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Embracing OAuth 2.0

· 11 min read
Nijesh Hirpara
Nijesh Hirpara
Senior Software Engineer

In today's digital age, where cybersecurity threats loom large and user experience is paramount, adopting robust authentication mechanisms is crucial for the success of any product. OAuth 2.0 stands out as a versatile protocol that not only enhances security but also enriches the user experience. It has emerged as a powerful protocol revolutionizing how applications interact with each other and authenticate users. At DAS, we are excited to integrate OAuth 2.0 into our product, confident that it will propel us towards greater heights. In this blog post, we'll explore how OAuth 2.0 is poised to revolutionize and elevate our product.

Understanding OAuth 2.0​

OAuth 2.0 is an open standard authorization protocol that enables secure authorization flows between different applications without sharing sensitive credentials. It allows users to grant third-party applications limited access to their resources on a server, such as accessing their profile information or performing actions on their behalf.

OAuth 2.0, being a comprehensive authorization framework, comes with its own set of terminology that is essential to understand when implementing or working with OAuth 2.0. Here are some key OAuth 2.0 actors:

  1. Resource Owner: The resource owner is typically the end-user or entity that owns the resources being protected. In OAuth 2.0, the resource owner grants permission to a client application to access their protected resources without sharing their credentials.

  2. Client: The client is the application requesting access to the protected resources on behalf of the resource owner. It can be a web application, mobile application, or other types of software. The client interacts with the authorization server to obtain authorization and access tokens.

  3. Authorization Server: The authorization server is responsible for authenticating the resource owner and issuing access tokens to client applications after successful authentication and authorization. It verifies the identity of the resource owner and grants access tokens based on the permissions granted.

  4. Resource Server: The resource server hosts the protected resources that the client application wants to access on behalf of the resource owner. It validates access tokens and grants or denies access to the requested resources based on the permissions associated with the token.

  5. User Agent: The user agent is the software used by the resource owner to interact with the client application and the authorization server. It could be a web browser, mobile app, or other user-facing interface through which the resource owner grants consent and interacts with the OAuth 2.0 flow.

How does OAuth 2.0 work?​

OAuth 2.0 allows users to grant limited access to their resources on one site (known as the "resource server") to another site or application (known as the "client") without sharing their credentials. It works through a series of interactions between the user, the client application, and the authorization server.

Here's a high-level overview of how OAuth 2.0 works:

  1. Authorization Request: The process begins when the client application requests authorization from the user to access their resources on a resource server. This typically involves redirecting the user to the authorization server, along with parameters specifying the requested scope of access and other details.

  2. User Authentication: The user is prompted to authenticate with the authorization server, typically by entering their credentials or using a pre-existing session if they are already logged in. The authorization server verifies the user's identity and determines whether to grant or deny the requested authorization.

  3. Authorization Grant: If the user grants authorization, the authorization server issues an authorization grant to the client application. The authorization grant is a credential representing the user's consent for the client to access their resources. There are several types of authorization grants defined in OAuth 2.0, including authorization code, implicit, resource owner password credentials, and client credentials.

  4. Token Request: The client application uses the authorization grant to request an access token from the authorization server. The access token is a credential that allows the client to access the user's resources on the resource server. Depending on the type of authorization grant used, the client may also request additional tokens such as refresh tokens or ID tokens.

  5. Token Issuance: The authorization server validates the authorization grant and issues an access token (and any additional tokens requested) to the client application. The access token is typically a random string that represents the user's authorization to access specific resources for a limited period.

  6. Resource Access: The client application uses the access token to request authorisation when accessing the user's resources on the resource server. The access token is included in API requests as an authorization header, query parameter, or form parameter, allowing the resource server to verify the client's identity and authorize access to the requested resources.

  7. Token Expiration and Refresh: Access tokens have a limited lifespan, after which they expire and become invalid. To continue accessing the user's resources beyond the token's expiration, the client application may use a refresh token (if provided) to request a new access token without requiring the user to reauthenticate.

By following this workflow, OAuth 2.0 enables secure and controlled access to user resources across different applications and services, without compromising user credentials or requiring users to share sensitive information. It provides a standardized framework for authentication and authorization, fostering interoperability and scalability in modern web and mobile applications.

Types of authorization grants​

OAuth 2.0 defines several types of authorization grants that clients can use to obtain access tokens from authorization servers. Each grant type is designed for specific use cases and security requirements. Here are the common types of OAuth 2.0 grants:

Authorization Code Grant (Authorization Code Flow)​

This is the most commonly used OAuth 2.0 grant type. It's suitable for web applications where the client can securely store a client secret. The flow involves two steps: authorization request and token request. The client first redirects the user to the authorization server's authorization endpoint, where the user logs in and grants permissions. Upon successful authorization, the authorization server redirects the user back to the client with an authorization code. The client then exchanges this authorization code for an access token by sending a token request to the authorization server's token endpoint. This grant type is suitable for server-side applications where the client can securely store the client secret.

Implicit Grant (Implicit Flow)​

This grant type is suitable for client-side applications, such as single-page applications (SPAs), where it's not possible to securely store a client secret. It's simpler than the authorization code grant as it skips the step of exchanging an authorization code for an access token. In the implicit flow, the access token is returned directly to the client as part of the authorization response. The client initiates the flow by redirecting the user to the authorization server's authorization endpoint. Upon successful authorization, the authorization server redirects the user back to the client with the access token included in the URL fragment. This grant type is less secure than the authorization code grant because the access token is exposed to the browser, increasing the risk of token theft through cross-site scripting (XSS) attacks.

Resource Owner Password Credentials Grant (Password Grant)​

This grant type allows clients to exchange the user's username and password for an access token directly. It's typically used when the client is highly trusted, such as first-party applications. The client collects the user's credentials and sends them directly to the authorization server's token endpoint to obtain an access token. This grant type bypasses the authorization server's authorization endpoint and is not suitable for public clients or applications where the client cannot be trusted with the user's credentials. It should be used with caution as it increases the risk of credential exposure and may not comply with best security practices.

Client Credentials Grant​

This grant type is used when the client is requesting access to its own resources, rather than on behalf of a user. It's commonly used for machine-to-machine communication or when the client is acting on behalf of itself. The client sends its own credentials (client ID and client secret) directly to the authorization server's token endpoint to obtain an access token. The access token is then used to authenticate the client when accessing protected resources. This grant type does not involve user authentication and is not suitable for scenarios where user consent or authorization is required.

Refresh Token Grant​

This grant type is not used to obtain access tokens directly but rather to obtain new access tokens when the original access token expires. It requires the use of a refresh token, which is issued alongside the access token during the initial token request. When the access token expires, the client can use the refresh token to request a new access token from the authorization server without requiring the user to reauthenticate. Refresh tokens have a longer lifespan than access tokens and should be securely stored by the client. This grant type enhances security by reducing the risk of long-lived access tokens and minimizing the need for frequent user authentication.

Each OAuth 2.0 grant type has its own advantages, security considerations, and use cases. It's essential to choose the appropriate grant type based on the specific requirements of your application and the level of trust between the client and the authorization server.

Adapting token based authentication​

Let's explore how token-based authentication would bring several advantages over existing session-based authentication:

  • Stateless Architecture: Token-based authentication operates in a stateless manner, meaning that the server does not need to store session information for each user. This contrasts with session-based authentication, where the server must maintain session state either in memory or in a persistent storage mechanism. This statelessness simplifies scaling as servers can handle requests independently, without relying on shared session data.

  • Scalability: Because token-based authentication is stateless, it inherently allows for better scalability. Servers can be easily scaled horizontally to handle increased loads without the need for shared session storage or sticky sessions. This makes token-based authentication well-suited for applications that need to handle large numbers of concurrent users or scale dynamically based on demand.

  • Cross-Origin Resource Sharing (CORS) Support: Token-based authentication aligns well with modern web application architectures, particularly those leveraging client-side frameworks like React, Angular, or Vue.js. Since tokens are typically transmitted via HTTP headers, they can be included in cross-origin requests, allowing for seamless integration with APIs hosted on different domains. Session-based authentication can be more restrictive in this regard due to limitations with cookies and same-origin policies.

  • Better Security: Tokens can be designed to have short expiration times, reducing the window of opportunity for attackers to exploit stolen tokens. Additionally, token-based authentication enables the implementation of industry-standard security mechanisms such as JSON Web Tokens (JWT) with built-in signature verification and encryption. This provides an extra layer of security compared to session-based authentication, where session identifiers may be susceptible to session hijacking or fixation attacks if not properly secured.

  • Single Page Application (SPA) Support: Token-based authentication is well-suited for single-page applications (SPAs) where maintaining server-side session state can be challenging. With token-based authentication, clients can securely store tokens locally and include them in API requests, enabling seamless authentication and authorization across different platforms and devices.

Ensuring Compliance​

Compliance with regulatory requirements such as GDPR, HIPAA, and PSD2 is non-negotiable in today's regulatory environment. OAuth 2.0 provides built-in support for industry best practices and regulatory standards, helping us ensure compliance while maintaining a competitive edge. By leveraging OAuth 2.0's robust security mechanisms and standardized protocols, we can demonstrate our commitment to protecting user privacy and data security, fostering trust and confidence among our user base and stakeholders.

Conclusion​

In conclusion, OAuth 2.0 is set to play a pivotal role in shaping the future of our products. By embracing OAuth 2.0, we are not only enhancing security and streamlining the user experience but also facilitating integration with third-party services and ensuring compliance with regulatory standards. As we embark on this journey, we are excited about the possibilities that OAuth 2.0 unlocks for our products and confident that it will enable us to deliver even greater value to our users and stakeholders. In our next post, we delve into the journey of decision-making at DAS regarding the adoption of OAuth 2.0 provider.