Creating a JSON Web Token (JWT) Bearer Token

How do you make a JWT Bearer Token?

JSON Web Token (JWT) is a standard way of representing claims securely between two parties, such as an API client and server. By passing a token to the server, the server can verify that the bearer of the token is who they say they are. Making a JWT Bearer token isn’t overly complicated, but there are a few steps involved. Here’s how to make a JWT bearer token.

Step 1: Create a Payload

The first step is to create a payload that contains the information that needs to be shared. This payload is encrypted and digitally signed by the issuer of the JWT. The payload might contain user data, such as their name and email address. It may also include details about the rights the user has, such as what resources they can access.

Step 2: Encode and Sign the Payload

Once the payload is created, it must be encoded using a Base64 algorithm. This encoding ensures the payload is secure. The payload must also be signed using a secret or public/private key pair. The signature is used as part of the authentication and authorization process.

Step 3: Create the JWT Token

The next step is to combine the encoded payload and the signature into one string, which is called the JWT token. This token is then passed to the server. When the server receives the token, it will decrypt it and verify the signature against the one stored in the database. If the signature is correct, then the server will accept the token and allow access to the requested resource.

Here is an example of how to make a JWT bearer token in Java:

import com.nimbusds.jose.jwt.JwtBuilder;
import com.nimbusds.jose.jwt.JwtClaims;
import com.nimbusds.jose.jwt.JwtHeader;

public class JwtGenerator {

    public static void main(String[] args) {
        // Choose a signing algorithm
        String signingAlgorithm = "HMACSHA256";

        // Generate a secret key
        String secretKey = "my-secret-key";

        // Create the header
        JwtHeader header = new JwtHeader.Builder(signingAlgorithm).build();

        // Create the payload
        JwtClaims claims = new JwtClaims.Builder()
                .setSubject("johndoe")
                .setIssuedAt(new Date())
                .setExpiration(new Date(System.currentTimeMillis() + 3600000))
                .build();

        // Sign the token
        JwtBuilder builder = new JwtBuilder(header)
                .setClaims(claims)
                .signWith(signingAlgorithm, secretKey);

        // Encode the token
        String token = builder.compact();

        System.out.println("The token is: " + token);
    }
}

• Subject: "johndoe"
• Issued At: The current time
• Expiration: One hour from now

The token is signed with the secret key "my-secret-key". You can use this token to authenticate users to your application.

Conclusion

Creating a JWT bearer token isn’t overly complicated, but it does require understanding the basics of JWT and the payload creation process. Make sure to use a secure secret or public/private key pair when signing the payload and don’t forget the encoding step. Following these simple steps will help you create a secure JWT token.