cryptutil.java

银行项目为后台ｓｏｃｋｅｔ通信写的程序

/****************************************************************************
 * Package		: com.ecSolutions.ecAppServer.util
 * File			: CryptUtil.java
 * Create Date  : 2007-7-20
 * Author		: Steven Chen
 * 
 * Copyright(C) 2006 ecSolutions(shanghai) Co.,Limited.All Rights Reserved.
 *			
 ***************************************************************************/

package com.ecSolutions.ecAppServer.util;

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.DESedeKeySpec;

import java.security.MessageDigest;


/**
 * 
 * @author Steven Chen
 * @version $Id$
 */
public class CryptUtil {

	//	默认使用3DES加密
	private static String algorithm = "DESede";

	/**
	 * 根据密钥对明文进行加密，返回密文
	 * @param plaintext byte[] 明文
	 * @param key byte[] 密钥
	 * @return byte[] 密文
	 * @throws Exception 加密过程中出现的各种异常
	 */
	public static byte[] encrypt(byte[] plaintext, byte[] key) throws Exception {
		try {
			SecureRandom sr = new SecureRandom();
			KeyGenerator keygen = KeyGenerator.getInstance(algorithm);
			SecretKey deskey  = keygen.generateKey();  
			/*
			DESedeKeySpec dks = new DESedeKeySpec(key);
			SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(algorithm);
			SecretKey keySpec = keyFactory.generateSecret(dks);
			*/
			//Cipher对象实际完成加密操作
			Cipher cipher = Cipher.getInstance(algorithm);
			//用密钥初始化Cipher对象
			cipher.init(Cipher.ENCRYPT_MODE, deskey);
			//执行加密操作
			byte[] cryptotext = cipher.doFinal(plaintext);
			return cryptotext;

		} catch (InvalidKeyException e) {
			throw new Exception("Invalid Key Exception:" + e.toString());
		} catch (NoSuchAlgorithmException e) {
			throw new Exception("No Such Algorithm Exception:" + e.toString());
		} catch (BadPaddingException e) {
			throw new Exception("Bad Padding Exception:" + e.toString());
		}
	}

	/**
	 * 根据密钥对密文进行加密，返回明文
	 * @param cryptotext byte[] 密文
	 * @param key byte[] 密钥
	 * @return byte[] 明文
	 * @throws Exception 解密过程中出现的各种异常
	 */
	public static byte[] decrypt(byte[] cryptotext, byte[] key) throws Exception {
		try {
			SecureRandom sr = new SecureRandom();
			DESedeKeySpec dks = new DESedeKeySpec(key);
			SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(algorithm);
			SecretKey keySpec = keyFactory.generateSecret(dks);
			//Cipher对象实际完成解密操作
			Cipher cipher = Cipher.getInstance(algorithm);
			//用密钥初始化Cipher对象
			cipher.init(Cipher.DECRYPT_MODE, keySpec,sr);
			//执行解密操作
			byte[] plaintext = cipher.doFinal(cryptotext);
			
			return plaintext;
		} catch (InvalidKeyException e) {
			throw new Exception("Invalid Key Exception:" + e.toString());
		} catch (NoSuchAlgorithmException e) {
			throw new Exception("No Such Algorithm Exception:" + e.toString());
		} catch (IllegalBlockSizeException e) {
			throw new Exception("Illegal BlockSize Exception:" + e.toString());
		} catch (BadPaddingException e) {
			throw new Exception("Bad Padding Exception:" + e.toString());
		}
	}

	public static String byte2hex(byte[] b) {
		String hs = "";
		String stmp = "";
		for (int n = 0; n < b.length; n++) {
			stmp = (java.lang.Integer.toHexString(b[n] & 0XFF));
			if (stmp.length() == 1)
				hs = hs + "0" + stmp;
			else
				hs = hs + stmp;
			if (n < b.length - 1)
				hs = hs + ":";
		}
		return hs.toUpperCase();
	}

	public final static String encryptMD5(String source) {
		if (source == null) {
			source = "";
		}

		String result = "";
		try {
			result = encrypt(source, "MD5");
		} catch (NoSuchAlgorithmException ex) {
			ex.printStackTrace();
		}
		return result;

	}

	/**
	 * Encrypt string
	 */
	public final static String encrypt(String source, String algorithm) throws NoSuchAlgorithmException {
		byte[] resByteArray = encrypt(source.getBytes(), algorithm);
		return toHexString(resByteArray);
	}

	public final static byte[] encrypt(byte[] source, String algorithm) throws NoSuchAlgorithmException {
		MessageDigest md = MessageDigest.getInstance(algorithm);
		md.reset();
		md.update(source);
		return md.digest();
	}

	public final static String toHexString(byte[] res) {
		StringBuffer sb = new StringBuffer(res.length << 1);
		for (int i = 0; i < res.length; i++) {
			String digit = Integer.toHexString(0xFF & res[i]);
			if (digit.length() == 1) {
				digit = '0' + digit;
			}
			sb.append(digit);
		}
		return sb.toString().toUpperCase();
	}
}