Authentication interview Questions & Answers(Level-3)

7. How is JWT (JSON Web Token) used in Authentication?

• Answer:JWT is a compact, URL-safe token used for securely transmitting information between parties. It is widely used for user authentication in modern applications. The JWT consists of three parts:
  
  1. Header (indicates the algorithm used for signing the token),
     
  2. Payload (contains the claims or user information),
     
  3. Signature (used to verify the token’s authenticity). In Postman, JWT can be generated and sent by selecting JWT Bearer in the Authorization tab. You must provide the payload, choose the algorithm, and use a secret or private key for signing.
     

8. What are the supported algorithms in JWT Bearer Authentication?

• Answer: Postman supports the following JWT algorithms for signing and verifying tokens:
  
  • HS (HMAC with SHA): A symmetric key algorithm used for creating the token.
    
  • RS (RSA): Asymmetric encryption using a public-private key pair.
    
  • ES (ECDSA): Elliptic curve digital signature algorithm for generating keys.
    
  • PS (RSA PSS): A secure padding scheme for RSA encryption.
    

9. What is the process of generating and using a JWT Token in Postman?

• Answer: To generate and use a JWT token in Postman:
  
  1. Select JWT Bearer as the Authorization Type.
     
  2. Enter the Payload in JSON format (user info, expiration time, etc.).
     
  3. Choose an algorithm (HS256, RS256, etc.) and provide the secret key or private key.
     
  4. Optionally, add headers or a prefix for custom configurations.
     
  5. The generated JWT token is added to the request’s Authorization header. This ensures secure and stateless authentication.
     

10. How do JWT Bearer Tokens improve API security?

• Answer:JWT Bearer Tokens enhance security by:
  
  1. Statelessness: The server doesn’t need to store session data, as all information is stored in the token itself.
     
  2. Tamper-Proof: The token is signed with a secret or private key, ensuring that any modification to the token is detectable.
     
  3. Scalability: JWT tokens can be used across multiple servers, making it ideal for distributed systems.
     

11. How does Postman handle Authorization Headers for Bearer Tokens?

Answer: Postman automatically appends the Bearer token to the Authorization header in the format:

makefile

Authorization: Bearer <Your API Token>

•  This simplifies the process of adding tokens to API requests, ensuring that only authenticated requests are processed.