3des的加解密过程

请看代码,这是3Des最简单的加解密过程：

/**
 * <pre>
 * Title: 		OaKeyHandle.java
 * Project: 	taxs_Portal
 * Type:		com.tenpay.taxs.web.util.OaKeyHandle
 * Author:		ben.liu
 * Create:	 	May 15, 2008 11:41:09 AM
 * Copyright: 	Copyright (c) 2008
 * Company:		
 * <pre>
 */


/**
 * <pre>
 * 用户登录解密
 * </pre>
 * 
 * @author ben.liu
 * @version 1.0, May 15, 2008
 */

import java.security.SecureRandom;
import java.security.spec.KeySpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;

public class OaKeyHandle
{

	// DES3 解密
	public static String decryptEde(String key, String src) // throws
															// DecryptException
	{
		String plainText = null;
		try
		{
			byte[] keyBytes = new byte[24]; // DES3 为24Bytes密钥
			asciiToBcdBytes(key, keyBytes, Math.min(32, key.length()) / 2);

			for (int i = 0; i < 8; ++i)
				keyBytes[16 + i] = keyBytes[i];

			// 从原始密匙数据创建一个DESKeySpec对象
			KeySpec dks = new DESedeKeySpec(keyBytes);

			// 创建一个密匙工厂，然后用它把DESKeySpec对象转换成
			// 一个SecretKey对象
			SecretKey secKey = SecretKeyFactory.getInstance("DESede").generateSecret(dks);

			// Cipher对象实际完成解密操作
			Cipher cipher = Cipher.getInstance("DESede/ECB/NoPadding");

			// DES算法要求有一个可信任的随机数源
			SecureRandom sr = new SecureRandom();

			// 用密匙初始化Cipher对象
			cipher.init(Cipher.DECRYPT_MODE, secKey, sr);

			int count = (src.length() + 1) / 2;
			byte[] inputBytes = new byte[count];
			asciiToBcdBytes(src, inputBytes, count);

			// 正式执行解密操作
			byte[] decryptBytes = cipher.doFinal(inputBytes);

			int olen = decryptBytes.length - 1;
			for (; decryptBytes[olen] == 0 && olen >= 0; --olen)
			{
			}

			plainText = new String(decryptBytes, 0, olen + 1);
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}

		return plainText;
	}

	private static void asciiToBcdBytes(String str, byte[] hex, int count)// throws
																			// Exception
	{
		byte[] inputBytes = str.getBytes();
		for (int i = 0, j = 0; j < inputBytes.length && i < count; ++i)
		{
			byte v = inputBytes[j];
			++j;
			if (v <= 0x39)
				hex[i] = (byte) (v - 0x30);
			else
				hex[i] = (byte) (v - 0x41 + 10);

			hex[i] <<= 4;

			if (j >= inputBytes.length)
				break;

			v = inputBytes[j];
			++j;

			if (v <= 0x39)
				hex[i] += (byte) (v - 0x30);
			else
				hex[i] += (byte) (v - 0x41 + 10);
		}
	}

	/**
	 * 加密
	 * */
	public static String encryptEde(String key, String src)// throws
															// DecryptException
	{
		String plainText = null;
		try
		{
			byte[] keyBytes = new byte[24]; // DES3 为24Bytes密钥
			asciiToBcdBytes(key, keyBytes, Math.min(32, key.length()) / 2);

			for (int i = 0; i < 8; ++i)
				keyBytes[16 + i] = keyBytes[i];

			// 从原始密匙数据创建一个DESKeySpec对象
			KeySpec dks = new DESedeKeySpec(keyBytes);

			// 创建一个密匙工厂，然后用它把DESKeySpec对象转换成
			// 一个SecretKey对象
			SecretKey secKey = SecretKeyFactory.getInstance("DESede").generateSecret(dks);

			// Cipher对象实际完成解密操作
			Cipher cipher = Cipher.getInstance("DESede/ECB/NoPadding");

			// DES算法要求有一个可信任的随机数源
			SecureRandom sr = new SecureRandom();

			// 用密匙初始化Cipher对象
			cipher.init(Cipher.ENCRYPT_MODE, secKey, sr);

			byte[] srcBytes = src.getBytes("GBK");
			int srcLen = srcBytes.length;
			int encLen = ((srcLen % 8) == 0) ? srcLen : ((srcLen / 8 + 1) * 8);

			byte[] encBytes = new byte[encLen];
			System.arraycopy(srcBytes, 0, encBytes, 0, srcLen);

			// 正式执行解密操作
			byte[] encryptBytes = cipher.doFinal(encBytes);
			plainText = bcdBytesToAscii(encryptBytes, encLen);
		}
		catch (Exception e)
		{
			e.printStackTrace();
		}

		return plainText;
	}

	private static String bcdBytesToAscii(byte[] hex, int count)// throws
																// Exception
	{
		byte[] ascii = new byte[2 * count];
		int t;
		for (int i = 0; i < count; i++)
		{
			t = hex[i] & 0xf0;
			t = t >> 4;
			if (t <= 9)
				t += '0';
			else if (t >= 10 && t <= 15)
				t += 'A' - 10;
			else
				t = '0';
			ascii[2 * i] = (byte) t;

			t = hex[i] & 0x0f;
			if (t <= 9)
				t += '0';
			else if (t >= 10 && t <= 15)
				t += 'A' - 10;
			else
				t = '0';
			ascii[2 * i + 1] = (byte) t;
		}

		return (new String(ascii));
	}

	/**
	 * 解密商户系统登录用户信息
	 */
	public static String[] onProcess(String passport, String key)
	{
		// 获取来自oa的请求信息
		String loginParam = passport;
		if (null == loginParam)
		{
			return null;
		}
		// 解密来自oa的用户信息
		String[] usrInfo = decryptEde(key, loginParam).split("&");
		if (usrInfo.length < 3)
		{
			return null;
		}
		return usrInfo;
	}
}