Java-RSA

A simple Java implementation of RSA encryption and decryption using the Java Cryptography Architecture (JCA).

Overview

This project provides a straightforward RSA encryption/decryption utility that demonstrates:

• RSA key pair generation
• Encrypting plaintext using a public key
• Decrypting ciphertext using a private key
• Base64 encoding/decoding for ciphertext handling

Features

• Key Generation: Generates 1024-bit RSA key pairs using SecureRandom
• Encryption: Encrypts byte arrays using a public key and returns Base64-encoded ciphertext
• Decryption: Decrypts Base64-encoded ciphertext using a private key

Requirements

• Java 8 or higher

Usage

Running the Example

Compile and run the RSA.java file:

cd src
javac RSA.java
java RSA

Using in Your Code

import java.security.KeyPair;

// Generate a key pair
KeyPair keys = RSA.generateRSAKeyPair();

// Encrypt a message
String encrypted = RSA.encrypt(keys.getPublic(), "Hello, World!".getBytes());

// Decrypt the message
String decrypted = RSA.decrypt(keys.getPrivate(), encrypted);

API Reference

generateRSAKeyPair()

Generates a new 1024-bit RSA key pair.

Returns: KeyPair - The generated public/private key pair

encrypt(PublicKey publicKey, byte[] plainText)

Encrypts plaintext bytes using the provided public key.

Parameters:

• publicKey - The RSA public key for encryption
• plainText - The bytes to encrypt

Returns: String - Base64-encoded ciphertext

decrypt(PrivateKey privateKey, String cipherText)

Decrypts Base64-encoded ciphertext using the provided private key.

Parameters:

• privateKey - The RSA private key for decryption
• cipherText - Base64-encoded ciphertext

Returns: String - The decrypted plaintext

Security Note

⚠️ Important: This implementation uses a 1024-bit key size for demonstration purposes only. Do not use 1024-bit keys in production as they are considered insecure by current standards. For production applications, use at least 2048-bit keys, with 3072-bit or 4096-bit keys recommended for new applications requiring long-term security.

License

This project is open source and available for use and modification.