JSON Web Token, or JWT, has grown in popularity for transferring information safely between two parties. First launched in 2010, JWT proposed an internet standard for generating data with optional encryption or signature. The technology ensures that the shared information is digitally signed and data is verified and confidential.

Do you want to learn more about JSON Web Token in detail? This post informs you about its structure, functions, and pros & cons.

Let’s get started.


JSON Web Token Overview

JWT enables users to share information safely between two parties. These two entities are a client and a server. You can take the example of the front end and back end of a web application. 

JWT comprises JSON objects having the information that needs to be shared. Every JWT has a digital signature with the help of hashing. It ensures that the content of JSON is not tweaked or modified by any 3rd party.


Structure of JSON Web Token

The structure of JWT consists of the following parts:


The header part further consists of two parts: The token type (typ.): JWT and the Algorithm used to sign the token (alg.). 


The payload comprises the JSON object or claims.


It is a string formed with the help of a cryptographic algorithm. It helps in verifying the integrity of the JSON payload.


How Does JSON Web Token Authentication Work?

JWT is a technology that supports server-to-server authorization and API authentication. It provides Single Sign-On authentication that helps users log into different applications with one set of authentication systems. 

JWT ensures that only authorized persons receive information from the authentication server. The user will have to provide a secret key to the identity provider to access the information. 

The service provider compares the received signature of the token. If the result matches the signature, the service provider gets to know that the information is coming from a legitimate source after the verification.

If we have to explain it in layman’s terms, it works like this:

The user signs in using a specific username and password. The verification server authenticates the credentials and provides a JWT-signed key. In the future, the client will use the JWT to secure information by passing the JSON web token in the HTTP authorization header.

After that, the resource server confirms the legitimacy of the token using the public key. The Identity Provider creates a JWT certifying user identity. Thereafter, the resource server interprets and confirms the authenticity of the token with the public key. 


Applications of JSON Web Tokens

Users can utilize JSON Web Tokens in multiple ways. Some of their primary usages are as follows:


One of the crucial roles of JWT is providing authentication. As soon as a user logs in using their credentials, an ID token is returned. This ID token is JWT.


When a user successfully logs in, an application requests to access routes and services on behalf of that user. However, the request has to pass an Access Token, which is in the form of JWT.

Single Sign-on utilizes JWT due to the small overhead of the format. Furthermore, you can use it across various domains.

Secured Exchange of Information

JWT is a secure way to transmit information between authorized parties. It ensures that the information is coming from a legitimate sender. The structure of a JWT lets you ensure that the information is not interfered with by a third party.  


Advantages of JSON Web Token

JWT offers numerous advantages in comparison to Simple Web Tokens (SWTs) and SAML tokens. Some primary ones include:

High Security

JWTs are highly secured. They employ public/private key pairs for signing. A JWT can also be signed by a shared secret with the help of the HMAC algorithm. SAML (Security Assertion Markup Language) tokens can use key pairs, such as JWT, signing XML with XML digital signature. 


JSON is less wordy in comparison to XML. As a result, its encoding is less than that of a SAML token. It makes JSON preferable for HTTP and HTML landscapes. 

Straightforward Process

Since JWT is utilized at an internet scale, you can process it effortlessly on smartphones and other devices.

Widely Used

JSON parsers are widely used in all the primary programming languages as they effortlessly connect to objects.


Limitations of JSON Web Token

JWT also comes with some limitations that you must be aware of.


JWT features an independent verification system. Therefore, you can’t cancel a JWT before it expires itself. As a result, it is tough to implement actions like banning a user immediately.

Reliant on One Secret Key

Another limitation that might bother some users is its dependency on a single secret key. If that key is compromised, the hacker may create their own JWT. However, you can prevent this scenario by changing the secret key frequently.

Final Words

So this is all about the JSON Web Token. Considering everything together, we can say that JWT is very useful for sharing information safely between a client and a server. It is compact and suitable for single-on implementations. JWT is a practical tool for modern web security.


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