MD5解密

package com.lofter.svntesr;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * 採用MD5加密解密
 * 
 * @author tfq
 * @datetime 2011-10-13
 */
public class MD5Test {

	/***
	 * MD5加碼 生成32位md5碼
	 */
	public static String string2MD5(String inStr) {
		MessageDigest md5 = null;
		try {
			md5 = MessageDigest.getInstance("MD5");
		} catch (Exception e) {
			System.out.println(e.toString());
			e.printStackTrace();
			return "";
		}
		char[] charArray = inStr.toCharArray();
		byte[] byteArray = new byte[charArray.length];

		for (int i = 0; i < charArray.length; i++)
			byteArray[i] = (byte) charArray[i];
		byte[] md5Bytes = md5.digest(byteArray);
		StringBuffer hexValue = new StringBuffer();
		for (int i = 0; i < md5Bytes.length; i++) {
			int val = ((int) md5Bytes[i]) & 0xff;
			if (val < 16)
				hexValue.append("0");
			hexValue.append(Integer.toHexString(val));
		}
		return hexValue.toString();

	}

	/**
	 * 加密解密算法 執行一次加密，兩次解密
	 */
	public static String convertMD5(String inStr) {

		char[] a = inStr.toCharArray();
		for (int i = 0; i < a.length; i++) {
			a[i] = (char) (a[i] ^ 't');
		}
		String s = new String(a);
		return s;

	}

	// 測試主函數
	public static void main(String args[]) {
		String s = new String("a");
		System.out.println("原始：" + s);
		System.out.println("MD5後：" + string2MD5(s));
		System.out.println("加密的：" + convertMD5(s));
		System.out.println("解密的：" + convertMD5(convertMD5(s)));

	}
}