Java Cryptography Extension Java 17

Sherry 104 Published: 10/22/2024

Java Cryptography Extension Java 17

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Java cryptography extension tutorial

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Introduction

Java provides built-in support for cryptographic algorithms through the java.security package, which allows you to implement various encryption and decryption techniques. In this tutorial, we will explore how to use these extensions to create a secure application.

Prerequisites

Before diving into the tutorial, make sure you have:

Java 8 or higher: The Java cryptography extension is available starting from Java 8. Maven or Gradle: We'll be using Maven as our build tool in this example. If you prefer to use Gradle, you can easily substitute.

Setting up the Project

Let's create a new Maven project in your favorite IDE (or terminal). Name it "CryptographyTutorial".

Open your IDE and navigate to the directory where you want to create the project. Create a new directory for the project, e.g., CryptographyTutorial. Navigate into this directory using your terminal or IDE's terminal panel. Run the command mvn archetype:generate -DgroupId=com.example -DartifactId=CryptographyTutorial -Darchetype=maven-archetype-simple (this will create a new Maven project with the specified settings). Open the newly created pom.xml file and add the following dependencies: 


org.bouncycastle


bcprov-jdk15on


160-165


org.apache.commons


commons-math3


3.6.1

Encryption and Decryption

Now let's create a simple program that encrypts and decrypts a message using the javax.crypto package.

Create a new class called CryptographyExample in your src/main/java directory: 
public class CryptographyExample {

public static void main(String[] args) throws Exception {


String originalMessage = "Hello, World!";


String encryptedMessage = encrypt(originalMessage);


System.out.println("Encrypted message: " + encryptedMessage);


String decryptedMessage = decrypt(encryptedMessage);


System.out.println("Decrypted message: " + decryptedMessage);


}


public static String encrypt(String plainText) throws Exception {


// Initialize the encryption algorithm


Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padder");


cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec("my_secret_key".getBytes(), "AES"));


AlgorithmParameters params = cipher.getParameters();


byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();


// Encrypt the message


byte[] encryptedBytes = cipher.doFinal(plainText.getBytes());


return Base64.getEncoder().encodeToString(ConcatenatedByteChannel.concatenate(iv, encryptedBytes));


}


public static String decrypt(String cipherText) throws Exception {


// Initialize the decryption algorithm


Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padder");


cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec("my_secret_key".getBytes(), "AES"), new IvParameterSpec(Base64.getDecoder().decodeToString(cipherText).substring(0, 16)));


AlgorithmParameters params = cipher.getParameters();


byte[] iv = params.getParameterSpec(IvParameterSpec.class).getIV();


// Decrypt the message


byte[] decryptedBytes = cipher.doFinal(Base64.getDecoder().decodeToString(cipherText).substring(16));


return new String(decryptedBytes);


}


}

In this code:

We define a CryptographyExample class with two methods, encrypt() and decrypt(), which perform encryption and decryption operations. The encrypt() method takes a plain text message as input and returns the encrypted version using AES/CBC/PKCS5Padder algorithm. The decrypt() method takes an encrypted message as input and returns the decrypted version.

Running the Example

To run this example, execute the command mvn clean package in your terminal (or IDE's terminal panel). This will compile and package your application. Then, you can run it using mvn exec:java -Dexec.mainClass=com.example.CryptographyExample.

This tutorial demonstrates how to use Java's built-in cryptography extensions for basic encryption and decryption tasks. Remember to handle sensitive data securely and follow best practices when working with cryptographic algorithms.

Conclusion

In this tutorial, we have covered the basics of using Java's cryptography extensions to create a secure application. We explored the process of creating a new project, setting up dependencies, implementing encryption and decryption methods, and running our example. This knowledge will help you build robust and secure applications in your future projects.

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