java MD5加密

http://blog.sina.com.cn/s/blog_543e73a80100cpli.html~type=v5_one&label=rela_nextarticle

package com.essencecode.test.md5;

import java.security.MessageDigest;

class MD5_test {
	public final static String MD5(String s) {
		char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
		try {
			byte[] strTemp = s.getBytes();
			MessageDigest mdTemp = MessageDigest.getInstance("MD5");
			mdTemp.update(strTemp);
			byte[] md = mdTemp.digest();
			int j = md.length;
			char str[] = new char[j * 2];
			int k = 0;
			for (int i = 0; i < j; i++) {
				byte byte0 = md[i];
				str[k++] = hexDigits[byte0 >>> 4 & 0xf];
				str[k++] = hexDigits[byte0 & 0xf];
			}
			return new String(str);
		} catch (Exception e) {
			return null;
		}
	}

	public static void main(String[] args) {
		// MD5_Test aa = new MD5_Test();
		System.out.print(MD5_test.MD5("b"));
	}
}

 

 

package com.essencecode.test.md5;

import java.security.MessageDigest;

public class MD5andKL {
	// MD5加码。32位
	public static String MD5(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();
	}

	// 可逆的加密算法
	public static String KL(String inStr) {
		// String s = new 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;
	}

	// 加密后解密
	public static String JM(String inStr) {
		char[] a = inStr.toCharArray();
		for (int i = 0; i < a.length; i++) {
			a[i] = (char) (a[i] ^ 't');
		}
		String k = new String(a);
		return k;
	}

	// 测试主函数
	public static void main(String args[]) {
		String s = new String("a");
		System.out.println("原始：" + s);
		System.out.println("MD5后：" + MD5(s));
		System.out.println("MD5后再加密：" + KL(MD5(s)));
		System.out.println("解密为MD5后的：" + JM(KL(MD5(s))));
	}
}