Decoding JWT Payloads - Thinkster (2024)

Each JWT contains a payload. The payload is a base64 encoded JSON object that sits between the two periods in the token. We can decode this payload by using atob() to decode the payload to a JSON string and use JSON.parse() to parse the string into an object.

JWTs can contain custom properties in the claims object, which we will want to decode. Create a custom method in authServiceto do that:

self.parseJwt = function(token) { var base64Url = token.split('.')[1]; var base64 = base64Url.replace('-', '+').replace('_', '/'); return JSON.parse($window.atob(base64));}

The test server includes three properties in the claims object:

  • username - should be the same you used when registering
  • id - allows the server to easily query the user from the database processing requests
  • exp - the expiration date in UNIX time

While you could store many attributes in the JWT, it's a good idea tokeep the number to a minimum as the token must be sent with every request andlarger tokens means larger requests sizes. Remember not to store any sensitive data inthe JWT payload since it can be decoded by anyone who can see the token.

Decoding JWT Payloads - Thinkster (2024)

FAQs

How to decode payload of JWT? ›

Each JWT contains a payload. The payload is a base64 encoded JSON object that sits between the two periods in the token. We can decode this payload by using atob() to decode the payload to a JSON string and use JSON. parse() to parse the string into an object.

Can you read the payload of issued JWT token? ›

By design, anyone can decode a JWT and read the contents of the header and payload sections. However, we need access to the secret key used to create the signature to verify a token's integrity.

How to decode a JWT password? ›

JWT Decoder
  1. *First, remember that JWTs are tokens that are often used as the credentials for SSO applications. ...
  2. Grab a JWT (RFC 7519) you want to decode. ...
  3. Paste the JWT into the first text box.
  4. Press the Decode button.
  5. Read the decoded outputs for the header and payload!

Can we decode a JWT token without a secret? ›

Summary: Please note that anyone can decode the information contained in a JWT without knowing the private keys. For this reason, you should never put secret information like passwords or cryptographic keys in a JWT.

How do I access data from JWT? ›

To authenticate in the JWT Grant flow, you will need to create a JWT containing data on the authentication request, then exchange it for an access token. Note: Although this information is required to create a JWT, it is not necessarily encoded within the created JWT.

What are the contents of JWT payload? ›

Anatomy of a JWT

It is Base64Url encoded to form the first part of the JWT. The payload contains the claims. There is a set of registered claims, for example: iss (issuer), exp (expiration time), sub (subject), and aud (audience).

What is the payload of a JWT token? ›

The payload, or body, is where things get interesting. This section contains the data that this JWT was created to transport. If the JWT, for instance, represents a user authorized to access certain data or functionality, the payload contains user data such as roles or other authorization info.

Is JWT payload encrypted? ›

Encrypted JWTs encrypt only the payload, while signed JWTs sign both the header and the payload. The header and payload of signed tokens are protected against tampering, but the data contained in the JWT can be changed without modifying the signature.

What is the difference between JWT decode and JWT verify? ›

the VerifyJWT policy verifies digitally-signed JWTs and claims within those JWTs. the DecodeJWT policy decodes signed JWTs without validating signatures on the token.

How do I encrypt and decrypt JWT? ›

sender will encrypt message with receiver_public key, and sign the message with sender_private key. when receiver receives the encrypted message. It should use receiver_private key to decrypt the message via so called the RSA asymmetric encryption mechanism. And use the sender_public key to verify the signature.

Should JWT be decoded on client side? ›

You expect the token to be decoded by the client, so it can use the data inside it. This token should not be passed to anyone else. Clients should discard ID tokens that do not contain their ID in the audience claim — these tokens are not meant for this client and should not be used by it.

What is the decode function in JWT? ›

jwtDecode() The function jsonDecode() decodes a JSON encoded string variable. The function encodes data into an JSON format string.

What goes in JWT payload? ›

JWS payload (set of claims): contains verifiable security statements, such as the identity of the user and the permissions they are allowed. JWS signature: used to validate that the token is trustworthy and has not been tampered with. When you use a JWT, you must check its signature before storing and using it.

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