So what the heck is JWT or JSON Web Token? (2024)

FAQs

What the heck is JWT? ›

JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed.

JWTs can be used as an authentication mechanism that does not require a database. The server can avoid using a database because the data store in the JWT sent to the client is safe.

A JSON web token(JWT) is JSON Object which is used to securely transfer information over the web(between two parties). It can be used for an authentication system and can also be used for information exchange. The token is mainly composed of header, payload, signature. These three parts are separated by dots(.).

Once the token is generated, it is used across the ecosystem to determine what the token holder can and cannot do. Additionally, API keys authenticate the application not the user; whereas, JWT authenticates both the user and the application.

JWTs can be best and secure but it is very secured only if it is used in the right way. Attacks like token stealing, XSS, Middle man attacks are still possible.

To authenticate a user, a client application must send a JSON Web Token (JWT) in the authorization header of the HTTP request to your backend API. API Gateway validates the token on behalf of your API, so you don't have to add any code in your API to process the authentication.

JWTs can be either signed, encrypted or both. If a token is signed, but not encrypted, everyone can read its contents, but when you don't know the private key, you can't change it. Otherwise, the receiver will notice that the signature won't match anymore.

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. If you have a JWT with more than three sections, it's probably a JWE.

Figure 1 shows that a JWT consists of three parts: a header, payload, and signature.

A JWT needs to be stored in a safe place inside the user's browser. Any way,you shouldn't store a JWT in local storage (or session storage). If you store it in a LocalStorage/SessionStorage then it can be easily grabbed by an XSS attack. If the answer is helpful, please click "Accept Answer" and upvote it.

How do I get the JWT token from my browser? ›

OAuth2, Passport, Spring Security, Auth0, and Keycloak are the most popular alternatives and competitors to JSON Web Token.

JWT authentication is a token-based stateless authentication mechanism. It is popularly used as a client-side-based stateless session, this means the server doesn't have to completely rely on a data store (or) database to save session information. JWTs can be encrypted, but they are typically encoded & signed.

At its core, authentication is a method for verifying that a user is who they claim to be, and used to keep bad actors out of your network. Unlike passwords, which can be easily compromised and used by hackers for data breaches, tokens are more secure. 61% of data breaches involve the use of unauthorized credentials.

Cracking the secret

It's almost impossible to crack a 256-bit key. However, sometimes developers take shortcuts and do not generate secure keys for signing and verifying their tokens. For example, the jwt.io uses “your-256-bit-secret” as the default HS256 secret, and many code samples use the string “secret”.

Using an expired JWT will cause operations to fail. As you saw above, we are told how long a token is valid through expires_in . This value is normally 1200 seconds or 20 minutes. Expired tokens are not refreshed.

As a result, using JWT for user sessions is dangerous. The biggest problem with JWTs is that the token will continue to work until it expires, and the server has no easy way to revoke it. This could be extremely dangerous in situations such as the following: Logout doesn't actually log you out of the system.

Since JWT auth is stateless, there is no way to revoke the user's session once the server signs a valid token. Consequently, using long expiration windows + unsafe Storage is the perfect combination for a hacker to inflict severe damage to our users.

JWT's are often not encrypted so anyone able to perform a man-in-the-middle attack and sniff the JWT now has your authentication credentials. This is made easier because the MITM attack only needs to be completed on the connection between the server and the client.

Can you verify a JWT without knowing the secret? ›

To verify the JWT's integrity, all services would need to have access to the same secret key. However, possession of the secret key is enough to generate arbitrary JWTs with a valid signature.

Go to Dashboard > Applications. Go to the Settings view, and open Advanced Settings. Go to the Certificates view, locate the Signed Certificate field, and copy the Public Key. Navigate to the JWT.io website, locate the Algorithm dropdown, and select RS256.

One of the most important steps is to ask your clients to change their passwords immediately if there's an instance where the JWT token is stolen. Changing the password of an account will prevent attackers from exploiting the account and would eventually help in avoiding a data breach.

JWT is created with a secret key and that secret key is private to you which means you will never reveal that to the public or inject inside the JWT token. When you receive a JWT from the client, you can verify that JWT with this that secret key stored on the server.

Browser in-memory scenarios

Auth0 recommends storing tokens in browser memory as the most secure option. Using Web Workers to handle the transmission and storage of tokens is the best way to protect the tokens, as Web Workers run in a separate global scope than the rest of the application.

The general opinion is that they're good for being used as ID Tokens or Access Tokens and that they're secure — as the tokens are usually signed or even encrypted. You have to remember though, that JWT is not a protocol but merely a message format.

With some Google APIs, you can make authorized API calls using a signed JWT instead of using OAuth 2.0, which can save you a network request.

JSON web token (JWT) is the most popular token-based authentication. However, many security threats have been exposed in recent years, causing people to migrate to other types of tokens. Platform Agnostic Security Token or PASETO is one such token which is being accepted as the best secured alternative for JWT.

The main difference between API Key auth and JWT token auth is that the JWT Token is self-contained - the information asserted by the token is in the token. Whereas with an API Key the asserted information is stored in an external system.

Is JWT signed or encrypted? ›

JSON Web Tokens (JWT) are commonly used in many different applications which require some sort of cryptographic primitive. Most often, the JSON Web Signature (JWS) structure is chosen as its contents are signed and not encrypted; however, the JSON Web Encryption (JWE) structure may also be used to make a JWT.

Cracking a JWT signed with weak keys is possible via brute force attacks.

JWT is simply a token format. A cookie is an HTTP state management mechanism really. As demonstrated, a web cookie can contain JWT and can be stored within your browser's Cookies storage. So, we need to stop comparing JWT vs Cookie.

The general opinion is that they're good for being used as ID tokens or access tokens and that they're secure — as the tokens are usually signed or even encrypted. You have to remember though, that JWT is not a protocol but merely a message format.

Lately, Netflix has been partnering with device manufacturers to merchandise Netflix content to members as well as nonmembers, and sometimes from the partners' UI itself. For these integrations, we built specific APIs and we chose to use an open standard like JWT to better integrate with partner infrastructure.

The restrictions could be anything ranging from the availability of a user to the role of the user. This is referred to as authorization. In this post, I am going to show you how to implement authorization with a frontend (React) and a backend (Node JS) using JSON Web Token (JWT).

It provides an entry point: “/auth/facebook” that redirects to FBs and proceeds to the authentication. After that it acquires the AccessToken for the logged user and creates a JWT Token that returns to the client.

The JWT way. JWT, especially when used as a session, attempts to solve the problem by completely eliminating the database lookup. The main idea is to store the user's info in the session token itself! So instead of some long random string, store the actual user info in the session token itself.

To retrieve the User Profile, your mobile application can decode the ID Token using one of the JWT libraries. This is done by verifying the signature and verifying the claims of the token.

How do I authenticate with JWT? ›

To authenticate a user, a client application must send a JSON Web Token (JWT) in the authorization header of the HTTP request to your backend API. API Gateway validates the token on behalf of your API, so you don't have to add any code in your API to process the authentication.

No way to log out or invalidate sessions for users. Moreover, there is no way for a user to disable their sessions across multiple devices. Since the tokens are generated and verified on the fly, we can't have access to the different logged-in clients which can pose problems when you need to identify the devices.