How is JSON web token generated?

JWT, or JSON Web Token, is an open standard used to share security information between two parties — a client and a server . Each JWT contains encoded JSON objects, including a set of claims. JWTs are signed using a cryptographic algorithm to ensure that the claims cannot be altered after the token is issued.

Information Exchange: JSON Web Tokens are a good way of securely transmitting information between parties . Because JWTs can be signed—for example, using public/private key pairs—you can be sure the senders are who they say they are.

JWT Structure. A JWS (the most common type of JWT) contains three parts separated by a dot ( . ) . The first two parts (the “header” and “payload”) are Base64-URL encoded JSON, and the third is a cryptographic signature.

A JWT needs to be stored in a safe place inside the user’s browser . If you store it inside localStorage, it’s accessible by any script inside your page. This is as bad as it sounds; an XSS attack could give an external attacker access to the token.

Claims constitute the payload part of a JSON web token and represent a set of information exchanged between two parties. The JWT standard distinguishes between reserved claims, public claims, and private claims. In API Gateway context, both public claims and private claims are considered custom claims.

How is a JWT token generated? We set the signing algorithm to be HMAC SHA256 (JWT supports multiple algorithms), then we create a buffer from this JSON-encoded object, and we encode it using base64 . The partial result is eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9 .

JWT contains three parts: Header, Payload, and Signature which are separated by a dot. The JWT Header consists of 2 parts: The token type (typ): JWT. Algorithm used to sign the token (alg)