Configuring OAuth 2.0

This topic provides the following information about OAuth 2.0:

OAuth 2.0 authorization

OAuth 2.0 (OAuth) is an authorization framework for third-party 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 HTTP service. In addition, OAuth 2.0 supports directs access to the HTTP services by the third-party application.

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 the 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 by the resource owner, and issues the access token to the client. In the BMC context, it is the Remedy Single Sign-On (Remedy SSO) server.

OAuth protocol flow

The following diagram depicts the OAuth protocol flow:

The OAuth protocol performs the following process for authorization:

(A) The client initiates the flow by directing the resource owner's user-agent to the authorization endpoint. The client includes its client identifier, requested scope, local state, and a redirection URI to which the authorization server sends the user-agent back after the access is granted (or denied).

(B) The authorization server authenticates the resource owner (via the user-agent) and establishes whether the resource owner grants or denies the client's access request.

(C) Assuming that the resource owner grants access, the authorization server redirects the user-agent back to the client using the redirection URI provided earlier (in the request or during client registration). The redirection URI includes an authorization code and any local state provided by the client earlier.

(D) The client requests an access token from the authorization server's token endpoint by including the authorization code received in the previous step. Access tokens are credentials used to access protected resources and is a string representing an authorization issued to the client. When making the request, the client authenticates with the authorization server. The client includes the redirection URI used to obtain the authorization code for verification.

(E) The authorization server authenticates the client, validates the authorization code, and ensures that the redirection URI received matches the URI used to redirect the client in step (C). If valid, the authorization server responds back with an access token and, optionally, a refresh token. 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.

OAuth grant types

An authorization grant is an credential representing the resource owner's authorization.The client receives one of the following authorization grants supported by Remedy SSO.

Authorization code—In this grant type, the application exchanges an authorization code received from the authorization server for an access token.
Refresh token—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—A third-party IdP (Identity Provider) issues a JSON Web Token (JWT), which is signed with a private key. The JWT contains information about the end user on behalf of whom the client wants to access resources. A certificate signed with the same private key as in the JWT must be configured in the PreAuth IdP on the Remedy SSO side. This certificate ensures that there is a trusted relationship between the third-party IdP and Remedy SSO. Hence Remedy SSO can generate access and refresh tokens for client applications.

OAuth client authentication

In earlier versions, Remedy SSO supported OAuth authentication of client applications by using one of the following methods: (a) parameters in the request, (b) HTTP basic authentication schema.

Starting from version 18.02, Remedy SSO enables a client application to authenticate itself with Remedy SSO using the JWT assertion. The JWT contains information about the client application and must be signed with a client secret (also known as private key) that is shared with the client application during registration. Remedy SSO then validates the client application by using the certificate generated by Remedy 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 is free to use any of the available authentication methods at any time.

To configure OAuth

Log in to the Remedy SSO Admin console.
From the menu, click the OAuth2 tab.

Enter the required OAuth2 details.

Field		Description
Settings	Access Token Timeout	Sets a timeout for the access token. After expiration, the issued access token is no longer valid.
Settings	Refresh Token Timeout	Sets a timeout for the refresh token. After expiration, the issued access token is no longer valid. Access and refresh tokens remain valid until their expiration. To avoid security concerns, access tokens must be of a short duration. Refresh tokens typically have a longer validity, but cannot be used without providing a valid client id and secret.
Clients	Client ID	Registers the client identifier issued to the client by Remedy SSO server during the registration process. This information is prepopulated.
	Client Name	Registers the client name specified during the registration process. This could be any name of the administrator's choice.
	Certificate	Comprises the certificate generated during client registration. The certificate is signed with the private key and contains the public key. This field will be displayed only during client registration and will not be displayed later.
	Redirect URIs	Registers the URI to which the authorization code is sent after a /authorize request succeeds. The URI must be properly handled on the client. Add multiple URIs, separted by commas, to deploy a client on multiple different URIs. After you click Save and the registration is successful, when you click Back to list and edit the existing client, the certificate is enabled and the URIs are parsed successfully. Each URI, seperated by a comma, cannot exceed 2000 characters.
	Enabled	Allows the client for authorization.
	Action	Enables editing or deleting a record.
Tokens	List of Tokens	Allows the administrator to search and view the list of valid tokens and refresh the content of the List of Tokens table.

On the Clients tab, click Register to register a client and view the list of all registered clients.
Click Save.
The Client ID and the Client secret (private key) are generated. You need to make a note of them because they will not be displayed again.

The private key is used to sign the JWT, which contains the client authorization. Note that this JWT is different from the one containing the end-user credentials and which is used in the JWT assertion grant type.
(Optional) To use the JWT assertion grant type, create a realm with PREAUTH as the authentication type and import the same certificate as the JWT containing 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 Remedy SSO.
(Optional) To invalidate the access or refresh the token, in the Tokens tab, click Delete in the Action column for the required token.