How can OAuth2 improve the security of your web application?

1 What is OAuth2?

OAuth2 is an open protocol that defines how a client application can request and obtain authorization from a resource owner (the user) to access a protected resource (the data) on a resource server (the service or platform). OAuth2 is based on the concept of scopes, which are specific permissions that the user can grant to the client application. For example, a user can authorize a photo-sharing app to access their Google Photos, but not their Gmail.

2 Why use OAuth2?

One of the main advantages of using OAuth2 is that it enhances the security of your web application by reducing the risk of credential theft and misuse. By using OAuth2, your web application does not need to store or handle the user's credentials for the other services or platforms. Instead, it relies on a trusted authorization server (the service or platform that provides the OAuth2 service) to issue access tokens, which are short-lived and limited in scope. This way, your web application only has access to the data that the user explicitly allows, and the user can revoke the access at any time.

3 What are the challenges of OAuth2?

While OAuth2 offers many benefits, it also comes with some challenges that you need to be aware of and address in your web application. One of the challenges is that OAuth2 is not a single specification, but a framework that allows different implementations and variations. This means that you need to understand and follow the specific requirements and best practices of each service or platform that you want to integrate with. Another challenge is that OAuth2 does not provide authentication, which is the process of verifying the identity of the user. OAuth2 only provides authorization, which is the process of granting access to the data. Therefore, you need to combine OAuth2 with another mechanism, such as OpenID Connect, to provide a secure and seamless authentication experience for your users.

5 Register your application

The first step is to register your application with the service or platform that you want to access. This will provide you with a client ID and a client secret, which are unique identifiers that you need to use in the OAuth2 flow. You also need to specify a redirect URI, which is the URL where your web application will receive the authorization code from the authorization server.

6 Obtain user authorization

The second step is to obtain user authorization by redirecting the user to the authorization server's URL, where they will be asked to log in and consent to the requested scopes. The authorization server will then redirect the user back to your web application's redirect URI, along with an authorization code, which is a temporary code that represents the user's consent.

7 Exchange authorization code for access token

The third step is to exchange the authorization code for an access token by sending a POST request to the authorization server's token endpoint, along with your client ID, client secret, redirect URI, and authorization code. The authorization server will then respond with an access token, which is a string that you need to include in the HTTP header of your requests to the resource server. The access token has a limited lifetime and scope, and may also come with a refresh token, which is a string that you can use to obtain a new access token when the old one expires.

8 Use access token to access data

The final step is to use the access token to access the data on the resource server by sending requests to the resource server's API endpoints, along with the access token in the HTTP header. The resource server will then validate the access token and return the data that you are authorized to access. You can use the refresh token to obtain a new access token when the old one expires, or you can ask the user to reauthorize your application if the refresh token is not available or invalid.

9 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?