OAuth 2.0 authorization

OAuth 2.0 (OAuth) is an authorization framework for web applications and native applications. On behalf of a resource owner, third-party applications use OAuth 2.0 to get limited access to an HTTP service. The framework also enables an approval interaction of the resource owner with the HTTP service. In addition, OAuth 2.0 supports direct access to the HTTP services by the third-party applications.

Related topics

RCF specification: OAuth 2.0 Authorization Framework Open link

Configuring OAuth 2.0

OpenID Connect authentication


OAuth roles

The following roles are supported by OAuth 2.0:

  • Resource Owner—The end user who grants access to protected resources.
  • Resource Server—The server that hosts the protected resources and allows access by receiving an access token from a third-party application. In the BMC context, it is a BMC application.
  • Client—The third-party application that requests access to protected resources on behalf of the resource owner. The client can also be a BMC application that requests resources from another BMC application.
  • Authorization server—The server that authenticates the resource owner, receives the authorization of the client provided by the resource owner, and issues the access token to the client. In the BMC context, it is the BMC Helix SSO server.


OAuth 2.0 flow


OAuth grant types

An authorization grant is a credential representing the resource owner's authorization. The client receives one of the following authorization grants supported by BMC Helix SSO:

Authorization grantSupport by native applicationsSupport by non-native applicationsDescription
Authorization code

yes

yes

In this grant type, the application exchanges an authorization code received from the authorization server for an access token.
Refresh token

remove

yes

Refresh tokens are credentials used to obtain access tokens. Refresh tokens are issued to the client by the authorization server and are used to obtain a new access token when the current access token becomes invalid or expires, or to obtain additional access tokens with identical scope.
JWT assertion

remove

yes

A third-party IdP (Identity Provider) issues a JSON Web Token (JWT), which is signed with a private key. The JWT contains information about an end user on behalf of whom the client wants to access the resources. A certificate signed with the same private key as in the JWT must be configured in the PreAuth IdP on the BMC Helix SSO side. This certificate ensures that there is a trusted relationship between a third-party IdP and BMC Helix SSO. Hence, BMC Helix SSO can generate access and refresh the tokens for clients.

To use the JWT assertion grant type, for a realm with PREAUTH authentication type, import the same certificate as the JWT that contains the end-user credentials. The user ID field has to be filled with a value and cannot be left blank even though OAuth automatically uses a claim called sub as the user ID. PREAUTH then validates the signature of the JWT that will be passed to BMC Helix SSO.


OAuth client authentication

BMC Helix SSO enables a client application to authenticate itself with BMC Helix SSO by using the JWT assertion. The JWT contains information about the client application and must be signed with a client secret key (also known as private key) that is shared with the client application during registration. BMC Helix SSO then validates the client application by using the certificate generated by BMC Helix SSO.

Though the client authentication method can be used with any of the grant types provided by OAuth, usage of client authentication with a grant type is not mandatory. A client application can use any of the available authentication methods at any time.


Endpoints for using BMC Helix SSO as an OpenID Connect provider

BMC Helix SSO provides the following OpenID Connect API endpoints:

EndpointDescriptionAdditional information

/rsso/oauth2/v1.1/token

Issues the access/refresh tokens. Additionally, this endpoint supports JWT as Authorization Grant Open link , returns the token_type parameter in the response, and may use JWT for Client Authentication Open link

Token Endpoint Open link

/rsso/oauth2/token

Issues the access/refresh tokens. Additionally, this endpoint supports JWT as Authorization Grant Open link and may use JWT for Client authentication Open link

Token Endpoint Open link

/rsso/oauth2/authorize

Obtains the OAuth2 authorization code.

Authorization Endpoint Open link

/rsso/oauth2/revoke

Enables BMC Helix SSO to invalidate its tokens if the end user logs out or changes identity. Additionally, this endpoint may use JWT for Client authentication Open link

Revocation Endpoint Open link

/rsso/oauth2/introspect

Enables BMC Helix SSO to check the validity of access tokens and obtain meta-information such as which end user and which scopes are associated with the token. Additionally, this endpoint may use JWT for Client authentication Open link

Introspection Endpoint Open link

/rsso/oauth2/userinfo

Retrieves the consented UserInfo and other claims about the logged-in end user in BMC Helix SSO. 

UserInfo Endpoint Open link

/rsso/oauth2/jwks

Returns information about the JWK Set for the specified OAuth provider.

JWKS Endpoint Open link

/rsso/.well-known/openid-configuration

Retrieves the OpenID Connect provider's configuration information. 

OpenID Connect Configuration Endpoint Open link


OpenID scope

OpenID Connect  is a simple identity layer on top of the OAuth 2.0 protocol. OpenID Connect provides the OpenID scope, which can be used with an Authorization code grant type flow. When an OAuth client uses OpenID scope, the Consent page (where an end user allows an OAuth client application to act on behalf of the user) is not displayed to end users.

The following table describes what tokens are returned in the resulting /token call when OpenID scope is used by native and non-native clients:

Usage of OpenID scope by an OAuth client Tokens returned for native clientsTokens returned for non-native clientsConsent page availability to end users

OpenID scope used

  • Access token
  • ID token

Note:

The timeout value for these tokens is set in the Max Session Time field available in the General > Basic configuration of the BMC Helix SSO server.

  • Access token
  • ID token

Note:

The timeout value for these tokens is set in the Access Token Timeout field.

Not displayed

OpenID scope not used

  • Access token

Note:

The timeout value for this token is set in the Max Session Time field available in the General > Basic configuration of theBMC Helix SSO server.

  • Access token
  • Refresh token

Note:

The timeout value for the Access token is set in the Access Token Timeout field available in the OAuth2 > Settings configuration of the OAuth2.

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