MD5加密解密例子1

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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 = newbyte[charArray.length];

for (int i = 0; i< charArray.length; i++)
byteArray[i]= (byte) charArray[i];

byte[] md5Bytes =md5.digest(byteArray);

StringBuffer hexValue = newStringBuffer();

  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));
  }

returnhexValue.toString();
}

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

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