package com.liwei.javasecu.serial;



import java.security.Key;

import java.security.SecureRandom;



import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;

import javax.crypto.SecretKey;

import javax.crypto.SecretKeyFactory;

import javax.crypto.spec.DESKeySpec;



/**

 * DES??????

 * 

 * <pre>

 * ?? DES?DESede(TripleDES,??3DES)?AES?Blowfish?RC2?RC4(ARCFOUR) 

 * DES                  key size must be equal to 56 

 * DESede(TripleDES)    key size must be equal to 112 or 168 

 * AES                  key size must be equal to 128, 192 or 256,but 192 and 256 bits may not be available 

 * Blowfish             key size must be multiple of 8, and can only range from 32 to 448 (inclusive) 

 * RC2                  key size must be between 40 and 1024 bits 

 * RC4(ARCFOUR)         key size must be between 40 and 1024 bits 

 * ???? ???? JDK Document http://.../docs/technotes/guides/security/SunProviders.html

 * </pre>

 * 

 * @author ??

 * @version 1.0

 * @since 1.0

 */

public abstract class DESCoder extends Coder {

	/**

	 * ALGORITHM ?? <br>

	 * ???????????????key??size?????

	 * 

	 * <pre>

	 * DES                  key size must be equal to 56 

	 * DESede(TripleDES)    key size must be equal to 112 or 168 

	 * AES                  key size must be equal to 128, 192 or 256,but 192 and 256 bits may not be available 

	 * Blowfish             key size must be multiple of 8, and can only range from 32 to 448 (inclusive) 

	 * RC2                  key size must be between 40 and 1024 bits 

	 * RC4(ARCFOUR)         key size must be between 40 and 1024 bits

	 * </pre>

	 * 

	 * ?Key toKey(byte[] key)?????????

	 * <code>SecretKey secretKey = new SecretKeySpec(key, ALGORITHM);</code> ??

	 * <code> 

	 * DESKeySpec dks = new DESKeySpec(key); 

	 * SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM); 

	 * SecretKey secretKey = keyFactory.generateSecret(dks); 

	 * </code>

	 */

	public static final String ALGORITHM = "DES";



	/**

	 * ????<br>

	 * 

	 * @param key

	 * @return

	 * @throws Exception

	 */

	public  static Key toKey(byte[] key) throws Exception {

		DESKeySpec dks = new DESKeySpec(key);

		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);

		SecretKey secretKey = keyFactory.generateSecret(dks);



		// ??????????????AES?Blowfish??????????????????

		// SecretKey secretKey = new SecretKeySpec(key, ALGORITHM);



		return secretKey;

	}



	/**

	 * ??

	 * 

	 * @param data

	 * @param key

	 * @return

	 * @throws Exception

	 */

	public static byte[] decrypt(byte[] data, String key) throws Exception {

		Key k = toKey(decryptBASE64(key));



		Cipher cipher = Cipher.getInstance(ALGORITHM);

		cipher.init(Cipher.DECRYPT_MODE, k);



		return cipher.doFinal(data);

	}



	/**

	 * ??

	 * 

	 * @param data

	 * @param key

	 * @return

	 * @throws Exception

	 */

	public static byte[] encrypt(byte[] data, String key) throws Exception {

		Key k = toKey(decryptBASE64(key));

		Cipher cipher = Cipher.getInstance(ALGORITHM);

		cipher.init(Cipher.ENCRYPT_MODE, k);



		return cipher.doFinal(data);

	}



	/**

	 * ????????????

	 * 

	 * @return

	 * @throws Exception

	 */

	public static String initKey() throws Exception {

		return initKey(null);

	}



	/**

	 * ???????????

	 * 

	 * @param seed

	 * @return

	 * @throws Exception

	 */

	public static String initKey(String seed) throws Exception {

		SecureRandom secureRandom = null;



		if (seed != null) {

			secureRandom = new SecureRandom(decryptBASE64(seed));

		} else {

			secureRandom = new SecureRandom();

		}



		KeyGenerator kg = KeyGenerator.getInstance(ALGORITHM);

		kg.init(secureRandom);



		SecretKey secretKey = kg.generateKey();



		return encryptBASE64(secretKey.getEncoded());

	}

}