揭秘MD5：如何用它为你的密码加密加把锁？

/**

* 对密码进行加密和验证的程序

* @author guoh

*

*/

public class Md5 {

privatefinal static String[] hexDigits = {"0" ,"1", "2","3", "4", "5", "6", "7","8", "9", "a" ,"b", "c","d", "e", "f"};

/**

* 把inputString加密

* @param inputSring

* @return

*/

publicstatic String createPassword(String inputSring){

returnencodeByMD5(inputSring);

}

/**

* 对字符串进行Md5进行编码

* @param originString

* @return

*/

publicstatic String encodeByMD5(String originString){

if(originString!= null){

try{

MessageDigestmd = MessageDigest.getInstance("MD5");

byte[]results = md.digest(originString.getBytes());

StringresultString = byteArrayToHexString(results);

returnresultString.toUpperCase();

}catch (NoSuchAlgorithmException e) {

//TODO Auto-generated catch block

e.printStackTrace();

}

}

returnnull;

}

/**

* 转换字节数组为十六进制形式的字符串

* @param str

* @return

*/

publicstatic String byteArrayToHexString(byte[] str){

StringBufferresultSb = new StringBuffer();

for(int i = 0; i < str.length; i++) {

resultSb.append(byteToHexString(str[i]));

}

returnresultSb.toString();

}

/**

* 将一个字节转换成十六进制形式的字符串

* @param b

* @return

*/

publicstatic String byteToHexString(byte b){

intn  = b;

if(n< 0) n = 256 + n;

intd1 = n / 16;

intd2 = n % 16;

returnhexDigits[d1] +hexDigits[d2];

}

/**

* 验证输入的密码是否正确

* @param password

* @param inputString

* @return

*/

publicstatic boolean authenticatePassword(String password,String inputString){

if(password.equals(encodeByMD5(inputString))){

returntrue;

}else{

returnfalse;

}

}

publicstatic void main(String[] args) {

Stringpassword  =Md5.createPassword("888888");

System.out.println("对888888用MD5加密之后的字符串："+password);

StringinputString = "8888";

System.out.println("8888与 密码匹配？"+Md5.authenticatePassword(password, inputString));

inputString= "888888";

System.out.println("888888与密码匹配？"+Md5.authenticatePassword(password, inputString));

}

}