JWT structure (header, payload, signature) in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are the three main parts of a JWT?

A JWT has three parts: Header, Payload, and Signature. These parts are separated by dots (.) in the token string.

beginner

What information does the JWT header contain?

The header usually contains the type of token (which is JWT) and the signing algorithm used, like HS256 or RS256.

beginner

What is stored in the JWT payload?

The payload contains the claims, which are statements about an entity (usually the user) and additional data. Claims can be registered, public, or private.

beginner

What is the purpose of the JWT signature?

The signature is used to verify that the token was not changed after it was issued. It is created by encoding the header and payload and signing them with a secret or private key.

beginner

How are the parts of a JWT separated in the token string?

The three parts of a JWT (header, payload, signature) are separated by dots (.). For example: header.payload.signature

Which part of a JWT contains the signing algorithm?

A Header

B Payload

C Signature

D Claims

The header contains metadata including the signing algorithm used.

What does the payload of a JWT usually contain?

A Signature data

B Claims about the user or entity

C Encryption keys

D Token expiration time only

The payload contains claims, which are statements about the user or entity.

What is the main purpose of the JWT signature?

A To verify token integrity

B To encrypt the payload

C To store user roles

D To define token expiration

The signature verifies that the token has not been tampered with.

How are the parts of a JWT separated?

A By commas

B By spaces

C By semicolons

D By dots (.)

JWT parts are separated by dots (.) in the token string.

Which of these is NOT a part of a JWT?

A Header

B Signature

C Certificate

D Payload

JWT does not include a certificate as a part; it has header, payload, and signature.

Explain the structure of a JWT and the role of each part.

Think of JWT as a sealed envelope with a label (header), letter inside (payload), and a seal (signature).

Why is the signature important in a JWT?

The signature is like a wax seal that proves the letter is original.