Keys can be rolled over by periodically adding new keys to the JWK Set at jwks_uri. The signer can begin using a new key at its discretion and signals the change to the verifier using the kid value. The verifier knows to go back to the jwks_uri to re-retrieve the keys when it sees an unfamiliar kid value. The JWK Set document at the jwks_uri SHOULD retain recently decommissioned signing keys for a reasonable period of time to facilitate a smooth transition.

10.4.  Encryption

The encrypting party MUST select an encryption algorithm based on the supported algorithms of the recipient in Section 10.1 (Supported Algorithms). All JWTs MUST be signed before encryption to enable verification of the Issuer.

Asymmetric Encryption: RSA

Use the link registered/discovered in Section 10.2 (Keys) to retrieve the relevant key. If there are multiple keys in the referenced JWK document, a kid value MUST be provided in the JWE header. Use the supported RSA key wrapping algorithm to wrap a random Content Master Key to be used for encrypting the signed JWT. The key usage of the respective keys MUST include encryption.

Asymmetric Encryption: Elliptic Curve

Create an ephemeral Elliptic Curve public key for the epk element of the JWE header. Use the link registered/discovered in Section 10.2 (Keys) to retrieve the relevant key. If there are multiple keys in the referenced JWK document, a kid value MUST be provided in the JWE header. Use the ECDH-ES algorithm to wrap a random Content Master Key to be used for encrypting the signed JWT. The key usage of the respective keys MUST support encryption.

Symmetric Encryption

The symmetric encryption key is derived from the client_secret value by using a left truncated SHA-256 hash of the octets of the UTF-8 representation of the client_secret. The SHA-256 value MUST be left truncated to the appropriate bit length for the AES key wrapping algorithm used, for instance, to 128 bits for A128KW. If a key wrapping key with greater than 256 bits is needed, a different method of deriving the key from the client_secret would have to be defined by an extension. Symmetric encryption MUST never be used by public (non-confidential) Clients because of their inability to keep secrets.

See Section 13.20 (Need for Encrypted Requests) for Security Considerations about the need for encrypted requests.

10.4.1.  Rotation of Asymmetric Encryption Keys

Rotating encryption keys is necessarily a different process than for signing keys because the encrypting party starts the process and thus cannot rely on a change in kid as a signal to know that keys need to change. The encrypting party still uses the kid header in the JWE to tell the decrypting party which private key to use to decrypt, however, the encrypting party needs to first select the most appropriate key from those provided in the JWK Set at jwks_uri. To rotate keys, the decrypting party can publish new keys at jwks_uri and remove from the JWK Set those that are being decommissioned. The jwks_uri SHOULD include a Cache-Control header in the response that contains a max-age directive, as defined in RFC 2616 (Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, “Hypertext Transfer Protocol -- HTTP/1.1,” June 1999.) [RFC2616], which allows the encrypting party to safely cache the JWK Set and not have to re-retrieve the document for every encryption event. The decrypting party SHOULD remove decommissioned keys from the JWK Set at jwks_uri but retain them internally for some reasonable period of time, coordinated with the cache duration, to facilitate a smooth transition between keys by allowing the encrypting party some time to obtain the new keys. The cache duration SHOULD also be coordinated with the issuance of new signing keys as described in Section 10.3.1 (Rotation of Asymmetric Signing Keys).

11.  String Operations and Serializations

11.1.  String Operations

Processing some OpenID Connect messages requires comparing values in the messages to known values. For example, the Claim Names returned by the UserInfo Endpoint might be compared to specific Claim Names such as sub. Comparing Unicode strings, however, has significant security implications.

Therefore, comparisons between JSON strings and other Unicode strings MUST be performed as specified below:

1. Remove any JSON applied escaping to produce an array of Unicode code points.
2. Unicode Normalization (Davis, M., Whistler, K., and M. Dürst, “Unicode Normalization Forms,” 09 2009.) [USA15] MUST NOT be applied at any point to either the JSON string or to the string it is to be compared against.
3. Comparisons between the two strings MUST be performed as a Unicode code point to code point equality comparison.

In several places, this specification uses space delimited lists of strings. In all such cases, only the ASCII space character (0x20) MAY be used for this purpose.

11.2.  Serializations

Messages are serialized using one of the following methods:

1. Query String Serialization
2. Form Serialization
3. JSON Serialization

Not all methods can be used for all messages.

11.2.1.  Query String Serialization

In order to serialize the parameters using the Query String Serialization, the Client constructs the string by adding the parameters and values to the query component of a URL using the application/x-www-form-urlencoded format as defined by [W3C.REC‑html401‑19991224] (Hors, A., Raggett, D., and I. Jacobs, “HTML 4.01 Specification,” December 1999.). Query String Serialization is typically used in HTTP GET requests. The same serialization method is also used when adding parameters to the fragment component of a URL.

Following is a non-normative example of this serialization (with line wraps within values for display purposes only):

  GET /authorize?scope=openid&response_type=code
    &client_id=s6BhdRkqt3
    &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb HTTP/1.1
  Host: server.example.com

11.2.2.  Form Serialization

Parameters and their values are Form Serialized by adding the parameter names and values to the entity body of the HTTP request using the application/x-www-form-urlencoded format as defined by [W3C.REC‑html401‑19991224] (Hors, A., Raggett, D., and I. Jacobs, “HTML 4.01 Specification,” December 1999.). Form Serialization is typically used in HTTP POST requests.

Following is a non-normative example of this serialization (with line wraps within values for display purposes only):

  POST /authorize HTTP/1.1
  Host: server.example.com
  Content-Type: application/x-www-form-urlencoded

  scope=openid&response_type=code
    &client_id=s6BhdRkqt3
    &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb

11.2.3.  JSON Serialization

The parameters are serialized into a JSON structure by adding each parameter at the highest structure level. Parameter names and string values are included as JSON strings. Numerical values are included as JSON numbers. Each parameter MAY have a JSON structure as its value.

Following is a non-normative example of this serialization:

  {
   "access_token":"SlAV32hkKG",
   "expires_in":3600,
   "refresh_token":"8xLOxBtZp8"
  }

12.  Implementation Considerations

This specification defines features used by both Relying Parties and OpenID Providers. Features that are mandatory to implement for Relying Parties are already described in the OpenID Connect Basic Client Profile 1.0 (Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and C. Mortimore, “OpenID Connect Basic Client Profile 1.0,” July 2013.) [OpenID.Basic] and OpenID Connect Implicit Client Profile 1.0 (Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., Mortimore, C., and E. Jay, “OpenID Connect Implicit Client Profile 1.0,” July 2013.) [OpenID.Implicit] specifications, and so are not discussed again here.

It is expected that some OpenID Providers will require static, out-of-band configuration of RPs using them, whereas others will support dynamic usage by RPs without a pre-established relationship between them. For that reason, the mandatory-to-implement features for OPs are listed below in two groups: the first for all OPs and the second for "Dynamic" OpenID Providers.

12.1.  Mandatory to Implement Features for All OpenID Providers

All OpenID Providers MUST implement the following features defined in this specification. This list augments the set of features that are already listed elsewhere as being "REQUIRED" or are described with a "MUST", and so is not, by itself, a comprehensive set of implementation requirements for OPs.

Signing ID Tokens with RSA SHA-256

OPs MUST support signing ID Tokens with the RSA SHA-256 algorithm (an alg value of RS256).

Prompt Parameter

OPs MUST support the prompt parameter, as defined in Section 3.1.1 (Request Parameters), including the specified user interface behaviors such as none and login.

Display Parameter

OPs MUST support the display parameter, as defined in Section 3.1.1 (Request Parameters). (Note that the minimum level of support required for this parameter is simply to have its use not result in an error.)

Preferred Locales

OPs MUST support requests for preferred languages and scripts for the user interface and for Claims via the ui_locales and claims_locales request parameters, as defined in Section 3.1.1 (Request Parameters). (Note that the minimum level of support required for these parameters is simply to have their use not result in errors.)

Authentication Time

OPs MUST support returning the time at which the End-User authenticated via the auth_time Claim, as defined in Section 3.2.4 (ID Token).

Maximum Authentication Age

OPs MUST support enforcing a maximum authentication age via the max_age parameter, as defined in Section 3.1.1 (Request Parameters).

Authentication Context Class Reference

OPs MUST support requests for specific Authentication Context Class Reference values via the acr_values parameter, as defined in Section 3.1.1 (Request Parameters). (Note that the minimum level of support required for this parameter is simply to have its use not result in an error.)

12.2.  Mandatory to Implement Features for Dynamic OpenID Providers

In addition to the features listed above, OpenID Providers supporting dynamic establishment of relationships with RPs that they do not have a pre-configured relationship with MUST also implement the following features defined in this and related specifications.

Discovery

These OPs MUST support Discovery, as defined in OpenID Connect Discovery 1.0 (Sakimura, N., Bradley, J., Jones, M., and E. Jay, “OpenID Connect Discovery 1.0,” July 2013.) [OpenID.Discovery].

Dynamic Registration

These OPs MUST support Dynamic Client Registration, as defined in OpenID Connect Dynamic Client Registration 1.0 (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Dynamic Client Registration 1.0,” July 2013.) [OpenID.Registration].

UserInfo Endpoint

All dynamic OPs that issue Access Tokens MUST support the UserInfo Endpoint, as defined in Section 6.4 (UserInfo Endpoint). (Self-Issued OPs do not issue Access Tokens.)

Public Keys Published as Bare Keys

These OPs MUST publish their public keys as bare keys, rather than in X.509 format.

Request URI

These OPs MUST support requests made using a Request Object value that is retrieved from a Request URI that is provided with the request_uri parameter, as defined in Section 3.1.1 (Request Parameters).

12.3.  Related Specifications

This specification is an abstract specification. It needs to be bound to a protocol to be used in practice. One such example of protocol binding is:

• OpenID Connect Standard 1.0 (Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., Mortimore, C., and E. Jay, “OpenID Connect Standard 1.0,” July 2013.) [OpenID.Standard] - Protocol binding for the full set of OpenID Connect messages

These related OpenID Connect specifications MAY OPTIONALLY be used in combination with this specification to provide additional functionality:

• OpenID Connect Discovery 1.0 (Sakimura, N., Bradley, J., Jones, M., and E. Jay, “OpenID Connect Discovery 1.0,” July 2013.) [OpenID.Discovery] - Dynamic discovery for user and Authorization Server endpoints and information
• OpenID Connect Dynamic Client Registration 1.0 (Sakimura, N., Bradley, J., and M. Jones, “OpenID Connect Dynamic Client Registration 1.0,” July 2013.) [OpenID.Registration] - Dynamic registration of OpenID Connect Clients with OpenID Providers
• OpenID Connect Basic Client Profile 1.0 (Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and C. Mortimore, “OpenID Connect Basic Client Profile 1.0,” July 2013.) [OpenID.Basic] - Protocol binding for a subset of the OpenID Connect Messages that is intended for use by basic Web-based Relying Parties using the OAuth authorization_code grant type.
• OpenID Connect Implicit Client Profile 1.0 (Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., Mortimore, C., and E. Jay, “OpenID Connect Implicit Client Profile 1.0,” July 2013.) [OpenID.Implicit] - Protocol binding for a subset of the OpenID Connect Messages that is intended for use by basic Web-based Relying Parties using the OAuth implicit grant type.
• OpenID Connect Session Management 1.0 (Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., Mortimore, C., and E. Jay, “OpenID Connect Session Management 1.0,” July 2013.) [OpenID.Session] - Session management for OpenID Connect sessions

13.  Security Considerations

OAuth 2.0 Threat Model and Security Considerations (Lodderstedt, T., McGloin, M., and P. Hunt, “OAuth 2.0 Threat Model and Security Considerations,” January 2013.) [RFC6819] provides an extensive list of threats and controls that applies to this standard as well. ISO/IEC 29115 (International Organization for Standardization, “ISO/IEC 29115:2013 -- Information technology - Security techniques - Entity authentication assurance framework,” March 2013.) [ISO29115] also provides threats and controls that implementers need to take into account. In addition, this standard provides additional control measures listed below.

13.1.  TLS Version

Whenever Transport Layer Security (TLS) is used by this specification, the appropriate version (or versions) of TLS will vary over time, based on the widespread deployment and known security vulnerabilities. At the time of this writing, TLS version 1.2 [RFC5246] (Dierks, T. and E. Rescorla, “The Transport Layer Security (TLS) Protocol Version 1.2,” August 2008.) is the most recent version, but has a very limited deployment base and might not be readily available for implementation. TLS version 1.0 [RFC2246] (Dierks, T. and C. Allen, “The TLS Protocol Version 1.0,” January 1999.) is the most widely deployed version and will provide the broadest interoperability.

13.2.  Request Disclosure

If appropriate measures are not taken, a request might be disclosed to an attacker, posing security and privacy threats.

In addition to what is stated in Section 5.1.1 of [RFC6819] (Lodderstedt, T., McGloin, M., and P. Hunt, “OAuth 2.0 Threat Model and Security Considerations,” January 2013.), this standard provides a way to provide the confidentiality of the request end to end through the use of request or request_uri parameters, where the content of the request is an encrypted JWT with the appropriate key and cipher. This protects even against a compromised User-Agent in the case of indirect request.

13.3.  Server Masquerading

A malicious Server might masquerade as the legitimate server using various means. To detect such an attack, the Client needs to authenticate the server.

In addition to what is stated in Section 5.1.2 of [RFC6819] (Lodderstedt, T., McGloin, M., and P. Hunt, “OAuth 2.0 Threat Model and Security Considerations,” January 2013.), this standard provides a way to authenticate the Server through either the use of Signed or Encrypted JWTs with an appropriate key and cipher.

13.4.  Token Manufacture/Modification

An Attacker might generate a bogus token or modify the token content (such as the authentication or attribute statements) of an existing parseable token, causing the RP to grant inappropriate access to the Client. For example, an Attacker might modify the parseable token to extend the validity period; a Client might modify the parseable token to have access to information that they should not be able to view.

There are two ways to mitigate this attack:

1. The token can be digitally signed by the OP. The Relying Party SHOULD validate the digital signature to verify that it was issued by a legitimate OP.
2. The token can be sent over a protected channel such as TLS. See Section 13.16 (TLS Requirements) for more information on using TLS. In this specification, the token is always sent over a TLS protected channel. Note however, that this measure is only a defense against third party attackers and is not applicable to the case where the Client is the attacker.

13.5.  Server Response Disclosure

The server response might contain authentication and attribute statements that include sensitive Client information. Disclosure of the response contents can make the Client vulnerable to other types of attacks.

The server response disclosure can be mitigated in the following two ways:

1. Using the code response type. The response is sent over a TLS protected channel, where the Client is authenticated by the client_id and client_secret.
2. For other response types, the signed response can be encrypted with the Client's public key or a shared secret as an encrypted JWT with an appropriate key and cipher.

13.6.  Server Response Repudiation

A response might be repudiated by the server if the proper mechanisms are not in place. For example, if a Server does not digitally sign a response, the Server can claim that it was not generated through the services of the Server.

To mitigate this threat, the response MAY be digitally signed by the Server using a key that supports non-repudiation. The Client SHOULD validate the digital signature to verify that it was issued by a legitimate Server and its integrity is intact.

13.7.  Request Repudiation

Since it is possible for a compromised or malicious Client to send a request to the wrong party, a Client that was authenticated using only a bearer token can repudiate any transaction.

To mitigate this threat, the Server MAY require that the request be digitally signed by the Client using a key that supports non-repudiation. The Server SHOULD validate the digital signature to verify that it was issued by a legitimate Client and the integrity is intact.

13.8.  Access Token Redirect

An Attacker uses the Access Token generated for one resource to obtain access to a second resource.

To mitigate this threat, the Access Token SHOULD be audience and scope restricted. One way of implementing it is to include the identifier of the resource for whom it was generated as audience. The resource verifies that incoming tokens include its identifier as the audience of the token.

13.9.  Token Reuse

An Attacker attempts to use a one-time use token such as an Authorization Code that has already been used once with the intended Resource. To mitigate this threat, the token SHOULD include a timestamp and a short validity lifetime. The Relying Party then checks the timestamp and lifetime values to ensure that the token is currently valid.

Alternatively, the server MAY record the state of the use of the token and check the status for each request.

13.10.  Eavesdropping or Leaking Authorization Codes (Secondary Authenticator Capture)

In addition to the attack patterns described in Section 4.4.1.1 of [RFC6819] (Lodderstedt, T., McGloin, M., and P. Hunt, “OAuth 2.0 Threat Model and Security Considerations,” January 2013.), an Authorization Code can be captured in the User-Agent where the TLS session is terminated if the User-Agent is infected by malware. However, capturing it is not useful as long as the profile uses either Client authentication or an encrypted response.

13.11.  Token Substitution

Token Substitution is a class of attacks in which a malicious user swaps various tokens, including swapping an Authorization Code for a legitimate user with another token that the attacker has. One means of accomplishing this is for the attacker to copy a token out one session and use it in an HTTP message for a different session, which is easy to do when the token is available to the browser; this is known as the "cut and paste" attack.

The implicit flow of OAuth 2.0 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749] is not designed to mitigate this risk. In Section 10.16, it normatively requires that any use of the authorization process as a form of delegated End-User authentication to the Client MUST NOT use the implicit flow without employing additional security mechanisms that enable the Client to determine whether the Access Token was issued for its use.

In OpenID Connect, this is mitigated through mechanisms provided through the ID Token. The ID Token is a signed security token that provides Claims such as iss (issuer), sub (subject), aud (audience), azp (authorized party), at_hash (access token hash), and c_hash (code hash). Using the ID Token, the Client is capable of detecting the Token Substitution Attack.

The c_hash in the ID Token enables Clients to prevent code substitution.

Also, a malicious user may attempt to impersonate a more privileged user by subverting the communication channel between the Authorization Endpoint and Client, or the Token Endpoint and Client, for example by swapping the code or reordering the messages, to convince the Token Endpoint that the attacker's authorization grant corresponds to a grant sent on behalf of a more privileged user.

For HTTP bindings such as OpenID Connect Standard 1.0, the responses to Token Requests are bound to the corresponding requests by message order in HTTP, as both the response containing the token and requests are protected by TLS, which will detect and prevent packet reordering.

When designing another binding of OpenID Connect Messages to a protocol incapable of strongly binding Token Endpoint requests to responses, additional mechanisms to address this issue MUST be utilized. One such mechanism could be to include an ID Token with a c_hash Claim in the token request and response.

13.12.  Timing Attack

A timing attack allows the attacker to obtain an unnecessary large amount of information through the elapsed time differences in the code paths taken by successful and unsuccessful decryption operations or successful and unsuccessful signature validation of a message. It can be used to reduce the effective key length of the cipher used.

Implementations SHOULD NOT terminate the validation process at the instant of the finding an error but SHOULD continue running until all the octets have been processed to avoid this attack.

13.13.  Other Crypto Related Attacks

There are various crypto related attacks possible depending on the method used for encryption and signature / integrity checking. Implementers need to consult the Security Considerations for the JWT (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.) [JWT] specification and specifications that it references to avoid the vulnerabilities identified in these specifications.

13.14.  Signing and Encryption Order

Signatures over encrypted text are not considered valid in many jurisdictions. Therefore, for integrity and non-repudiation, this specification requires signing the plain text JSON Claims.

13.15.  Issuer Identifier

OpenID Connect supports multiple issuers per Host and Port combination. The issuer returned by discovery MUST exactly match the value of iss in the ID Token.

OpenID Connect treats the path component of any URI as part of the user identifier. For instance, the subject "1234" with an issuer of "https://example.com" is not equivalent to the subject "1234" with an issuer of "https://example.com/sales".

It is RECOMMENDED that only a single issuer per host be used.

13.16.  TLS Requirements

Implementations MUST support TLS. Which version(s) ought to be implemented will vary over time, and depend on the widespread deployment and known security vulnerabilities at the time of implementation. At the time of this writing, TLS version 1.2 [RFC5246] (Dierks, T. and E. Rescorla, “The Transport Layer Security (TLS) Protocol Version 1.2,” August 2008.) is the most recent version, but has very limited actual deployment, and might not be readily available in implementation toolkits. TLS version 1.0 [RFC2246] (Dierks, T. and C. Allen, “The TLS Protocol Version 1.0,” January 1999.) is the most widely deployed version, and will give the broadest interoperability.

To protect against information disclosure and tampering, confidentiality protection MUST be applied using TLS with a ciphersuite that provides confidentiality and integrity protection.

Whenever TLS is used, a TLS server certificate check MUST be performed, per RFC 6125 (Saint-Andre, P. and J. Hodges, “Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS),” March 2011.) [RFC6125].

13.17.  Lifetimes of Access Tokens and Refresh Tokens

Access Token grants are not revocable by the Authorization Server. Access Token grant lifetimes SHOULD be kept to single use or very short lifetimes.

If access to the UserInfo Endpoint or other protected resources is required, a Refresh Token SHOULD be used. The Client MAY then exchange the Refresh Token at the Token Endpoint for a fresh short-lived Access Token that can be used to access the resource.

The Authorization Server SHOULD clearly identify long-term grants to the User during Authorization. The Authorization Server SHOULD provide a mechanism for the End-User to revoke Refresh Tokens granted to a Client.

13.18.  Symmetric Key Entropy

In Section 10.3 (Signing) and Section 10.4 (Encryption), keys are derived from the client_secret value. Thus, when used with symmetric signing or encryption operations, client_secret values MUST contain sufficient entropy to generate cryptographically strong keys. Also, client_secret values MUST also contain at least the minimum of number of octets required for MAC keys for the particular algorithm used. So for instance, for HS256, the client_secret value MUST contain at least 8 octets (and almost certainly SHOULD contain more, since client_secret values are likely to use a restricted alphabet.

13.19.  Need for Signed Requests

In some situations, Clients might need to use signed requests to ensure that the desired request parameters are delivered to the OP without having been tampered with. For instance, the max_age and acr_values provide more assurance about the nature of the authentication performed when delivered in signed requests.

13.20.  Need for Encrypted Requests

In some situations, knowing the contents of an OpenID Connect request can, in and of itself, reveal sensitive information about the End-User. For instance, knowing that the Client is requesting a particular Claim or that it is requesting that a particular authentication method be used can reveal sensitive information about the End-User. OpenID Connect enables requests to be encrypted to the OpenID Provider to prevent such potentially sensitive information from being revealed.

14.  Privacy Considerations

14.1.  Personally Identifiable Information

The UserInfo Response typically contains Personally Identifiable Information (PII). As such, End-User consent for the release of the information for the specified purpose SHOULD be obtained at or prior to the authorization time in accordance with relevant regulations. The purpose of use is typically registered in association with the redirect_uris.

Only necessary UserInfo data should be stored at the Client and the Client SHOULD associate the received data with the purpose of use statement.

14.2.  Data Access Monitoring

The Resource Server SHOULD make the UserInfo access log available to the End-User so that the End-User can monitor who accessed his data.

14.3.  Correlation

To protect the End-User from a possible correlation among Clients, the use of a Pairwise Pseudonymous Identifier (PPID) as the sub (subject) SHOULD be considered.

14.4.  Offline Access

Offline access enables access to Claims when the user is not present, posing greater privacy risk than the Claims transfer when the user is present. Therefore, it is prudent to obtain explicit consent for offline access to resources. This specification mandates the use of the prompt parameter to obtain consent unless it is a priori known that the request complies with the conditions for processing in each jurisdiction.

When an Access Token is returned in the front channel, there is a greater risk of it being exposed to an attacker, who could later use it to access the UserInfo endpoint. If the Access Token does not enable offline access and the server can differentiate whether the Client request has been made offline or online, the risk will be substantially reduced. Therefore, this specification mandates ignoring the offline access request when the Access Token is transmitted in the front channel. Note that differentiating between online and offline access from the server can be difficult especially for native clients. The server may well have to rely on heuristics. Also, the risk of exposure for the Access Token delivered in the front channel for the response types of code token and token is the same. Thus, the implementations should be prepared to detect the channel from which the Access Token was issued and deny offline access if the token was issued in the front channel.

Note that although these provisions require an explicit consent dialogue through the prompt parameter, the mere fact that the user pressed an "accept" button etc., might not constitute a valid consent. Developers should be aware that for the act of consent to be valid, typically, the impact of the terms have to be understood by the End-User, the consent must be freely given and not forced (i.e., other options have to be available), and the terms must fair and equitable. In general, it is advisable for the service to follow the required privacy principles in each jurisdiction and rely on other conditions of processing than simply explicit consent, as online self-service "explicit consent" often does not form a valid consent in some jurisdictions.

15.  IANA Considerations

15.1.  JSON Web Token Claims Registry

This specification registers the Claims defined in Section 6.2 (Standard Claims) and Section 3.2.4 (ID Token) in the IANA JSON Web Token Claims registry defined in [JWT] (Jones, M., Bradley, J., and N. Sakimura, “JSON Web Token (JWT),” May 2013.).

15.1.1.  Registry Contents

• Claim Name: name
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: given_name
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: family_name
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: middle_name
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: nickname
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: preferred_username
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: profile
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: picture
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: website
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: email
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: email_verified
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: gender
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: birthdate
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: zoneinfo
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: locale
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: phone_number
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: address
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: updated_at
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 6.2 (Standard Claims) of this document

• Claim Name: azp
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 3.2.4 (ID Token) of this document

• Claim Name: nonce
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 3.2.4 (ID Token) of this document

• Claim Name: auth_time
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 3.2.4 (ID Token) of this document

• Claim Name: at_hash
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 3.2.4 (ID Token) of this document

• Claim Name: c_hash
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 3.2.4 (ID Token) of this document

• Claim Name: acr
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 3.2.4 (ID Token) of this document

• Claim Name: amr
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 3.2.4 (ID Token) of this document

• Claim Name: sub_jwk
• Change Controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification Document(s): Section 3.2.4 (ID Token) of this document

15.2.  OAuth Parameters Registry

This specification registers the following parameters in the IANA OAuth Parameters registry defined in RFC 6749 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749].

15.2.1.  Registry Contents

• Parameter name: nonce
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: display
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: prompt
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: max_age
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: ui_locales
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: claims_locales
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: id_token_hint
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: login_hint
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: acr_values
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: claims
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: registration
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: request
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: request_uri
• Parameter usage location: Authorization Request
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.1.1 (Request Parameters) of this document
• Related information: None

• Parameter name: id_token
• Parameter usage location: Authorization Response, Access Token Response
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 3.2.3 (Access Token Response) of this document
• Related information: None

15.3.  OAuth Extensions Error Registry

This specification registers the following errors in the IANA OAuth Extensions Error registry defined in RFC 6749 (Hardt, D., “The OAuth 2.0 Authorization Framework,” October 2012.) [RFC6749].

15.3.1.  Registry Contents

• Error name: interaction_required
• Error usage location: Authorization Endpoint
• Related protocol extension: OpenID Connect
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 7.3 (Authorization Error Response) of this document

• Error name: login_required
• Error usage location: Authorization Endpoint
• Related protocol extension: OpenID Connect
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 7.3 (Authorization Error Response) of this document

• Error name: session_selection_required
• Error usage location: Authorization Endpoint
• Related protocol extension: OpenID Connect
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 7.3 (Authorization Error Response) of this document

• Error name: consent_required
• Error usage location: Authorization Endpoint
• Related protocol extension: OpenID Connect
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 7.3 (Authorization Error Response) of this document

• Error name: invalid_request_uri
• Error usage location: Authorization Endpoint
• Related protocol extension: OpenID Connect
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 7.3 (Authorization Error Response) of this document

• Error name: invalid_request_object
• Error usage location: Authorization Endpoint
• Related protocol extension: OpenID Connect
• Change controller: OpenID Foundation Artifact Binding Working Group - openid-specs-ab@lists.openid.net
• Specification document(s): Section 7.3 (Authorization Error Response) of this document

16.  References

16.1. Normative References

16.2. Informative References

Appendix A.  Examples

In this appendix, several examples on the request and responses are shown to aid the developers test their code.

response_type=code

  https://server.example.com/op/authorize?
    response_type=code
    &client_id=s6BhdRkqt3
    &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb
    &scope=openid
    &nonce=n-0S6_WzA2Mj
    &state=af0ifjsldkj

  HTTP/1.1 302 Found
  Location: https://client.example.org/cb?
    code=Qcb0Orv1zh30vL1MPRsbm-diHiMwcLyZvn1arpZv-Jxf_11jnpEX3Tgfvk
    &state=af0ifjsldkj

Upon receipt of the code, the Client sends Token Request to the Token Endpoint to obtain the Tokens.

  POST /token HTTP/1.1
  Host: server.example.com
  Content-Type: application/x-www-form-urlencoded
  Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW

  grant_type=authorization_code&code=SplxlOBeZQQYbYS6WxSbIA
    &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb

 HTTP/1.1 200 OK

  {
   "access_token": "SlAV32hkKG",
   "token_type": "Bearer",
   "refresh_token": "8xLOxBtZp8",
   "expires_in": 3600,
   "id_token": "eyJ0 ... NiJ9.eyJ1c ... I6IjIifX0.DeWt4Qu ... ZXso"
  }

Verifying and decoding the ID Token will yield the following Claims:

  {
   "iss": "http://server.example.com",
   "sub": "248289761001",
   "aud": "s6BhdRkqt3",
   "nonce": "n-0S6_WzA2Mj",
   "exp": 1311281970,
   "iat": 1311280970,
   "at_hash": "77QmUPtjPfzWtF2AnpK9RQ"
  }

Appendix B.  Acknowledgements

As a successor version of OpenID, this specification heavily relies on ideas explored in OpenID Authentication 2.0 (OpenID Foundation, “OpenID Authentication 2.0,” December 2007.) [OpenID.2.0]. Please refer to Appendix C of OpenID Authentication 2.0 for the full list of the contributors for that specification.

In addition, the OpenID Community would like to thank the following people for the work they have done in the drafting and editing of this specification.

Naveen Agarwal (naa@google.com), Google

Amanda Anganes (aanganes@mitre.org), Mitre

Casper Biering (cb@peercraft.com), Peercraft

John Bradley (ve7jtb@ve7jtb.com), Ping Identity

Tim Bray (tbray@textuality.com), Google

Johnny Bufu (jbufu@janrain.com), Janrain

Brian Campbell (bcampbell@pingidentity.com), Ping Identity

Breno de Medeiros (breno@gmail.com), Google

Pamela Dingle (pdingle@pingidentity.com), Ping Identity

Vladimir Dzhuvinov (vladimir@nimbusds.com), Nimbus Directory Services

George Fletcher (george.fletcher@corp.aol.com), AOL

Roland Hedberg (roland.hedberg@adm.umu.se), University of Umea

Ryo Ito (ryo.ito@mixi.co.jp), mixi, Inc.

Edmund Jay (ejay@mgi1.com), Illumila

Michael B. Jones (mbj@microsoft.com), Microsoft

Torsten Lodderstedt (t.lodderstedt@telekom.de), Deutsche Telekom

Nov Matake (nov@matake.jp), Independent

Chuck Mortimore (cmortimore@salesforce.com), Salesforce

Anthony Nadalin (tonynad@microsoft.com), Microsoft

Hideki Nara (hdknr@ic-tact.co.jp), Tact Communications

Axel Nennker (axel.nennker@telekom.de), Deutsche Telekom

David Recordon (dr@fb.com), Facebook

Justin Richer (jricher@mitre.org), Mitre

Nat Sakimura (n-sakimura@nri.co.jp), Nomura Research Institute, Ltd.

Luke Shepard (lshepard@fb.com), Facebook

Andreas Akre Solberg (andreas.solberg@uninett.no), UNINET

Paul Tarjan (pt@fb.com), Facebook

Appendix C.  Notices

Copyright (c) 2013 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 or Final Specification solely for the purposes of (i) developing specifications, and (ii) implementing Implementers Drafts and Final Specifications 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 requires contributors to offer a patent promise not to assert certain patent claims against other contributors and against implementers. The OpenID Foundation 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.

Authors' Addresses