/**

 * This file is part of aion-emu <aion-emu.com>.

 *

 *  aion-emu is free software: you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation, either version 3 of the License, or

 *  (at your option) any later version.

 *

 *  aion-emu is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with aion-emu.  If not, see <http://www.gnu.org/licenses/>.

 */



package com.aionemu.loginserver.network.ncrypt;



import java.security.GeneralSecurityException;

import java.security.KeyPairGenerator;

import java.security.spec.RSAKeyGenParameterSpec;



import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;

import javax.crypto.SecretKey;



import org.apache.log4j.Logger;



import com.aionemu.commons.utils.Rnd;



/**

 * Key generator. It generates keys or keyPairs for Blowfish and RSA

 * 

 * @author -Nemesiss-

 * 

 */

public class KeyGen

{

	/**

	 * Logger for this class.

	 */

	protected static final Logger			log	= Logger.getLogger(KeyGen.class);



	/**

	 * Key generator for blowfish

	 */

	private static KeyGenerator				blowfishKeyGen;



	/**

	 * Public/Static RSA KeyPairs with encrypted modulus N

	 */

	private static EncryptedRSAKeyPair[]	encryptedRSAKeyPairs;



	/**

	 * Initialize Key Generator (Blowfish keygen and RSA keygen)

	 * 

	 * @throws GeneralSecurityException

	 */

	public static void init() throws GeneralSecurityException

	{

		log.info("Initializing Key Generator...");



		blowfishKeyGen = KeyGenerator.getInstance("Blowfish");



		KeyPairGenerator rsaKeyPairGenerator = KeyPairGenerator.getInstance("RSA");



		RSAKeyGenParameterSpec spec = new RSAKeyGenParameterSpec(1024, RSAKeyGenParameterSpec.F4);



		rsaKeyPairGenerator.initialize(spec);



		encryptedRSAKeyPairs = new EncryptedRSAKeyPair[10];



		for (int i = 0; i < 10; i++)

		{

			encryptedRSAKeyPairs[i] = new EncryptedRSAKeyPair(rsaKeyPairGenerator.generateKeyPair());

		}



		// Pre-init RSA cipher.. saving about 300ms

		Cipher rsaCipher = Cipher.getInstance("RSA/ECB/nopadding");



		rsaCipher.init(Cipher.DECRYPT_MODE, encryptedRSAKeyPairs[0].getRSAKeyPair().getPrivate());

	}



	/**

	 * Generate and return blowfish key

	 * 

	 * @return Random generated blowfish key

	 */

	public static SecretKey generateBlowfishKey()

	{

		return blowfishKeyGen.generateKey();

	}



	/**

	 * Get common RSA Public/Static Key Pair with encrypted modulus N

	 * 

	 * @return encryptedRSAkeypairs

	 */

	public static EncryptedRSAKeyPair getEncryptedRSAKeyPair()

	{

		return encryptedRSAKeyPairs[Rnd.nextInt(10)];

	}

}