Although the web is the primary platform for OAuth 2, the specification also covers how to handle delegated access to other client types (browser-based applications, server-side web applications, native/mobile apps, connected devices, and so on).

Principles of OAuth 2.0

OAuth 2 authentication is NOT an authentication protocol, but rather an authorization protocol. As such, it is intended primarily to grant access to a set of resources, such as remote APIs or user data.

Access Tokens are used in OAuth 2 authentication. An Access Token with OAuth authentication is a piece of data that represents the end-authorization user to access resources. The OAuth 2 authentication protocol does not specify a format for Access Tokens. However, the JSON Web Token (JWT) format is frequently used in some contexts. Token issuers can now include data in the token itself. Access Tokens may also have an expiration date for security reasons.

OAuth 2.0 Roles

The concept of roles is part of the OAuth 2.0 authorization framework's core specification. The following are the essential components of an OAuth 2authentication system:

• The user or system that owns the protected resources and can grant access to them is known as the resource owner.

• The client is the system that needs to access the protected resources. The Client must have the appropriate Access Token to access resources.

• Authorization Server: This server receives Access Token requests from the Client and issues them after successful authentication and consent by the Resource Owner. The authorization server exposes two endpoints: the Authorization endpoint, which handles the user's interactive authentication and consent, and the Token endpoint, which handles machine-to-machine interaction.

• The server that protects the user's resources and receives access requests from the Client is known as a resource server. It accepts and validates the Client's Access Token and returns the appropriate resources to it.

Scope of OAuth 2 Authentication

The concept of scopes is critical in OAuth 2authentication. They are used to specify the precise reason for which resources may be granted access. Acceptable scope values and the resources to which they apply are determined by the Resource Server.

Access Tokens and Authorization Codes for OAuth 2 Authentication

After the Resource Owner has authorized access, the OAuth 2 Authorization server may not immediately return an Access Token. An Authorization Code may be returned instead to improve security, which is then exchanged for an Access Token. Furthermore, the Authorization server may issue a Refresh Token along with the Access Token. Refresh Tokens, unlike Access Tokens, typically have long expiry times and can be exchanged for new Access Tokens when the latter expires. Clients must securely store Refresh Tokens because they have these properties.

Process of OAuth 2 Authentication

At the most basic level, before using OAuth 2authentication, the Client must obtain its credentials from the Authorization Server to identify and authenticate itself when requesting an Access Token.

The Client, for example, a mobile app, website, smart TV app, desktop application, etc., initiates access requests using OAuth 2 authentication. This is the general flow of the token request, exchange, and response:

1. The Client requests authorization (authorization request) from the Authorization server, providing the client id and secret as identification, as well as the scopes and an endpoint URI (redirect URI) to which the Access Token or the Authorization Code should be sent.

2. The Authorization server verifies the requested scopes and authenticates the Client.

3. To grant access, the Resource owner communicates with the Authorization server.

4. Depending on the grant type, the Authorization server returns to the Client with either an Authorization Code or an Access Token, as explained in the following section. In addition, a Refresh Token may be returned.

5. The Client uses the Access Token to request access to the resource from the Resource server.

OAuth 2 Authentication Grant Types

Grants are the set of steps that a Client must take to obtain resource access authorization in OAuth 2 authentication. To address various scenarios, the authorization framework provides several grant types:

• Grant of Authorization Code: The Authorization server returns a single-use Authorization Code to the Client, which is then exchanged for an Access Tokenworking as an Integration platform. This is the best option for traditional web apps where the exchange can take place securely on the server. Single Page Apps (SPA) and mobile/native apps may use the Authorization Code flow. However, because the client's secret cannot be securely stored in this case, authentication during the exchange is limited to the use of the client id alone. The Authorization Code with PKCE grant, shown below, is a better option.

• Implicit Grant: A simplified flow in which the Access Token is returned to the Client directly. In this process of API, IntegrationThe authorization server may return the Access Token as a parameter in the callback URI or as a response to a form post in the Implicit flow. Due to the possibility of token leakage, the first option is now deprecated.

• Grant of Authorization Code with Proof Key for Code Exchange (PKCE): This authorization flow is similar to the Authorization Code grant, but with additional steps that make mobile/native apps and SPAs more secure.

• Resource Owner Credentials Grant Type: The Client must first obtain the resource owner's credentials, which are then passed to the Authorization server. As a result, it is restricted to Clients who can be completely trusted. It does not require a redirect to the Authorization server, making it suitable for use cases where a redirect is impractical.

• Client Credentials Grant Type: This type of grant is used for non-interactive applications such as automated processes, microservices, and so on. The application is authenticated in this case by using its client id and secret.

• Device Authorization Flow: This grant allows apps to run on input-restricted devices such as smart TVs.

• Grant Refresh Token: The flow that involves exchanging a Refresh Token for a new Access Token.

Closing Remarks

OAuth 2 provides a more secure and user-friendly way to authorize access to third-party resources. When users try to access a resource protected by OAuth 2, they are redirected to a login page where they enter their credentials. Once the user is authenticated, they are redirected back to the original resource and are granted access. OAuth 2 is an improvement over OAuth1.0 in several ways. First, it is more secure because it uses a state parameter to prevent CSRF attacks. Second, it is more user-friendly because it does not require the user to enter their credentials every time they want to access a protected resource exploring scope with Applet. io could be a good way forward.

Finally, we could say it is more flexible because it allows for different types of authorization grants, such as authorization code, implicit, and resource owner password. Overall, OAuth 2 is a more secure and user-friendly way to authorize access to third-party resources. It is also more flexible, allowing for different types of authorization grants.