KeyDerivationFunctionAPI.java

package java25.crypto;

import java.security.spec.KeySpec;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.util.Base64;

/**
 * Java 25 Key Derivation Function API (JEP 510) Demonstrates standardized API for key derivation functions
 * NOTE: This feature is finalized in Java 25 - no preview flag needed!
 */
public class KeyDerivationFunctionAPI
{
	public static void main(String[] args)
	{
		System.out.println("=== Java 25 Key Derivation Function API (JEP 510) ===\n");

		System.out.println("Overview:");
		System.out.println("--------");
		System.out.println("Java 25 introduces a standardized API for cryptographic key derivation functions,");
		System.out.println("such as PBKDF2, allowing developers to implement password-based encryption");
		System.out.println("without external libraries.\n");

		try
		{
			System.out.println("Example 1: PBKDF2 Key Derivation");
			System.out.println("--------------------------------");
			char[] password = "mySecurePassword".toCharArray();
			byte[] salt = generateSalt();
			int iterations = 10000;
			int keyLength = 256; // 256 bits = 32 bytes

			byte[] derivedKey = deriveKey(password, salt, iterations, keyLength);
			System.out.println("Derived key (Base64): " + Base64.getEncoder().encodeToString(derivedKey));
			System.out.println("Key length: " + derivedKey.length + " bytes");

			System.out.println("\nExample 2: Different Algorithms");
			System.out.println("-------------------------------");
			System.out.println("Supported algorithms:");
			System.out.println("- PBKDF2WithHmacSHA1");
			System.out.println("- PBKDF2WithHmacSHA256");
			System.out.println("- PBKDF2WithHmacSHA512");
			System.out.println("- And more...");

			System.out.println("\nExample 3: Key Derivation for Encryption");
			System.out.println("----------------------------------------");
			System.out.println("""
					// Derive key from password
					byte[] key = deriveKey(password, salt, iterations, keyLength);
					
					// Use key for encryption
					SecretKey secretKey = new SecretKeySpec(key, "AES");
					Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
					cipher.init(Cipher.ENCRYPT_MODE, secretKey);
					""");

		}
		catch (Exception e)
		{
			System.out.println("Error: " + e.getMessage());
			System.out.println("\nExample code structure:");
			System.out.println("""
					import java.security.spec.KeySpec;
					import javax.crypto.SecretKeyFactory;
					import javax.crypto.spec.PBEKeySpec;
					
					public class KeyDerivationExample {
					    public static byte[] deriveKey(char[] password, byte[] salt, 
					                                    int iterations, int keyLength) 
					            throws Exception {
					        KeySpec spec = new PBEKeySpec(password, salt, iterations, keyLength);
					        SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
					        return factory.generateSecret(spec).getEncoded();
					    }
					}
					""");
		}

		System.out.println("\nKey Features:");
		System.out.println("- Standardized API for key derivation");
		System.out.println("- Support for PBKDF2 and other algorithms");
		System.out.println("- Password-based key derivation");
		System.out.println("- Configurable iterations");
		System.out.println("- Salt-based security");
		System.out.println("- Finalized feature (no preview flag needed)");

		System.out.println("\nBenefits:");
		System.out.println("- No external libraries needed");
		System.out.println("- Standardized implementation");
		System.out.println("- Better security practices");
		System.out.println("- Improved interoperability");
		System.out.println("- Production-ready (finalized)");

		System.out.println("\nUse Cases:");
		System.out.println("- Password-based encryption");
		System.out.println("- Secure key storage");
		System.out.println("- Cryptographic key derivation");
		System.out.println("- Authentication systems");

		System.out.println("\nNote: This feature is finalized in Java 25 (JEP 510).");
		System.out.println("No --enable-preview flag needed!");
	}

	private static byte[] deriveKey(char[] password, byte[] salt, int iterations, int keyLength)
			throws NoSuchAlgorithmException, InvalidKeySpecException
	{
		KeySpec spec = new PBEKeySpec(password, salt, iterations, keyLength);
		SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
		return factory.generateSecret(spec).getEncoded();
	}

	private static byte[] generateSalt()
	{
		// Generate random salt (in production, use SecureRandom)
		byte[] salt = new byte[16];
		for (int i = 0; i < salt.length; i++)
		{
			salt[i] = (byte) (Math.random() * 256);
		}
		return salt;
	}
}