20 Token-Based Authentication Interview Questions and Answers

Token-based authentication is a popular method for securing web applications. When applying for a position that involves working with web applications, you may be asked questions about token-based authentication during your interview. Answering these questions confidently can help you impress the hiring manager and earn the job. In this article, we discuss some common questions about token-based authentication and how you should answer them.

Token-Based Authentication Interview Questions and Answers

Here are 20 commonly asked Token-Based Authentication interview questions and answers to prepare you for your interview:

1. What is token-based authentication?

Token-based authentication is a security measure that involves providing a user with a token that can be used to authenticate their identity. This token is typically a long and random string of characters that is difficult to guess. When a user tries to access a protected resource, they will need to provide this token in order to prove that they are who they say they are. Token-based authentication can be more secure than other methods, such as password-based authentication, because it is much harder for an attacker to guess a user’s token than it is to guess their password.

2. Can you explain what a JSON Web Token (JWT) is?

A JSON Web Token is a type of token that is used to authenticate a user. It is a string of characters that is generated by the server and then sent to the client. The client then sends the token back to the server with each request. The server can then use the token to verify the identity of the user.

3. Do you know of any other forms of tokens that can be used for authentication and authorization?

There are a few other forms of tokens that can be used for authentication and authorization, such as JWT (JSON Web Token) and SAML (Security Assertion Markup Language). JWT is a popular choice for authentication in web applications, as it is compact and easy to use. SAML is typically used in enterprise applications, as it offers a more robust and secure solution.

4. What are the advantages of using token-based authentication over other methods like cookies or sessions?

Token-based authentication has a number of advantages over other methods. One advantage is that it is much more difficult to steal a user’s token than it is to steal a cookie or session ID. Another advantage is that tokens can be easily revoked if necessary, whereas revoking a cookie or session ID can be more complicated. Finally, token-based authentication can be used to provide a more secure authentication experience for users by allowing them to authenticate with a biometric or other factor in addition to their password.

5. Can you explain how token-based authentication works with an example?

Token-based authentication is a security measure that is used to prevent unauthorized access to resources. A token is a piece of data that is used to identify a user or a client. When a user or client tries to access a resource, the token is sent to the server. The server then checks the token to see if it is valid. If the token is valid, the server allows the user or client to access the resource. If the token is invalid, the server denies the user or client access to the resource.

6. What happens if someone steals a JWT from my app?

If someone manages to steal a JWT from your app, they will be able to use it to impersonate a user and gain access to the data that the user is authorized to see. This is why it is important to make sure that your JWTs are properly secured and that you only use them over HTTPS.

7. What’s the difference between authentication and authorization?

Authentication is the process of verifying that a user is who they say they are, while authorization is the process of verifying that a user has the permissions necessary to access a particular resource. In token-based authentication, a user’s credentials are used to generate a token, which is then used to verify the user’s identity and authorize their access to the resources they are requesting.

8. Why do we need to use both authentication and authorization in our apps?

Authentication is the process of verifying that a user is who they say they are, while authorization is the process of verifying that a user has the permissions necessary to access a particular resource. In most cases, you will need to use both authentication and authorization in order to properly secure your app.

9. In the context of security, why do you think it’s important to separate authentication and authorization?

Authentication is the process of verifying that a user is who they say they are, while authorization is the process of verifying that a user has the permissions to access a particular resource. It’s important to keep these two concepts separate because they serve different purposes. Authentication is about verifying identity, while authorization is about verifying permissions. If you try to combine the two, it can lead to security vulnerabilities. For example, if you store both authentication and authorization information in the same place, then a hacker who manages to compromise the security of that location would be able to gain access to both authentication and authorization information. This would allow them to not only impersonate other users, but also to gain access to resources that they wouldn’t normally have access to. By keeping these two concepts separate, you can reduce the risk of such vulnerabilities.

10. What are some libraries or frameworks you have worked with in the past that support token-based authentication?

I have worked with a few different libraries and frameworks that support token-based authentication, such as the Django Rest Framework and the Ruby on Rails Devise gem. I have also used a few different third-party libraries that provide support for token-based authentication, such as the Auth0 JWT library.

11. How does token-based authentication work in node.js?

Token-based authentication is a process where the server creates a token that is attached to the user’s session. This token is then sent to the client with each request. The client then sends the token back to the server with each request. The server then uses the token to authenticate the user.

12. Is it possible to set expiration time on a JWT? If yes, then how?

Yes, it is possible to set an expiration time on a JWT. This is done by setting the “exp” claim in the JWT payload. The value of this claim should be a Unix timestamp indicating when the token should expire.

13. How does token-based authentication help reduce load on servers?

Token-based authentication helps reduce load on servers by eliminating the need to constantly authenticate users with each request. With token-based authentication, a user is authenticated once and then given a token that they can use to access resources. This token is typically stored in the user’s session, so the server only needs to authenticate the user once per session. This can help reduce the load on the server, as it eliminates the need to constantly authenticate users.

14. What are the different ways of authenticating users who access your web application?

There are a few different ways of authenticating users who access your web application. One way is to use a username and password. Another way is to use a token-based system, where each user is given a unique token that they must use to access the application. Finally, you can also use a combination of both methods.

15. When should I use basic auth vs OAuth 2.0 in production?

Basic auth is typically used for authenticating against an API or service that is not publicly available, or when the data being accessed is not sensitive. OAuth 2.0, on the other hand, is the industry standard for authenticating against a publicly available API or service. If you are building an application that will be used by other people, or if the data being accessed is sensitive, then you should use OAuth 2.0.

16. What is a bearer token?

A bearer token is an access token that is issued to a client by an authorization server. The token can then be used by the client to access protected resources.

17. Where do you store your tokens when building a mobile app?

There are a few different ways to store tokens when building a mobile app. One option is to store the token in a database, either locally on the device or on a remote server. Another option is to store the token in the app’s preferences. Finally, you can also store the token in the keychain on iOS devices.

18. What would happen if you stored your tokens in local storage instead of memory?

If you stored your tokens in local storage instead of memory, it would be possible for an attacker to access them if they were able to gain access to the user’s device. Local storage is not as secure as memory, so it is generally not recommended to store sensitive information in local storage.

19. Is it bad practice to use the same secret key across multiple applications or microservices?

Using the same secret key across multiple applications or microservices is generally considered bad practice, as it increases the risk of the key being compromised. If a secret key is compromised, then all of the applications or services that use that key are also at risk. It is generally recommended to use a different secret key for each application or service.

20. What are HMACs and how are they created?

HMACs are created by combining a message with a secret key using a hashing algorithm. The result is a message that is difficult to forge without knowing the secret key.