JWT token generation and verification in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a JWT token?

A JWT (JSON Web Token) is a compact, URL-safe token used to securely transmit information between parties as a JSON object. It is often used for authentication and authorization.

beginner

What are the three parts of a JWT token?

A JWT token has three parts separated by dots: Header, Payload, and Signature. The Header describes the token type and algorithm, the Payload contains the data, and the Signature verifies the token's integrity.

beginner

Which Node.js library is commonly used for JWT token generation and verification?

The 'jsonwebtoken' library is commonly used in Node.js to create and verify JWT tokens easily.

intermediate

How do you generate a JWT token in Node.js using 'jsonwebtoken'?

Use the sign() method from 'jsonwebtoken' with a payload and a secret key. Example: jwt.sign({ userId: 123 }, 'secretKey', { expiresIn: '1h' }) creates a token valid for 1 hour.

intermediate

How do you verify a JWT token in Node.js?

Use the verify() method from 'jsonwebtoken' with the token and the secret key. It checks the token's signature and expiration, returning the decoded payload if valid or throwing an error if not.

What does the 'Payload' part of a JWT token contain?

A The token expiration time only

B The token's signature

C The encryption algorithm used

D The data or claims about the user

The Payload contains the data or claims, such as user ID or roles.

Which method from 'jsonwebtoken' is used to create a JWT token?

A sign()

B verify()

C decode()

D encrypt()

The sign() method creates a JWT token by encoding the payload and signing it.

What happens if you verify a JWT token with the wrong secret key?

A Verification fails and an error is thrown

B The token is accepted anyway

C The token expires immediately

D The payload is changed

Using the wrong secret key causes verification to fail and throws an error.

What is the purpose of the Signature in a JWT token?

A To set the token expiration

B To store user data

C To verify the token's integrity and authenticity

D To encrypt the payload

The Signature ensures the token was not tampered with and is from a trusted source.

Which of these is a valid option to set token expiration when generating a JWT?

A { timeout: 120 }

B { expiresIn: '2h' }

C { expireAfter: 3600 }

D { validFor: '1d' }

The 'expiresIn' option sets how long the token is valid, e.g., '2h' for 2 hours.

Explain how to generate and verify a JWT token in Node.js using the 'jsonwebtoken' library.

Think about the two main methods: sign and verify.

Describe the structure of a JWT token and the role of each part.

Remember the token has three parts separated by dots.